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Sample records for linear organic molecules

  1. Linear Ion Traps in Space: The Mars Organic Molecule Analyzer (MOMA) Instrument and Beyond

    Arevalo, Ricardo; Brinckerhoff, William; Mahaffy, Paul; van Amerom, Friso; Danell, Ryan; Pinnick, Veronica; Li, Xiang; Hovmand, Lars; Getty, Stephanie; Grubisic, Andrej; Goesmann, Fred; Cottin, Hervé

    2015-11-01

    Historically, quadrupole mass spectrometer (QMS) instruments have been used to explore a wide survey of planetary targets in our solar system, from Venus (Pioneer Venus) to Saturn (Cassini-Huygens). However, linear ion trap (LIT) mass spectrometers have found a niche as smaller, versatile alternatives to traditional quadrupole analyzers.The core astrobiological experiment of ESA’s ExoMars Program is the Mars Organic Molecule Analyzer (MOMA) onboard the ExoMars 2018 rover. The MOMA instrument is centered on a linear (or 2-D) ion trap mass spectrometer. As opposed to 3-D traps, LIT-based instruments accommodate two symmetrical ion injection pathways, enabling two complementary ion sources to be used. In the case of MOMA, these two analytical approaches are laser desorption mass spectrometry (LDMS) at Mars ambient pressures, and traditional gas chromatography mass spectrometry (GCMS). The LIT analyzer employed by MOMA also offers: higher ion capacity compared to a 3-D trap of the same volume; redundant detection subassemblies for extended lifetime; and, a link to heritage QMS designs and assembly logistics. The MOMA engineering test unit (ETU) has demonstrated the detection of organics in the presence of wt.%-levels of perchlorate, effective ion enhancement via stored waveform inverse Fourier transform (SWIFT), and derivation of structural information through tandem mass spectrometry (MS/MS).A more progressive linear ion trap mass spectrometer (LITMS), funded by the NASA ROSES MatISSE Program, is being developed at NASA GSFC and promises to augment the capabilities of the MOMA instrument by way of: an expanded mass range (i.e., 20 - 2000 Da); detection of both positive and negative ions; spatially resolved (<1 mm) characterization of individual rock core layers; and, evolved gas analysis and GCMS with pyrolysis up to 1300° C (enabling breakdown of refractory phases). The Advanced Resolution Organic Molecule Analyzer (AROMA) instrument, being developed through NASA

  2. Before the Ring: synthesis of linear organic molecules in astrophysical ices by low energy electron impact

    Huels, Michael A.; Bass Andrew, D.; Mirsaleh-Kohan, Nasrin; Sanche, Leon

    The question of the origin for the building blocks of life, either synthesized here on earth, or in space [1], has been the subject of much debate, experimental investigation, or astronomical observation, much of it stimulated by the early experiments of Miller [2], and subsequent space radiation related variations thereof [3-5]. And while the precise details of the formation of even the simplest biomolecules that make up life on earth still remain shrouded inmystery, one of the notions that persist throughout the debate is that the building blocks of life, such as amino-acids, or even the cyclic components of RNA and DNA, or other cyclic hydrocarbons (e.g. PHAs), where synthesized via radiolysis [6] either in the earths proto-atmosphere, its early oceans, or in the near interstellar space surrounding the early earth. Here we provide experimental evidence for the hypothesis that interactions of low energy secondary electrons and ions, formed during the radiolysis of matter, with atoms and molecules in the medium, may have played, and may still play an important role in the chemical transformation of astrophysical or planetary surface ices [7], where they lead to the synthesis of more complex chemical species from less complex, naturally occurring components. We report the synthesis and desorption of new chemical species from simple molecular surface ices, containing CH4 / CD4 , C2 D2 , O2 , CO, CO2 , or N2 in various combination mixtures, irradiated by low energy (CO+ (n = 1-3), among others. The formation of all these linear, pre-biotic molecular species, produced here by electron initiated cation-reactions in simple molecular films, suggests that similar mechanisms likely precede the synthesis of life's most basic cyclic molecular components in planetary, or astrophysical surface ices that are continuously subjected to the types of space radiations (UV, X-or -ray, or heavy ions) that can generate such low energy secondary electrons. [Funded by NSERC and Canadian

  3. The synthesis and properties of linear A-π-D-π-A type organic small molecule containing diketopyrrolopyrrole terminal units

    Zhang, Shanshan; Niu, Qingfen; Sun, Tao; Li, Yang; Li, Tianduo; Liu, Haixia

    2017-08-01

    A novel linear A-π-D-π-A-type organic small molecule Ph2(PDPP)2 consisting diketopyrrolopyrrole (DPP) as acceptor unit, biphenylene as donor unit and acetylene unit as π-linkage has been successfully designed and synthesized. Its corresponding thermal, photophysical and electrochemical properties as well as the photoinduced charge-separation process were investigated. Ph2(PDPP)2 exhibits high thermal stability and it can be soluble in common organic solvents such as chloroform and tetrahydrofuran. The photophysical properties show that DPP2Ph2 harvests sunlight over the entire visible spectrum range in the thin-film state (300-800 nm). DPP2Ph2 has lower band gaps and appropriate energy levels to satisfy the requirement of solution-processable organic solar cells. The efficient photoinduced charge separation process was clearly observed between DPP2Ph2 with PC61BM and the Ksv value was found to be as high as 2.13 × 104 M- 1. Therefore, these excellent properties demonstrate that the designed A-π-D-π-A-type small molecule Ph2(PDPP)2 is the prospective candidate as donor material for organic photovoltaic material.

  4. Organic Molecules in Meteorites

    Martins, Zita

    2015-08-01

    Carbonaceous meteorites are primitive samples from the asteroid belt, containing 3-5wt% organic carbon. The exogenous delivery of organic matter by carbonaceous meteorites may have contributed to the organic inventory of the early Earth. The majority (>70%) of the meteoritic organic material consist of insoluble organic matter (IOM) [1]. The remaining meteoritic organic material (meteorites contain soluble organic molecules with different abundances and distributions, which may reflect the extension of aqueous alteration or thermal metamorphism on the meteorite parent bodies. Extensive aqueous alteration on the meteorite parent body may result on 1) the decomposition of α-amino acids [5, 6]; 2) synthesis of β- and γ-amino acids [2, 6-9]; 3) higher relative abundances of alkylated polycyclic aromatic hydrocarbons (PAHs) [6, 10]; and 4) higher L-enantiomer excess (Lee) value of isovaline [6, 11, 12].The soluble organic content of carbonaceous meteorites may also have a contribution from Fischer-Tropsch/Haber-Bosch type gas-grain reactions after the meteorite parent body cooled to lower temperatures [13, 14].The analysis of the abundances and distribution of the organic molecules present in meteorites helps to determine the physical and chemical conditions of the early solar system, and the prebiotic organic compounds available on the early Earth.[1] Cody and Alexander (2005) GCA 69, 1085. [2] Cronin and Chang (1993) in: The Chemistry of Life’s Origin. pp. 209-258. [3] Martins and Sephton (2009) in: Amino acids, peptides and proteins in organic chemistry. pp. 1-42. [4] Martins (2011) Elements 7, 35. [5] Botta et al. (2007) MAPS 42, 81. [6] Martins et al. (2015) MAPS, in press. [7] Cooper and Cronin (1995) GCA 59, 1003. [8] Glavin et al. (2006) MAPS. 41, 889. [9] Glavin et al. (2011) MAPS 45, 1948. [10] Elsila et al. (2005) GCA 5, 1349. [11] Glavin and Dworkin (2009) PNAS 106, 5487. [12] Pizzarello et al. (2003) GCA 67, 1589. [13] Chan et al. (2012) MAPS. 47, 1502

  5. Performance of the Linear Ion Trap Mass Spectrometer for the Mars Organic Molecule Analyzer (MOMA) Investigation on the 2018 Exomars Rover

    Arevalo, Ricardo, Jr.; Brinckerhoff, William B.; Pinnick, Veronica T.; van Amerom, Friso H. W.; Danell, Ryan M.; Li, Xiang; Getty, Stephanie; Hovmand, Lars; Atanassova, Martina; Mahaffy, Paul R.; hide

    2014-01-01

    The 2018 ExoMars rover mission includes the Mars Organic Molecule Analyzer (MOMA) investigation. MOMA will examine the chemical composition of samples acquired from depths of up to two meters below the martian surface, where organics may be protected from degradation derived from cosmic radiation and/or oxidative chemical reactions. When combined with the complement of instruments in the rover's Pasteur Payload, MOMA has the potential to reveal the presence of a wide range of organics preserved in a variety of mineralogical environments, and to begin to understand the structural character and potential origin of those compounds. The MOMA investigation is led by the Max Planck Institute for Solar System Research (MPS) with the mass spectrometer subsystem provided by NASA GSFC. MOMA's linear ion trap mass spectrometer (ITMS) is designed to analyze molecular composition of: (i) gas evolved from pyrolyzed powder samples and separated in a gas chromatograph; and, (ii) ions directly desorbed from crushed solid samples at Mars ambient pressure, as enabled by a pulsed UV laser system, fast-actuating aperture valve and capillary ion inlet. Breadboard ITMS and associated electronics have been advanced to high end-to-end fidelity in preparation for flight hardware delivery to Germany in 2015.

  6. Excimers of organic molecules

    Barashkov, Nikolai N.; Sakhno, T. V.; Nurmukhametov, Ravil'N.; Khakhel', O. A.

    1993-06-01

    Studies devoted to excimers in organic systems are surveyed. Processes leading to the excitation of the excimer luminescence are examined. Examples of the excimer-like glow of dimers are described. The relation between the structure of the complexes and their fluorescence properties is demonstrated. The bibliography includes 218 references.

  7. Organizing and addressing magnetic molecules.

    Gatteschi, Dante; Cornia, Andrea; Mannini, Matteo; Sessoli, Roberta

    2009-04-20

    Magnetic molecules ranging from simple organic radicals to single-molecule magnets (SMMs) are intensively investigated for their potential applications in molecule-based information storage and processing. The goal of this Article is to review recent achievements in the organization of magnetic molecules on surfaces and in their individual probing and manipulation. We stress that the inherent fragility and redox sensitivity of most SMM complexes, combined with the noninnocent role played by the substrate, ask for a careful evaluation of the structural and electronic properties of deposited molecules going beyond routine methods for surface analysis. Detailed magnetic information can be directly obtained using X-ray magnetic circular dichroism or newly emerging scanning probe techniques with magnetic detection capabilities.

  8. Rotational partition functions for linear molecules

    McDowell, R.S.

    1988-01-01

    An accurate closed-form expression for the rotational partition function of linear polyatomic molecules in 1 summation electronic states is derived, including the effect of nuclear spin (significant at very low temperatures) and of quartic and sextic centrifugal distortion terms (significant at moderate and high temperatures). The proper first-order quantum correction to the classical rigid-rotator partition function is shown to yield Q/sub r/ ≅β -1 exp(β/3), where βequivalenthcB/kT and B is the rotational constant in cm -1 ; for β≥0.2 additional power-series terms in β are necessary. Comparison between the results of this treatment and exact summations are made for HCN and C 2 H 2 at temperatures from 2 to 5000 K, including separate evaluation of the contributions of nuclear spin and centrifugal distortion

  9. Fascinating Organic Molecules from Nature

    Home; Journals; Resonance – Journal of Science Education; Volume 18; Issue 5. Fascinating Organic Molecules from Nature - Using a Natural ... Road Banashankari 2nd Stage Bangalore 560 070, India. Department of Chemistry Sri Sathya Sai Institute of Higher Learning Brindavan Campus Bangalore 560 067, India.

  10. Fascinating Organic Molecules from Nature

    Home; Journals; Resonance – Journal of Science Education; Volume 18; Issue 7. Fascinating Organic Molecules from Nature - Sweet Stimulants of ... Road Banashankari 2nd Stage Bangalore 560 070, India. Department of Chemistry Sri Sathya Sai Institute of Higher Learning Brindavan Campus Bangalore 560 067, India.

  11. Bond-based linear indices of the non-stochastic and stochastic edge-adjacency matrix. 1. Theory and modeling of ChemPhys properties of organic molecules.

    Marrero-Ponce, Yovani; Martínez-Albelo, Eugenio R; Casañola-Martín, Gerardo M; Castillo-Garit, Juan A; Echevería-Díaz, Yunaimy; Zaldivar, Vicente Romero; Tygat, Jan; Borges, José E Rodriguez; García-Domenech, Ramón; Torrens, Francisco; Pérez-Giménez, Facundo

    2010-11-01

    Novel bond-level molecular descriptors are proposed, based on linear maps similar to the ones defined in algebra theory. The kth edge-adjacency matrix (E(k)) denotes the matrix of bond linear indices (non-stochastic) with regard to canonical basis set. The kth stochastic edge-adjacency matrix, ES(k), is here proposed as a new molecular representation easily calculated from E(k). Then, the kth stochastic bond linear indices are calculated using ES(k) as operators of linear transformations. In both cases, the bond-type formalism is developed. The kth non-stochastic and stochastic total linear indices are calculated by adding the kth non-stochastic and stochastic bond linear indices, respectively, of all bonds in molecule. First, the new bond-based molecular descriptors (MDs) are tested for suitability, for the QSPRs, by analyzing regressions of novel indices for selected physicochemical properties of octane isomers (first round). General performance of the new descriptors in this QSPR studies is evaluated with regard to the well-known sets of 2D/3D MDs. From the analysis, we can conclude that the non-stochastic and stochastic bond-based linear indices have an overall good modeling capability proving their usefulness in QSPR studies. Later, the novel bond-level MDs are also used for the description and prediction of the boiling point of 28 alkyl-alcohols (second round), and to the modeling of the specific rate constant (log k), partition coefficient (log P), as well as the antibacterial activity of 34 derivatives of 2-furylethylenes (third round). The comparison with other approaches (edge- and vertices-based connectivity indices, total and local spectral moments, and quantum chemical descriptors as well as E-state/biomolecular encounter parameters) exposes a good behavior of our method in this QSPR studies. Finally, the approach described in this study appears to be a very promising structural invariant, useful not only for QSPR studies but also for similarity

  12. Excitonic Coupling in Linear and Trefoil Trimer Perylenediimide Molecules Probed by Single-Molecule Spectroscopy

    Yoo, Hyejin

    2012-10-25

    Perylenediimide (PDI) molecules are promising building blocks for photophysical studies of electronic interactions within multichromophore arrays. Such PDI arrays are important materials for fabrication of molecular nanodevices such as organic light-emitting diodes, organic semiconductors, and biosensors because of their high photostability, chemical and physical inertness, electron affinity, and high tinctorial strength over the entire visible spectrum. In this work, PDIs have been organized into linear (L3) and trefoil (T3) trimer molecules and investigated by single-molecule fluorescence microscopy to probe the relationship between molecular structures and interchromophoric electronic interactions. We found a broad distribution of coupling strengths in both L3 and T3 and hence strong/weak coupling between PDI units by monitoring spectral peak shifts in single-molecule fluorescence spectra upon sequential photobleaching of each constituent chromophore. In addition, we used a wide-field defocused imaging technique to resolve heterogeneities in molecular structures of L3 and T3 embedded in a PMMA polymer matrix. A systematic comparison between the two sets of experimental results allowed us to infer the correlation between intermolecular interactions and molecular structures. Our results show control of the PDI intermolecular interactions using suitable multichromophoric structures. © 2012 American Chemical Society.

  13. Excitonic Coupling in Linear and Trefoil Trimer Perylenediimide Molecules Probed by Single-Molecule Spectroscopy

    Yoo, Hyejin; Furumaki, Shu; Yang, Jaesung; Lee, Ji-Eun; Chung, Heejae; Oba, Tatsuya; Kobayashi, Hiroyuki; Rybtchinski, Boris; Wilson, Thea M.; Wasielewski, Michael R.; Vacha, Martin; Kim, Dongho

    2012-01-01

    Perylenediimide (PDI) molecules are promising building blocks for photophysical studies of electronic interactions within multichromophore arrays. Such PDI arrays are important materials for fabrication of molecular nanodevices such as organic light-emitting diodes, organic semiconductors, and biosensors because of their high photostability, chemical and physical inertness, electron affinity, and high tinctorial strength over the entire visible spectrum. In this work, PDIs have been organized into linear (L3) and trefoil (T3) trimer molecules and investigated by single-molecule fluorescence microscopy to probe the relationship between molecular structures and interchromophoric electronic interactions. We found a broad distribution of coupling strengths in both L3 and T3 and hence strong/weak coupling between PDI units by monitoring spectral peak shifts in single-molecule fluorescence spectra upon sequential photobleaching of each constituent chromophore. In addition, we used a wide-field defocused imaging technique to resolve heterogeneities in molecular structures of L3 and T3 embedded in a PMMA polymer matrix. A systematic comparison between the two sets of experimental results allowed us to infer the correlation between intermolecular interactions and molecular structures. Our results show control of the PDI intermolecular interactions using suitable multichromophoric structures. © 2012 American Chemical Society.

  14. Characterization of Interstellar Organic Molecules

    Gencaga, Deniz; Knuth, Kevin H.; Carbon, Duane F.

    2008-01-01

    Understanding the origins of life has been one of the greatest dreams throughout history. It is now known that star-forming regions contain complex organic molecules, known as Polycyclic Aromatic Hydrocarbons (PAHs), each of which has particular infrared spectral characteristics. By understanding which PAH species are found in specific star-forming regions, we can better understand the biochemistry that takes place in interstellar clouds. Identifying and classifying PAHs is not an easy task: we can only observe a single superposition of PAH spectra at any given astrophysical site, with the PAH species perhaps numbering in the hundreds or even thousands. This is a challenging source separation problem since we have only one observation composed of numerous mixed sources. However, it is made easier with the help of a library of hundreds of PAH spectra. In order to separate PAH molecules from their mixture, we need to identify the specific species and their unique concentrations that would provide the given mixture. We develop a Bayesian approach for this problem where sources are separated from their mixture by Metropolis Hastings algorithm. Separated PAH concentrations are provided with their error bars, illustrating the uncertainties involved in the estimation process. The approach is demonstrated on synthetic spectral mixtures using spectral resolutions from the Infrared Space Observatory (ISO). Performance of the method is tested for different noise levels.

  15. A linear algebraic approach to electron-molecule collisions

    Collins, L.A.; Schnieder, B.I.

    1982-01-01

    The linear algebraic approach to electron-molecule collisions is examined by firstly deriving the general set of coupled integrodifferential equations that describe electron collisional processes and then describing the linear algebraic approach for obtaining a solution to the coupled equations. Application of the linear algebraic method to static-exchange, separable exchange and effective optical potential, is examined. (U.K.)

  16. Linear algebraic approach to electron-molecule collisions

    Schneider, B.I.; Collins, L.A.

    1983-01-01

    The various levels of sophistication of the linear algebraic method are discussed and its application to electron-molecule collisions of H 2 , N 2 LiH, LiF and HCl is described. 13 references, 2 tables

  17. Excited-state potential-energy surfaces of metal-adsorbed organic molecules from linear expansion Δ-self-consistent field density-functional theory (ΔSCF-DFT).

    Maurer, Reinhard J; Reuter, Karsten

    2013-07-07

    Accurate and efficient simulation of excited state properties is an important and much aspired cornerstone in the study of adsorbate dynamics on metal surfaces. To this end, the recently proposed linear expansion Δ-self-consistent field method by Gavnholt et al. [Phys. Rev. B 78, 075441 (2008)] presents an efficient alternative to time consuming quasi-particle calculations. In this method, the standard Kohn-Sham equations of density-functional theory are solved with the constraint of a non-equilibrium occupation in a region of Hilbert-space resembling gas-phase orbitals of the adsorbate. In this work, we discuss the applicability of this method for the excited-state dynamics of metal-surface mounted organic adsorbates, specifically in the context of molecular switching. We present necessary advancements to allow for a consistent quality description of excited-state potential-energy surfaces (PESs), and illustrate the concept with the application to Azobenzene adsorbed on Ag(111) and Au(111) surfaces. We find that the explicit inclusion of substrate electronic states modifies the topologies of intra-molecular excited-state PESs of the molecule due to image charge and hybridization effects. While the molecule in gas phase shows a clear energetic separation of resonances that induce isomerization and backreaction, the surface-adsorbed molecule does not. The concomitant possibly simultaneous induction of both processes would lead to a significantly reduced switching efficiency of such a mechanism.

  18. Quantum transport through organic molecules

    Maiti, Santanu K.

    2007-01-01

    We investigate the electronic transport for the model of benzene-1, 4-dithiolate (BDT) molecule and some other geometric models of benzene molecule attached with two semi-infinite metallic electrodes by the use of Green's function technique. An analytic approach for the electronic transport through the molecular bridges is presented, based on the tight-binding model. Transport of electrons in such molecular bridges is strongly affected by the geometry of the molecules and their coupling strength with the electrodes. Conductance (g) shows resonance peaks associated with the molecular energy eigenstates. In the weak molecule-to-electrodes coupling limit current (I) passing through the molecules shows staircase-like behavior with sharp steps, while, it varies quite continuously in the limit of strong molecular coupling with the applied bias voltage (V). In presence of the transverse magnetic field conductance gives oscillatory behavior with flux φ, threaded by the molecular ring, showing φ 0 ( = ch/e) flux-quantum periodicity. Though conductance changes with the application of transverse magnetic field, but the current-voltage characteristics remain same in presence of this magnetic field for these molecular bridge systems

  19. Conserved linear dynamics of single-molecule Brownian motion

    Serag, Maged F.

    2017-06-06

    Macromolecular diffusion in homogeneous fluid at length scales greater than the size of the molecule is regarded as a random process. The mean-squared displacement (MSD) of molecules in this regime increases linearly with time. Here we show that non-random motion of DNA molecules in this regime that is undetectable by the MSD analysis can be quantified by characterizing the molecular motion relative to a latticed frame of reference. Our lattice occupancy analysis reveals unexpected sub-modes of motion of DNA that deviate from expected random motion in the linear, diffusive regime. We demonstrate that a subtle interplay between these sub-modes causes the overall diffusive motion of DNA to appear to conform to the linear regime. Our results show that apparently random motion of macromolecules could be governed by non-random dynamics that are detectable only by their relative motion. Our analytical approach should advance broad understanding of diffusion processes of fundamental relevance.

  20. Conserved linear dynamics of single-molecule Brownian motion

    Serag, Maged F.; Habuchi, Satoshi

    2017-06-01

    Macromolecular diffusion in homogeneous fluid at length scales greater than the size of the molecule is regarded as a random process. The mean-squared displacement (MSD) of molecules in this regime increases linearly with time. Here we show that non-random motion of DNA molecules in this regime that is undetectable by the MSD analysis can be quantified by characterizing the molecular motion relative to a latticed frame of reference. Our lattice occupancy analysis reveals unexpected sub-modes of motion of DNA that deviate from expected random motion in the linear, diffusive regime. We demonstrate that a subtle interplay between these sub-modes causes the overall diffusive motion of DNA to appear to conform to the linear regime. Our results show that apparently random motion of macromolecules could be governed by non-random dynamics that are detectable only by their relative motion. Our analytical approach should advance broad understanding of diffusion processes of fundamental relevance.

  1. Conserved linear dynamics of single-molecule Brownian motion

    Serag, Maged F.; Habuchi, Satoshi

    2017-01-01

    Macromolecular diffusion in homogeneous fluid at length scales greater than the size of the molecule is regarded as a random process. The mean-squared displacement (MSD) of molecules in this regime increases linearly with time. Here we show that non-random motion of DNA molecules in this regime that is undetectable by the MSD analysis can be quantified by characterizing the molecular motion relative to a latticed frame of reference. Our lattice occupancy analysis reveals unexpected sub-modes of motion of DNA that deviate from expected random motion in the linear, diffusive regime. We demonstrate that a subtle interplay between these sub-modes causes the overall diffusive motion of DNA to appear to conform to the linear regime. Our results show that apparently random motion of macromolecules could be governed by non-random dynamics that are detectable only by their relative motion. Our analytical approach should advance broad understanding of diffusion processes of fundamental relevance.

  2. Dispersion interaction between an atom and linear molecule

    Carvalho, I.L. de

    1987-01-01

    The Jacobi-Csanak method is adapted to the calculation of the dipole-dipole, dipole-quadrupole, quadrupole-dipole, and quadrupole-quadrupole terms of the dispersion energy of an atom-linear molecule system. The angle-dependent parts of the Born amplitudes for the linear molecule are represented by real spherical harmonics. The dispersion energy is finite at all distances and reproduces the usual expression in the asymptotic region (R≥4.7 (angstrom)). In the intermediary region (2.4(angstrom) ≤ R [pt

  3. Characterization of Interstellar Organic Molecules

    National Aeronautics and Space Administration — Understanding the origins of life has been one of the greatest dreams throughout history. It is now known that star-forming regions contain complex organic...

  4. Laser spectroscopy on organic molecules.

    Imasaka, T

    1996-06-01

    Various laser spectrometric methods have been developed until now. Especially, laser fluorometry is most sensitive and is frequently combined with a separation technique such as capillary electrophoresis. For non-fluorescent compounds, photothermal spectrometry may be used instead. A diode laser is potentially useful for practical trace analysis, because of its low cost and long-term trouble-free operation. On the other hand, monochromaticity of the laser is essential in high-resolution spectrometry, e.g. in low temperature spectrometry providing a very sharp spectral feature. Closely-related compounds such as isomers can easily be differentiated, and information for assignment is obtained from the spectrum. Multiphoton ionization mass spectrometry is useful for soft ionization, providing additional information concerned with molecular weight and chemical structure. A short laser pulse with a sufficient energy is suitable for rapid heating of the solid surface. A matrix-assisted laser desorption/ion-ization technique is recently employed for introduction of a large biological molecule into a vacuum for mass analysis. In the future, laser spectrometry will be developed by a combination with state-of-the-art laser technology. In the 21st century, new laser spectrometry will be developed, which may be based on revolutionary ideas or unexpected discoveries. Such studies will open new frontiers in analytical laser spectroscopy.

  5. Our Galactic Neighbor Hosts Complex Organic Molecules

    Hensley, Kerry

    2018-03-01

    For the first time, data from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal the presence of methyl formate and dimethyl ether in a star-forming region outside our galaxy. This discovery has important implications for the formation and survival of complex organic compounds importantfor the formation of life in low-metallicity galaxies bothyoung and old.No Simple Picture of Complex Molecule FormationALMA, pictured here with the Magellanic Clouds above, has observed organic molecules in our Milky Way Galaxy and beyond. [ESO/C. Malin]Complex organic molecules (those with at least six atoms, one or more of which must be carbon) are the precursors to the building blocks of life. Knowing how and where complex organic molecules can form is a key part of understanding how life came to be on Earth and how it might arise elsewhere in the universe. From exoplanet atmospheres to interstellar space, complex organic molecules are ubiquitous in the Milky Way.In our galaxy, complex organic molecules are often found in the intense environments of hot cores clumps of dense molecular gas surrounding the sites of star formation. However, its not yet fully understood how the complex organic molecules found in hot cores come to be. One possibility is that the compounds condense onto cold dust grains long before the young stars begin heating their natal shrouds. Alternatively, they might assemble themselves from the hot, dense gas surrounding the blazing protostars.Composite infrared and optical image of the N 113 star-forming region in the LMC. The ALMA coverage is indicated by the gray line. Click to enlarge. [Sewio et al. 2018]Detecting Complexity, a Galaxy AwayUsing ALMA, a team of researchers led by Marta Sewio (NASA Goddard Space Flight Center) recently detected two complex organic molecules methyl formate and dimethyl ether for the first time in our neighboring galaxy, the Large Magellanic Cloud (LMC). Previous searches for organic molecules in the LMC detected

  6. Organic- and molecule-based magnets

    The discovery of organic- and molecule-based magnets has led to design and synthesis of several families with magnetic ordering temperatures as high as ∼ 125° C. Examples of soft and hard magnets with coercivities as high as 27 kOe have also been reported. Examples from our laboratory of organic-based magnets ...

  7. Organic molecules with abnormal geometric parameters

    Komarov, Igor V

    2001-01-01

    Organic molecules, the structural parameters of which (carbon-carbon bond lengths, bond and torsion angles) differ appreciably from the typical most frequently encountered values, are discussed. Using many examples of 'record-breaking' molecules, the limits of structural distortions in carbon compounds and their unusual chemical properties are demonstrated. Particular attention is devoted to strained compounds not yet synthesised whose properties have been predicted using quantum-chemical calculations. Factors that ensure the stability of such compounds are outlined. The bibliography includes 358 references.

  8. In Situ Detection of Organic Molecules on the Martian Surface With the Mars Organic Molecule Analyzer (MOMA) on Exomars 2018

    Li, Xiang; Brinckerhoff, William B.; Pinnick, Veronica T; van Amerom, Friso H. W.; Danell, Ryan M.; Arevalo, Ricardo D., Jr.; Getty, Stephanie; Mahaffy, Paul R.

    2015-01-01

    The Mars Organic Molecule Analyzer (MOMA) investigation on the 2018 ExoMars rover will examine the chemical composition of samples acquired from depths of up to two meters below the martian surface, where organics may be protected from radiative and oxidative degradation. The MOMA instrument is centered around a miniaturized linear ion trap (LIT) that facilitates two modes of operation: i) pyrolysisgas chromatography mass spectrometry (pyrGC-MS); and, ii) laser desorptionionization mass spectrometry (LDI-MS) at ambient Mars pressures. The LIT also enables the structural characterization of complex molecules via complementary analytical capabilities, such as multi-frequency waveforms (i.e., SWIFT) and tandem mass spectrometry (MSMS). When combined with the complement of instruments in the rovers Pasteur Payload, MOMA has the potential to reveal the presence of a wide range of organics preserved in a variety of mineralogical environments, and to begin to understand the structural character and potential origin of those compounds.

  9. Organization of central synapses by adhesion molecules.

    Tallafuss, Alexandra; Constable, John R L; Washbourne, Philip

    2010-07-01

    Synapses are the primary means for transmitting information from one neuron to the next. They are formed during the development of the nervous system, and the formation of appropriate synapses is crucial for the establishment of neuronal circuits that underlie behavior and cognition. Understanding how synapses form and are maintained will allow us to address developmental disorders such as autism, mental retardation and possibly also psychological disorders. A number of biochemical and proteomic studies have revealed a diverse and vast assortment of molecules that are present at the synapse. It is now important to untangle this large array of proteins and determine how it assembles into a functioning unit. Here we focus on recent reports describing how synaptic cell adhesion molecules interact with and organize the presynaptic and postsynaptic specializations of both excitatory and inhibitory central synapses. © The Authors (2010). Journal Compilation © Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  10. Quantum interference experiments with complex organic molecules

    Eibenberger, S. I.

    2015-01-01

    Matter-wave interference with complex particles is a thriving field in experimental quantum physics. The quest for testing the quantum superposition principle with highly complex molecules has motivated the development of the Kapitza-Dirac-Talbot-Lau interferometer (KDTLI). This interferometer has enabled quantum interference with large organic molecules in an unprecedented mass regime. In this doctoral thesis I describe quantum superposition experiments which we were able to successfully realize with molecules of masses beyond 10 000 amu and consisting of more than 800 atoms. The typical de Broglie wavelengths of all particles in this thesis are in the order of 0.3-5 pm. This is significantly smaller than any molecular extension (nanometers) or the delocalization length in our interferometer (hundreds of nanometers). Many vibrational and rotational states are populated since the molecules are thermally highly excited (300-1000 K). And yet, high-contrast quantum interference patterns could be observed. The visibility and position of these matter-wave interference patterns is highly sensitive to external perturbations. This sensitivity has opened the path to extensive studies of the influence of internal molecular properties on the coherence of their associated matter waves. In addition, it enables a new approach to quantum-assisted metrology. Quantum interference imprints a high-contrast nano-structured density pattern onto the molecular beam which allows us to resolve tiny shifts and dephasing of the molecular beam. I describe how KDTL interferometry can be used to investigate a number of different molecular properties. We have studied vibrationally-induced conformational changes of floppy molecules and permanent electric dipole moments using matter-wave deflectometry in an external electric field. We have developed a new method for optical absorption spectroscopy which uses the recoil of the molecules upon absorption of individual photons. This allows us to

  11. Small organic molecule based flow battery

    Huskinson, Brian; Marshak, Michael; Aziz, Michael J.; Gordon, Roy G.; Betley, Theodore A.; Aspuru-Guzik, Alan; Er, Suleyman; Suh, Changwon

    2018-05-08

    The invention provides an electrochemical cell based on a new chemistry for a flow battery for large scale, e.g., gridscale, electrical energy storage. Electrical energy is stored chemically at an electrochemical electrode by the protonation of small organic molecules called quinones to hydroquinones. The proton is provided by a complementary electrochemical reaction at the other electrode. These reactions are reversed to deliver electrical energy. A flow battery based on this concept can operate as a closed system. The flow battery architecture has scaling advantages over solid electrode batteries for large scale energy storage.

  12. Triton - Stratospheric molecules and organic sediments

    Thompson, W. Reid; Singh, Sushil K.; Khare, B. N.; Sagan, Carl

    1989-01-01

    Continuous-flow plasma discharge techniques show production rates of hydrocarbons and nitriles in N2 + CH4 atmospheres appropriate to the stratosphere of Titan, and indicate that a simple eddy diffusion model together with the observed electron flux quantitatively matches the Voyager IRIS observations for all the hydrocarbons, except for the simplest ones. Charged particle chemistry is very important in Triton's stratosphere. In the more CH4-rich case of Titan, many hydrocarbons and nitriles are produced in high yield. If N2 is present, the CH4 fraction is low, but hydrocarbons and nitriles are produced in fair yield, abundances of HCN and C2H2 in Triton's stratosphere exceed 10 to the 19th molecules/sq cm per sec, and NCCN, C3H4, and other species are predicted to be present. These molecules may be detected by IRIS if the stratosphere is as warm as expected. Both organic haze and condensed gases will provide a substantial UV and visible opacity in Triton's atmosphere.

  13. Mechanochemical synthesis of small organic molecules

    Tapas Kumar Achar

    2017-09-01

    Full Text Available With the growing interest in renewable energy and global warming, it is important to minimize the usage of hazardous chemicals in both academic and industrial research, elimination of waste, and possibly recycle them to obtain better results in greener fashion. The studies under the area of mechanochemistry which cover the grinding chemistry to ball milling, sonication, etc. are certainly of interest to the researchers working on the development of green methodologies. In this review, a collection of examples on recent developments in organic bond formation reactions like carbon–carbon (C–C, carbon–nitrogen (C–N, carbon–oxygen (C–O, carbon–halogen (C–X, etc. is documented. Mechanochemical syntheses of heterocyclic rings, multicomponent reactions and organometallic molecules including their catalytic applications are also highlighted.

  14. The interaction of linear and ring forms of DNA molecules with nanodiamonds synthesized by detonation

    Purtov, K V; Burakova, L P; Puzyr, A P; Bondar, V S

    2008-01-01

    Nanodiamonds synthesized by detonation have been found not to immobilize the ring form of pUC19 plasmid DNA. Linear pUC19 molecules with blunt ends, prepared by restriction of the initial ring form of pUC19 DNA, and linear 0.25-10 kb DNA fragments are adsorbed on nanodiamonds. The amount of adsorbed linear DNA molecules depends on the size of the molecules and the size of the nanodiamond clusters

  15. Organic Optoelectronic Devices Employing Small Molecules

    Fleetham, Tyler Blain

    Organic optoelectronic devices have remained a research topic of great interest over the past two decades, particularly in the development of efficient organic photovoltaics (OPV) and organic light emitting diodes (OLED). In order to improve the efficiency, stability, and materials variety for organic optoelectronic devices a number of emitting materials, absorbing materials, and charge transport materials were developed and employed in a device setting. Optical, electrical, and photophysical studies of the organic materials and their corresponding devices were thoroughly carried out. Two major approaches were taken to enhance the efficiency of small molecule based OPVs: developing material with higher open circuit voltages or improved device structures which increased short circuit current. To explore the factors affecting the open circuit voltage (VOC) in OPVs, molecular structures were modified to bring VOC closer to the effective bandgap, DeltaE DA, which allowed the achievement of 1V VOC for a heterojunction of a select Ir complex with estimated exciton energy of only 1.55eV. Furthermore, the development of anode interfacial layer for exciton blocking and molecular templating provide a general approach for enhancing the short circuit current. Ultimately, a 5.8% PCE was achieved in a single heterojunction of C60 and a ZnPc material prepared in a simple, one step, solvent free, synthesis. OLEDs employing newly developed deep blue emitters based on cyclometalated complexes were demonstrated. Ultimately, a peak EQE of 24.8% and nearly perfect blue emission of (0.148,0.079) was achieved from PtON7dtb, which approaches the maximum attainable performance from a blue OLED. Furthermore, utilizing the excimer formation properties of square-planar Pt complexes, highly efficient and stable white devices employing a single emissive material were demonstrated. A peak EQE of over 20% for pure white color (0.33,0.33) and 80 CRI was achieved with the tridentate Pt complex, Pt

  16. Evaluation of synthetic linear motor-molecule actuation energetics

    Brough, Branden; Northrop, Brian H.; Schmidt, Jacob J.; Tseng, Hsian-Rong; Houk, Kendall N.; Stoddart, J. Fraser; Ho, Chih-Ming

    2006-01-01

    By applying atomic force microscope (AFM)-based force spectroscopy together with computational modeling in the form of molecular force-field simulations, we have determined quantitatively the actuation energetics of a synthetic motor-molecule. This multidisciplinary approach was performed on specifically designed, bistable, redox-controllable [2]rotaxanes to probe the steric and electrostatic interactions that dictate their mechanical switching at the single-molecule level. The fusion of expe...

  17. Superradiance Effects in the Linear and Nonlinear Optical Response of Quantum Dot Molecules

    Sitek, A.; Machnikowski, P.

    2008-11-01

    We calculate the linear optical response from a single quantum dot molecule and the nonlinear, four-wave-mixing response from an inhomogeneously broadened ensemble of such molecules. We show that both optical signals are affected by the coupling-dependent superradiance effect and by optical interference between the two polarizations. As a result, the linear and nonlinear responses are not identical.

  18. Organic small molecule semiconducting chromophores for use in organic electronic devices

    Welch, Gregory C.; Hoven, Corey V.; Nguyen, Thuc-Quyen

    2018-02-13

    Small organic molecule semi-conducting chromophores containing a pyridalthiadiazole, pyridaloxadiazole, or pyridaltriazole core structure are disclosed. Such compounds can be used in organic heterojunction devices, such as organic small molecule solar cells and transistors.

  19. Strong-field ionization of linear molecules by a bicircular laser field: Symmetry considerations

    Gazibegović-Busuladžić, A.; Busuladžić, M.; Hasović, E.; Becker, W.; Milošević, D. B.

    2018-04-01

    Using the improved molecular strong-field approximation, we investigate (high-order) above-threshold ionization [(H)ATI] of various linear polyatomic molecules by a two-color laser field of frequencies r ω and s ω (with integer numbers r and s ) having coplanar counter-rotating circularly polarized components (a so-called bicircular field). Reflection and rotational symmetries for molecules aligned in the laser-field polarization plane, analyzed for diatomic homonuclear molecules in Phys. Rev. A 95, 033411 (2017), 10.1103/PhysRevA.95.033411, are now considered for diatomic heteronuclear molecules and symmetric and asymmetric linear triatomic molecules. There are additional rotational symmetries for (H)ATI spectra of symmetric linear molecules compared to (H)ATI spectra of the asymmetric ones. It is shown that these symmetries manifest themselves differently for r +s odd and r +s even. For example, HATI spectra for symmetric molecules with r +s even obey inversion symmetry. For ATI spectra of linear molecules, reflection symmetry appears only for certain molecular orientation angles ±90∘-j r 180∘/(r +s ) (j integer). For symmetric linear molecules, reflection symmetry appears also for the angles -j r 180∘/(r +s ) . For perpendicular orientation of molecules with respect to the laser-field polarization plane, the HATI spectra are very similar to those of the atomic targets, i.e., both spectra are characterized by the same type of the (r +s )-fold symmetry.

  20. Nanoscale contacts to organic molecules based on layered semiconductor substrates

    Strobel, Sebastian

    2009-06-15

    This work reports on the integration of organic molecules as nanoelectronic device units on semiconductor substrates. Two novel preparation methods for sub-10-nm separated metal electrodes are presented using current microelectronics process technology. The first method utilises AlGaAs/GaAs heterostructures grown by molecular beam epitaxy (MBE) as mold to create planar metal electrodes employing a newly developed, high resolution nanotransfer printing (nTP) process. The second method uses commercially available Silicon-on-Insulator (SOI) substrates as base material for the fabrication of nanogap electrode devices. This sandwich-like material stack consists of a silicon substrate, a thin silicon oxide layer, and a capping silicon layer on top. Electronic transport measurements verified their excellent electrical properties at liquid helium temperatures. Specifically tailored nanogap devices featured an electrode insulation in the GW range even up to room temperature as well as within aqueous electrolyte solution. Finally, the well defined layer architecture facilitated the fabrication of electrodes with gap separations below-10-nm to be directly bridged by molecules. Approximately 12-nm-long conjugated molecules with extended -electron system were assembled onto the devices from solution. A large conductance gap was observed with a steep increase in current at a bias voltage of V{sub T}{approx}{+-}1.5 V. Theoretical calculations based on density functional theory and non-equilibrium Green's function formalism confirmed the measured non-linear IV-characteristics qualitatively and lead to the conclusion that the conductance gap mainly originates from the oxygen containing linker. Temperature dependent investigations of the conductance indicated a hopping charge transport mechanism through the central part of the molecule for bias voltages near but below V{sub T}. (orig.)

  1. X-ray characterization of solid small molecule organic materials

    Billinge, Simon; Shankland, Kenneth; Shankland, Norman; Florence, Alastair

    2014-06-10

    The present invention provides, inter alia, methods of characterizing a small molecule organic material, e.g., a drug or a drug product. This method includes subjecting the solid small molecule organic material to x-ray total scattering analysis at a short wavelength, collecting data generated thereby, and mathematically transforming the data to provide a refined set of data.

  2. Rotational and vibrational synthetic spectra of linear parent molecules in comets

    Crovisier, J.

    1987-01-01

    We evaluate and model the excitation conditions of linear parent molecules in cometary atmospheres. The model is valid for most linear molecules without electronic angular momentum. It takes into account collisions and infrared excitation. The molecule rotational population distribution is computed as a function of distance to nucleus. The line intensities of the strongest parallel and perpendicular fundamental vibrational bands, as well as the pure rotational lines, can then be evaluated. This model is applied to several candidate parent molecules, for observing conditions corresponding to available or planned instruments, either ground-based or aboard aircrafts, satellites or space probes

  3. Hierarchical organization in aggregates of protein molecules

    Bohr, Henrik; Kyhle, Anders; Sørensen, Alexis Hammer

    1997-01-01

    of the solution and the density of protein are varied shows the existence of specific growth processes resulting in different branch-like structures. The resulting structures are strongly influenced by the shape of each protein molecule. Lysozyme and ribonuclease are found to form spherical structures...

  4. Application of the method of continued fractions for electron scattering by linear molecules

    Lee, M.-T.; Iga, I.; Fujimoto, M.M.; Lara, O.; Brasilia Univ., DF

    1995-01-01

    The method of continued fractions (MCF) of Horacek and Sasakawa is adapted for the first time to study low-energy electron scattering by linear molecules. Particularly, we have calculated the reactance K-matrices for an electron scattered by hydrogen molecule and hydrogen molecular ion as well as by a polar LiH molecule in the static-exchange level. For all the applications studied herein. the calculated physical quantities converge rapidly, even for a strongly polar molecule such as LiH, to the correct values and in most cases the convergence is monotonic. Our study suggests that the MCF could be an efficient method for studying electron-molecule scattering and also photoionization of molecules. (Author)

  5. Structure and Structure-activity Relationship of Functional Organic Molecules

    2011-01-01

    @@ Research theme The group is made up of junior scientists from the State Key Laboratory of Elemento-organic Chemistry, Nankai University.The scientists focus their studis on the structure and structure-activity relationship of functional organic molecules not only because it has been the basis of their research, but also because the functional study of organic compounds is now a major scientific issue for organic chemists around the world.

  6. Crystallization of Organic Semiconductor Molecules in Nanosized Cavities

    Milita, Silvia; Dionigi, Chiara; Borgatti, Francesco

    2008-01-01

    The crystallization of an organic semiconductor, viz., tetrahexil-sexithiophene (H4T6) molecules, confined into nanosized cavities of a self-organized polystyrene beads template, has been investigated by means of in situ grazing incidence X-ray diffraction measurements, during the solvent evapora...

  7. Study on infrared multiphoton excitation of the linear triatomic molecule by the Lie-algebra approach

    Feng, H.; Zheng, Y.; Ding, S.

    2007-01-01

    Infrared multiphoton vibrational excitation of the linear triatomic molecule has been studied using the quadratic anharmonic Lie-algebra model, unitary transformations, and Magnus approximation. An explicit Lie-algebra expression for the vibrational transition probability is obtained by using a Lie-algebra approach. This explicit Lie-algebra expressions for time-evolution operator and vibrational transition probabilities make the computation clearer and easier. The infrared multiphoton vibrational excitation of the DCN linear tri-atomic molecule is discussed as an example

  8. Developing Density of Laser-Cooled Neutral Atoms and Molecules in a Linear Magnetic Trap

    Velasquez, Joe, III; Walstrom, Peter; di Rosa, Michael

    2013-05-01

    In this poster we show that neutral particle injection and accumulation using laser-induced spin flips may be used to form dense ensembles of ultracold magnetic particles, i.e., laser-cooled paramagnetic atoms and molecules. Particles are injected in a field-seeking state, are switched by optical pumping to a field-repelled state, and are stored in the minimum-B trap. The analogous process in high-energy charged-particle accumulator rings is charge-exchange injection using stripper foils. The trap is a linear array of sextupoles capped by solenoids. Particle-tracking calculations and design of our linear accumulator along with related experiments involving 7Li will be presented. We test these concepts first with atoms in preparation for later work with selected molecules. Finally, we present our preliminary results with CaH, our candidate molecule for laser cooling. This project is funded by the LDRD program of Los Alamos National Laboratory.

  9. Electrocatalytic hydrogenation of organic molecules on conductive new catalytic material

    Tountian, D. [Louis Pasteur Univ., Strasbourg (France). Laboratoire d' Electrochimie et de Chimie Physique du Corps Solide; Sherbrooke Univ., Sherbrooke, PQ (Canada). Dept. de Chimie, Centre de Recherche en Electrochimie et Electrocatalyse; Brisach-Wittmeyer, A.; Menard, H. [Sherbrooke Univ., Sherbrooke, PQ (Canada). Dept. de Chimie, Centre de Recherche en Electrochimie et Electrocatalyse; Nkeng, P.; Poillerat, G. [Louis Pasteur Univ., Strasbourg (France). Laboratoire d' Electrochimie et de Chimie Physique du Corps Solide

    2008-07-01

    Electrocatalytic hydrogenation (ECH) of organic molecules is a process where chemisorbed hydrogen is produced by electroreduction of water which reacts with the species in bulk. Greater emphasis is being placed on improving the nature of the building material of the electrodes in order to increase ECH efficiency. The effectiveness of the ECH is known to be linked to the nature of electrode materials used and their adsorption properties. This work presented the effect of conductive support material on ECH. The conductive catalysts were obtained from tin dioxide which is chemically stable. Palladium was the catalytic metal used in this study. The production of chemisorbed hydrogen was shown to depend on the quantity of metallic nanoaggregates in electrical contact with the reticulated vitreous carbon use as electrode. The conductive support, F-doped tin dioxide, was obtained by the sol-gel method. The electrocatalysts were characterized by different methods as resistivity measurements, linear sweep voltammetry, XRD, SEM, TGA/DSC, and FTIR analysis. The effects of temperature and time of calcination were also investigated. The study showed that the F-doped SnO2 electrocatalyst appeared to increase the rate of phenol electrohydrogenation. It was concluded that the improved electrocatalytic activity of Pd/F-doped SnO2 can be attributed to the simultaneous polarization of all the metallic Pd nanoaggregates present on the surface as well as in the pores of the matrix by contact with RVC. This results in a better production of chemisorbed atomic hydrogen with a large number of adlienation points. 9 refs., 3 figs.

  10. Force microscopy on insulators: imaging of organic molecules

    Pfeiffer, O; Gnecco, E; Zimmerli, L; Maier, S; Meyer, E; Nony, L; Bennewitz, R; Diederich, F; Fang, H; Bonifazi, D

    2005-01-01

    So far, most of the high resolution scanning probe microscopy studies of organic molecules were restricted to metallic substrates. Insulating substrates are mandatory when the molecules need to be electrically decoupled in a electronic circuit. In such a case, atomic force microscopy is required. In this paper we will discuss our recent studies on different organic molecules deposited on KBr surfaces in ultra-high vacuum, and then imaged by AFM at room temperature. The distance between tip and surface was controlled either by the frequency-shift of the cantilever resonance or by the excitation signal required to keep the oscillation amplitude constant. Advantages and drawbacks of both techniques are discussed. The high mobility of the molecules, due to their weak interaction with the substrate, hinders the formation of regular self assembled structures. To overcome this problem we created artificial structures on the surface by annealing and by electron irradiation, which made possible the growth of the molecules onto step edges and their confinement into rectangular pits

  11. Electron re-scattering from aligned linear molecules using the R-matrix method

    Harvey, A G; Tennyson, J

    2009-01-01

    Electron re-scattering in a strong laser field provides an important probe of molecular structure and processes. The laser field drives the ionization of the molecule, followed by acceleration and subsequent recollision of the electron with the parent molecular ion, the scattered electrons carry information about the nuclear geometry and electronic states of the molecular ion. It is advantageous in strong field experiments to work with aligned molecules, which introduces extra physics compared to the standard gas-phase, electron-molecule scattering problem. The formalism for scattering from oriented linear molecules is presented and applied to H 2 and CO 2 . Differential cross sections are presented for (re-)scattering by these systems concentrating on the most common, linear alignment. In H 2 these cross sections show significant angular structure which, particularly for a scattering angle of 90 deg., are predicted to vary significantly between re-collisions stimulated by an even or an odd number of photons. In CO 2 these cross sections are zero indicating the necessity of using non-parallel alignment with this molecule.

  12. Study of the electronic properties of organic molecules within a metal-molecule-metal junction

    Lambert, Mathieu

    2003-01-01

    This ph-D thesis is about electronic transport through organic molecules inserted in a metal molecule-metal junction. We describe first a simple process to prepare sub-3 nm gaps by controllable breakage (under an electrical stress) of gold wires lithographed on a SiO 2 Si substrate at low temperature (4.2 K). We show that the involved mechanism is thermally assisted electromigration. We observe that current-voltage (I-V) characteristics of resulting electrodes are stable up to ∼5 V. which gives access to the well-known Fowler-Nordheim regime in the I-V, allowing an accurate characterisation of the gap size. The average gap is found lo be between 1.5 nm in width and 2.5 eV in height. Molecules and nanoparticles have then been inserted in the junction in the case of nanoparticles for example. The resulting IV clearly shows the suppression of electrical current at low bias known as Coulomb blockade. Characteristic of single-electron tunnelling through nanometer-sized structures, finally we fabricated a single-electron tunneling device based on Au nanoparticles connected to the electrodes via terthiophene (T3) molecule. We use the silicon substrate, separated from the planar structure by a silicon oxide of 200 nm, as an electrostatic gate and observed clear current modulation with possible signature of the transport properties of the terthiophene molecules. (author) [fr

  13. Detection of kinetic change points in piece-wise linear single molecule motion

    Hill, Flynn R.; van Oijen, Antoine M.; Duderstadt, Karl E.

    2018-03-01

    Single-molecule approaches present a powerful way to obtain detailed kinetic information at the molecular level. However, the identification of small rate changes is often hindered by the considerable noise present in such single-molecule kinetic data. We present a general method to detect such kinetic change points in trajectories of motion of processive single molecules having Gaussian noise, with a minimum number of parameters and without the need of an assumed kinetic model beyond piece-wise linearity of motion. Kinetic change points are detected using a likelihood ratio test in which the probability of no change is compared to the probability of a change occurring, given the experimental noise. A predetermined confidence interval minimizes the occurrence of false detections. Applying the method recursively to all sub-regions of a single molecule trajectory ensures that all kinetic change points are located. The algorithm presented allows rigorous and quantitative determination of kinetic change points in noisy single molecule observations without the need for filtering or binning, which reduce temporal resolution and obscure dynamics. The statistical framework for the approach and implementation details are discussed. The detection power of the algorithm is assessed using simulations with both single kinetic changes and multiple kinetic changes that typically arise in observations of single-molecule DNA-replication reactions. Implementations of the algorithm are provided in ImageJ plugin format written in Java and in the Julia language for numeric computing, with accompanying Jupyter Notebooks to allow reproduction of the analysis presented here.

  14. Surface functionalization of aluminosilicate nanotubes with organic molecules

    Wei Ma

    2012-02-01

    Full Text Available The surface functionalization of inorganic nanostructures is an effective approach for enriching the potential applications of existing nanomaterials. Inorganic nanotubes attract great research interest due to their one-dimensional structure and reactive surfaces. In this review paper, recent developments in surface functionalization of an aluminosilicate nanotube, “imogolite”, are introduced. The functionalization processes are based on the robust affinity between phosphate groups of organic molecules and the aluminol (AlOH surface of imogolite nanotubes. An aqueous modification process employing a water soluble ammonium salt of alkyl phosphate led to chemisorption of molecules on imogolite at the nanotube level. Polymer-chain-grafted imogolite nanotubes were prepared through surface-initiated polymerization. In addition, the assembly of conjugated molecules, 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-ylethylphosphonic acid (HT3P and 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-ylethylphosphonic acid 1,1-dioxide (HT3OP, on the imogolite nanotube surface was achieved by introducing a phosphonic acid group to the corresponding molecules. The optical and photophysical properties of these conjugated-molecule-decorated imogolite nanotubes were characterized. Moreover, poly(3-hexylthiophene (P3HT chains were further hybridized with HT3P modified imogolite to form a nanofiber hybrid.

  15. Adsorption of polar organic molecules on sediments: Case-study on Callovian-Oxfordian claystone.

    Rasamimanana, S; Lefèvre, G; Dagnelie, R V H

    2017-08-01

    The release and transport of anthropogenic organic matter through the geosphere is often an environmental criterion of safety. Sedimentary rocks are widely studied in this context as geological barriers for waste management. It is the case of Callovian-Oxfordian claystone (COx), for which several studies report adsorption of anthropogenic organic molecules. In this study, we evaluated and reviewed adsorption data of polar organic molecules on COx claystone. Experiments were performed on raw claystone, decarbonated and clay fractions. Adsorption isotherms were measured with adsorbates of various polarities: adipate, benzoate, ortho-phthalate, succinate, gluconate, oxalate, EDTA, citrate. A significant adsorption was observed for multidentate polycarboxylic acids as evidenced with phthalate, succinate, oxalate, gluconate, EDTA and citrate (R d  = 1.53, 3.52, 8.4, 8.8, 12.4, 54.7 L kg -1 respectively). Multiple linear regression were performed as a statistical analysis to determine the predictors from these adsorption data. A linear correlation between adsorption data (R d ) and dipole moment (μ) of adsorbates was evidenced (R 2  = 0.91). Molecules with a high dipole moment, μ(D) > 2.5, displayed a significant adsorption, R d ≫1 L kg -1 . A qualitative correlation can be easily estimated using the water/octanol partition coefficient, P ow , of adsorbates (R 2  = 0.77). In this case, two opposite trends were distinguished for polar and apolar molecules. The use of organic carbon content in sediments is relevant for predicting adsorption of apolar compounds, log (P ow )>+1. The oxides/clays contents may be relevant regarding polar molecules, log ( apparent P ow )<-1. The proposed scheme offers a general methodology for investigation of geo-barriers towards heterogeneous organic plumes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Symmetry Adaptation of the Rotation-Vibration Theory for Linear Molecules

    Katy L. Chubb

    2018-04-01

    Full Text Available A numerical application of linear-molecule symmetry properties, described by the D ∞ h point group, is formulated in terms of lower-order symmetry groups D n h with finite n. Character tables and irreducible representation transformation matrices are presented for D n h groups with arbitrary n-values. These groups can subsequently be used in the construction of symmetry-adapted ro-vibrational basis functions for solving the Schrödinger equations of linear molecules. Their implementation into the symmetrisation procedure based on a set of “reduced” vibrational eigenvalue problems with simplified Hamiltonians is used as a practical example. It is shown how the solutions of these eigenvalue problems can also be extended to include the classification of basis-set functions using ℓ, the eigenvalue (in units of ℏ of the vibrational angular momentum operator L ^ z . This facilitates the symmetry adaptation of the basis set functions in terms of the irreducible representations of D n h . 12 C 2 H 2 is used as an example of a linear molecule of D ∞ h point group symmetry to illustrate the symmetrisation procedure of the variational nuclear motion program Theoretical ROVibrational Energies (TROVE.

  17. Conformational Effects in Non-Stoichiometric Complexes of Two Hyperbranched Molecules with a Linear Polyelectrolyte

    Alexey Lyulin

    2012-01-01

    Full Text Available We report results from Brownian dynamics computer simulations of systems comprised by two terminally charged hyperbranched molecules preferentially branched in the periphery, with an oppositely charged linear chain of varying length. Comparison of the findings from the present study to stoichiometric counterparts and to analogous dendrimer-based complexes, reveal that the presence of the second hyperbranched molecule incurs significant changes in the conformational characteristics of both components of the complex. Instead of step-like changes in the average size and shape of the hyperbranched component that were noted in the previously studied stoichiometric systems, a rather smooth change is observed upon increase of the length of the linear component. In addition, a markedly different behavior is also noticed in the conformational characteristics of the linear chain when compared to that in similar dendrimer-based systems. The above findings are consistent with the higher degree of deformability of the peripherally branched molecules which allow appropriate rearrangements in shape in order to accommodate the favorable Coulombic interactions between the two components of the complex. This behavior offers new insight towards the design of more efficient hyperbranched-based systems which can take advantage of the multifunctionality and the structural properties of the highly branched polymer components.

  18. Luminescence stability of porous Si terminated by hydrophilic organic molecules

    Matsumoto, Kimihisa; Kamiguchi, Masao; Kamiya, Kazuhide; Nomura, Takashi; Suzuki, Shinya

    2016-02-01

    The effects of the surface termination of a porous Si surface by propionic acid and by undecylenic acid on their hydrophilicity and luminescence stability were studied. In the measurements of the contact angle of water droplets on porous Si films, the hydrophilicity of porous Si is improved by the surface termination each types of organic molecule. The PL intensity of as-prepared porous Si decreased with increasing aging time in ambient air. As PL quenching involves PL blue shift and increasing Si-O bonds density, nonradiative recombination centers are formed in the surface oxide. After the hydrosilylation process of propionic acid and undecylenic acid, PL intensity decreased and became 30% that of as-prepared porous Si film. However, the PL intensity was stable and exceeded that of the as-prepared film after 1000 min of aging in the ambient air. The PL stabilities are contributed to the termination by organic molecules that inhibits surface oxidation.

  19. Complex organic molecules in organic-poor massive young stellar objects

    Fayolle, Edith C.; Öberg, Karin I.; Garrod, Robin T.

    2015-01-01

    to search for complex organic molecules over 8-16 GHz in the 1 mm atmospheric window toward three MYSOs with known ice abundances, but without luminous molecular hot cores. Results. Complex molecules are detected toward all three sources at comparable abundances with respect to CH3OH to classical hot core......Context. Massive young stellar objects (MYSOs) with hot cores are classic sources of complex organic molecules. The origins of these molecules in such sources, as well as the small-and large-scale differentiation between nitrogen-and oxygen-bearing complex species, are poorly understood. Aims. We...... aim to use complex molecule abundances toward a chemically less explored class of MYSOs with weak hot organic emission lines to constrain the impact of hot molecular cores and initial ice conditions on the chemical composition toward MYSOs. Methods. We use the IRAM 30 m and the Submillimeter Array...

  20. The tritium labelling of organic molecules by heterogeneous catalytic exchange

    Angoso, M.; Kaiser, F.

    1977-01-01

    The influence of the temperature at 65degC and 120degC on the labelling of three organic molecules with tritium was studied. The compounds were: benzoic acid, diphenyl glioxal and 2,3-tetramethylene-4-phenylthien-7-oxodiacetin. The method employed was the heterogeneous catalytic exchange between tritiaded water and the organic compound. The purification was made by thin-layer chromatography and the concentration, purity and specific activity of the products were determined by counting and ultraviolet techniques. The thermal stability and the radiolitic effects on labelled benzoic acid were also considered. (author) [es

  1. The tritium labelling of organic molecules by heterogeneous catalytic exchange

    Angoso Marina, M.; Kaiser Ruiz del Olmo, F.

    1977-01-01

    The influence of the temperature at 65 degree centigree and 120 degree centigree on the labelling of three organic molecules with tritium was studied. The compounds were: benzoic acid, de phenyl glyoxal and 2,3-tetramethylene-4-pantothenyl-7-oxo diacetin.The method employed was the heterogeneous catalytic exchange between tritiated water and the organic compound. The purification was made by thin-layer chromatography and the concentration, purity and specific activity of the products were determined by counting and ultraviolet techniques. The thermal stability and the radiolytic effects on labelled benzoic acid were also considered. (Author) 9 refs

  2. Acenes, Heteroacenes and Analogous Molecules for Organic Photovoltaic and Field Effect Transistor Applications

    Granger, Devin Benjamin

    Polycyclic aromatic hydrocarbons composed of benzenoid rings fused in a linear fashion comprise the class of compounds known as acenes. The structures containing three to six ring fusions are brightly colored and possess band gaps and charge transport efficiencies sufficient for semiconductor applications. These molecules have been investigated throughout the past several decades to assess their optoelectronic properties. The absorption, emission and charge transport properties of this series of molecules has been studied extensively to elucidate structure-property relationships. A wide variety of analogous molecules, incorporating heterocycles in place of benzenoid rings, demonstrate similar properties to the parent compounds and have likewise been investigated. Functionalization of acene compounds by placement of groups around the molecule affects the way in which molecules interact in the solid state, in addition to the energetics of the molecule. The use of electron donating or electron withdrawing groups affects the frontier molecular orbitals and thus affects the optical and electronic gaps of the molecules. The use of bulky side groups such as alkylsilylethynyl groups allows for crystal engineering of molecular aggregates, and changing the volume and dimensions of the alkylsilyl groups affects the intermolecular interactions and thus changes the packing motif. In chapter 2, a series of tetracene and pentacene molecules with strongly electron withdrawing groups is described. The investigation focuses on the change in energetics of the frontier molecular orbitals between the base acene and the nitrile and dicyanovinyl derivatives as well as the differences between the pentacene and tetracene molecules. The differences in close packing motifs through use of bulky alkylsilylethynyl groups is also discussed in relation to electron acceptor material design and bulk heterojunction organic photovoltaic characteristics. Chapter 3 focuses on molecular acceptor and

  3. Permeability of uncharged organic molecules in reverse osmosis desalination membranes.

    Dražević, Emil; Košutić, Krešimir; Svalina, Marin; Catalano, Jacopo

    2017-06-01

    Reverse osmosis (RO) membranes are primarily designed for removal of salts i.e. for desalination of brackish and seawater, but they have also found applications in removal of organic molecules. While it is clear that steric exclusion is the dominant removal mechanism, the fundamental explanation for how and why the separation occurs remains elusive. Until recently there was no strong microscopic evidences elucidating the structure of the active polyamide layers of RO membranes, and thus they have been conceived as "black boxes"; or as an array of straight capillaries with a distribution of radii; or as polymers with a small amount of polymer free domains. The knowledge of diffusion and sorption coefficients is a prerequisite for understanding the intrinsic permeability of any organic solute in any polymer. At the same time, it is technically challenging to accurately measure these two fundamental parameters in very thin (20-300 nm) water-swollen active layers. In this work we have measured partition and diffusion coefficients and RO permeabilities of ten organic solutes in water-swollen active layers of two types of RO membranes, low (SWC4+) and high flux (XLE). We deduced from our results and recent microscopic studies that the solute flux of organic molecules in polyamide layer of RO membranes occurs in two domains, dense polymer (the key barrier layer) and the water filled domains. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Effects of Perchlorate on Organic Molecules under Simulated Mars Conditions

    Carrier, B. L.; Kounaves, S. P.

    2014-12-01

    Perchlorate (ClO4-) was discovered in the northern polar region of Mars by the Mars Phoenix Lander in 2008 and has also been recently detected by the Curiosity Rover in Gale Crater [1,2]. Perchlorate has also been shown to be formed under current Mars conditions via the oxidation of mineral chlorides, further supporting the theory that perchlorate is present globally on Mars [3]. The discovery of perchlorate on Mars has raised important questions about the effects of perchlorate on the survival and detection of organic molecules. Although it has been shown that pyrolysis in the presence of perchlorate results in the alteration or destruction of organic molecules [4], few studies have been conducted on the potential effects of perchlorate on organic molecules under martian surface conditions. Although perchlorate is typically inert under Mars-typical temperatures [5], perchlorate does absorb high energy UV radiation, and has been shown to decompose to form reactive oxychlorine species such as chlorite (ClO2-) when exposed to martian conditions including UV or ionizing radiation [6,7]. Here we investigate the effects of perchlorate on the organic molecules tryptophan, benzoic acid and mellitic acid in order to determine how perchlorate may alter these compounds under Mars conditions. Experiments are performed in a Mars Simulation Chamber (MSC) capable of reproducing the temperature, pressure, atmospheric composition and UV flux found on Mars. Soil simulants are prepared consisting of SiO2 and each organic, as well as varying concentrations of perchlorate salts, and exposed in the MSC. Subsequent to exposure in the MSC samples are leached and the leachate analyzed by HPLC and LC-MS to determine the degree of degradation of the original organic and the identity of any potential decomposition products formed by oxidation or chlorination. References: [1] Kounaves et al., J. Geophys. Res. Planets, Vol. 115, p. E00E10, 2010 [2] Glavin et al., J. Geophys. Res. Planets, Vol

  5. Investigating organic molecules responsible of auxin-like activity of humic acid fraction extracted from vermicompost

    Scaglia, Barbara, E-mail: barbara.scaglia@unimi.it [Gruppo Ricicla Labs – DiSAA, Università degli Studi di Milano, Via Celoria 2 (Italy); Nunes, Ramom Rachide; Rezende, Maria Olímpia Oliveira [Laboratório de Química Ambiental, Universidade de São Paulo, Instituto de Química de São Carlos, Avenida Trabalhador São Carlense, 400, São Carlos (Brazil); Tambone, Fulvia [Gruppo Ricicla Labs – DiSAA, Università degli Studi di Milano, Via Celoria 2 (Italy); Adani, Fabrizio, E-mail: fabrizio.adani@unimi.it [Gruppo Ricicla Labs – DiSAA, Università degli Studi di Milano, Via Celoria 2 (Italy)

    2016-08-15

    This work studied the auxin-like activity of humic acids (HA) obtained from vermicomposts produced using leather wastes plus cattle dung at different maturation stages (fresh, stable and mature). Bioassays were performed by testing HA concentrations in the range of 100–6000 mg carbon L{sup −1}. {sup 13}C CPMAS-NMR and GC–MS instrumental methods were used to assess the effect of biological processes and starting organic mixtures on HA composition. Not all HAs showed IAA-like activity and in general, IAA-like activity increased with the length of the vermicomposting process. The presence of leather wastes was not necessary to produce the auxin-like activity of HA, since HA extracted from a mix of cattle manure and sawdust, where no leather waste was added, showed IAA-like activity as well. CPMAS {sup 13}CNMR revealed that HAs were similar independently of the mix used and that the humification process involved the increasing concentration of pre-existing alkali soluble fractions in the biomass. GC/MS allowed the identification of the molecules involved in IAA-like effects: carboxylic acids and amino acids. The concentration of active molecules, rather than their simple presence in HA, determined the bio-stimulating effect, and a good linear regression between auxin-like activity and active stimulating molecules concentration was found (R{sup 2} = − 0.85; p < 0.01, n = 6). - Highlights: • Vermicomposting converts waste into organic fertilizer. • Vermicomposts can have biostimulating effect for the presence of hormone-like molecules. • Auxine-like activity was associated to the vermicompost humic acid fraction (HA). • HA carboxylic acids and amino acids, were reported to act as auxin-like molecules. • A linear regression was found between molecules and auxin-like activity.

  6. Organic Semiconductor-Containing Supramolecules: Effect of Small Molecule Crystallization and Molecular Packing

    Rancatore, Benjamin J.

    2016-01-21

    © 2016 American Chemical Society. Small molecules (SMs) with unique optical or electronic properties provide an opportunity to incorporate functionality into block copolymer (BCP)-based supramolecules. However, the assembly of supramolecules based on these highly crystalline molecules differs from their less crystalline counterparts. Here, two families of organic semiconductor SMs are investigated, where the composition of the crystalline core, the location (side- vs end-functionalization) of the alkyl solubilizing groups, and the constitution (branched vs linear) of the alkyl groups are varied. With these SMs, we present a systematic study of how the phase behavior of the SMs affects the overall assembly of these organic semiconductor-based supramolecules. The incorporation of SMs has a large effect on the interfacial curvature, the supramolecular periodicity, and the overall supramolecular morphology. The crystal packing of the SM within the supramolecule does not necessarily lead to the assembly of the comb block within the BCP microdomains, as is normally observed for alkyl-containing supramolecules. An unusual lamellar morphology with a wavy interface between the microdomains is observed due to changes in the packing structure of the small molecule within BCP microdomains. Since the supramolecular approach is modular and small molecules can be readily switched out, present studies provide useful guidance toward access supramolecular assemblies over several length scales using optically active and semiconducting small molecules.

  7. Theory of photoelectron spectroscopy for organic molecules and their crystals

    Fujikawa, Takashi, E-mail: tfujikawa@faculty.chiba-u.jp; Niki, Kaori; Sakuma, Hiroto

    2015-10-01

    Highlights: • Some specific features in photoemission theory from organic solids are reviewed. • Extrinsic and intrinsic effects are discussed. • Photoemission from extended levels is compared with that from core levels. • First principle many-body theories are discussed on the basis of nonequilibrium Green's functions. - Abstract: In this short review we discuss recent progress in photoemission theory for organic molecules and their crystals. We discuss some important features in Keldysh Green's function theory for the photoemission. We briefly discuss many-body aspects in photoemission from core and extended levels. In particular phonon effects are investigated in more detail since organic solids are typically soft where electron–phonon interaction is important. Debye–Waller factor suppresses the interference effects of photoelectron waves which makes ARPES analyses useless, particularly in high energy region.

  8. Theory of photoelectron spectroscopy for organic molecules and their crystals

    Fujikawa, Takashi; Niki, Kaori; Sakuma, Hiroto

    2015-01-01

    Highlights: • Some specific features in photoemission theory from organic solids are reviewed. • Extrinsic and intrinsic effects are discussed. • Photoemission from extended levels is compared with that from core levels. • First principle many-body theories are discussed on the basis of nonequilibrium Green's functions. - Abstract: In this short review we discuss recent progress in photoemission theory for organic molecules and their crystals. We discuss some important features in Keldysh Green's function theory for the photoemission. We briefly discuss many-body aspects in photoemission from core and extended levels. In particular phonon effects are investigated in more detail since organic solids are typically soft where electron–phonon interaction is important. Debye–Waller factor suppresses the interference effects of photoelectron waves which makes ARPES analyses useless, particularly in high energy region.

  9. Lanczos-driven coupled-cluster damped linear response theory for molecules in polarizable environments

    List, Nanna Holmgaard; Coriani, Sonia; Kongsted, Jacob

    2014-01-01

    are specifically motivated by a twofold aim: (i) computation of core excitations in realistic surroundings and (ii) examination of the effect of the differential response of the environment upon excitation solely related to the CC multipliers (herein denoted the J matrix) in computations of excitation energies......We present an extension of a previously reported implementation of a Lanczos-driven coupled-cluster (CC) damped linear response approach to molecules in condensed phases, where the effects of a surrounding environment are incorporated by means of the polarizable embedding formalism. We...... and transition moments of polarizable-embedded molecules. Numerical calculations demonstrate that the differential polarization of the environment due to the first-order CC multipliers provides only minor contributions to the solvatochromic shift for all transitions considered. We thus complement previous works...

  10. Nonadiabatic dynamics of electron injection into organic molecules

    Zhu Li-Ping; Qiu Yu; Tong Guo-Ping

    2012-01-01

    We numerically investigate the injection process of electrons from metal electrodes to one-dimensional organic molecules by combining the extended Su—Schrieffer—Heeger (SSH) model with a nonadiabatic dynamics method. It is found that a match between the Fermi level of electrodes and the highest occupied molecular orbital (HOMO) or the lowest unoccupied molecular orbital (LUMO) of organic molecules can be greatly affected by the length of the organic chains, which has a great impact on electron injection. The correlation between oligomers and electrodes is found to open more efficient channels for electron injection as compared with that in polymer/electrode structures. For oligomer/electrode structures, we show that the Schottky barrier essentially does not affect the electron injection as the electrode work function is smaller than a critical value. This means that the Schottky barrier is pinned for a small work-function electrode. For polymer/electrode structures, we find that it is possible for the Fermi level of electrodes to be pinned to the polaronic level. The condition under which the Fermi level of electrodes exceeds the polaronic level of polymers is shown to not always lead to spontaneous electron transfer from electrodes to polymers. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  11. Linear-algebraic approach to electronic excitation of atoms and molecules by electron impact

    Collins, L.A.; Schneider, B.I.

    1983-01-01

    A linear-algebraic method, based on an integral equations formulation, is applied to the excitation of atoms and molecules by electron impact. Various schemes are devised for treating the one-electron terms that sometimes cause instabilities when directly incorporated into the solution matrix. These include introducing Lagrange undetermined multipliers and correlation terms. Good agreement between the method and other computational techniques is obtained for electron scattering for hydrogenic and Li-like atomic ions and for H 2 + in two- to five-state close-coupling calculations

  12. Electronic excitation of atoms and molecules by electron impact in a linear algebraic, separable potential approach

    Collins, L.A.; Schneider, B.I.

    1984-01-01

    The linear algebraic, separable potential approach is applied to the electronic excitation of atoms and molecules by electron impact. By representing the exchange and off-diagonal direct terms on a basis, the standard set of coupled inelastic equations is reduced to a set of elastic inhomogeneous equations. The procedure greatly simplifies the formulation by allowing a large portion of the problem to be handled by standard bound-state techniques and by greatly reducing the order of the scattering equations that must be solved. Application is made to the excitation of atomic hydrogen in the three-state close-coupling (1s, 2s, 2p) approximation. (author)

  13. On structure of some laminated crystals with organic molecules

    Volodina, G.F.; Ivanova, V.Ya.; Malinovskij, T.I.

    1982-01-01

    A survey is made of papers dealing with intercalation of organic molecules into crystals of dihalcogenides of some transition metals (TaS 2 , TiS 2 , NbS 2 , ZrS 2 , TaSe 2 ), variation of their structure and physical properties. Among the used intercalates ammonia, pyridine, aniline and other aromatic amines proved to be most satisfactory from the viewpoint of reaction rate and product stability. A possibility is discussed of intercalation into PbI 2 and CdI 2 crystals that are of the same structural type as dihalcogenides

  14. Linear-algebraic approach to electron-molecule collisions: General formulation

    Collins, L.A.; Schneider, B.I.

    1981-01-01

    We present a linear-algebraic approach to electron-molecule collisions based on an integral equations form with either logarithmic or asymptotic boundary conditions. The introduction of exchange effects does not alter the basic form or order of the linear-algebraic equations for a local potential. In addition to the standard procedure of directly evaluating the exchange integrals by numerical quadrature, we also incorporate exchange effects through a separable-potential approximation. Efficient schemes are developed for reducing the number of points and channels that must be included. The method is applied at the static-exchange level to a number of molecular systems including H 2 , N 2 , LiH, and CO 2

  15. Core Level Spectra of Organic Molecules Adsorbed on Graphene

    Abhilash Ravikumar

    2018-03-01

    Full Text Available We perform first principle calculations based on density functional theory to investigate the effect of the adsorption of core-excited organic molecules on graphene. We simulate Near Edge X-ray absorption Fine Structure (NEXAFS and X-ray Photoemission Spectroscopy (XPS at the N and C edges for two moieties: pyridine and the pyridine radical on graphene, which exemplify two different adsorption characters. The modifications of molecular and graphene energy levels due to their interplay with the core-level excitation are discussed. We find that upon physisorption of pyridine, the binding energies of graphene close to the adsorption site reduce mildly, and the NEXAFS spectra of the molecule and graphene resemble those of gas phase pyridine and pristine graphene, respectively. However, the chemisorption of the pyridine radical is found to significantly alter these core excited spectra. The C 1s binding energy of the C atom of graphene participating in chemisorption increases by ∼1 eV, and the C atoms of graphene alternate to the adsorption site show a reduction in the binding energy. Analogously, these C atoms also show strong modifications in the NEXAFS spectra. The NEXAFS spectrum of the chemisorbed molecule is also modified as a result of hybridization with and screening by graphene. We eventually explore the electronic properties and magnetism of the system as a core-level excitation is adiabatically switched on.

  16. Hydrogen transfer reactions of interstellar Complex Organic Molecules

    Álvarez-Barcia, S.; Russ, P.; Kästner, J.; Lamberts, T.

    2018-06-01

    Radical recombination has been proposed to lead to the formation of complex organic molecules (COMs) in CO-rich ices in the early stages of star formation. These COMs can then undergo hydrogen addition and abstraction reactions leading to a higher or lower degree of saturation. Here, we have studied 14 hydrogen transfer reactions for the molecules glyoxal, glycoaldehyde, ethylene glycol, and methylformate and an additional three reactions where CHnO fragments are involved. Over-the-barrier reactions are possible only if tunneling is invoked in the description at low temperature. Therefore the rate constants for the studied reactions are calculated using instanton theory that takes quantum effects into account inherently. The reactions were characterized in the gas phase, but this is expected to yield meaningful results for CO-rich ices due to the minimal alteration of reaction landscapes by the CO molecules. We found that rate constants should not be extrapolated based on the height of the barrier alone, since the shape of the barrier plays an increasingly larger role at decreasing temperature. It is neither possible to predict rate constants based only on considering the type of reaction, the specific reactants and functional groups play a crucial role. Within a single molecule, though, hydrogen abstraction from an aldehyde group seems to be always faster than hydrogen addition to the same carbon atom. Reactions that involve heavy-atom tunneling, e.g., breaking or forming a C-C or C-O bond, have rate constants that are much lower than those where H transfer is involved.

  17. Self-organized lattice of ordered quantum dot molecules

    Lippen, T. von; Noetzel, R.; Hamhuis, G.J.; Wolter, J.H.

    2004-01-01

    Ordered groups of InAs quantum dots (QDs), lateral QD molecules, are created by self-organized anisotropic strain engineering of a (In,Ga)As/GaAs superlattice (SL) template on GaAs (311)B in molecular-beam epitaxy. During stacking, the SL template self-organizes into a two-dimensionally ordered strain modulated network on a mesoscopic length scale. InAs QDs preferentially grow on top of the nodes of the network due to local strain recognition. The QDs form a lattice of separated groups of closely spaced ordered QDs whose number can be controlled by the GaAs separation layer thickness on top of the SL template. The QD groups exhibit excellent optical properties up to room temperature

  18. Challenges for single molecule electronic devices with nanographene and organic molecules. Do single molecules offer potential as elements of electronic devices in the next generation?

    Enoki, Toshiaki; Kiguchi, Manabu

    2018-03-01

    Interest in utilizing organic molecules to fabricate electronic materials has existed ever since organic (molecular) semiconductors were first discovered in the 1950s. Since then, scientists have devoted serious effort to the creation of various molecule-based electronic systems, such as molecular metals and molecular superconductors. Single-molecule electronics and the associated basic science have emerged over the past two decades and provided hope for the development of highly integrated molecule-based electronic devices in the future (after the Si-based technology era has ended). Here, nanographenes (nano-sized graphene) with atomically precise structures are among the most promising molecules that can be utilized for electronic/spintronic devices. To manipulate single small molecules for an electronic device, a single molecular junction has been developed. It is a powerful tool that allows even small molecules to be utilized. External electric, magnetic, chemical, and mechanical perturbations can change the physical and chemical properties of molecules in a way that is different from bulk materials. Therefore, the various functionalities of molecules, along with changes induced by external perturbations, allows us to create electronic devices that we cannot create using current top-down Si-based technology. Future challenges that involve the incorporation of condensed matter physics, quantum chemistry calculations, organic synthetic chemistry, and electronic device engineering are expected to open a new era in single-molecule device electronic technology.

  19. Cometary delivery of organic molecules to the early earth

    Chyba, Christopher F.; Thomas, Paul J.; Sagan, Carl; Brookshaw, Leigh

    1990-01-01

    It has long been speculated that earth accreted prebiotic organic molecules important for the origins of life from impacts of carbonaceous asteroids and comets during the period of heavy bombardment 4.5 x 10 to the 9th to 3.8 x 10 to the 9th years ago. A comprehensive treatment of comet-asteroid interaction with the atmosphere, surface impact, and resulting organic pyrolysis demonstrates that organics will not survive impacts at velocities greater than about 10 kilometers per second and that even comets and asteroids as small as 100 meters in radius cannot be aerobraked to below this velocity in 1-bar atmospheres. However, for plausible dense (10-bar carbon dioxide) early atmospheres, it is found that 4.5 x 10 to the 9th years ago earth was accreting intact cometary organics at a rate of at least about 10 to the 6th to 10 to the 7th kilograms per year, a flux that thereafter declined with a half-life of about 10 to the 8th years. These results may be put in context by comparison with terrestrial oceanic and total biomasses, about 3 x 10 to the 12th kilograms and about 6 x 10 to the 14th kilograms, respectively.

  20. Effect of deuteration on the vibrational spectra of organic molecules

    Billes, Ferenc; Endredi, Henrietta; Varady, Balazs

    2001-01-01

    The stable isotope substitution of organic compounds deforms their vibrational spectra. The modifications of the spectra appear as band shifts and changes in intensities and shapes of the bands. The magnitude of the effect depends on the ratio of the masses of the new and old isotopes and on the atom active position. According to these mentioned reasons large effects can be observed only if hydrogen atoms are substituted. With the effect of the substitution we dealt already in a former lecture. In this lecture we concentrate on the effect of the change of hydrogen to deuterium. We investigate the changes both experimentally and theoretically. There are two possibilities: - the hydrogen atom is in an active position, its interaction with the environment is strong, either it can dissociate or move on the skeleton of the molecule (tautomerism, resonance) and it can build hydrogen bond, (e.g. it is connected to nitrogen and oxygen atoms); - the hydrogen atom is in an indifferent position in the molecule, its interaction with the environment is weak (e.g. it joins carbon atom). When building the hydrogen bond besides the hydrogen donors also acceptors exist, namely, oxygen and nitrogen atoms having non-bonded electron pairs. When comparing the experimental and theoretical (calculated) effects of this type of isotope changes one must take into account that the calculations refer to the isolated molecule while the experimental spectra characterize the compound. The hydrogen bond is a very strong intermolecular interaction and produces tremendous changes in the infrared spectrum of the molecule in comparison to the imagined theoretical spectrum of the molecule. Some bands disappear, appear, or shift and deform drastically. The H/D change diminishes these effects. Of course, these changes entail the shift of several bands. The Raman spectrum is less sensitive to the large dipole moment changes therefore the deuteration effect is there less dramatic. Deuteration of hydrogen

  1. Hyperthermal surface ionization mass spectrometry of organic molecules: monoterpenes

    Kishi, Hiroshi; Fujii, Toshihiro.

    1997-01-01

    This paper describes an experimental study on the influence of kinetic energy of fast monoterpene molecules on the surface ionization efficiency and on the mass spectral patterns, using rhenium oxide (ReO 2 ) surface. Molecular kinetic energy, given to the molecules through the acceleration in the seeded supersonic molecular beam, ranged from 1 to 10 eV. Hyperthermal surface ionization mass spectra (HSIMS) were taken for various incident kinetic energies and surface temperatures. The observed mass spectra were interpreted in a purely empirical way, by means of evidence from the previous investigations, and they were compared with conventional EI techniques and with the thermal energy surface ionization technique (SIOMS; Surface Ionization Organic Mass Spectrometry). Ionization efficiency (β) was also studied. Under hyperthermal surface ionization (HSI) conditions, many kinds of fragment ions, including quite abundant odd electron ions (OE +· ) are observed. HSIMS patterns of monoterpenes are different among 6-isomers, contrary to those of SIOMS and EIMS, where very similar patterns for isomers are observed. HSIMS patterns are strongly dependent on the molecular kinetic energies. The surface temperature does not affect much the spectral patterns, but it controls the total amount of ion formation. We conclude from these mass spectral findings, HSI-mechanism contains an impulsive process of ion formation, followed by the fragmentation process as a results of the internal energies acquired through the collision processes. (author)

  2. Light incoupling in small molecule organic solar cells

    Allinger, Nikola; Meiss, Jan; Riede, Moritz; Leo, Karl [Institut fuer Angewandte Photophysik, Technische Universitaet Dresden, 01069 Dresden (Germany); Gnehr, Wolf-Michael [Heliatek GmbH, Liebigstrasse 26, 01187 Dresden (Germany)

    2008-07-01

    Light incoupling is an essential topic for optimization of organic solar cells. In our group, we examine light incoupling of different kinds of transparent contacting materials as well as external dielectric coatings, using optical simulation of thin film systems and experimental methods. Thin films of small molecules are prepared by thermal evaporation in a multi-chamber UHV system. Complex refraction indices of various materials are calculated from reflection and transmission measurements of monolayers. For modelling of optical properties of thin film systems, we developed a numerical simulation program based on the transfer matrix method. The cell structures investigated consist of nanolayers of small molecules, using ZnPc/C60 as an acceptor-donor heterojunction. As contact materials, we compare the expensive standard material indium tin oxide (ITO) with more cost-efficient alternatives like thin Ag layers or spin-coated layers of the polymer PEDOT:PSS, and discuss the resulting cell properties. Additional dielectric layers of varying materials, like tris(8-hydroxy-quinolinate)-aluminum (Alq3) or N,N'-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD), are deposited on top of the stack and their influence on cell efficiencies is investigated.

  3. On the SIMS Ionization Probability of Organic Molecules.

    Popczun, Nicholas J; Breuer, Lars; Wucher, Andreas; Winograd, Nicholas

    2017-06-01

    The prospect of improved secondary ion yields for secondary ion mass spectrometry (SIMS) experiments drives innovation of new primary ion sources, instrumentation, and post-ionization techniques. The largest factor affecting secondary ion efficiency is believed to be the poor ionization probability (α + ) of sputtered material, a value rarely measured directly, but estimated to be in some cases as low as 10 -5 . Our lab has developed a method for the direct determination of α + in a SIMS experiment using laser post-ionization (LPI) to detect neutral molecular species in the sputtered plume for an organic compound. Here, we apply this method to coronene (C 24 H 12 ), a polyaromatic hydrocarbon that exhibits strong molecular signal during gas-phase photoionization. A two-dimensional spatial distribution of sputtered neutral molecules is measured and presented. It is shown that the ionization probability of molecular coronene desorbed from a clean film under bombardment with 40 keV C 60 cluster projectiles is of the order of 10 -3 , with some remaining uncertainty arising from laser-induced fragmentation and possible differences in the emission velocity distributions of neutral and ionized molecules. In general, this work establishes a method to estimate the ionization efficiency of molecular species sputtered during a single bombardment event. Graphical Abstract GRAPHICAL ABSTRACT TEXT HERE] -->.

  4. Predicting Complex Organic Molecule Emission from TW Hya

    Vissapragada, Shreyas; Walsh, Catherine

    2017-01-01

    The Atacama Large Millimeter/submillimeter Array (ALMA) has significantly increased our ability to observe the rich chemical inventory of star and planet formation. ALMA has recently been used to detect CH3OH (methanol) and CH3CN (methyl cyanide) in protoplanetary disks; these molecules may be vital indicators of the complex organic ice reservoir in the comet-forming zone. We have constructed a physiochemical model of TW Hya, a well-studied protoplanetary disk, to explore the different formation mechanisms of complex ices. By running our model through a radiative transfer code and convolving with beam sizes appropriate for ALMA, we have obtained synthetic observations of methanol and methyl cyanide. Here, we compare and comment on these synthetic observations, and provide astrochemical justification for their spatial distributions.

  5. Formation of highly oxygenated organic molecules from aromatic compounds

    Molteni, Ugo; Bianchi, Federico; Klein, Felix; El Haddad, Imad; Frege, Carla; Rossi, Michel J.; Dommen, Josef; Baltensperger, Urs

    2018-02-01

    Anthropogenic volatile organic compounds (AVOCs) often dominate the urban atmosphere and consist to a large degree of aromatic hydrocarbons (ArHCs), such as benzene, toluene, xylenes, and trimethylbenzenes, e.g., from the handling and combustion of fuels. These compounds are important precursors for the formation of secondary organic aerosol. Here we show that the oxidation of aromatics with OH leads to a subsequent autoxidation chain reaction forming highly oxygenated molecules (HOMs) with an O : C ratio of up to 1.09. This is exemplified for five single-ring ArHCs (benzene, toluene, o-/m-/p-xylene, mesitylene (1,3,5-trimethylbenzene) and ethylbenzene), as well as two conjugated polycyclic ArHCs (naphthalene and biphenyl). We report the elemental composition of the HOMs and show the differences in the oxidation patterns of these ArHCs. A potential pathway for the formation of these HOMs from aromatics is presented and discussed. We hypothesize that AVOCs may contribute substantially to new particle formation events that have been detected in urban areas.

  6. Formation of highly oxygenated organic molecules from aromatic compounds

    U. Molteni

    2018-02-01

    Full Text Available Anthropogenic volatile organic compounds (AVOCs often dominate the urban atmosphere and consist to a large degree of aromatic hydrocarbons (ArHCs, such as benzene, toluene, xylenes, and trimethylbenzenes, e.g., from the handling and combustion of fuels. These compounds are important precursors for the formation of secondary organic aerosol. Here we show that the oxidation of aromatics with OH leads to a subsequent autoxidation chain reaction forming highly oxygenated molecules (HOMs with an O : C ratio of up to 1.09. This is exemplified for five single-ring ArHCs (benzene, toluene, o-/m-/p-xylene, mesitylene (1,3,5-trimethylbenzene and ethylbenzene, as well as two conjugated polycyclic ArHCs (naphthalene and biphenyl. We report the elemental composition of the HOMs and show the differences in the oxidation patterns of these ArHCs. A potential pathway for the formation of these HOMs from aromatics is presented and discussed. We hypothesize that AVOCs may contribute substantially to new particle formation events that have been detected in urban areas.

  7. Developing powerful tritide technique: Organic and biological molecule labeling

    Anon.

    1991-01-01

    Complex hydrides are very important reagents in organic synthesis due to the range of reducing powers and selectivities available from different agents. Unfortunately, the availability of these compounds for radiosynthesis has been extremely limited due to the difficulty of making them with adequate levels of tritium. Investigators at the Lawrence Berkeley Laboratory (LBL) National Tritium Labeling Facility have developed a new addition to the repertoire of the tritium-labeling chemist. The new method allows site-specific incorporation of tritium into organic and biological molecules by efficient reduction processes. Exceptionally reactive and selective reducing agents are prepared and used for labeling in a on-pot process. Three new tritide reagents - supertritide (lithium triethyl borotritide), LiAlT 4 (lithium aluminum tritide), and L-Selectride (sterically hindered lithium tri-sec-butyl borotritide) - have been synthesized at carrier-free levels, and have been demonstrated to be fully reactive. The availability of these versatile and reactive reagents gives the tritium radiochemist great control over chemoselectivity and stereoselectivity. The LBL tritide reagents can drive numerous conventional chemical reactions, and have been used to reduce p-toluene sulfonates, amides, lactones, esters, and aldehydes. These reactions produce good yields and result in products with maximum specific activities. The reagents clearly exhibit superior reactivity and may be used in many more synthetic processes than sodium borohydride, which is the currently used reagent. In addition, tritide reagents such as L-selectride have been shown to give greater control over stereochemistry and selectivity than sodium borohydride

  8. Small organic molecules modulating iodine uptake in thyroid

    Ambroise, Y.

    2006-01-01

    The thyroid gland accumulates large quantities of iodine. This uptake is needed for the production of iodinated hormones (T3 and T4). The first step in the iodine accumulation is a basolateral transport of iodide ions by the cloned 'Natrium Iodide Sym-porter' also called NIS. Using high-throughput screening techniques, we have identified a series of inhibitors of the iodide uptake in thyrocytes. These compounds are of medical significance in case of thyroid deregulation and can also offer solutions for radio-iodine detoxification in case of emergency situations (nuclear industry...). In addition, these small organic molecules can be important tools for the understanding of NIS structure and functions In parallel, we have identified and characterized a single compound capable to strongly enhance the amount of intra-cellular iodide in rat thyrocytes (FRTL5) as well as in HEK293 cells transfected with hNIS (Natrium/Iodide Sym-porter). Preliminary studies show that this effect is NIS dependant, and is induced by alternative and unknown mechanisms. Future work will consist in unraveling the mode of action of this molecule. These informations will help us not only to better understand the iodide pathways in the thyroid, but also to design more active analogues. We will use photo-labelling techniques to identify new proteins involved in the iodide transfer and retention. In addition, preliminary experiments are underway to validate our compound as an anti-cancer agent. Targeted NIS gene delivery into tumors plus radio-iodide injection leads to tumor size regression. Unfortunately, doses of radioactivity are to high for safe treatment. Our compound may lead to enhanced radio-iodide entrapment, thus necessitating lower doses of radioactivity for tumor regression. (author)

  9. Complex organic molecules in strongly UV-irradiated gas

    Cuadrado, S.; Goicoechea, J. R.; Cernicharo, J.; Fuente, A.; Pety, J.; Tercero, B.

    2017-07-01

    We investigate the presence of complex organic molecules (COMs) in strongly UV-irradiated interstellar molecular gas. We have carried out a complete millimetre (mm) line survey using the IRAM 30 m telescope towards the edge of the Orion Bar photodissociation region (PDR), close to the H2 dissociation front, a position irradiated by a very intense far-UV (FUV) radiation field. These observations have been complemented with 8.5'' resolution maps of the H2CO JKa,Kc = 51,5 → 41,4 and C18O J = 3 → 2 emission at 0.9 mm. Despite being a harsh environment, we detect more than 250 lines from COMs and related precursors: H2CO, CH3OH, HCO, H2CCO, CH3CHO, H2CS, HCOOH, CH3CN, CH2NH, HNCO, H213CO, and HC3N (in decreasing order of abundance). For each species, the large number of detected lines allowed us to accurately constrain their rotational temperatures (Trot) and column densities (N). Owing to subthermal excitation and intricate spectroscopy of some COMs (symmetric- and asymmetric-top molecules such as CH3CN and H2CO, respectively), a correct determination of N and Trot requires building rotational population diagrams of their rotational ladders separately. The inferred column densities are in the 1011-1013 cm-2 range. We also provide accurate upper limit abundances for chemically related molecules that might have been expected, but are not conclusively detected at the edge of the PDR (HDCO, CH3O, CH3NC, CH3CCH, CH3OCH3, HCOOCH3, CH3CH2OH, CH3CH2CN, and CH2CHCN). A non-thermodynamic equilibrium excitation analysis for molecules with known collisional rate coefficients suggests that some COMs arise from different PDR layers but we cannot resolve them spatially. In particular, H2CO and CH3CN survive in the extended gas directly exposed to the strong FUV flux (Tk = 150-250 K and Td≳ 60 K), whereas CH3OH only arises from denser and cooler gas clumps in the more shielded PDR interior (Tk = 40-50 K). The non-detection of HDCO towards the PDR edge is consistent with the

  10. Small molecules as tracers in atmospheric secondary organic aerosol

    Yu, Ge

    Secondary organic aerosol (SOA), formed from in-air oxidation of volatile organic compounds, greatly affects human health and climate. Although substantial research has been devoted to SOA formation and evolution, the modeled and lab-generated SOA are still low in mass and degree of oxidation compared to ambient measurements. In order to compensate for these discrepancies, the aqueous processing pathway has been brought to attention. The atmospheric waters serve as aqueous reaction media for dissolved organics to undergo further oxidation, oligomerization, or other functionalization reactions, which decreases the vapor pressure while increasing the oxidation state of carbon atoms. Field evidence for aqueous processing requires the identification of tracer products such as organosulfates. We synthesized the standards for two organosulfates, glycolic acid sulfate and lactic acid sulfate, in order to measure their aerosol-state concentration from five distinct locations via filter samples. The water-extracted filter samples were analyzed by LC-MS. Lactic acid sulfate and glycolic acid sulfate were detected in urban locations in the United States, Mexico City, and Pakistan with varied concentrations, indicating their potential as tracers. We studied the aqueous processing reaction between glyoxal and nitrogen-containing species such as ammonium and amines exclusively by NMR spectrometry. The reaction products formic acid and several imidazoles along with the quantified kinetics were reported. The brown carbon generated from these reactions were quantified optically by UV-Vis spectroscopy. The organic-phase reaction between oxygen molecule and alkenes photosensitized by alpha-dicarbonyls were studied in the same manner. We observed the fast kinetics transferring alkenes to epoxides under simulated sunlight. Statistical estimations indicate a very effective conversion of aerosol-phase alkenes to epoxides, potentially forming organosulfates in a deliquescence event and

  11. Single Molecule Study of DNA Organization and Recombination

    Xiao, Botao

    We have studied five projects related to DNA organization and recombination using mainly single molecule force-spectroscopy and statistical tools. First, HU is one of the most abundant DNA-organizing proteins in bacterial chromosomes and participates in gene regulation. We report experiments that study the dependence of DNA condensation by HU on force, salt and HU concentration. A first important result is that at physiological salt levels, HU only bends DNA, resolving a previous paradox of why a chromosome-compacting protein should have a DNA-stiffening function. A second major result is quantitative demonstration of strong dependencies of HU-DNA dissociation on both salt concentration and force. Second, we have used a thermodynamic Maxwell relation to count proteins driven off large DNAs by tension, an effect important to understanding DNA organization. Our results compare well with estimates of numbers of proteins HU and Fis in previous studies. We have also shown that a semi-flexible polymer model describes our HU experimental data well. The force-dependent binding suggests mechano-chemical mechanisms for gene regulation. Third, the elusive role of protein H1 in chromatin has been clarified with purified H1 and Xenopus extracts. We find that H1 compacts DNA by both bending and looping. Addition of H1 enhances chromatin formation and maintains the plasticity of the chromatin. Fourth, the topology and mechanics of DNA twisting are critical to DNA organization and recombination. We have systematically measured DNA extension as a function of linking number density from 0.08 to -2 with holding forces from 0.2 to 2.4 pN. Unlike previous proposals, the DNA extension decreases with negative linking number. Finally, DNA recombination is a dynamic process starting from enzyme-DNA binding. We report that the Int-DBD domain of lambda integrase binds to DNA without compaction at low Int-DBD concentration. High concentration of Int-DBD loops DNA below a threshold force

  12. Polarizable Atomic Multipole-based Molecular Mechanics for Organic Molecules.

    Ren, Pengyu; Wu, Chuanjie; Ponder, Jay W

    2011-10-11

    An empirical potential based on permanent atomic multipoles and atomic induced dipoles is reported for alkanes, alcohols, amines, sulfides, aldehydes, carboxylic acids, amides, aromatics and other small organic molecules. Permanent atomic multipole moments through quadrupole moments have been derived from gas phase ab initio molecular orbital calculations. The van der Waals parameters are obtained by fitting to gas phase homodimer QM energies and structures, as well as experimental densities and heats of vaporization of neat liquids. As a validation, the hydrogen bonding energies and structures of gas phase heterodimers with water are evaluated using the resulting potential. For 32 homo- and heterodimers, the association energy agrees with ab initio results to within 0.4 kcal/mol. The RMS deviation of hydrogen bond distance from QM optimized geometry is less than 0.06 Å. In addition, liquid self-diffusion and static dielectric constants computed from molecular dynamics simulation are consistent with experimental values. The force field is also used to compute the solvation free energy of 27 compounds not included in the parameterization process, with a RMS error of 0.69 kcal/mol. The results obtained in this study suggest the AMOEBA force field performs well across different environments and phases. The key algorithms involved in the electrostatic model and a protocol for developing parameters are detailed to facilitate extension to additional molecular systems.

  13. Singlet oxygen: photosensitized generation, detection and reaction with organic molecules

    Barik, Atanu; Indira Priyadarsini, K; Mohan, Hari; Bajaj, P N; Sapre, A V; Mittal, J P; Mukherjee, T [Radiation and Photochemistry Div., Bhabha Atomic Research Centre, Mumbai (India)

    2006-10-15

    Singlet molecular oxygen ({sup 1}O{sub 2}) is an excited state of molecular oxygen, having antiparallel spin in the same {pi} antibonding orbital. The study of singlet oxygen production and reactivity has emerged as a rich and diverse area, with implication in diverse fields, such as synthetic chemistry, polymer chemistry, photodynamic therapy, etc. There are several known methods to produce singlet oxygen, and also various techniques employed to detect it. Out of these, photosensitization method is the most popular one. In this article, photosensitized production of singlet oxygen from triplet oxygen and photosensitizers in presence of light, and its detection by the infrared luminescence at 1270 nm have been presented. Further, some results using different types of photosensitizers, effect of solvent on singlet oxygen quantum yields and lifetime have been discussed. The quenching rate constants of singlet oxygen have been determined with different types of organic molecules such as derivatives of thiourea and its analogues, hydroxy indoles and antioxidants and the results have been presented. (author)

  14. Singlet oxygen: photosensitized generation, detection and reaction with organic molecules

    Barik, Atanu; Indira Priyadarsini, K.; Hari Mohan; Bajaj, P.N.; Sapre, A.V.; Mittal, J.P.; Mukherjee, T.

    2006-10-01

    Singlet molecular oxygen ( 1 O 2 ) is an excited state of molecular oxygen, having antiparallel spin in the same π antibonding orbital. The study of singlet oxygen production and reactivity has emerged as a rich and diverse area, with implication in diverse fields, such as synthetic chemistry, polymer chemistry, photodynamic therapy, etc. There are several known methods to produce singlet oxygen, and also various techniques employed to detect it. Out of these, photosensitization method is the most popular one. In this article, photosensitized production of singlet oxygen from triplet oxygen and photosensitizers in presence of light, and its detection by the infrared luminescence at 1270 nm have been presented. Further, some results using different types of photosensitizers, effect of solvent on singlet oxygen quantum yields and lifetime have been discussed. The quenching rate constants of singlet oxygen have been determined with different types of organic molecules such as derivatives of thiourea and its analogues, hydroxy indoles and antioxidants and the results have been presented. (author)

  15. Advances in ultrasensitive mass spectrometry of organic molecules.

    Kandiah, Mathivathani; Urban, Pawel L

    2013-06-21

    Ultrasensitive mass spectrometric analysis of organic molecules is important for various branches of chemistry, and other fields including physics, earth and environmental sciences, archaeology, biomedicine, and materials science. It finds applications--as an enabling tool--in systems biology, biological imaging, clinical analysis, and forensics. Although there are a number of technical obstacles associated with the analysis of samples by mass spectrometry at ultratrace level (for example analyte losses during sample preparation, insufficient sensitivity, ion suppression), several noteworthy developments have been made over the years. They include: sensitive ion sources, loss-free interfaces, ion optics components, efficient mass analyzers and detectors, as well as "smart" sample preparation strategies. Some of the mass spectrometric methods published to date can achieve sensitivity which is by several orders of magnitude higher than that of alternative approaches. Femto- and attomole level limits of detection are nowadays common, while zepto- and yoctomole level limits of detection have also been reported. We envision that the ultrasensitive mass spectrometric assays will soon contribute to new discoveries in bioscience and other areas.

  16. Aperture Valve for the Mars Organic Molecule Analyzer (MOMA)

    Hakun, Claef F.; Engler, Charles D.; Barber, Willie E.; Canham, John S.

    2014-01-01

    NASA's participation in the multi-nation ExoMars 2018 Rover mission includes a critical astrobiology Mass Spectrometer Instrument on the Rover called the Mars Organic Molecule Analyzer (MOMA). The Aperture Valve is a critical electromechanical valve used by the Mass Spectrometer to facilitate the transfer of ions from Martian soil to the Mass Spectrometer for analysis. The MOMA Aperture Valve development program will be discussed in terms of the Initial valve design and subsequent improvements that resulted from prototype testing. The Initial Aperture Valve concept seemed promising, based on calculations and perceived merits. However, performance results of this design were disappointing, due to delamination of TiN and DLC coatings applied to the Titanium base metals, causing debris from the coatings to seize the valve. While peer reviews and design trade studies are important forums to vet a concept design, results from testing should not be underestimated.Despite the lack of development progress to meet requirements, valuable information from weakness discovered in the Initial Valve design was used to develop a second, more robust Aperture valve. Based on a check-ball design, the ETU flight valve design resulted in significantly less surface area to create the seal. Moreover, PVD coatings were eliminated in favor of hardened, nonmagnetic corrosion resistant alloys. Test results were impressive, with the valve achieving five orders of magnitude better sealing leak rate over end of life requirements. Cycle life was equally impressive, achieving 280,000 cycles without failure.

  17. Polarization properties of below-threshold harmonics from aligned molecules H2+ in linearly polarized laser fields.

    Dong, Fulong; Tian, Yiqun; Yu, Shujuan; Wang, Shang; Yang, Shiping; Chen, Yanjun

    2015-07-13

    We investigate the polarization properties of below-threshold harmonics from aligned molecules in linearly polarized laser fields numerically and analytically. We focus on lower-order harmonics (LOHs). Our simulations show that the ellipticity of below-threshold LOHs depends strongly on the orientation angle and differs significantly for different harmonic orders. Our analysis reveals that this LOH ellipticity is closely associated with resonance effects and the axis symmetry of the molecule. These results shed light on the complex generation mechanism of below-threshold harmonics from aligned molecules.

  18. Self-organizing ontology of biochemically relevant small molecules.

    Chepelev, Leonid L; Hastings, Janna; Ennis, Marcus; Steinbeck, Christoph; Dumontier, Michel

    2012-01-06

    The advent of high-throughput experimentation in biochemistry has led to the generation of vast amounts of chemical data, necessitating the development of novel analysis, characterization, and cataloguing techniques and tools. Recently, a movement to publically release such data has advanced biochemical structure-activity relationship research, while providing new challenges, the biggest being the curation, annotation, and classification of this information to facilitate useful biochemical pattern analysis. Unfortunately, the human resources currently employed by the organizations supporting these efforts (e.g. ChEBI) are expanding linearly, while new useful scientific information is being released in a seemingly exponential fashion. Compounding this, currently existing chemical classification and annotation systems are not amenable to automated classification, formal and transparent chemical class definition axiomatization, facile class redefinition, or novel class integration, thus further limiting chemical ontology growth by necessitating human involvement in curation. Clearly, there is a need for the automation of this process, especially for novel chemical entities of biological interest. To address this, we present a formal framework based on Semantic Web technologies for the automatic design of chemical ontology which can be used for automated classification of novel entities. We demonstrate the automatic self-assembly of a structure-based chemical ontology based on 60 MeSH and 40 ChEBI chemical classes. This ontology is then used to classify 200 compounds with an accuracy of 92.7%. We extend these structure-based classes with molecular feature information and demonstrate the utility of our framework for classification of functionally relevant chemicals. Finally, we discuss an iterative approach that we envision for future biochemical ontology development. We conclude that the proposed methodology can ease the burden of chemical data annotators and

  19. Self-organizing ontology of biochemically relevant small molecules

    2012-01-01

    Background The advent of high-throughput experimentation in biochemistry has led to the generation of vast amounts of chemical data, necessitating the development of novel analysis, characterization, and cataloguing techniques and tools. Recently, a movement to publically release such data has advanced biochemical structure-activity relationship research, while providing new challenges, the biggest being the curation, annotation, and classification of this information to facilitate useful biochemical pattern analysis. Unfortunately, the human resources currently employed by the organizations supporting these efforts (e.g. ChEBI) are expanding linearly, while new useful scientific information is being released in a seemingly exponential fashion. Compounding this, currently existing chemical classification and annotation systems are not amenable to automated classification, formal and transparent chemical class definition axiomatization, facile class redefinition, or novel class integration, thus further limiting chemical ontology growth by necessitating human involvement in curation. Clearly, there is a need for the automation of this process, especially for novel chemical entities of biological interest. Results To address this, we present a formal framework based on Semantic Web technologies for the automatic design of chemical ontology which can be used for automated classification of novel entities. We demonstrate the automatic self-assembly of a structure-based chemical ontology based on 60 MeSH and 40 ChEBI chemical classes. This ontology is then used to classify 200 compounds with an accuracy of 92.7%. We extend these structure-based classes with molecular feature information and demonstrate the utility of our framework for classification of functionally relevant chemicals. Finally, we discuss an iterative approach that we envision for future biochemical ontology development. Conclusions We conclude that the proposed methodology can ease the burden of

  20. Self-organizing ontology of biochemically relevant small molecules

    Chepelev Leonid L

    2012-01-01

    Full Text Available Abstract Background The advent of high-throughput experimentation in biochemistry has led to the generation of vast amounts of chemical data, necessitating the development of novel analysis, characterization, and cataloguing techniques and tools. Recently, a movement to publically release such data has advanced biochemical structure-activity relationship research, while providing new challenges, the biggest being the curation, annotation, and classification of this information to facilitate useful biochemical pattern analysis. Unfortunately, the human resources currently employed by the organizations supporting these efforts (e.g. ChEBI are expanding linearly, while new useful scientific information is being released in a seemingly exponential fashion. Compounding this, currently existing chemical classification and annotation systems are not amenable to automated classification, formal and transparent chemical class definition axiomatization, facile class redefinition, or novel class integration, thus further limiting chemical ontology growth by necessitating human involvement in curation. Clearly, there is a need for the automation of this process, especially for novel chemical entities of biological interest. Results To address this, we present a formal framework based on Semantic Web technologies for the automatic design of chemical ontology which can be used for automated classification of novel entities. We demonstrate the automatic self-assembly of a structure-based chemical ontology based on 60 MeSH and 40 ChEBI chemical classes. This ontology is then used to classify 200 compounds with an accuracy of 92.7%. We extend these structure-based classes with molecular feature information and demonstrate the utility of our framework for classification of functionally relevant chemicals. Finally, we discuss an iterative approach that we envision for future biochemical ontology development. Conclusions We conclude that the proposed methodology

  1. High mass-resolution electron-ion-ion coincidence measurements on core-excited organic molecules

    Tokushima, T; Senba, Y; Yoshida, H; Hiraya, A

    2001-01-01

    Total electron-ion-ion coincidence measurements on core excited organic molecules have been carried out with high mass resolution by using multimode (reflectron/linear) time-of-flight mass analyzer. From the ion correlation spectra of core excited CH sub 3 OH and CD sub 3 OH, the reaction pathway to form H sub 3 sup + (D sub 3 sup +) is identified as the elimination of three H (D) atoms from the methyl group, not as the inter-group (-CH sub 3 and -OH) interactions. In a PEPIPICO spectrum of acetylacetone (CH sub 3 COCH sub 2 COCH sub 3) measured by using a reflectron TOF, correlations between ions up to mass number 70 with one-mass resolution was recorded.

  2. Differential solvation of intrinsically disordered linkers drives the formation of spatially organized droplets in ternary systems of linear multivalent proteins

    Harmon, Tyler S.; Holehouse, Alex S.; Pappu, Rohit V.

    2018-04-01

    Intracellular biomolecular condensates are membraneless organelles that encompass large numbers of multivalent protein and nucleic acid molecules. The bodies assemble via a combination of liquid–liquid phase separation and gelation. A majority of condensates included multiple components and show multilayered organization as opposed to being well-mixed unitary liquids. Here, we put forward a simple thermodynamic framework to describe the emergence of spatially organized droplets in multicomponent systems comprising of linear multivalent polymers also known as associative polymers. These polymers, which mimic proteins and/or RNA have the architecture of domains or motifs known as stickers that are interspersed by flexible spacers known as linkers. Using a minimalist numerical model for a four-component system, we have identified features of linear multivalent molecules that are necessary and sufficient for generating spatially organized droplets. We show that differences in sequence-specific effective solvation volumes of disordered linkers between interaction domains enable the formation of spatially organized droplets. Molecules with linkers that are preferentially solvated are driven to the interface with the bulk solvent, whereas molecules that have linkers with negligible effective solvation volumes form cores in the core–shell architectures that emerge in the minimalist four-component systems. Our modeling has relevance for understanding the physical determinants of spatially organized membraneless organelles.

  3. Desorption of large organic molecules by laser-induced plasmon excitation

    Lee, I.; Callcott, T.A.

    1991-01-01

    Ejection of large organic molecules from surfaces by laser-induced electronic-excited desorption has attracted considerable interest in recent years. In addition to the importance of this effect for fundamental investigations of the ejection process, this desorption technique has been applied to the study of large, fragile molecules by mass spectrometry. In this paper, we present a new method to induce electronic excitation on the metal surface for the desorption of large organic molecules. 3 refs., 3 figs

  4. Organic Materials in the Undergraduate Laboratory: Microscale Synthesis and Investigation of a Donor-Acceptor Molecule

    Pappenfus, Ted M.; Schliep, Karl B.; Dissanayake, Anudaththa; Ludden, Trevor; Nieto-Ortega, Belen; Lopez Navarrete, Juan T.; Ruiz Delgado, M. Carmen; Casado, Juan

    2012-01-01

    A series of experiments for undergraduate courses (e.g., organic, physical) have been developed in the area of small molecule organic materials. These experiments focus on understanding the electronic and redox properties of a donor-acceptor molecule that is prepared in a convenient one-step microscale reaction. The resulting intensely colored…

  5. Effect of molecular structure on fragmentation of isolated organic molecules in solid rare gas matrices

    Kobrazenko, A.V.; Sukhov, F.F.; Orlov, A.Yu.; Kovalev, G.V.; Baranova, I.A.; Feldman, V.I.

    2011-01-01

    Complete text of publication follows. Elucidation of high-energy reaction pathways in the condensed phase is an important issue for basic understanding of the radiation stability of complex organic molecules. As was shown previously, organic radical cations (RC) may undergo fragmentation or rearrangement in solid matrices due to excess energy. The probability of this process depends on both ionization potential (IP) of the molecule and molecular structure. In the present work we have studied the role of 'hot' ionic reaction channels for RC of some bifunctional compounds and alkynes. The effect of excess energy was simulated by matrix isolation method as described in detail earlier. The formation of fragmentation products was monitored by EPR and FTIR spectroscopy. In the present work it was shown that the RC of bifunctional compounds (CH 3 OCH 2 COCH 3 , CH 3 CO(CH 2 ) n COCH 3 , n 0/2) dissociated efficiently producing · CH 3 radicals upon irradiation in solid argon matrix at T ≤ 16 K. The probability of fragmentation decreases with decrease of excess energy by switching from Ar to Xe. It is worth noting that acetone RC does not show fragmentation under these conditions. Thus, bifunctional molecules were found to be less stable to 'hot' ionic fragmentation in low-temperature solids in comparison with simple prototype carbonyl compounds. In the case of alkynes of the R-C ≡ CH type, a noticeable yield of fragmentation products was observed when R = -C(CH 3 ) 3 , but it was negligible for R = -CH 3 . It means that the presence of triple bond stabilizes the molecular skeleton of linear alkynes toward 'hot' fragmentation, similarly as it was shown for alkenes. The mechanisms of 'hot' reactions and excess energy relaxation are discussed. This work was supported by the Russian Foundation for Basic Research (project 09-03-00848a).

  6. High resolution SPM imaging of organic molecules with functionalized tips

    Jelínek, Pavel

    2017-01-01

    Roč. 29, č. 34 (2017), 1-18, č. článku 343002. ISSN 0953-8984 R&D Projects: GA MŠk LM2015087; GA MŠk 8E15B010; GA ČR(CZ) GC14-16963J Grant - others:AV ČR(CZ) Praemium Academiae Institutional support: RVO:68378271 Keywords : atomic- force microscopy * scanning tunneling microscope * on-surface synthesis * single-molecule * AFM * STM * high resolution * molecules * surfaces Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.649, year: 2016

  7. Efficient organic tandem solar cells based on small molecules

    Riede, Moritz; Widmer, Johannes; Timmreck, Ronny; Wynands, David; Leo, Karl [Institut fuer Angewandte Photophysik, Technische Universitaet Dresden, George-Baehr-Str. 1, 01069 Dresden (Germany); Uhrich, Christian; Schwartz, Gregor; Gnehr, Wolf-Michael; Hildebrandt, Dirk; Weiss, Andre; Pfeiffer, Martin [Heliatek GmbH, Treidlerstr. 3, 01139 Dresden (Germany); Hwang, Jaehyung; Sundarraj, Sudhakar; Erk, Peter [BASF SE, GVC/E-J542, 67056 Ludwigshafen (Germany)

    2011-08-23

    In this paper, two vacuum processed single heterojunction organic solar cells with complementary absorption are described and the construction and optimization of tandem solar cells based on the combination of these heterojunctions demonstrated. The red-absorbing heterojunction consists of C{sub 60} and a fluorinated zinc phthalocyanine derivative (F4-ZnPc) that leads to a 0.1-0.15 V higher open circuit voltage V{sub oc} than the commonly used ZnPc. The second heterojunction incorporates C{sub 60} and a dicyanovinyl-capped sexithiophene derivative (DCV6T) that mainly absorbs in the green. The combination of both heterojunctions into one tandem solar cell leads to an absorption over the whole visible range of the sun spectrum. Thickness variations of the transparent p-doped optical spacer between both subcells in the tandem solar cell is shown to lead to a significant change in short circuit current density j{sub sc} due to optical interference effects, whereas V{sub oc} and fill factor are hardly affected. The maximum efficiency {eta} of about 5.6% is found for a spacer thickness of 150-165 nm. Based on the optimized 165nm thick spacer, effects of intensity and angle of illumination, and temperature on a tandem device are investigated. Variations in illumination intensity lead to a linear change in j{sub sc} over three orders of magnitude and a nearly constant {eta} in the range of 30 to 310 mW cm{sup -2}. Despite the stacked heterojunctions, the performance of the tandem device is robust against different illumination angles: j{sub sc} and {eta} closely follow a cosine behavior between 0 and 70 . Investigations of the temperature behavior of the tandem device show an increase in {eta} of 0.016 percentage points per Kelvin between -20 C and 25 C followed by a plateau up to 50 C. Finally, further optimization of the tandem stack results in a certified {eta} of (6.07 {+-} 0.24)% on (1.9893 {+-} 0.0060)cm{sup 2} (Fraunhofer ISE), i.e., areas large enough to be of

  8. Radiation-induced transformations of isolated organic molecules in solid rare gas matrices

    Feldman, V.I.

    1998-01-01

    Complete text of publication follows. The studies of radiation-chemical behaviour of isolated organic molecules in rigid inert media are of considerable interest for radiation chemistry and general structural chemistry. Previous efforts were limited to the ESR studies of radicals resulting from some small hydrocarbon molecules in frozen rare gas solutions. Recently, we developed an approach to the radiation chemistry of isolated organic molecules using classic matrix isolation procedure for sample preparation and a combination of ESR and IR spectroscopy for characterization of paramagnetic and diamagnetic species resulting form electron irradiation or organic molecules in solid rare gas matrices at 10-15 K. The results obtained reveal high efficiency of energy transfer from rare gas matrix to organic molecules. The total radiation-chemical yields of degradation of organic molecules in argon and xenon matrices were measured directly by IR spectroscopy. The studies of the effect of electron scavengers on the radiolysis of organic molecules in solid rare gases show that the main primary process is positive hole transfer from matrix to additive molecule. ESR spectra of a number of radical cations (alkanes, ethers, arenes) were first characterized in a low-disturbing environment. It was found that the electronic characteristics (IP, polarizability) of the matrix used had crucial effect on trapping and degradation of primary organic radical cations. Using matrices with various IP provides an unique possibility to examine the chemical meaning of excess energy resulting from exothermic positive hole transfer, that is, to follow the fate of excited cations in condensed phase

  9. Intrinsic coincident linear polarimetry using stacked organic photovoltaics.

    Roy, S Gupta; Awartani, O M; Sen, P; O'Connor, B T; Kudenov, M W

    2016-06-27

    Polarimetry has widespread applications within atmospheric sensing, telecommunications, biomedical imaging, and target detection. Several existing methods of imaging polarimetry trade off the sensor's spatial resolution for polarimetric resolution, and often have some form of spatial registration error. To mitigate these issues, we have developed a system using oriented polymer-based organic photovoltaics (OPVs) that can preferentially absorb linearly polarized light. Additionally, the OPV cells can be made semitransparent, enabling multiple detectors to be cascaded along the same optical axis. Since each device performs a partial polarization measurement of the same incident beam, high temporal resolution is maintained with the potential for inherent spatial registration. In this paper, a Mueller matrix model of the stacked OPV design is provided. Based on this model, a calibration technique is developed and presented. This calibration technique and model are validated with experimental data, taken with a cascaded three cell OPV Stokes polarimeter, capable of measuring incident linear polarization states. Our results indicate polarization measurement error of 1.2% RMS and an average absolute radiometric accuracy of 2.2% for the demonstrated polarimeter.

  10. Polarization and ellipticity of high-order harmonics from aligned molecules generated by linearly polarized intense laser pulses

    Le, Anh-Thu; Lin, C. D.; Lucchese, R. R.

    2010-01-01

    We present theoretical calculations for polarization and ellipticity of high-order harmonics from aligned N 2 , CO 2 , and O 2 molecules generated by linearly polarized lasers. Within the rescattering model, the two polarization amplitudes of the harmonics are determined by the photo-recombination amplitudes for photons emitted with polarization parallel or perpendicular to the direction of the same returning electron wave packet. Our results show clear species-dependent polarization states, in excellent agreement with experiments. We further note that the measured polarization ellipse of the harmonic furnishes the needed parameters for a 'complete' experiment in molecules.

  11. Collision cross section calculations for polyatomic ions considering rotating diatomic/linear gas molecules

    Larriba-Andaluz, Carlos; Hogan, Christopher J.

    2014-01-01

    Structural characterization of ions in the gas phase is facilitated by measurement of ion collision cross sections (CCS) using techniques such as ion mobility spectrometry. Further information is gained from CCS measurement when comparison is made between measurements and accurately predicted CCSs for model ion structures and the gas in which measurements are made. While diatomic gases, namely molecular nitrogen and air, are being used in CCS measurement with increasingly prevalency, the majority of studies in which measurements are compared to predictions use models in which gas molecules are spherical or non-rotating, which is not necessarily appropriate for diatomic gases. Here, we adapt a momentum transfer based CCS calculation approach to consider rotating, diatomic gas molecule collisions with polyatomic ions, and compare CCS predictions with a diatomic gas molecule to those made with a spherical gas molecular for model spherical ions, tetra-alkylammonium ions, and multiply charged polyethylene glycol ions. CCS calculations are performed using both specular-elastic and diffuse-inelastic collisions rules, which mimic negligible internal energy exchange and complete thermal accommodation, respectively, between gas molecule and ion. The influence of the long range ion-induced dipole potential on calculations is also examined with both gas molecule models. In large part we find that CCSs calculated with specular-elastic collision rules decrease, while they increase with diffuse-inelastic collision rules when using diatomic gas molecules. Results clearly show the structural model of both the ion and gas molecule, the potential energy field between ion and gas molecule, and finally the modeled degree of kinetic energy exchange between ion and gas molecule internal energy are coupled to one another in CCS calculations, and must be considered carefully to obtain results which agree with measurements

  12. Toxicology of organic-inorganic hybrid molecules: bio-organometallics and its toxicology.

    Fujie, Tomoya; Hara, Takato; Kaji, Toshiyuki

    2016-01-01

    Bio-organometallics is a research strategy of biology that uses organic-inorganic hybrid molecules. The molecules are expected to exhibit useful bioactivities based on the unique structure formed by interaction between the organic structure and intramolecular metal(s). However, studies on both biology and toxicology of organic-inorganic hybrid molecules have been incompletely performed. There can be two types of toxicological studies of bio-organometallics; one is evaluation of organic-inorganic hybrid molecules and the other is analysis of biological systems from the viewpoint of toxicology using organic-inorganic hybrid molecules. Our recent studies indicate that cytotoxicity of hybrid molecules containing a metal that is nontoxic in inorganic forms can be more toxic than that of hybrid molecules containing a metal that is toxic in inorganic forms when the structure of the ligand is the same. Additionally, it was revealed that organic-inorganic hybrid molecules are useful for analysis of biological systems important for understanding the toxicity of chemical compounds including heavy metals.

  13. Using a Spectrofluorometer for Resonance Raman Spectra of Organic Molecules

    Vadivel Masilamani

    2017-01-01

    Full Text Available Scattering (Rayleigh and Raman and fluorescence are two common light signals that frequently occur together, confusing the researchers and graduate students experimenting in molecular spectroscopy laboratories. This report is a brief study presenting a clear discrimination between the two signals mentioned, employing a common spectrofluorometer such as the PerkinElmer LS 55. Even better, the resonance Raman signal of a molecule (e.g., acetone can be obtained elegantly using the same instrument.

  14. Revival structures of linear molecules in a field-free alignment condition as probed by high-order harmonic generation

    Lee, G. H.; Kim, H. T.; Park, J. Y.; Nam, C. H.; Kim, T. K.; Lee, J. H.; Ihee, H.

    2006-01-01

    Revival structures (rotational coherence) of three linear molecules (N 2 , O 2 , and CO 2 ) in a field free alignment condition have been investigated using high-order harmonic generation. The harmonic yields of these molecules were measured in a pump-probe manner by using a weak femtosecond (fs) laser pulse for field-free alignment of molecules and another intense fs laser pulse for harmonic generation. The harmonic intensities from 23rd to 29th order with respect to the time delay between the pump and the probe pulses showed revival structures in the condition of a field-free alignment of molecules. While the revival structure of a N 2 molecule had one-fourth the period of the full revival time and different degrees of modulation among different fractional revival times, the revival structures of O 2 and CO 2 molecules showed one-eighth the periods of the full revival time and similar degrees of modulation among all fractional revival times. The revival structures could be interpreted in terms of the nature of the highest occupied molecular orbital and the total nuclear spin.

  15. First-principles Hubbard U approach for small molecule binding in metal-organic frameworks

    Mann, Gregory W., E-mail: gmann@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Mesosphere, Inc., San Francisco, California 94105 (United States); Lee, Kyuho, E-mail: kyuholee@lbl.gov [Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720 (United States); Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Synopsys, Inc., Mountain View, California 94043 (United States); Cococcioni, Matteo, E-mail: matteo.cococcioni@epfl.ch [Theory and Simulation of Materials (THEOS), École Polytechnique Fédérale de Lausanne, Lausanne (Switzerland); Smit, Berend, E-mail: Berend-Smit@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720 (United States); Laboratory of Molecular Simulation, Institut des Sciences et Ingénierie Chimiques, Valais Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de l’Industrie 17, CH-1951 Sion (Switzerland); Neaton, Jeffrey B., E-mail: jbneaton@lbl.gov [Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of California, Berkeley, California 94720 (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720 (United States)

    2016-05-07

    We apply first-principles approaches with Hubbard U corrections for calculation of small molecule binding energetics to open-shell transition metal atoms in metal-organic frameworks (MOFs). Using density functional theory with van der Waals dispersion-corrected functionals, we determine Hubbard U values ab initio through an established linear response procedure for M-MOF-74, for a number of different metal centers (M = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu). While our ab initio U values differ from those used in previous work, we show that they result in lattice parameters and electronic contributions to CO{sub 2}-MOF binding energies that lead to excellent agreement with experiments and previous results, yielding lattice parameters within 3%. In addition, U-dependent calculations for an example system, Co-MOF-74, suggest that the CO{sub 2} binding energy grows monotonically with the value of Hubbard U, with the binding energy shifting 4 kJ/mol (or 0.041 eV) over the range of U = 0-5.4 eV. These results provide insight into an approximate but computationally efficient means for calculation of small molecule binding energies to open-shell transition metal atoms in MOFs and suggest that the approach can be predictive with good accuracy, independent of the cations used and the availability of experimental data.

  16. Carbon Chain Anions and the Growth of Complex Organic Molecules in Titan’s Ionosphere

    Desai, R. T.; Coates, A. J.; Wellbrock, A.; Vuitton, V.; Crary, F. J.; González-Caniulef, D.; Shebanits, O.; Jones, G. H.; Lewis, G. R.; Waite, J. H.; Cordiner, M.; Taylor, S. A.; Kataria, D. O.; Wahlund, J.-E.; Edberg, N. J. T.; Sittler, E. C.

    2017-08-01

    Cassini discovered a plethora of neutral and ionized molecules in Titan’s ionosphere including, surprisingly, anions and negatively charged molecules extending up to 13,800 u q-1. In this Letter, we forward model the Cassini electron spectrometer response function to this unexpected ionospheric component to achieve an increased mass resolving capability for negatively charged species observed at Titan altitudes of 950-1300 km. We report on detections consistently centered between 25.8 and 26.0 u q-1 and between 49.0-50.1 u q-1 which are identified as belonging to the carbon chain anions, CN-/C3N- and/or C2H-/C4H-, in agreement with chemical model predictions. At higher ionospheric altitudes, detections at 73-74 u q-1 could be attributed to the further carbon chain anions C5N-/C6H- but at lower altitudes and during further encounters extend over a higher mass/charge range. This, as well as further intermediary anions detected at >100 u, provide the first evidence for efficient anion chemistry in space involving structures other than linear chains. Furthermore, at altitudes below environments where chain anions have been observed and shows that anion chemistry plays a role in the formation of complex organics within a planetary atmosphere as well as in the interstellar medium.

  17. First-principles Hubbard U approach for small molecule binding in metal-organic frameworks

    Mann, Gregory W.; Lee, Kyuho; Cococcioni, Matteo; Smit, Berend; Neaton, Jeffrey B.

    2016-01-01

    We apply first-principles approaches with Hubbard U corrections for calculation of small molecule binding energetics to open-shell transition metal atoms in metal-organic frameworks (MOFs). Using density functional theory with van der Waals dispersion-corrected functionals, we determine Hubbard U values ab initio through an established linear response procedure for M-MOF-74, for a number of different metal centers (M = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu). While our ab initio U values differ from those used in previous work, we show that they result in lattice parameters and electronic contributions to CO 2 -MOF binding energies that lead to excellent agreement with experiments and previous results, yielding lattice parameters within 3%. In addition, U-dependent calculations for an example system, Co-MOF-74, suggest that the CO 2 binding energy grows monotonically with the value of Hubbard U, with the binding energy shifting 4 kJ/mol (or 0.041 eV) over the range of U = 0-5.4 eV. These results provide insight into an approximate but computationally efficient means for calculation of small molecule binding energies to open-shell transition metal atoms in MOFs and suggest that the approach can be predictive with good accuracy, independent of the cations used and the availability of experimental data.

  18. Importance of the alignment of polar π conjugated molecules inside carbon nanotubes in determining second-order non-linear optical properties.

    Yumura, Takashi; Yamamoto, Wataru

    2017-09-20

    We employed density functional theory (DFT) calculations with dispersion corrections to investigate energetically preferred alignments of certain p,p'-dimethylaminonitrostilbene (DANS) molecules inside an armchair (m,m) carbon nanotube (n × DANS@(m,m)), where the number of inner molecules (n) is no greater than 3. Here, three types of alignments of DANS are considered: a linear alignment in a parallel fashion and stacking alignments in parallel and antiparallel fashions. According to DFT calculations, a threshold tube diameter for containing DANS molecules in linear or stacking alignments was found to be approximately 1.0 nm. Nanotubes with diameters smaller than 1.0 nm result in the selective formation of linearly aligned DANS molecules due to strong confinement effects within the nanotubes. By contrast, larger diameter nanotubes allow DANS molecules to align in a stacking and linear fashion. The type of alignment adopted by the DANS molecules inside a nanotube is responsible for their second-order non-linear optical properties represented by their static hyperpolarizability (β 0 values). In fact, we computed β 0 values of DANS assemblies taken from optimized n × DANS@(m,m) structures, and their values were compared with those of a single DANS molecule. DFT calculations showed that β 0 values of DANS molecules depend on their alignment, which decrease in the following order: linear alignment > parallel stacking alignment > antiparallel stacking alignment. In particular, a linear alignment has a β 0 value more significant than that of the same number of isolated molecules. Therefore, the linear alignment of DANS molecules, which is only allowed inside smaller diameter nanotubes, can strongly enhance their second-order non-linear optical properties. Since the nanotube confinement determines the alignment of DANS molecules, a restricted nanospace can be utilized to control their second-order non-linear optical properties. These DFT findings can assist in the

  19. A linear solvation energy relationship model of organic chemical partitioning to dissolved organic carbon.

    Kipka, Undine; Di Toro, Dominic M

    2011-09-01

    Predicting the association of contaminants with both particulate and dissolved organic matter is critical in determining the fate and bioavailability of chemicals in environmental risk assessment. To date, the association of a contaminant to particulate organic matter is considered in many multimedia transport models, but the effect of dissolved organic matter is typically ignored due to a lack of either reliable models or experimental data. The partition coefficient to dissolved organic carbon (K(DOC)) may be used to estimate the fraction of a contaminant that is associated with dissolved organic matter. Models relating K(DOC) to the octanol-water partition coefficient (K(OW)) have not been successful for many types of dissolved organic carbon in the environment. Instead, linear solvation energy relationships are proposed to model the association of chemicals with dissolved organic matter. However, more chemically diverse K(DOC) data are needed to produce a more robust model. For humic acid dissolved organic carbon, the linear solvation energy relationship predicts log K(DOC) with a root mean square error of 0.43. Copyright © 2011 SETAC.

  20. Application of the weak-field asymptotic theory to the analysis of tunneling ionization of linear molecules

    Madsen, Lars Bojer; Tolstikhin, Oleg I.; Morishita, Toru

    2012-01-01

    The recently developed weak-field asymptotic theory [ Phys. Rev. A 84 053423 (2011)] is applied to the analysis of tunneling ionization of a molecular ion (H2+), several homonuclear (H2, N2, O2) and heteronuclear (CO, HF) diatomic molecules, and a linear triatomic molecule (CO2) in a static...... electric field. The dependence of the ionization rate on the angle between the molecular axis and the field is determined by a structure factor for the highest occupied molecular orbital. This factor is calculated using a virtually exact discrete variable representation wave function for H2+, very accurate...... Hartree-Fock wave functions for the diatomics, and a Hartree-Fock quantum chemistry wave function for CO2. The structure factors are expanded in terms of standard functions and the associated structure coefficients, allowing the determination of the ionization rate for any orientation of the molecule...

  1. Effect of organic molecules on hydrolysis of peptide bond: A DFT study

    Makshakova, Olga; Ermakova, Elena

    2013-01-01

    Highlights: ► DFT study of the effects of small organic molecules on the hydrolysis reactions of peptide bonds. ► Organic molecules can activate nonenzymatic hydrolysis reaction. ► Influence of organic acids on activation energy barrier correlates with their electronegativity. - Abstract: The activation and inhibition effects of small organic molecules on peptide hydrolysis have been studied using a model compound dialanine and DFT approach. Solvent-assisted and non-assisted concerted mechanisms were analyzed. Several transition states for the systems: alanine dipeptide–water molecule in complexes with alcohol molecules, acetonitrile, dimethylsulfoxide, propionic, lactic and pyruvic acids and water molecules were localized. The formation of hydrogen bonds between dipeptide, reactive water molecule and molecules of solvents influences the activation energy barrier of the peptide bond hydrolytic reaction. Strong effect of organic acids on the activation energy barrier correlates with their electronegativity. Acetonitrile can act as an inhibitor of reaction. Mechanisms of regulation of the activation energy barrier are discussed in the terms of donor-acceptor interactions

  2. Carbon Chain Anions and the Growth of Complex Organic Molecules in Titan’s Ionosphere

    Desai, R. T.; Coates, A. J.; Wellbrock, A.; González-Caniulef, D.; Jones, G. H.; Lewis, G. R.; Taylor, S. A.; Kataria, D. O. [Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Surrey RH5 6NT (United Kingdom); Vuitton, V. [Université Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble (France); Crary, F. J. [Laboratory for Atmospheric and Space Physics, University of Colorado, Innovation Drive, Boulder, CO 80303 (United States); Shebanits, O.; Wahlund, J.-E. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Waite, J. H. [Space Science and Engineering Division, Southwest Research Institute (SWRI), 6220 Culebra Road, San Antonio, TX 78238 (United States); Cordiner, M.; Sittler, E. C. [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Edberg, N. J. T., E-mail: r.t.desai@ucl.ac.uk [Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala (Sweden)

    2017-08-01

    Cassini discovered a plethora of neutral and ionized molecules in Titan’s ionosphere including, surprisingly, anions and negatively charged molecules extending up to 13,800 u q{sup −1}. In this Letter, we forward model the Cassini electron spectrometer response function to this unexpected ionospheric component to achieve an increased mass resolving capability for negatively charged species observed at Titan altitudes of 950–1300 km. We report on detections consistently centered between 25.8 and 26.0 u q{sup −1} and between 49.0–50.1 u q{sup −1} which are identified as belonging to the carbon chain anions, CN{sup −}/C{sub 3}N{sup −} and/or C{sub 2}H{sup −}/C{sub 4}H{sup −}, in agreement with chemical model predictions. At higher ionospheric altitudes, detections at 73–74 u q{sup −1} could be attributed to the further carbon chain anions C{sub 5}N{sup −}/C{sub 6}H{sup −} but at lower altitudes and during further encounters extend over a higher mass/charge range. This, as well as further intermediary anions detected at >100 u, provide the first evidence for efficient anion chemistry in space involving structures other than linear chains. Furthermore, at altitudes below <1100 km, the low-mass anions (<150 u q{sup −1}) were found to deplete at a rate proportional to the growth of the larger molecules, a correlation that indicates the anions are tightly coupled to the growth process. This study adds Titan to an increasing list of astrophysical environments where chain anions have been observed and shows that anion chemistry plays a role in the formation of complex organics within a planetary atmosphere as well as in the interstellar medium.

  3. Carbon Chain Anions and the Growth of Complex Organic Molecules in Titan’s Ionosphere

    Desai, R. T.; Coates, A. J.; Wellbrock, A.; González-Caniulef, D.; Jones, G. H.; Lewis, G. R.; Taylor, S. A.; Kataria, D. O.; Vuitton, V.; Crary, F. J.; Shebanits, O.; Wahlund, J.-E.; Waite, J. H.; Cordiner, M.; Sittler, E. C.; Edberg, N. J. T.

    2017-01-01

    Cassini discovered a plethora of neutral and ionized molecules in Titan’s ionosphere including, surprisingly, anions and negatively charged molecules extending up to 13,800 u q"−"1. In this Letter, we forward model the Cassini electron spectrometer response function to this unexpected ionospheric component to achieve an increased mass resolving capability for negatively charged species observed at Titan altitudes of 950–1300 km. We report on detections consistently centered between 25.8 and 26.0 u q"−"1 and between 49.0–50.1 u q"−"1 which are identified as belonging to the carbon chain anions, CN"−/C_3N"− and/or C_2H"−/C_4H"−, in agreement with chemical model predictions. At higher ionospheric altitudes, detections at 73–74 u q"−"1 could be attributed to the further carbon chain anions C_5N"−/C_6H"− but at lower altitudes and during further encounters extend over a higher mass/charge range. This, as well as further intermediary anions detected at >100 u, provide the first evidence for efficient anion chemistry in space involving structures other than linear chains. Furthermore, at altitudes below <1100 km, the low-mass anions (<150 u q"−"1) were found to deplete at a rate proportional to the growth of the larger molecules, a correlation that indicates the anions are tightly coupled to the growth process. This study adds Titan to an increasing list of astrophysical environments where chain anions have been observed and shows that anion chemistry plays a role in the formation of complex organics within a planetary atmosphere as well as in the interstellar medium.

  4. On the origin of organic molecules in interstellar space and some of its consequences

    Johansson, K.L.V.

    1981-01-01

    The possible sources of complex organic molecules observed in the interstellar space are discussed. It is found that a leakage from lifebearing planets cannot possibly explain the observed amounts of complex organic molecules. They are probably formed in interstellar clouds, either free in space or on the surface of grains. This opens the possibility that planets (also the earth) moving through such clouds may have collected appreciable amounts of complex organic molecules. It would therefore be feasible to perform experiments like the Urey-Miller's, starting with a considerably more complex mixture than the traditional one. (Auth.)

  5. Prediction of Physicochemical Properties of Organic Molecules Using Semi-Empirical Methods

    Kim, Chan Kyung; Kim, Chang Kon; Kim, Miri; Lee, Hai Whang; Cho, Soo Gyeong

    2013-01-01

    Prediction of physicochemical properties of organic molecules is an important process in chemistry and chemical engineering. The MSEP approach developed in our lab calculates the molecular surface electrostatic potential (ESP) on van der Waals (vdW) surfaces of molecules. This approach includes geometry optimization and frequency calculation using hybrid density functional theory, B3LYP, at the 6-31G(d) basis set to find minima on the potential energy surface, and is known to give satisfactory QSPR results for various properties of organic molecules. However, this MSEP method is not applicable to screen large database because geometry optimization and frequency calculation require considerable computing time. To develop a fast but yet reliable approach, we have re-examined our previous work on organic molecules using two semi-empirical methods, AM1 and PM3. This new approach can be an efficient protocol in designing new molecules with improved properties

  6. Theoretical study of molecular vibration and Application to linear triatomic molecules: case of OCS

    Andrianavalomahefa, A.

    2014-01-01

    Our aim is to give a theoretical approach to the calculation of vibrational energy levels of polyatomic molecules. By using matrix calculation, we have to solve an eigenvalue equation that gives normal vibration frequencies of the system. A basis change introduces normal coordinates of vibration, which diagonalize the Hamiltonian. The harmonic approximation gives a rough evaluation of parameters which describe the system. Then, we introduce nonlinear terms to take into account the anharmonicity of interatomic bounds. Morse oscillator gives good approximation for diatomic molecules. We consider cubic and quartic potential terms for polyatomic molecules. We treat the problem both in classical and quantum approach. The results thus obtained are applied to study longitudinal vibration of carbonyl sulfide. [fr

  7. Small organic molecules on surfaces fundamentals and applications

    Draxl, Claudia; Ramsey, Michael

    2013-01-01

    This book deals with basic aspects of polymer electronics and optoelectronics. There is an enormous world-wide effort both in basic scientific research as well as in industrial development in the area of organic electronics. It is becoming increasingly clear that, if devices based on organic materials are ever going to have a significant relevance beyond being a cheap replacement for inorganic semiconductors, there will be a need to understand interface formation, film growth and functionality. A control of these aspects will allow the realisation of totally new device concepts exploiting the enormous flexibility inherent in organic chemistry. In this book we focus on oligomeric/molecular films as we believe that the control of molecular structures and interfaces provides highly defined systems which allow, on the one hand the study of the basic physics and on the other hand to find the important parameters necessary to improve organic devices.

  8. Structural and electronic properties of single molecules and organic layers on surfaces

    Sotthewes, Kai

    2016-01-01

    Single molecules and organic layers on well-defined solid surfaces have attracted tremendous attention owing to their interesting physical and chemical properties. The ultimate utility of single molecules or self-assembled monolayers (SAMs) for potential applications is critically dependent on the

  9. Anchoring of organic molecules to a metal surface: HtBDC on Cu(110)

    Schunack, M.; Petersen, L.; Kuhnle, A.

    2001-01-01

    The interaction of largish molecules with metal surfaces has been studied by combining the imaging and manipulation capabilities of the scanning tunneling microscope (STM). At the atomic scale, the STM results directly reveal that the adsorption of a largish organic molecule can induce...

  10. Inorganic-Organic Molecules and Solids with Nanometer-Sized Pores

    Maverick, Andrew W

    2011-12-17

    We are constructing porous inorganic-organic hybrid molecules and solids, many of which contain coordinatively unsaturated metal centers. In this work, we use multifunctional ²-diketone ligands as building blocks to prepare extended-solid and molecular porous materials that are capable of reacting with a variety of guest molecules.

  11. Spin thermoelectric effects in organic single-molecule devices

    Wang, H.L.; Wang, M.X.; Qian, C.; Hong, X.K.; Zhang, D.B.; Liu, Y.S.; Yang, X.F., E-mail: xfyang@cslg.edu.cn

    2017-05-25

    Highlights: • A stronger spin thermoelectric performance in a polyacetylene device is observed. • For the antiferromagnetic (AFM) ordering, a transport gap is opened. Thus the thermoelectric effects are largely enhanced. - Abstract: The spin thermoelectric performance of a polyacetylene chain bridging two zigzag graphene nanoribbons (ZGNRs) is investigated based on first principles method. Two different edge spin arrangements in ZGNRs are considered. For ferromagnetic (FM) ordering, transmission eigenstates with different spin indices distributed below and above Fermi level are observed, leading directly to a strong spin thermoelectric effect in a wide temperature range. With the edge spins arranged in the antiferromagnetic (AFM) ordering, an obvious transport gap appears in the system, which greatly enhances the thermoelectric effects. The presence of a small spin splitting also induces a spin thermoelectric effect greater than the charge thermoelectric effect in certain temperature range. In general, the single-molecule junction exhibits the potential to be used for the design of perfect thermospin devices.

  12. Molecules with linear pi-conjugated pathways between all substituents : Omniconjugation

    van der Veen, M.H.; Rispens, M.T; Jonkman, H.T.; Hummelen, J.C.

    In this paper, omniconjugation is introduced as a topological phenomenon in pi-conjugated systems. Omniconjugated molecules are defined by the fact that they provide direct and fully pi-conjugated pathways between all subdstituents attached to them. Surprisingly, until now such topologies have never

  13. Molecules with Linear π-Conjugated Pathways between All Substituents : Omniconjugation

    Veen, Marleen H. van der; Rispens, Minze T.; Jonkman, Harry T.; Hummelen, Jan C.

    2004-01-01

    In this paper, omniconjugation is introduced as a topological phenomenon in π-conjugated systems. Omniconjugated molecules are defined by the fact that they provide direct and fully π-conjugated pathways between all substituents attached to them. Surprisingly, until now such topologies have never

  14. Conductance mechanism in a linear non-conjugated trimethylsilyl-acetylene molecule: tunneling through localized states

    Petrov, E.G.; Marchenko, A.; Kapitanchuk, O.; Katsonis, Nathalie Hélène; Fichou, D.

    2014-01-01

    The conductance properties of 1,3-(trimethylsilyl)-1-tridecene-6,12-diyne, a non-conjugated trimethylsil-acetylene molecule have been investigated both experimentally and theoretically. Based on scanning tunnelling spectroscopy experiments, a discussion on the mechanisms controlling the charge

  15. Organic Semiconductor-Containing Supramolecules: Effect of Small Molecule Crystallization and Molecular Packing

    Rancatore, Benjamin J.; Kim, BongSoo; Mauldin, Clayton E.; Frechet, Jean; Xu, Ting

    2016-01-01

    on these highly crystalline molecules differs from their less crystalline counterparts. Here, two families of organic semiconductor SMs are investigated, where the composition of the crystalline core, the location (side- vs end-functionalization) of the alkyl

  16. Bifunctional Pt-Si Alloys for Small Organic Molecule Electro-oxidation

    Permyakova, Anastasia Aleksandrovna; Suntivich, Jin; Han, Binghong

    Designing highly active catalysts for electro-oxidation of small organic molecules can help to reduce the anodic overpotential for more efficient utilization of hydrocarbon fuels. The challenge in developing more active electrocatalysts for electro-oxidation reactions is to satisfy the stringent...... adsorption site. We will discuss the enhanced activity of Pt-Si alloys for small organic molecule oxidation, which can be attributed to the improved CO electro-oxidation kinetics on Pt-Si....

  17. Organic molecules in the Sheepbed Mudstone, Gale Crater, Mars

    Freissinet, C.; Glavin, D. P.; Mahaffy, P. R.; Miller, K. E.; Eigenbrode, J. L.; Summons, R. E.; Brunner, A. E.; Buch, A.; Szopa, C.; Archer, P. D.; Franz, H. B.; Atreya, S. K.; Brinckerhoff, W. B.; Cabane, M.; Coll, P.; Conrad, P. G.; Des Marais, D. J.; Dworkin, J. P.; Fairén, A. G.; François, P.; Grotzinger, J. P.; Kashyap, S.; ten Kate, I. L.; Leshin, L. A.; Malespin, C. A.; Martin, M. G.; Martin-Torres, F. J.; Mcadam, A. C.; Ming, D. W.; Navarro-González, R.; Pavlov, A. A.; Prats, B. D.; Squyres, S. W.; Steele, A.; Stern, J. C.; Sumner, D. Y.; Sutter, B.; Zorzano, M. P.

    The Sample Analysis at Mars (SAM) instrument on board the Mars Science Laboratory Curiosity rover is designed to conduct inorganic and organic chemical analyses of the atmosphere and the surface regolith and rocks to help evaluate the past and present habitability potential of Mars at Gale Crater.

  18. Power losses in bilayer inverted small molecule organic solar cells

    Trinh, Cong; Bakke, Jonathan R.; Brennan, Thomas P.; Bent, Stacey F.; Navarro, Francisco; Bartynski, Andrew; Thompson, Mark E.

    2012-01-01

    Inverted bilayer organic solar cells using copper phthalocyanine (CuPc) as a donor and C60 as an acceptor with the structure: glass/indium tin oxide (ITO)/ZnO/C60/CuPc/MoO3/Al, in which the zinc oxide (ZnO) was deposited by atomic layer deposition

  19. Tuning Interfacial States Using Organic Molecules as Spin Filters

    Deloach, Andrew; Wang, Jingying; Papa, Christopher M.; Myahkostupov, Mykhaylo; Castellano, Felix N.; Dougherty, Daniel B.; Jiang, Wei; Liu, Feng

    Organic semiconductors are known to have long spin relaxation times which makes them a good candidate for spintronics. However, an issue with these materials is that at metal-organic interfaces there is a conductivity mismatch problem that suppresses spin injection. To overcome this, orbital mixing at the interface can be tuned with an organic spacer layer to promote the formation of spin polarized interface states. These states act as a ``spin filters'' and have been proposed as an explanation for the large tunneling magnetoresistance seen in devices using tris-(8-hydroxyquinolate)-aluminum(Alq3). Here, we show that the spin polarized interface states can be tuned from metallic to resistive by subtle changes in molecular orbitals. This is done using spin polarized scanning tunneling microscopy with three different tris-(8-hydroxyquinolate) compounds: aluminum, chromium, and iron. Differences in d-orbital mixing results in different mechanisms of interfacial coupling, giving rise to metallic or resistive interface states. Supported by the U.S. DoE award No. DE-SC0010324.

  20. Magnesium Sulfate as a Key Mineral for the Detection of Organic Molecules on Mars Using Pyrolysis

    Francois, P.; Szopa, C.; Buch, A.; Coll, P.; McAdam, A. C.; Mahaffy, P. R.; Freissinet, C.; Glavin, D. P.; Navarro-Gonzalez, R.; Cabane, M.

    2016-01-01

    Pyrolysis of soil or rock samples is the preferred preparation technique used on Mars to search for organic molecules up today. During pyrolysis, oxichlorines present in the soil of Mars release oxidant species that alter the organic molecules potentially contained in the samples collected by the space probes.This process can explain the difficulty experienced by in situ exploration probes to detect organic materials in Mars soil samples until recently. Within a few months, the Curiosity rover should reach and analyze for the first time soils rich in sulfates which could induce a different behavior of the organics during the pyrolysis compared with the types of soils analyzed up today. For this reason, we systematically studied the pyrolysis of organic molecules trapped in magnesium sulfate, in the presence or absence of calcium perchlorate. Our results show that organics trapped in magnesium sulfate can undergo some oxidation and sulfuration during the pyrolysis. But these sulfates are also shown to protect organics trapped inside the crystal lattice and/or present in fluid inclusions from the oxidation induced by the decomposition of calcium perchlorate and probably other oxychlorine phases currently detected on Mars. Trapped organics may also be protected from degradation processes induced by other minerals present in the sample, at least until these organics are released from the pyrolyzed sulfate mineral (700C in our experiment). Hence, we suggest magnesium sulfate as one of the minerals to target in priority for the search of organic molecules by the Curiosity and ExoMars 2018 rovers.

  1. Inducing elliptically polarized high-order harmonics from aligned molecules with linearly polarized femtosecond pulses

    Etches, Adam; Madsen, Christian Bruun; Madsen, Lars Bojer

    2010-01-01

    A recent paper reported elliptically polarized high-order harmonics from aligned N2 using a linearly polarized driving field [X. Zhou et al., Phys. Rev. Lett. 102, 073902 (2009)]. This observation cannot be explained in the standard treatment of the Lewenstein model and has been ascribed to many...

  2. A Linear Tetranuclear Dysprosium(III) Compound Showing Single-Molecule Magnet Behavior

    Ke, Hongshan; Xu, Gong Feng; Guo, Yun-Nan; Gamez, Patrick; Beavers, Christine M; Teat, Simon J; Tang, Jinkui

    2010-04-20

    Although magnetic measurements reveal a single-relaxation time for a linear tetranuclear Dy(III) compound, the wide distribution of the relaxation time observed clearly suggests the presence of two slightly different anisotropic centres, therefore opening new avenues for investigating the relaxation dynamics of lanthanide aggregates.

  3. Nuclear spin-spin coupling constants of linear carbon chains terminated by coronene molecules: a first principles study

    Oliveira, Joao Paulo Cavalcante; Mota, F. de Brito; Rivelino, Roberto

    2011-01-01

    Full text. Carbon nano wires made of long linear atomic chains have attracted considerable interest due to their potential applications in nano electronics. We report a density-functional-theory study of the nuclear spin-spin coupling constants for nano assemblies made of two coronene molecules bridged by carbon linear chains, considering distinct sizes and spin multiplicities. Also, we examine the effects of two terminal conformations (syn and anti) of the terminal anchor pieces on the magnetic properties of the carbon chains via 13 C NMR calculations. Our results reveal that simplified chemical models such as those based on cumulenes or polyynes are not appropriate to describe the linear chains with sp 2 terminations. For these types of atomic chains, the electronic ground state of the even-numbered chains can be singlet or triplet, whereas the ground state of the odd-numbered chains can be doublet or quartet. We discuss how the 13 C NMR chemical shift absorption is affected by increasing the size and changing the parity of the linear carbon chains. We have found that the J coupling constants between the carbon atoms in the linear chains present a well-defined pattern, in good accordance with our electronic structure calculations. For example, in the -C 4 - units we obtain couplings of 43.8, 114.5, 84.6, 114.5, and 43.8 Hz from one end to the other

  4. Characterisation of aggregation of tributylphosphate molecules in organic solvent

    Mandin, C.; Martinet, L.; Zemb, Th.; Berthon, L.; Madic, Ch.

    2000-01-01

    This report presents a structural study of the aggregates formed with the organic phases of the extractant tri-n-butyl phosphate, used in the industrial PUREX process (Plutonium and Uranium Extraction; liquid-liquid solvent extraction) for the treatment of high radioactive waste. Combined Small Angle X-ray Scattering and Small Angle Neutron Scattering show that organic TBP solutions (in equilibrium with acid solutions) are organised in oligomeric aggregates. The influence of various parameters such as HNO 3 or TBP concentrations, diluent or acid natures, does not seem to modify the aggregate shape and size, whereas the interactions are modified. Moreover the aggregates disappear under high temperatures, whereas the attractive interactions between them increase at low temperatures. The 'drop weight' method gives the critical micellar concentration values of TBP in case of H 2 O or HNO 3 extractions (H 2 O: 0.48 M; HNO 3 2M: 0.65 M; at 21 deg C). Furthermore, the measures at different acid concentrations show that the c.m.c. varies with the acidity. The more acid the aqueous phase is, the smaller is the entropy in the system because of the numerous negative charges, i.e. the harder the micellization occurs, so the higher the c.m.c. value is. The sticky sphere model proposed by Baxter, can be used to model successfully small reverse micelles of the organic TBP phases. The aggregation number would be 4±1 (water extraction) and 5±1(HNO 3 2M extraction). These values are also given by vapor pressure measurements. (authors)

  5. Simultaneous atomization and ionization of large organic molecules using femtosecond laser ablation

    Kurata-Nishimura, Mizuki; Tokanai, Fuyuki; Matsuo, Yukari; Kobayashi, Tohru; Kawai, Jun; Kumagai, Hiroshi; Midorikawa, Katsumi; Tanihata, Isao; Hayashizaki, Yoshihide

    2002-01-01

    We have experimentally demonstrated femtosecond laser ablation for simultaneous atomization and ionization (fs-SAI) of organic molecules on solid substrates. We find most of the constituent atoms of organic molecules are atomized and ionized non-resonantly by femtosecond laser ablation. This observation is in contrast with that for the photoionization of cyclic aromatic hydrocarbons by femtosecond laser in the gas phase where little fragmentation has been observed. Crucial contribution of ablation plasma of solid sample to fs-SAI process is suggested. The ratio of natural abundance of stable isotopes contained in sample molecules is well reproduced, which confirms fs-SAI can be applied to the quantitative chemical analysis of isotope-labeled large organic molecules

  6. Power losses in bilayer inverted small molecule organic solar cells

    Trinh, Cong

    2012-01-01

    Inverted bilayer organic solar cells using copper phthalocyanine (CuPc) as a donor and C60 as an acceptor with the structure: glass/indium tin oxide (ITO)/ZnO/C60/CuPc/MoO3/Al, in which the zinc oxide (ZnO) was deposited by atomic layer deposition, are compared with a conventional device: glass/ITO/CuPc/C60/bathocuproine/Al. These inverted and conventional devices give short circuit currents of 3.7 and 4.8 mA/cm 2, respectively. However, the inverted device gives a reduced photoresponse from the CuPc donor compared to that of the conventional device. Optical field models show that the arrangement of organic layers in the inverted devices leads to lower absorption of long wavelengths by the CuPc donor; the low energy portion of the spectrum is concentrated near the metal oxide electrode in both devices. © 2012 American Institute of Physics.

  7. Interface properties of organic molecules on metal surfaces; Grenzflaecheneigenschaften organischer Molekuele auf Metalloberflaechen

    Karacuban, Hatice

    2010-01-28

    In this work, the growth of the archetype molecules CuPc and PTCDA was investigated on Cu(111). PTCDA was also studied on NaCl/Cu(111). The main experiments were carried out with a scanning tunneling microscope. Structural analysis of CuPc on Cu (111) is only possible at low temperatures, since at room temperature the molecules exhibit a high surface mobility. For the investigation of these structures and especially to enable scanning tunneling spectroscopy, a low-temperature scanning tunneling microscope was developed. Using this home built STM the experiments could be carried out at about 10 K. After the adsorption of CuPc on Cu (111) a substrate-induced symmetry reduction of the molecules can be observed in scanning tunneling microscopy. When the occupied states of the molecules are imaged, a switching between two distinct levels is found. These modifications are determined by the adsorption geometry of the molecules. Based on high resolution STM data, an on-top adsorption geometry of the CuPc-molecules on Cu (111)-substrate can be deducted. At low temperatures, two new superstructures of PTCDA on Cu(111) are observed. The molecules within these superstructures are tilted with respect to the substrate. Intermolecular interactions may be the crucial factor for the realignment of the molecules. If PTCDA molecules are adsorbed on a NaCl/Cu (111) substrate, at room temperature, also two new superstructures on the copper substrate were found. They indicate the formation of a metall-organic-complex. On top of the NaCl layer the molecules exclusively grow at polar NaCl step edges. This is an indication for electrostatic interaction between the PTCDA molecules and the NaCl layer. When the molecule density is further increased, a Vollmer-Weber growth sets in. If both molecules PTCDA and CuPc are present on the sample at the same time, local spectroscopy provides information on the metal-organic interface in direct comparison. The STS-results of CuPc/PTCDA on Cu (111

  8. Organic molecules in the atmosphere of Jupiter. Final report

    Ponnamperuma, C.A.

    1978-01-01

    Organic synthesis in the primitive solar system was simulated by Fischer Tropsch type experiments. Particular attention was given to the formation of lower molecular weight hydrocarbons. In a gas flow experiment, a gas mixture of H 2 and CO was introduced into a heated reaction tube at a constant flow rate and passed through a catalyst (powdered Canyon Diablo). The products that emerged were directly analyzed by gas chromatography. The results of 21 runs under various gas mixing rations, reaction temperatures, and gas-catalyst contact times showed the predominance of the saturated hydrocarbon formation at C 4 and C 5 over the unsaturated ones. Saturate/unsaturate ratios were mostly less than 0.4 and none showed over 0.7

  9. Quinone-Catalyzed Selective Oxidation of Organic Molecules

    Wendlandt, Alison E.

    2016-01-01

    Lead In Quinones are common stoichiometric reagents in organic chemistry. High potential para-quinones, such as DDQ and chloranil, are widely used and typically promote hydride abstraction. In recent years, many catalytic applications of these methods have been achieved by using transition metals, electrochemistry or O2 to regenerate the oxidized quinone in situ. Complementary studies have led to the development of a different class of quinones that resemble the ortho-quinone cofactors in Copper Amine Oxidases and mediate efficient and selective aerobic and/or electrochemical dehydrogenation of amines. The latter reactions typically proceed via electrophilic transamination and/or addition-elimination reaction mechanisms, rather than hydride abstraction pathways. The collective observations show that the quinone structure has a significant influence on the reaction mechanism and have important implications for the development of new quinone reagents and quinone-catalyzed transformations. PMID:26530485

  10. Ultrafast photoelectron spectroscopy of small molecule organic films

    Read, Kendall Laine

    As research in the field of ultrafast optics has produced shorter and shorter pulses, at an ever-widening range of frequencies, ultrafast spectroscopy has grown correspondingly. In particular, ultrafast photoelectron spectroscopy allows direct observation of electrons in transient or excited states, regardless of the eventual relaxation mechanisms. High-harmonic conversion of 800nm, femtosecond, Ti:sapphire laser pulses allows excite/probe spectroscopy down into atomic core level states. To this end, an ultrafast, X-UV photoelectron spectroscopic system is described, including design considerations for the high-harmonic generation line, the time of flight detector, and the subsequent data collection electronics. Using a similar experimental setup, I have performed several ultrafast, photoelectron excited state decay studies at the IBM, T. J. Watson Research Center. All of the observed materials were electroluminescent thin film organics, which have applications as the emitter layer in organic light emitting devices. The specific materials discussed are: Alq, BAlq, DPVBi, and Alq doped with DCM or DMQA. Alq:DCM is also known to lase at low photoexcitation thresholds. A detailed understanding of the involved relaxation mechanisms is beneficial to both applications. Using 3.14 eV excite, and 26.7 eV probe, 90 fs laser pulses, we have observed the lowest unoccupied molecular orbital (LUMO) decay rate over the first 200 picoseconds. During this time, diffusion is insignificant, and all dynamics occur in the absence of electron transport. With excitation intensities in the range of 100μJ/cm2, we have modeled the Alq, BAlq, and DPVBi decays via bimolecular singlet-singlet annihilation. At similar excitations, we have modeled the Alq:DCM decay via Förster transfer, stimulated emission, and excimeric formation. Furthermore, the Alq:DCM occupied to unoccupied molecular orbital energy gap was seen to shrink as a function of excite-to-probe delay, in accordance with the

  11. Results of the First Mars Organic Molecule Analyzer (MOMA) GC-MS Coupling

    Buch, Arnaud; Pinnick, Veronica; Szopa, Cyril; Danell, Ryan; Grand, Noel; Van Amerom, Friso; Glavin, Daniel; Freissinet, Caroline; Humeau, Olivier; Coll, Patrice; Arevalo, Ricardo; Stalport, Fabien; Brinckerhoff, William; Steininger, Harald; Goesmann, Fred; Mahaffy, Paul; Raulin, Francois

    2014-11-01

    The Mars Organic Molecule Analyzer (MOMA) aboard the ExoMars rover will be a key analytical tool in providing chemical (molecular) information from the solid samples collected by the rover, with a particular focus on the char-acterization of the organic content. The core of the MOMA instrument is a gas chromatograph coupled with a mass spectrometer (GC-MS) which provides the unique capability to characterize a broad range of compounds, including both of volatile and non-volatile species. Samples will be crushed and deposited into sample cups seated in a rotating carousel. Soil samples will be analyzed either by UV laser desorption / ionization (LDI) or pyrolysis gas chromatography ion trap mass spectrometry (pyr-GC-ITMS).The French GC brassboard was coupled to the US ion trap mass spectrometer brassboard in a flight-like con-figuration for several coupling campains. The MOMA GC setup is based on the SAM heritage design with a He reservoir and 4 separate analytical modules including traps, columns and Thermal Conductivity Detectors. Solid samples are sealed and heated in this setup using a manual tapping station, designed and built at MPS in Germany, for GC-MS analysis. The gaseous species eluting from the GC are then ionized by an electron impact ionization source in the MS chamber and analyzed by the linear ion trap mass spectrometer. Volatile and non-volatile compounds were injected in the MOMA instrumental suite. Both of these compounds classes were detected by the TCD and by the MS. MS signal (total ion current) and single mass spectra by comparison with the NIST library, gave us an unambiguous confirmation of these identifications. The mass spectra arise from an average of 10 mass spectra averaged around a given time point in the total ion chromatogram.Based on commercial instrument, the MOMA requirement for sensitivity in the GC-MS mode for organic molecules is 1 pmol. In this test, sensitivity was determined for the GC TCD and MS response to a dilution

  12. Adsorption of organic molecules may explain growth of newly nucleated clusters and new particle formation

    Wang, Jian; Wexler, Anthony S.

    2013-05-01

    New particle formation consists of formation of thermodynamically stable clusters from trace gas molecules (homogeneous nucleation) followed by growth of these clusters to a detectable size. Because of the large coagulation rate of clusters smaller than 3 nm with the preexisting aerosol population, for new particle formation to take place, these clusters need to grow sufficiently fast to escape removal by coagulation. Previous studies have indicated that condensation of low-volatility organic vapor may play an important role in the initial growth of the clusters. However, due to the relatively high vapor pressure and partial molar volume of even highly oxidized organic compounds, the strong Kelvin effect may prevent typical ambient organics from condensing on these small clusters. Earlier studies did not consider that adsorption of organic molecules on the cluster surface, due to the intermolecular forces between the organic molecule and cluster, may occur and substantially alter the growth process under sub-saturated conditions. Using the Brunauer-Emmett-Teller (BET) isotherm, we show that the adsorption of organic molecules onto the surface of clusters may significantly reduce the saturation ratio required for condensation of organics to occur, and therefore may provide a physico-chemical explanation for the enhanced initial growth by condensation of organics despite the strong Kelvin effect.

  13. Stability of organic molecules against shocks in the young Solar nebula

    Kamp, Inga; Milosavljevic, Milica; Stempels, E

    2009-01-01

    One of the fundamental astrobiology questions is how life has formed in our Solar System. In this context the formation and stability of abiotic organic molecules such as CH(4), formic acid and amino acids, is important for understanding how organic material has formed and survived shocks and

  14. Storage of charge carriers on emitter molecules in organic light-emitting diodes

    Weichsel, Caroline; Burtone, Lorenzo; Reineke, Sebastian; Hintschich, Susanne I.; Gather, Malte C.; Leo, Karl; Lüssem, Björn

    2012-08-01

    Organic light-emitting diodes (OLEDs) using the red phosphorescent emitter iridium(III)bis(2-methyldibenzo[f,h]quinoxaline) (acetylacetonate) [Ir(MDQ)2(acac)] are studied by time-resolved electroluminescence measurements. A transient overshoot after voltage turn-off is found, which is attributed to electron accumulation on Ir(MDQ)2(acac) molecules. The mechanism is verified via impedance spectroscopy and by application of positive and negative off-voltages. We calculate the density of accumulated electrons and find that it scales linearly with the doping concentration of the emitter. Using thin quenching layers, we locate the position of the emission zone during normal OLED operation and after voltage turn-off. In addition, the transient overshoot is also observed in three-color white-emitting OLEDs. By time- and spectrally resolved measurements using a streak camera, we directly attribute the overshoot to electron accumulation on Ir(MDQ)2(acac). We propose that similar processes are present in many state-of-the-art OLEDs and believe that the quantification of charge carrier storage will help to improve the efficiency of OLEDs.

  15. Ejection of Coulomb Crystals from a Linear Paul Ion Trap for Ion-Molecule Reaction Studies.

    Meyer, K A E; Pollum, L L; Petralia, L S; Tauschinsky, A; Rennick, C J; Softley, T P; Heazlewood, B R

    2015-12-17

    Coulomb crystals are being increasingly employed as a highly localized source of cold ions for the study of ion-molecule chemical reactions. To extend the scope of reactions that can be studied in Coulomb crystals-from simple reactions involving laser-cooled atomic ions, to more complex systems where molecular reactants give rise to multiple product channels-sensitive product detection methodologies are required. The use of a digital ion trap (DIT) and a new damped cosine trap (DCT) are described, which facilitate the ejection of Coulomb-crystallized ions onto an external detector for the recording of time-of-flight (TOF) mass spectra. This enables the examination of reaction dynamics and kinetics between Coulomb-crystallized ions and neutral molecules: ionic products are typically cotrapped, thus ejecting the crystal onto an external detector reveals the masses, identities, and quantities of all ionic species at a selected point in the reaction. Two reaction systems are examined: the reaction of Ca(+) with deuterated isotopologues of water, and the charge exchange between cotrapped Xe(+) with deuterated isotopologues of ammonia. These reactions are examples of two distinct types of experiment, the first involving direct reaction of the laser-cooled ions, and the second involving reaction of sympathetically-cooled heavy ions to form a mixture of light product ions. Extensive simulations are conducted to interpret experimental results and calculate optimal operating parameters, facilitating a comparison between the DIT and DCT approaches. The simulations also demonstrate a correlation between crystal shape and image shape on the detector, suggesting a possible means for determining crystal geometry for nonfluorescing ions.

  16. Theoretical studies of MHD plasma molecules. I. Potential energy curves and dipole moments of linear KOH

    England, W.B.

    1978-01-01

    Uncorrelated and correlated potential energy curves and dipole moments are reported for linear KOH. The compound is found to be ionic, K + OH - . Minimum energy bond lengths are R/sub KO/=4.2913 au and R/sub OH/=1.7688 au, with an estimated accuracy of 2%. The corresponding dipole moment is 3.3 au (8.46 D) with a similar accuracy estimate. This is to our knowledge the first value ever reported for the KOH dipole moment, and the large value suggests that KOH will be an effective electron scatterer in MHD plasmas

  17. Organic molecule fluorescence as an experimental test-bed for quantum jumps in thermodynamics.

    Browne, Cormac; Farrow, Tristan; Dahlsten, Oscar C O; Taylor, Robert A; Vlatko, Vedral

    2017-08-01

    We demonstrate with an experiment how molecules are a natural test bed for probing fundamental quantum thermodynamics. Single-molecule spectroscopy has undergone transformative change in the past decade with the advent of techniques permitting individual molecules to be distinguished and probed. We demonstrate that the quantum Jarzynski equality for heat is satisfied in this set-up by considering the time-resolved emission spectrum of organic molecules as arising from quantum jumps between states. This relates the heat dissipated into the environment to the free energy difference between the initial and final state. We demonstrate also how utilizing the quantum Jarzynski equality allows for the detection of energy shifts within a molecule, beyond the relative shift.

  18. Selective transformation of carbonyl ligands to organic molecules

    Cutler, A.R.

    1992-05-12

    Studies on the carbonylation of ({eta}{sup 5}-indenyl)(L)(CO)Ru-R complexes (L = CO, PPh{sub 3}; R = CH{sub 2}OMe, CH{sub 3}) have been completed. Particularly noteworthy is that the methoxymethyl complexes readily transform to their acyl derivatives under mild conditions that leave their iron congeners inert towards CO. Surprisingly, even ({eta}{sup 5}-indenyl)(PPh{sub 3}){sub 2}Ru-CH{sub 3} carbonylates and gives ({eta}{sup 5}-indenyl)(PPh{sub 3})(CO)Ru-C(O)CH{sub 3}. Mechanistic studies on the non catalyzed'' hydrosilation of the manganese acyls (CO){sub 5}Mn-C(O)CH{sub 2}R (R = H, OCH{sub 3}, CH{sub 3}) with Et{sub 3}SiH and of cobalt acetyls (CO){sub 3}(PR{sub 3})CoC(O)CH{sub 3} with several monohydrosilanes have been completed. The cobalt acetyls cleanly give ethoxysilanes (not acetaldehyde), and the manganese acyls provide {alpha}-siloxyvinyl complexes Z-(CO){sub 5}Mn-C(OSiEt{sub 3})=CHR (R = H, CH{sub 3}, OCH{sub 3}). Carbonylation and protolytic cleavage of the latter generate pyruvoyl complexes (CO){sub 5}Mn-COCOR (R = CH{sub 3}, CH{sub 2}CH{sub 3}), formally the products of net double carbonylation'' sequences. Studies in progress are concerned with how manganese complexes as diverse as (CO){sub 5}Mn-Y (Y = C(O)R, R, BR - but not SiMe{sub 3} or Mn(CO){sub 5}) and ({eta}{sup 3}-C{sub 3}H{sub 5})Mn(CO){sub 2}L (but not CpMn(CO){sub 3} or CpMn(CO){sub 2}({eta}{sup 2}HSiR{sub 3})) function as efficient hydrosilation catalysts towards Cp(CO){sub 2}FeC(O)CH{sub 3}, for example. These reactions cleanly afford fully characterized {alpha}-siloxyethyl complexes Fp-CH(OSiR{sub 3})CH{sub 3} under conditions where typically Rh(1) hydrosilation catalysts are inactive. Several of these manganese complexes also catalytically hydrosilate organic esters, including lactones, to their ethers R-CH{sub 2}OR; these novel ester reductions occur quantitatively at room temperature and appear to be general in scope.

  19. A Self-Perpetuating Catalyst for the Production of Complex Organic Molecules in Protostellar Nebulae

    Nuth, Joseph A.; Johnson, N. M.

    2010-01-01

    The formation of abundant carbonaceous material in meteorites is a long standing problem and an important factor in the debate on the potential for the origin of life in other stellar systems. Many mechanisms may contribute to the total organic content in protostellar nebulae, ranging from organics formed via ion-molecule and atom-molecule reactions in the cold dark clouds from which such nebulae collapse, to similar ion-molecule and atom-molecule reactions in the dark regions of the nebula far from the proto star, to gas phase reactions in sub-nebulae around growing giant planets and in the nebulae themselves. The Fischer-Tropsch-type (FTT) catalytic reduction of CO by hydrogen was once the preferred model for production of organic materials in the primitive solar nebula. The Haber-Bosch catalytic reduction of N2 by hydrogen was thought to produce the reduced nitrogen found in meteorites. However, the clean iron metal surfaces that catalyze these reactions are easily poisoned via reaction with any number of molecules, including the very same complex organics that they produce and both reactions work more efficiently in the hot regions of the nebula. We have demonstrated that many grain surfaces can catalyze both FTT and HB-type reactions, including amorphous iron and magnesium silicates, pure silica smokes as well as several minerals. Although none work as well as pure iron grains, and all produce a wide range of organic products rather than just pure methane, these materials are not truly catalysts.

  20. Phase-coherent electron transport through metallic atomic-sized contacts and organic molecules

    Pauly, F.

    2007-02-02

    This work is concerned with the theoretical description of systems at the nanoscale, in particular the electric current through atomic-sized metallic contacts and organic molecules. In the first part, the characteristic peak structure in conductance histograms of different metals is analyzed within a tight-binding model. In the second part, an ab-initio method for quantum transport is developed and applied to single-atom and single-molecule contacts. (orig.)

  1. The cell adhesion molecule Fasciclin2 regulates brush border length and organization in Drosophila renal tubules

    Halberg, Kenneth Agerlin; Rainey, Stephanie M.; Veland, Iben Rønn

    2016-01-01

    Multicellular organisms rely on cell adhesion molecules to coordinate cell-cell interactions, and to provide navigational cues during tissue formation. In Drosophila, Fasciclin 2 (Fas2) has been intensively studied due to its role in nervous system development and maintenance; yet, Fas2 is most...... role for this well-known cell adhesion molecule, and propose that Fas2-mediated intermicrovillar homophilic adhesion complexes help stabilize the brush border....

  2. A Nonfullerene Small Molecule Acceptor with 3D Interlocking Geometry Enabling Efficient Organic Solar Cells.

    Lee, Jaewon; Singh, Ranbir; Sin, Dong Hun; Kim, Heung Gyu; Song, Kyu Chan; Cho, Kilwon

    2016-01-06

    A new 3D nonfullerene small-molecule acceptor is reported. The 3D interlocking geometry of the small-molecule acceptor enables uniform molecular conformation and strong intermolecular connectivity, facilitating favorable nanoscale phase separation and electron charge transfer. By employing both a novel polymer donor and a nonfullerene small-molecule acceptor in the solution-processed organic solar cells, a high-power conversion efficiency of close to 6% is demonstrated. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Molecular-beam electric-resonance studies of linear triatomic molecules

    Reinartz, J.M.L.J.

    1976-01-01

    In the present work, the MBER technique has been employed to investigate the spectra of the high temperature species KCN and CsOH and at low temperatures the spectra of five different isotopic species of OCS in natural mixture and the most abundant isotopic species of N 2 O and ClCN. For the low temperature species, spectra in the ground state and in the first excited state of the bending mode have been obtained. Bending vibrational effects on hyperfine constants and on electric and magnetic constants have been deduced from these spectra. The introduction of nozzle beam sources has been a factor of great importance for this study. For the ground states, high resolution spectra have been obtained both in external electric and in combined parallel electric and magnetic fields. These spectra could well be explained by the known theories for molecules in a 1 Σ state to within an experimental accuracy of about 50-150 Hz. Extension of the theory needed for the interpretation of the spectra for excited bending states is given. Hyperfine properties and electric and magnetic constants have been obtained with very high accuracy from the analysis of the frequencies of the observed transitions within one rotational state (ΔJ = 0 transitions)

  4. Adsorption of organic molecules on mineral surfaces studied by first-principle calculations: A review.

    Zhao, Hongxia; Yang, Yong; Shu, Xin; Wang, Yanwei; Ran, Qianping

    2018-04-09

    First-principle calculations, especially by the density functional theory (DFT) methods, are becoming a power technique to study molecular structure and properties of organic/inorganic interfaces. This review introduces some recent examples on the study of adsorption models of organic molecules or oligomers on mineral surfaces and interfacial properties obtained from first-principles calculations. The aim of this contribution is to inspire scientists to benefit from first-principle calculations and to apply the similar strategies when studying and tailoring interfacial properties at the atomistic scale, especially for those interested in the design and development of new molecules and new products. Copyright © 2017. Published by Elsevier B.V.

  5. Computer software for linear and nonlinear regression in organic NMR

    Canto, Eduardo Leite do; Rittner, Roberto

    1991-01-01

    Calculation involving two variable linear regressions, require specific procedures generally not familiar to chemist. For attending the necessity of fast and efficient handling of NMR data, a self explained and Pc portable software has been developed, which allows user to produce and use diskette recorded tables, containing chemical shift or any other substituent physical-chemical measurements and constants (σ T , σ o R , E s , ...)

  6. Solution processable organic polymers and small molecules for bulk-heterojunction solar cells: A review

    Sharma, G. D.

    2011-01-01

    Solution processed bulk heterojunction (BHJ) organic solar cells (OSCs) have gained wide interest in past few years and are established as one of the leading next generation photovoltaic technologies for low cost power production. Power conversion efficiencies up to 6% and 6.5% have been reported in the literature for single layer and tandem solar cells, respectively using conjugated polymers. A recent record efficiency about 8.13% with active area of 1.13 cm 2 has been reported. However Solution processable small molecules have been widely applied for photovoltaic (PV) devices in recent years because they show strong absorption properties, and they can be easily purified and deposited onto flexible substrates at low cost. Introducing different donor and acceptor groups to construct donor--acceptor (D--A) structure small molecules has proved to be an efficient way to improve the properties of organic solar cells (OSCs). The power conversion efficiency about 4.4 % has been reported for OSCs based on the small molecules. This review deals with the recent progress of solution processable D--A structure small molecules and discusses the key factors affecting the properties of OSCs based on D--A structure small molecules: sunlight absorption, charge transport and the energy level of the molecules.

  7. Influence of thermocleavable functionality on organic field-effect transistor performance of small molecules

    Mahale, Rajashree Y.; Dharmapurikar, Satej S.; Chini, Mrinmoy Kumar; Venugopalan, Vijay

    2017-06-01

    Diketopyrrolopyrrole based donor-acceptor-donor conjugated small molecules using ethylene dioxythiophene as a donor was synthesized. Electron deficient diketopyrrolopyrrole unit was substituted with thermocleavable (tert-butyl acetate) side chains. The thermal treatment of the molecules at 160 °C eliminated the tert-butyl ester group results in the formation of corresponding acid. Optical and theoretical studies revealed that the molecules adopted a change in molecular arrangement after thermolysis. The conjugated small molecules possessed p-channel charge transport characteristics in organic field effect transistors. The charge carrier mobility was increased after thermolysis of tert-butyl ester group to 5.07 × 10-5 cm2/V s.

  8. Development of new methods in modern selective organic synthesis: preparation of functionalized molecules with atomic precision

    Ananikov, V P; Khemchyan, L L; Ivanova, Yu V; Dilman, A D; Levin, V V; Bukhtiyarov, V I; Sorokin, A M; Prosvirin, I P; Romanenko, A V; Simonov, P A; Vatsadze, S Z; Medved'ko, A V; Nuriev, V N; Nenajdenko, V G; Shmatova, O I; Muzalevskiy, V M; Koptyug, I V; Kovtunov, K V; Zhivonitko, V V; Likholobov, V A

    2014-01-01

    The challenges of the modern society and the growing demand of high-technology sectors of industrial production bring about a new phase in the development of organic synthesis. A cutting edge of modern synthetic methods is introduction of functional groups and more complex structural units into organic molecules with unprecedented control over the course of chemical transformation. Analysis of the state-of-the-art achievements in selective organic synthesis indicates the appearance of a new trend — the synthesis of organic molecules, biologically active compounds, pharmaceutical substances and smart materials with absolute selectivity. Most advanced approaches to organic synthesis anticipated in the near future can be defined as 'atomic precision' in chemical reactions. The present review considers selective methods of organic synthesis suitable for transformation of complex functionalized molecules under mild conditions. Selected key trends in the modern organic synthesis are considered including the preparation of organofluorine compounds, catalytic cross-coupling and oxidative cross-coupling reactions, atom-economic addition reactions, methathesis processes, oxidation and reduction reactions, synthesis of heterocyclic compounds, design of new homogeneous and heterogeneous catalytic systems, application of photocatalysis, scaling up synthetic procedures to industrial level and development of new approaches to investigation of mechanisms of catalytic reactions. The bibliography includes 840 references

  9. Ordered microporous layered lanthanide 1,3,5-benzenetriphosphonates pillared with cationic organic molecules.

    Araki, Takahiro; Kondo, Atsushi; Maeda, Kazuyuki

    2015-04-13

    Novel isomorphous pillared-layer-type crystalline lanthanide 1,3,5-benzenetriphosphonates were prepared with bpy and dbo as organic pillars (LnBP-bpy and LnBP-dbo; Ln: Ce, Pr, and Nd). Ab initio crystal structure solution using synchrotron X-ray powder diffraction data revealed that the organic pillars do not exist as neutral coordinating ligands but as cationic molecules. Especially the LnBP-dbo phases have ordered interlayer space filled with water molecules between the dbo pillars, and the interlayer water is successfully removed by heating under vacuum with slightly distorted but basically retained pillared layer structures. Microporosity of the materials is confirmed by adsorption of nitrogen, carbon dioxide, and hydrogen gases. Such microporous layered metal phosphonates pillared with cationic molecules should be unprecedented and should offer new strategies to design ordered microporous materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. The inherent dynamics of a molecular liquid: Geodesic pathways through the potential energy landscape of a liquid of linear molecules

    Jacobson, Daniel; Stratt, Richard M.

    2014-05-01

    Because the geodesic pathways that a liquid follows through its potential energy landscape govern its slow, diffusive motion, we suggest that these pathways are logical candidates for the title of a liquid's "inherent dynamics." Like their namesake "inherent structures," these objects are simply features of the system's potential energy surface and thus provide views of the system's structural evolution unobstructed by thermal kinetic energy. This paper shows how these geodesic pathways can be computed for a liquid of linear molecules, allowing us to see precisely how such molecular liquids mix rotational and translational degrees of freedom into their dynamics. The ratio of translational to rotational components of the geodesic path lengths, for example, is significantly larger than would be expected on equipartition grounds, with a value that scales with the molecular aspect ratio. These and other features of the geodesics are consistent with a picture in which molecular reorientation adiabatically follows translation—molecules largely thread their way through narrow channels available in the potential energy landscape.

  11. Diffusion as a function of guest molecule length and functionalization in flexible metal–organic frameworks

    Zheng, B.; Wang, L. L.; Du, L.; Pan, Y.; Lai, Zhiping; Huang, Kuo-Wei; Du, H. L.

    2016-01-01

    Understanding guest diffusion in nanoporous host-guest systems is crucial in the efficient design of metal-organic frameworks (MOFs) for chemical separation and drug delivery applications. In this work, we investigated the effect of molecule length on the diffusion rate in the zeolitic imidazolate framework 8 (ZIF-8), trying to find a simple and straightforward variable to characterize the complicated guest diffusion. We found that, counter-intuitively, long guest molecules can diffuse as quickly as short molecules; the diffusion coefficient of ethyl acetate for example is of the same order of magnitude as ethane and ethanol, as excludes the existence of a simple relationship between molecule length and diffusion rate. This phenomenon is explained by a study of the contributions of intra- and inter-cage movement to overall transport. Steric confinement limits the degrees of freedom of long guest molecules, shortening their residence time and increasing the efficiency of radial diffusion. In contrast, shorter molecules meander within MOF cages, reducing transport. Furthermore, the energy barrier of inter-cage transport also does not exhibit a simple dependence on a guest molecule length, attributing to the effect of the type of functional group on diffusion. Guests over varying lengths were investigated by using theoretical methods, revealing that the guest diffusion in ZIF-8 depends on the number of contiguous carbon atoms in a molecule, rather than its overall length. Thus, we proposed simple criteria to predict arbitrary guest molecule diffusivity in ZIF-8 without time-consuming experimentation. © 2016 The Royal Society of Chemistry.

  12. Diffusion as a function of guest molecule length and functionalization in flexible metal–organic frameworks

    Zheng, B.

    2016-05-11

    Understanding guest diffusion in nanoporous host-guest systems is crucial in the efficient design of metal-organic frameworks (MOFs) for chemical separation and drug delivery applications. In this work, we investigated the effect of molecule length on the diffusion rate in the zeolitic imidazolate framework 8 (ZIF-8), trying to find a simple and straightforward variable to characterize the complicated guest diffusion. We found that, counter-intuitively, long guest molecules can diffuse as quickly as short molecules; the diffusion coefficient of ethyl acetate for example is of the same order of magnitude as ethane and ethanol, as excludes the existence of a simple relationship between molecule length and diffusion rate. This phenomenon is explained by a study of the contributions of intra- and inter-cage movement to overall transport. Steric confinement limits the degrees of freedom of long guest molecules, shortening their residence time and increasing the efficiency of radial diffusion. In contrast, shorter molecules meander within MOF cages, reducing transport. Furthermore, the energy barrier of inter-cage transport also does not exhibit a simple dependence on a guest molecule length, attributing to the effect of the type of functional group on diffusion. Guests over varying lengths were investigated by using theoretical methods, revealing that the guest diffusion in ZIF-8 depends on the number of contiguous carbon atoms in a molecule, rather than its overall length. Thus, we proposed simple criteria to predict arbitrary guest molecule diffusivity in ZIF-8 without time-consuming experimentation. © 2016 The Royal Society of Chemistry.

  13. Carbon-13 nuclear magnetic resonance of strained organic molecules: III estimates of steric effects

    Seidl, P.R.; Leal, K.Z.; Costa, V.E.U.; Rio Grande do Sul Univ., Porto Alegre

    1985-01-01

    A study of cyclic organic molecules using carbon-13 NMR spectroscopy is analysed. The preparation of compounds and the use of norbornyl compounds as a basis for chemical shifts, bicyclic, tricyclic and tetracyclic derivatives are compared. Relevant distances, angles and non-bonded interactions are shown. (M.J.C.) [pt

  14. Vibrational emission analysis of the CN molecules in laser-induced breakdown spectroscopy of organic compounds

    Fernández-Bravo, Ángel; Delgado, Tomás; Lucena, Patricia; Laserna, J. Javier, E-mail: laserna@uma.es

    2013-11-01

    Laser-induced breakdown spectroscopy (LIBS) of organic materials is based on the analysis of atomic and ionic emission lines and on a few molecular bands, the most important being the CN violet system and the C{sub 2} Swan system. This paper is focused in molecular emission of LIBS plasmas based on the CN (B{sup 2}Σ–X{sup 2}Σ) band, one of the strongest emissions appearing in all carbon materials when analyzed in air atmosphere. An analysis of this band with sufficient spectral resolution provides a great deal of information on the molecule, which has revealed that valuable information can be obtained from the plume chemistry and dynamics affecting the excitation mechanisms of the molecules. The vibrational emission of this molecular band has been investigated to establish the dependence of this emission on the molecular structure of the materials. The paper shows that excitation/emission phenomena of molecular species observed in the plume depend strongly on the time interval selected and on the irradiance deposited on the sample surface. Precise time resolved LIBS measurements are needed for the observation of distinctive CN emission. For the organic compounds studied, larger differences in the behavior of the vibrational emission occur at early stages after plasma ignition. Since molecular emission is generally more complex than that involving atomic emission, local plasma conditions as well as plume chemistry may induce changes in vibrational emission of molecules. As a consequence, alterations in the distribution of the emissions occur in terms of relative intensities, being sensitive to the molecular structure of every single material. - Highlights: • Vibrational emission of CN species in laser-induced plasmas has been investigated. • Distribution of vibrational emission of CN has been found to be time dependent. • Laser irradiance affects the vibrational distribution of the CN molecules. • Plume chemistry controls the excitation mechanisms of CN

  15. Evidence of thermal transport anisotropy in stable glasses of vapor deposited organic molecules

    Ràfols-Ribé, Joan; Dettori, Riccardo; Ferrando-Villalba, Pablo; Gonzalez-Silveira, Marta; Abad, Llibertat; Lopeandía, Aitor F.; Colombo, Luciano; Rodríguez-Viejo, Javier

    2018-03-01

    Vapor deposited organic glasses are currently in use in many optoelectronic devices. Their operation temperature is limited by the glass transition temperature of the organic layers and thermal management strategies become increasingly important to improve the lifetime of the device. Here we report the unusual finding that molecular orientation heavily influences heat flow propagation in glassy films of small molecule organic semiconductors. The thermal conductivity of vapor deposited thin-film semiconductor glasses is anisotropic and controlled by the deposition temperature. We compare our data with extensive molecular dynamics simulations to disentangle the role of density and molecular orientation on heat propagation. Simulations do support the view that thermal transport along the backbone of the organic molecule is strongly preferred with respect to the perpendicular direction. This is due to the anisotropy of the molecular interaction strength that limits the transport of atomic vibrations. This approach could be used in future developments to implement small molecule glassy films in thermoelectric or other organic electronic devices.

  16. Organization of extracting molecules of the diamide type: link with the extracting properties?

    Meridiano, Y.

    2009-02-01

    The aim of these studies is to establish a link between the different organizations of diamide extractants (used in the DIAMEX process) and their extracting properties. The effects of the key parameters leading the liquid-liquid extraction (concentration of extractant, nature of solute, activity of the aqueous phase, nature of the diluent and temperature) are studied: 1) at the supramolecular scale, with the characterization of the extractant organizations by vapor-pressure osmometry (VPO) and small angle neutron and X-ray scattering (SANS/SAXS) experiments; 2) at the molecular scale, with the quantification of the extracted solutes (water, nitric acid, metal nitrate) and the determination of extracted complexes stoichiometries by electro-spray mass spectrometry (ESI-MS) experiments. The DMDOHEMA molecule acts as a classical surfactant and forms aggregates of the reverse micelle type. Taking into account the established supramolecular diagrams, a quantitative link between the extractants structures and their extracting properties has been brought to light. To model the europium nitrate extraction, two approaches have been developed: - an approach based on mass action laws. Extractions equilibria have been proposed taking into account the supramolecular speciation; - an innovative approach considering the extracted ions as adsorbed on a specific surface of the extractant molecule which depends on the extractant organization state. The ion extraction can be considered as a sum of isotherms corresponding to the different states of organization. This approach allows to compare the extraction efficiency of an extracting molecule as a function of its organization state. (author)

  17. Investigation of Multiconfigurational Short-Range Density Functional Theory for Electronic Excitations in Organic Molecules

    Hubert, Mickaël; Hedegård, Erik D.; Jensen, Hans Jørgen Aa

    2016-01-01

    -srDFT for a selected benchmark set of electronic excitations of organic molecules, covering the most common types of organic chromophores. This investigation confirms the expectation that the MC-srDFT method is accurate for a broad range of excitations and comparable to accurate wave function methods such as CASPT2......Computational methods that can accurately and effectively predict all types of electronic excitations for any molecular system are missing in the toolbox of the computational chemist. Although various Kohn-Sham density-functional methods (KS-DFT) fulfill this aim in some cases, they become...... and double excitations have been promising, it is nevertheless important that the accuracy of MC-srDFT is at least comparable to the best KS-DFT methods also for organic molecules that are typically of single-reference character. In this paper we therefore systematically investigate the performance of MC...

  18. Nucleation of Organic Molecules via a Hot Precursor State: Pentacene on Amorphous Mica

    2013-01-01

    Organic thin films have attracted considerable interest due to their applicability in organic electronics. The classical scenario for thin film nucleation is the diffusion-limited aggregation (DLA). Recently, it has been shown that organic thin film growth is better described by attachment-limited aggregation (ALA). However, in both cases, an unusual relationship between the island density and the substrate temperature was observed. Here, we present an aggregation model that goes beyond the classical DLA or ALA models to explain this behavior. We propose that the (hot) molecules impinging on the surface cannot immediately equilibrate to the substrate temperature but remain in a hot precursor state. In this state, the molecules can migrate considerable distances before attaching to a stable or unstable island. This results in a significantly smaller island density than expected by assuming fast equilibration and random diffusion. We have applied our model to pentacene film growth on amorphous Muscovite mica. PMID:24340130

  19. EVAPORATION: a new vapour pressure estimation methodfor organic molecules including non-additivity and intramolecular interactions

    S. Compernolle

    2011-09-01

    Full Text Available We present EVAPORATION (Estimation of VApour Pressure of ORganics, Accounting for Temperature, Intramolecular, and Non-additivity effects, a method to predict (subcooled liquid pure compound vapour pressure p0 of organic molecules that requires only molecular structure as input. The method is applicable to zero-, mono- and polyfunctional molecules. A simple formula to describe log10p0(T is employed, that takes into account both a wide temperature dependence and the non-additivity of functional groups. In order to match the recent data on functionalised diacids an empirical modification to the method was introduced. Contributions due to carbon skeleton, functional groups, and intramolecular interaction between groups are included. Molecules typically originating from oxidation of biogenic molecules are within the scope of this method: aldehydes, ketones, alcohols, ethers, esters, nitrates, acids, peroxides, hydroperoxides, peroxy acyl nitrates and peracids. Therefore the method is especially suited to describe compounds forming secondary organic aerosol (SOA.

  20. CARBON DIOXIDE INFLUENCE ON THE THERMAL FORMATION OF COMPLEX ORGANIC MOLECULES IN INTERSTELLAR ICE ANALOGS

    Vinogradoff, V.; Fray, N.; Bouilloud, M.; Cottin, H. [LISA Laboratoire Interuniversitaire des Systèmes Atmosphériques, UMR CNRS 7583, Université Paris Est Créteil (UPEC), Université Paris Diderot (UPD), Institut Pierre Simon Laplace, Labex ESEP, Paris (France); Duvernay, F.; Chiavassa, T., E-mail: vvinogradoff@mnhn.fr [PIIM, Laboratoire de Physique des Interactions Ioniques et Moléculaires, Université Aix-Marseille, UMR CNRS 7345, Marseille (France)

    2015-08-20

    Interstellar ices are submitted to energetic processes (thermal, UV, and cosmic-ray radiations) producing complex organic molecules. Laboratory experiments aim to reproduce the evolution of interstellar ices to better understand the chemical changes leading to the reaction, formation, and desorption of molecules. In this context, the thermal evolution of an interstellar ice analogue composed of water, carbon dioxide, ammonia, and formaldehyde is investigated. The ice evolution during the warming has been monitored by IR spectroscopy. The formation of hexamethylenetetramine (HMT) and polymethylenimine (PMI) are observed in the organic refractory residue left after ice sublimation. A better understanding of this result is realized with the study of another ice mixture containing methylenimine (a precursor of HMT) with carbon dioxide and ammonia. It appears that carbamic acid, a reaction product of carbon dioxide and ammonia, plays the role of catalyst, allowing the reactions toward HMT and PMI formation. This is the first time that such complex organic molecules (HMT, PMI) are produced from the warming (without VUV photolysis or irradiation with energetic particles) of abundant molecules observed in interstellar ices (H{sub 2}O, NH{sub 3}, CO{sub 2}, H{sub 2}CO). This result strengthens the importance of thermal reactions in the ices’ evolution. HMT and PMI, likely components of interstellar ices, should be searched for in the pristine objects of our solar system, such as comets and carbonaceous chondrites.

  1. CARBON DIOXIDE INFLUENCE ON THE THERMAL FORMATION OF COMPLEX ORGANIC MOLECULES IN INTERSTELLAR ICE ANALOGS

    Vinogradoff, V.; Fray, N.; Bouilloud, M.; Cottin, H.; Duvernay, F.; Chiavassa, T.

    2015-01-01

    Interstellar ices are submitted to energetic processes (thermal, UV, and cosmic-ray radiations) producing complex organic molecules. Laboratory experiments aim to reproduce the evolution of interstellar ices to better understand the chemical changes leading to the reaction, formation, and desorption of molecules. In this context, the thermal evolution of an interstellar ice analogue composed of water, carbon dioxide, ammonia, and formaldehyde is investigated. The ice evolution during the warming has been monitored by IR spectroscopy. The formation of hexamethylenetetramine (HMT) and polymethylenimine (PMI) are observed in the organic refractory residue left after ice sublimation. A better understanding of this result is realized with the study of another ice mixture containing methylenimine (a precursor of HMT) with carbon dioxide and ammonia. It appears that carbamic acid, a reaction product of carbon dioxide and ammonia, plays the role of catalyst, allowing the reactions toward HMT and PMI formation. This is the first time that such complex organic molecules (HMT, PMI) are produced from the warming (without VUV photolysis or irradiation with energetic particles) of abundant molecules observed in interstellar ices (H 2 O, NH 3 , CO 2 , H 2 CO). This result strengthens the importance of thermal reactions in the ices’ evolution. HMT and PMI, likely components of interstellar ices, should be searched for in the pristine objects of our solar system, such as comets and carbonaceous chondrites

  2. UP-scaling of inverted small molecule based organic solar cells

    Patil, Bhushan Ramesh; Madsen, Morten

    Organic solar cells (OSC), in spite of being a promising technology, still face challenges regarding large-scale fabrication. Although efficiencies of up to 12 % has been reached for small molecule OSC, their performance, both in terms of device efficiency and stability, is significantly reduced...... during up-scaling processes. The work presented here is focused on an approach towards up-scaling of small molecule based OSC with inverted device configuration. Bilayer OSC from Tetraphenyldibenzoperiflanthene (DBP) and Fullerenes (C70), as electron donor and acceptor respectively, with cell area...

  3. Partition Coefficients of Organic Molecules in Squalane and Water/Ethanol Mixtures by Molecular Dynamics Simulations

    Lundsgaard, Rasmus; Kontogeorgis, Georgios; Economou, Ioannis G.

    2011-01-01

    coefficient can be estimated for both a small hydrophilic and a hydrophobic organic molecules between squalane (used here to mimic low density poly ethylene) and water/ethanol solutes using thermodynamic integration to calculate the free energy of solvation. Molecular dynamics simulations are performed, using...... the GROMACS software, by slowly decoupling of firstly the electrostatic and then the Lennard–Jones interactions between molecules in the simulation box. These calculations depend very much on the choice of force field. Two force fields have been tested in this work, the TraPPE-UA (united-atom) and the OPLS...

  4. Structure of the Buried Metal-Molecule Interface in Organic Thin Film Devices

    Hansen, Christian Rein; Sørensen, Thomas Just; Glyvradal, Magni

    2009-01-01

    By use of specular X-ray reflectivity (XR) the structure of a metal-covered organic thin film device is measured with angstrom resolution. The model system is a Langmuir-Blodgett (LB) film, sandwiched between a silicon substrate and a top electrode consisting of 25 Å titanium and 100 Å aluminum....... By comparison of XR data for the five-layer Pb2+ arachidate LB film before and after vapor deposition of the Ti/Al top electrode, a detailed account of the structural damage to the organic film at the buried metal-molecule interface is obtained. We find that the organized structure of the two topmost LB layers...

  5. Complex organic molecules toward low-mass and high-mass star forming regions

    Favre, C.; Ceccarelli, C.; Lefloch, B.; Bergin, E.; Carvajal, M.; Brouillet, N.; Despois, D.; Jørgensen, J.; Kleiner, I.

    2016-12-01

    One of the most important questions in molecular astrophysics is how, when, and where complex organic molecules, COMs (≥ 6 atoms) are formed. In the Interstellar-Earth connection context, could this have a bearing on the origin of life on Earth? Formation mechanisms of COMs, which include potentially prebiotic molecules, are still debated and may include grain-mantle and/or gas-phase chemistry. Understanding the mechanisms that lead to the interstellar molecular complexification, along with the involved physicochemical processes, is mandatory to answer the above questions. In that context, active researches are ongoing in theory, laboratory experiment, chemical modeling and observations. Thanks to recent progress in radioastronomy instrumentation for both single-dish and millimeter array (e.g. Herschel, NOEMA, ALMA), new results have been obtained. I will review some notable results on the detection of COMs, including prebiotic molecules, towards star forming regions.

  6. Searching for Bio-Precursors and Complex Organic Molecules in Space using the GBT

    Cordiner, M.; Charnley, S.; Kisiel, Z.

    2012-01-01

    Using the latest microwave receiver technology, large organic molecules with abundances as low as approx. 10(exp -11) times that of molecular hydrogen are detectable in cold interstellar clouds via their rotational emission line spectra. We report new observations to search for complex molecules, including molecules of possible pre-biotic importance, using the newly-commissioned Kband focal plane array (KFPA) of the NRAO Robert C. Byrd Green Bank Telescope. Spectra are presented of the dense molecular cloud TMC-1, showing strict upper limits on the level of emission from nitrogen-bearing rings pyrimidine, quinoline and iso-quinoline, carbon-chain oxides C60, C70, HC60 and HC70, and the carbon-chain anion C4H-. The typical RMS brightness temperature noise levels we achieved are approx. 1 mK at around 20 GHz.

  7. Control of the Thermal Evaporation of Organic Semiconductors via Exact Linearization

    Martin Steinberger; Martin Horn

    2011-01-01

    In this article, a high vacuum system for the evaporation of organic semiconductors is introduced and a mathematical model is given. Based on the exact input output linearization a deposition rate controller is designed and tested with different evaporation materials.

  8. Conduction mechanism in assemblies of metal nanoparticles linked by organic molecules

    Mueller, K.-H.; Herrmann, J.; Raguse, B.; Baxter, G.; Reda, T.

    2002-01-01

    Full text: We have investigated theoretically and experimentally electron transport through thin films of gold nanoparticles which are linked by alkanedithiol molecules of different chain lengths. We find that conduction between neighbouring nanoparticles takes place by electron tunnelling along weakly conducting organic linker molecules. Using a tight binding model for the alkanedithiol molecules to describe the tunnelling process we predict the conductivity to decrease exponentially with the length of the molecules. During tunnelling the electron has to overcome a charging energy due to the electron-hole interaction between tunnelling electrons and the corresponding holes left behind on the donor nanoparticle. Experimentally we find that large applied voltages cause nonlinear I-V characteristics and that the temperature dependence of the conductivity does not show Arrhenius behaviour but instead is of the form exp[-(E o /kT) 1/2 ]. Using percolation theory for a network of metal nanoparticles separated by barriers we show that strong disorder caused by variations in nanoparticle size and linker length as well as randomly trapped electric charges on the linker molecules can well explain our experimental data

  9. Desorption of large organic molecules induced by keV projectiles

    Delcorte, A.; Garrison, B.J.

    2001-01-01

    In order to understand the emission of organic molecules in sputtering, classical molecular dynamics (MD) is used to model the 5 keV Ar atom bombardment of polystyrene oligomers adsorbed on Ag{1 1 1}. The analysis of the results shows that a significant fraction of the trajectories generates high action events in the sample. These events are characterized by the simultaneous motion of several hundreds of substrate atoms and, oftentimes, by high emission yields of substrate atoms, clusters and polystyrene molecules. Collision trees representing the energetic part of the cascades confirm that high sputtering yields of molecules occur when a large portion of the primary particle energy is quickly dissipated in the upper layers of the silver substrate. This class of events where high action occurs in the surface region might explain the ejection of organic species with a mass of several kilodaltons such as biomolecules and synthetic polymers. In the simulation, these events are capable of desorbing polystyrene molecules of ∼2 kDa

  10. Laser-induced desorption of organic molecules from front- and back-irradiated metal foils

    Zinovev, Alexander V.; Veryovkin, Igor V.; Pellin, Michael J.

    2009-01-01

    Laser-Induced Acoustic Desorption (LIAD) from thin metal foils is a promising technique for gentle and efficient volatilization of intact organic molecules from surfaces of solid substrates. Using the Single Photon Ionization (SPI) method combined with time-of-flight mass-spectrometry (TOF MS), desorbed flux in LIAD was examined and compared to that from direct laser desorption (LD). Molecules of various organic dyes were used in experiments. Translational velocities of the desorbed intact molecules did not depend on the desorbing laser intensity, which implies the presence of more sophisticated mechanism of energy transfer than the direct mechanical or thermal coupling between the laser pulse and the adsorbed molecules. The results of our experiments indicate that the LIAD phenomenon cannot be described in terms of a simple mechanical shake-off nor the direct laser desorption. Rather, they suggest that multi-step energy transfer processes are involved. Possible qualitative mechanism of LIAD that are based on formation of non-equilibrium energy states in the adsorbate-substrate system are proposed and discussed.

  11. Oxidative addition of C--H bonds in organic molecules to transition metal centers

    Bergman, R.G.

    1989-04-01

    Alkanes are among the most chemically inert organic molecules. They are reactive toward a limited range of reagents, such as highly energetic free radicals and strongly electrophilic and oxidizing species. This low reactivity is a consequence of the C--H bond energies in most saturated hydrocarbons. These values range from 90 to 98 kcal/mole for primary and secondary C--H bonds; in methane, the main constituent of natural gas, the C--H bond energy is 104 kcal/mole. This makes methane one of the most common but least reactive organic molecules in nature. This report briefly discusses the search for metal complexes capable of undergoing the C--H oxidative addition process allowing alkane chemistry to be more selective than that available using free radical reagents. 14 refs

  12. Nanocoating of titanium implant surfaces with organic molecules. Polysaccharides including glycosaminoglycans

    Gurzawska, Katarzyna Aleksandra; Svava, Rikke; Jørgensen, Niklas Rye

    2012-01-01

    Long-term stability of titanium implants are dependent on a variety of factors. Nanocoating with organic molecules is one of the method used to improve osseointegration. Nanoscale modification of titanium implants affects surface properties, such as hydrophilicity, biochemical bonding capacity...... and roughness. This influences cell behaviour on the surface such as adhesion, proliferation and differentiation of cells as well as the mineralization of the extracellular matrix at the implant surfaces. The aim of the present systematic review was to describe organic molecules used for surface nanocoating...... nanocoatings. The included in vivo studies, showed improvement of bone interface reactions measured as increased Bone-to-Implant Contact length and Bone Mineral Density adjacent to the polysaccharide coated surfaces. Based on existing literature, surface modification with polysaccharide and glycosaminoglycans...

  13. Application of terahertz spectroscopy for characterization of biologically active organic molecules in natural environment

    Karaliūnas, Mindaugas; Jakštas, Vytautas; Nasser, Kinan E.; Venckevičius, Rimvydas; Urbanowicz, Andrzej; Kašalynas, Irmantas; Valušis, Gintaras

    2016-09-01

    In this work, a comparative research of biologically active organic molecules in its natural environment using the terahertz (THz) time domain spectroscopy (TDS) and Fourier transform spectroscopy (FTS) systems is carried out. Absorption coefficient and refractive index of Nicotiana tabacum L. leaves containing nicotine, Cannabis sativa L. leaves containing tetrahydrocannabinol, and Humulu lupulus L. leaves containing α-acids, active organic molecules that obtain in natural environment, were measured in broad frequency range from 0.1 to 13 THz at room temperature. In the spectra of absorption coefficient the features were found to be unique for N. tabacum, C. sativa and H. lupulus. Moreover, those features can be exploited for identification of C. sativa sex and N. tabacum origin. The refractive index can be also used to characterize different species.

  14. Employing exciton transfer molecules to increase the lifetime of phosphorescent red organic light emitting diodes

    Lindla, Florian; Boesing, Manuel; van Gemmern, Philipp; Bertram, Dietrich; Keiper, Dietmar; Heuken, Michael; Kalisch, Holger; Jansen, Rolf H.

    2011-04-01

    The lifetime of phosphorescent red organic light emitting diodes (OLEDs) is investigated employing either N,N'-diphenyl-N,N'-bis(1-naphthylphenyl)-1,1'-biphenyl-4,4'-diamine (NPB), TMM117, or 4,4',4″-tris(N-carbazolyl)-triphenylamine (TCTA) as hole-conducting host material (mixed with an electron conductor). All OLED (organic vapor phase deposition-processed) show similar efficiencies around 30 lm/W but strongly different lifetimes. Quickly degrading OLED based on TCTA can be stabilized by doping exciton transfer molecules [tris-(phenyl-pyridyl)-Ir (Ir(ppy)3)] to the emission layer. At a current density of 50 mA/cm2 (12 800 cd/m2), a lifetime of 387 h can be achieved. Employing exciton transfer molecules is suggested to prevent the degradation of the red emission layer in phosphorescent white OLED.

  15. Nature of chalcogen hor ellipsis chalcogen contact interactions in organic donor-molecule salts

    Novoa, J.J.; Whangbo, Myung-Hwan (North Carolina State Univ., Raleigh, NC (USA). Dept. of Chemistry); Williams, J.M. (Argonne National Lab., IL (USA))

    1990-01-01

    The nature of chalcogen{hor ellipsis}chalcogen contact interactions in organic donor-molecule salts was examined by performing ab initio SCF-MO/MP2 calculations on H{sub 2}X{hor ellipsis}XH{sub 2}(X = O, S, SE, Te) and MM2 calculations on donor dimers (TXF){sub 2} (X = S, SE, Te) and (BEDX-TTF){sub 2} (X = O, S). 14 refs., 4 figs., 4 tabs.

  16. Layered Zinc Hydroxide Salts Intercalated with Anionic Surfactants and Adsolubilized with UV Absorbing Organic Molecules

    Cursino,Ana C. T.; Rives,Vicente; Carlos,Luís D.; Rocha,João; Wypych,Fernando

    2015-01-01

    Two anionic surfactants, dodecylsulfate (DDS) and dodecylbenzenesulfonate (DBS), were intercalated into layered zinc hydroxide salts (LHS) using the direct alkaline co-precipitation method, and characterized by powder X-ray diffraction (PXRD), Fourier-transform infrared (FTIR) and thermogravimetric analysis/differential thermal analysis (TGA/DTA). Different UV-absorbing organic molecules, like salicylates, cinnamates and benzophenones, were adsolubilized in the LHS interlayer following two di...

  17. Nonlinear Transport in Organic Thin Film Transistors with Soluble Small Molecule Semiconductor.

    Kim, Hyeok; Song, Dong-Seok; Kwon, Jin-Hyuk; Jung, Ji-Hoon; Kim, Do-Kyung; Kim, SeonMin; Kang, In Man; Park, Jonghoo; Tae, Heung-Sik; Battaglini, Nicolas; Lang, Philippe; Horowitz, Gilles; Bae, Jin-Hyuk

    2016-03-01

    Nonlinear transport is intensively explained through Poole-Frenkel (PF) transport mechanism in organic thin film transistors with solution-processed small molecules, which is, 6,13-bis(triisopropylsilylethynyl) (TIPS) pentacene. We outline a detailed electrical study that identifies the source to drain field dependent mobility. Devices with diverse channel lengths enable the extensive exhibition of field dependent mobility due to thermal activation of carriers among traps.

  18. Expert systems for structure elucidation of organic molecules by spectral methods

    Elyashberg, Mikhail E

    1999-01-01

    The state-of-the-art of the investigations aimed at creating expert systems for establishing the structure of organic molecules from IR, 1 H and 13 C NMR spectra is analysed. Computer methods used for identification of molecular fragments, generation of their structure and spectra prediction are considered. Principles of the creation of modern expert systems and general strategy of solving structural problems are discussed. The bibliography includes 174 references.

  19. Crystal chemistry of uranyl carboxylate coordination networks obtained in the presence of organic amine molecules

    Mihalcea, Ionut; Henry, Natacha; Loiseau, Thierry [Unite de Catalyse et Chimie du Solide (UCCS) - UMR CNRS 8181, Universite de Lille Nord de France, USTL-ENSCL, Villeneuve d' Ascq (France)

    2014-03-15

    Three uranyl isophthalates (1,3-bdc) and two uranyl pyromellitates (btec) of coordination-polymer type were hydrothermally synthesized (200 C for 24 h) in the presence of different amine-based molecules [1,3-diaminopropane (dap) or dimethylamine (dma) originating from the in situ decomposition of N,N-dimethylformamide]. (UO{sub 2}){sub 2}(OH){sub 2}(H{sub 2}O)(1,3-bdc).H{sub 2}O (1) is composed of inorganic tetranuclear cores, which are linked to each other through the isophthalato ligand to generate infinite neutral ribbons, which are intercalated by free H{sub 2}O molecules. The compounds (UO{sub 2}){sub 1.5}(H{sub 2}O)(1,3-bdc){sub 2}.0.5H{sub 2}dap.1.5H{sub 2}O (2) and UO{sub 2}(1,3-bdc){sub 1.5}.0.5H{sub 2}dap.2H{sub 2}O (3) consist of discrete uranyl-centered hexagonal bipyramids connected to each other by a ditopic linker to form a single-layer network for 2 or a double-layer network for 3. The protonated diamine molecules are located between the uranyl-organic sheets and balance the negative charge of the layered sub-networks. The phase (UO{sub 2}){sub 2}O(btec).2Hdma.H{sub 2}O (4) presents a 2D structure built up from tetranuclear units, which consist of two central sevenfold coordinated uranium centers and two peripheral eightfold coordinated uranium centers. The connection of the resulting tetramers through the pyromellitate molecules generates an anionic layerlike structure, in which the protonated dimethylammonium species are inserted. The compound UO{sub 2}(btec).2Hdma (5) is also a lamellar coordination polymer, which contains isolated eightfold coordinated uranium cations linked through pyromellitate molecules and intercalated by protonated dimethylammonium species. In both phases 4 and 5, the btec linker has non-bonded carboxyl oxygen atoms, which preferentially interact with the protonated amine molecules through a hydrogen-bond network. The different illustrations show the structural diversity of uranyl-organic coordination polymers with organic

  20. Spatial and temporal superresolution concepts to study plasma membrane organization by single molecule fluorescence techniques

    Ruprecht, V.

    2010-01-01

    Fluorescence microscopy techniques are currently among the most important experimental tools to study cellular processes. Ultra-sensitive detection devices nowadays allow for measuring even individual farnesylacetate labeled target molecules with nanometer spatial accuracy and millisecond time resolution. The emergence of single molecule fluorescence techniques especially contributed to the field of membrane biology and provided basic knowledge on structural and dynamic features of the cellular plasma membrane. However, we are still confronted with a rather fragmentary understanding of the complex architecture and functional interrelations of membrane constituents. In this thesis new concepts in one- and dual-color single molecule fluorescence techniques are presented that allow for addressing organization principles and interaction dynamics in the live cell plasma membrane. Two complementary experimental strategies are described which differ in their detection principle: single molecule fluorescence imaging and fluorescence correlation spectroscopy. The presented methods are discussed in terms of their implementation, accuracy, quantitative and statistical data analysis, as well as live cell applications. State-of-the-art dual color single molecule imaging is introduced as the most direct experimental approach to study interaction dynamics between differently labeled target molecules. New analytical estimates for robust data analysis are presented that facilitate quantitative recording and identification of co localizations in dual color single molecule images. A novel dual color illumination scheme is further described that profoundly extends the current range and sensitivity of conventional dual color single molecule experiments. The method enables working at high surface densities of fluorescent molecules - a feature typically incommensurable with single molecule imaging - and is especially suited for the detection of rare interactions by tracking co localized

  1. Luminescence of Rubrene and DCJTB molecules in organic light-emitting devices

    Moon, Chang-Bum, E-mail: cbmoon@hoseo.edu [Department of Display Engineering, Hoseo University, Sechul-Ri 160, Baebang, Asan, Chung-Nam 336-795 (Korea, Republic of); Department of Engineering Physics, McMaster University, Hamilton, Ontario, Canada L8S4L7 (Canada); Song, Wook; Meng, Mei; Kim, Nam Ho; Yoon, Ju-An [Department of Display Engineering, Hoseo University, Sechul-Ri 160, Baebang, Asan, Chung-Nam 336-795 (Korea, Republic of); Kim, Woo Young, E-mail: wykim@hoseo.edu [Department of Display Engineering, Hoseo University, Sechul-Ri 160, Baebang, Asan, Chung-Nam 336-795 (Korea, Republic of); Wood, Richard; Mascher, Peter [Department of Engineering Physics, McMaster University, Hamilton, Ontario, Canada L8S4L7 (Canada)

    2014-02-15

    We investigated the optical properties of light emission based on the resonance energy transfer mechanism between two molecules in the host–dopant systems. For this purpose, we fabricated the organic light-emitting devices with the different doped emissive layers. The host matrices were made of 4,4′,4″-tris(carbasol-l-nyl)triphenylamine (TCTA) and 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) molecules and the doped molecules were 5,6,11,12-tetraphenylnaphtacene (Rubrene) and 4-(Dicyanomethylene)-2-tert-butyl-6- (1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran (DCJTB). The concentrations of the doped molecules were 0.1%, 0.3%, 0.5%, and 0.8%. Through spectroscopic analysis using multi-peak fits with a Gaussian function to the emission spectra, we obtained the relative light intensity of the two dopants according to the doping concentrations and examined the relations between the molecular excited energy states and the nature of energy transfer in the host and dopant systems. We show that the luminous efficiency of the devices has a strong correlation between the energy transfer owing to the individual molecular intrinsic properties and the electrical characteristics associated with the bulky properties in the devices. -- Highlights: • Fabrication and characterization of the OLEDs with a host–dopant system in the emissive layer. • Investigation of the optical properties of light emission based on the resonance energy transfer mechanism between the dopant molecules. • EL and PL spectroscopic study for the structure of the molecular energy levels in the dopant molecules.

  2. Near-unity mass accommodation coefficient of organic molecules of varying structure.

    Julin, Jan; Winkler, Paul M; Donahue, Neil M; Wagner, Paul E; Riipinen, Ilona

    2014-10-21

    Atmospheric aerosol particles have a significant effect on global climate, air quality, and consequently human health. Condensation of organic vapors is a key process in the growth of nanometer-sized particles to climate relevant sizes. This growth is very sensitive to the mass accommodation coefficient α, a quantity describing the vapor uptake ability of the particles, but knowledge on α of atmospheric organics is lacking. In this work, we have determined α for four organic molecules with diverse structural properties: adipic acid, succinic acid, naphthalene, and nonane. The coefficients are studied using molecular dynamics simulations, complemented with expansion chamber measurements. Our results are consistent with α = 1 (indicating nearly perfect accommodation), regardless of the molecular structural properties, the phase state of the bulk condensed phase, or surface curvature. The results highlight the need for experimental techniques capable of resolving the internal structure of nanoparticles to better constrain the accommodation of atmospheric organics.

  3. Assessment of Density-Functional Tight-Binding Ionization Potentials and Electron Affinities of Molecules of Interest for Organic Solar Cells Against First-Principles GW Calculations

    Ala Aldin M. H. M. Darghouth

    2015-12-01

    Full Text Available Ionization potentials (IPs and electron affinities (EAs are important quantities input into most models for calculating the open-circuit voltage (Voc of organic solar cells. We assess the semi-empirical density-functional tight-binding (DFTB method with the third-order self-consistent charge (SCC correction and the 3ob parameter set (the third-order DFTB (DFTB3 organic and biochemistry parameter set against experiments (for smaller molecules and against first-principles GW (Green’s function, G, times the screened potential, W calculations (for larger molecules of interest in organic electronics for the calculation of IPs and EAs. Since GW calculations are relatively new for molecules of this size, we have also taken care to validate these calculations against experiments. As expected, DFTB is found to behave very much like density-functional theory (DFT, but with some loss of accuracy in predicting IPs and EAs. For small molecules, the best results were found with ΔSCF (Δ self-consistent field SCC-DFTB calculations for first IPs (good to ± 0.649 eV. When considering several IPs of the same molecule, it is convenient to use the negative of the orbital energies (which we refer to as Koopmans’ theorem (KT IPs as an indication of trends. Linear regression analysis shows that KT SCC-DFTB IPs are nearly as accurate as ΔSCF SCC-DFTB eigenvalues (± 0.852 eV for first IPs, but ± 0.706 eV for all of the IPs considered here for small molecules. For larger molecules, SCC-DFTB was also the ideal choice with IP/EA errors of ± 0.489/0.740 eV from ΔSCF calculations and of ± 0.326/0.458 eV from (KT orbital energies. Interestingly, the linear least squares fit for the KT IPs of the larger molecules also proves to have good predictive value for the lower energy KT IPs of smaller molecules, with significant deviations appearing only for IPs of 15–20 eV or larger. We believe that this quantitative analysis of errors in SCC-DFTB IPs and EAs may be of

  4. Single Molecule Spectroelectrochemistry of Interfacial Charge Transfer Dynamics In Hybrid Organic Solar Cell

    Pan, Shanlin [Univ. of Alabama, Tuscaloosa, AL (United States)

    2014-11-16

    Our research under support of this DOE grant is focused on applied and fundamental aspects of model organic solar cell systems. Major accomplishments are: 1) we developed a spectroelectorchemistry technique of single molecule single nanoparticle method to study charge transfer between conjugated polymers and semiconductor at the single molecule level. The fluorescence of individual fluorescent polymers at semiconductor surfaces was shown to exhibit blinking behavior compared to molecules on glass substrates. Single molecule fluorescence excitation anisotropy measurements showed the conformation of the polymer molecules did not differ appreciably between glass and semiconductor substrates. The similarities in molecular conformation suggest that the observed differences in blinking activity are due to charge transfer between fluorescent polymer and semiconductor, which provides additional pathways between states of high and low fluorescence quantum efficiency. Similar spectroelectrochemistry work has been done for small organic dyes for understand their charge transfer dynamics on various substrates and electrochemical environments; 2) We developed a method of transferring semiconductor nanoparticles (NPs) and graphene oxide (GO) nanosheets into organic solvent for a potential electron acceptor in bulk heterojunction organic solar cells which employed polymer semiconductor as the electron donor. Electron transfer from the polymer semiconductor to semiconductor and GO in solutions and thin films was established through fluorescence spectroscopy and electroluminescence measurements. Solar cells containing these materials were constructed and evaluated using transient absorption spectroscopy and dynamic fluorescence techniques to understand the charge carrier generation and recombination events; 3) We invented a spectroelectorchemistry technique using light scattering and electroluminescence for rapid size determination and studying electrochemistry of single NPs in an

  5. Intracellular delivery of peptide nucleic acid and organic molecules using zeolite-L nanocrystals.

    Bertucci, Alessandro; Lülf, Henning; Septiadi, Dedy; Manicardi, Alex; Corradini, Roberto; De Cola, Luisa

    2014-11-01

    The design and synthesis of smart nanomaterials can provide interesting potential applications for biomedical purposes from bioimaging to drug delivery. Manufacturing multifunctional systems in a way to carry bioactive molecules, like peptide nucleic acids able to recognize specific targets in living cells, represents an achievement towards the development of highly selective tools for both diagnosis and therapeutics. This work describes a very first example of the use of zeolite nanocrystals as multifunctional nanocarriers to deliver simultaneously PNA and organic molecules into living cells. Zeolite-L nanocrystals are functionalized by covalently attaching the PNA probes onto the surface, while the channel system is filled with fluorescent guest molecules. The cellular uptake of the PNA/Zeolite-L hybrid material is then significantly increased by coating the whole system with a thin layer of biodegradable poly-L-lysine. The delivery of DAPI as a model drug molecule, inserted into the zeolite pores, is also demonstrated to occur in the cells, proving the multifunctional ability of the system. Using this zeolite nanosystem carrying PNA probes designed to target specific RNA sequences of interest in living cells could open new possibilities for theranostic and gene therapy applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Signatures of dynamics in charge transport through organic molecules; Dynamisches Verhalten beim Ladungstransport durch organische Molekuele

    Secker, Daniel

    2008-06-03

    The aim of the thesis at hand was to investigate dynamical behaviour in charge transport through organic molecules experimentally with the help of the mechanically controlled break junction (MCBJ) technique. the thesis concentrates on the complex interaction between the molecular contact configuration and the electronic structure. it is shown that by variation of the electrode distance and so by a manipulation of the molecule and contact configuration the electronic structure as well as the coupling between the molecule and the electrodes is affected. The latter statement is an additional hint how closely I-V-characteristics depend on the molecular contact configuration. Depending on the applied voltage and so the electric field there are two different configurations preferred by the molecular contact. A potential barrier between these two states is the origin of the hysteresis. A central part of the thesis is dealing with measurements of the current noise. Finally it can be concluded that the detailed discussion reveals the strong effect of dynamical interactions between the atomic configuration of the molecular contact and the electronic structure on the charge transport in single molecule junctions. (orig.)

  7. Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules.

    Gruden, Maja; Andjeklović, Ljubica; Jissy, Akkarapattiakal Kuriappan; Stepanović, Stepan; Zlatar, Matija; Cui, Qiang; Elstner, Marcus

    2017-09-30

    Density Functional Tight Binding (DFTB) models are two to three orders of magnitude faster than ab initio and Density Functional Theory (DFT) methods and therefore are particularly attractive in applications to large molecules and condensed phase systems. To establish the applicability of DFTB models to general chemical reactions, we conduct benchmark calculations for barrier heights and reaction energetics of organic molecules using existing databases and several new ones compiled in this study. Structures for the transition states and stable species have been fully optimized at the DFTB level, making it possible to characterize the reliability of DFTB models in a more thorough fashion compared to conducting single point energy calculations as done in previous benchmark studies. The encouraging results for the diverse sets of reactions studied here suggest that DFTB models, especially the most recent third-order version (DFTB3/3OB augmented with dispersion correction), in most cases provide satisfactory description of organic chemical reactions with accuracy almost comparable to popular DFT methods with large basis sets, although larger errors are also seen for certain cases. Therefore, DFTB models can be effective for mechanistic analysis (e.g., transition state search) of large (bio)molecules, especially when coupled with single point energy calculations at higher levels of theory. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  8. Doping effect on photoabsorption and charge-separation dynamics in light-harvesting organic molecule

    Satoshi Ohmura

    2016-01-01

    Full Text Available Using ab-initio theoretical methods, we demonstrate possible enhancement of photo-conversion efficiency of an organic solar cell via intentional doping in molecular graphene-fullerene heterojunction [the hexabenzocoronene (HBC-triethylene glycol (TEG–C60 molecule]. Photoabsorption analysis indicates oxygen substitution into HBC leads to an extension of the spectra up to an infrared regime. A quantum-mechanical molecular dynamics simulation incorporating nonadiabatic electronic transitions reveals that a dissociated charge state (D+ and A- in the O-doped system is more stable than the pristine case due to the presence of an effective barrier by the TEG HOMO/LUMO level. We also find that oxygen doping in HBC enhances the intermolecular carrier mobility after charge separation. On the other hand, the pristine molecule undergoes rapid recombination between donor and acceptor charges at the interface. These analyses suggest that the graphene oxidation opens a new window in the application of organic super-molecules to solar cells.

  9. Biradical and triradical organic magnetic molecules as spin filters and rectifiers

    Zhu, L.; Yao, K.L.; Liu, Z.L.

    2012-01-01

    Graphical abstract: (a) Negative differential resistance (NDR) characteristic and antiparallel spin-current (ASC) rectification; (b) spin-current (SC) rectification and charge-current (CC) rectification properties Display Omitted Highlights: ► Organic magnetic molecules at gold electrodes as spin/charge rectifier. ► Spin diode/rectification stems from length and asymmetry of molecular framework. ► Negative differential resistance, spin-filtering and switching evidenced. - Abstract: We have theoretically investigated the spin-polarized transport properties of molecular junctions consisting of biradical and triradical organic magnetic molecules sandwiched between two symmetric gold electrodes, respectively. It shows that these junctions function as a spin rectifier or a combination of spin and charge rectifiers with high spin rectification ratios exceeding 100, wherein the spin diode/rectification effect stems from the conjugated length and asymmetry of the molecular framework, which is the pre-requisite for electronic asymmetry of the adsorbed species. The negative differential resistance, spin-filtering and switching properties are also unveiled. In particular, it is revealed that the strong couplings between the electrodes and molecules are responsible for the negative differential resistance.

  10. Biradical and triradical organic magnetic molecules as spin filters and rectifiers

    Zhu, L. [School of Physics, School of Optoelectronics Science and Engineering, Wuhan Pulsed Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Yao, K.L., E-mail: klyao@hust.edu.cn [School of Physics, School of Optoelectronics Science and Engineering, Wuhan Pulsed Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); International Center of Materials Physics, Chinese Academy of Science, Shengyang 110015 (China); Liu, Z.L. [School of Physics, School of Optoelectronics Science and Engineering, Wuhan Pulsed Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2012-03-13

    Graphical abstract: (a) Negative differential resistance (NDR) characteristic and antiparallel spin-current (ASC) rectification; (b) spin-current (SC) rectification and charge-current (CC) rectification properties Display Omitted Highlights: Black-Right-Pointing-Pointer Organic magnetic molecules at gold electrodes as spin/charge rectifier. Black-Right-Pointing-Pointer Spin diode/rectification stems from length and asymmetry of molecular framework. Black-Right-Pointing-Pointer Negative differential resistance, spin-filtering and switching evidenced. - Abstract: We have theoretically investigated the spin-polarized transport properties of molecular junctions consisting of biradical and triradical organic magnetic molecules sandwiched between two symmetric gold electrodes, respectively. It shows that these junctions function as a spin rectifier or a combination of spin and charge rectifiers with high spin rectification ratios exceeding 100, wherein the spin diode/rectification effect stems from the conjugated length and asymmetry of the molecular framework, which is the pre-requisite for electronic asymmetry of the adsorbed species. The negative differential resistance, spin-filtering and switching properties are also unveiled. In particular, it is revealed that the strong couplings between the electrodes and molecules are responsible for the negative differential resistance.

  11. Doping effect on photoabsorption and charge-separation dynamics in light-harvesting organic molecule

    Ohmura, Satoshi, E-mail: s.ohmura.m4@cc.it-hiroshima.ac.jp [Research Center for Condensed Matter Physics, Department of Civil Engineering and Urban Design, Hiroshima Institute of Technology, Hiroshima 731-5193 (Japan); Tsuruta, Kenji [Department of Electrical and Electronic Engineering, Okayama University, Okayama 700-8530 (Japan); Shimojo, Fuyuki [Department of Physics, Kumamoto University, Kumamoto 860-8555 Japan (Japan); Nakano, Aiichiro [Collaboratory for Advanced Computing and Simulations, Department of Computer Science, Department of Physics & Astronomy, Department of Chemical Engineering & Materials Science, Department of Biological Sciences, University of Southern California, CA90089-024 (United States)

    2016-01-15

    Using ab-initio theoretical methods, we demonstrate possible enhancement of photo-conversion efficiency of an organic solar cell via intentional doping in molecular graphene-fullerene heterojunction [the hexabenzocoronene (HBC)-triethylene glycol (TEG)–C{sub 60} molecule]. Photoabsorption analysis indicates oxygen substitution into HBC leads to an extension of the spectra up to an infrared regime. A quantum-mechanical molecular dynamics simulation incorporating nonadiabatic electronic transitions reveals that a dissociated charge state (D{sup +} and A{sup -}) in the O-doped system is more stable than the pristine case due to the presence of an effective barrier by the TEG HOMO/LUMO level. We also find that oxygen doping in HBC enhances the intermolecular carrier mobility after charge separation. On the other hand, the pristine molecule undergoes rapid recombination between donor and acceptor charges at the interface. These analyses suggest that the graphene oxidation opens a new window in the application of organic super-molecules to solar cells.

  12. The Effects of Perchlorate and its Precursors on Organic Molecules under Simulated Mars Conditions

    Carrier, B. L.; Beegle, L. W.; Bhartia, R.; Abbey, W. J.

    2016-12-01

    Perchlorate (ClO4-) was first detected on Mars by the Phoenix Lander in 2008 [1] and has subsequently been detected by Curiosity in Gale Crater [2], in Mars meteorite EETA79001 [3], and has been proposed as a possible explanation for results obtained by Viking [4]. Perchlorate has also been shown to be formed under current Mars conditions via the oxidation of mineral chlorides, further supporting the theory that perchlorate is present globally on Mars [5]. The discovery of perchlorate on Mars has raised important questions about its effects on the survival and detection of organic molecules. Although it has been shown that pyrolysis in the presence of perchlorate results in the alteration or destruction of organic molecules [2, 4], few studies have been conducted on the potential effects of perchlorate and its precursors on organic molecules prior to analysis. Perchlorate is typically inert under Mars temperatures and pressures, but it has been shown to decompose to form reactive oxychlorine species such as chlorite (ClO2-), hypochlorite (ClO-) and chlorine dioxide (ClO2) when exposed to Mars conditions including ionizing radiation [6]. The oxidation of chloride to perchlorate also results in the formation of reactive oxychlorine species such as chlorate (ClO3-) [5]. Here we investigate the effects of perchlorate and its oxychlorine precursors on organic molecules. Experiments are performed in a Mars Simulation Chamber (MSC) capable of reproducing the temperature, pressure, atmospheric composition and UV flux found on Mars. Soil simulants are prepared consisting of Mojave Mars Simulant (MMS) [7] and each organic, as well as varying concentrations of perchlorate and/or chloride salts, and exposed in the MSC. Subsequent to exposure in the MSC samples are leached and the leachate analyzed by HPLC and LC-MS to determine the degree of degradation of the original organic and the identity of any potential decomposition products formed by oxidation or chlorination

  13. Retention of U(VI) onto silica in presence of model organic molecules

    Pham, T.T.H.; Mercier-Bion, F.; Drot, R.; Lagarde, G.; Simoni, E.; Lambert, J.

    2008-01-01

    It is well-known that the organic matter influences the retention of ions onto mineral surfaces. However, the major part of concerned studies implies humic substances and complex solids. Another approach for identifying the sorption mechanisms is possible by studying simpler solids than those present in natural medium. So, silica is chosen as mineral surface because of its abundance in soils and of the presence of Si-O groups in clayey minerals. Uranium (VI) is selected as cation. Simple organic molecules like acetic (one carboxylic group) and oxalic (two carboxylic functions) acids are considered as models of the natural organic matter for understanding their role in the retention of U(VI) onto powders and slides of silica. Binary (organics/silica, U(VI)/silica) and ternary systems (organics/silica/U(VI)) are studied by complementary approaches. Sorption edges as function of pH are obtained by liquid scintillation methods and capillary electrophoresis. Different spectroscopic techniques are used to deduce the interactions between the organic matter and U(VI) sorbed onto the silica whose: Time-Resolved Laser induced Fluorescence Spectroscopy (TRLFS), X-ray Photoelectron Spectroscopy (XPS), Nuclear Microprobe Analysis (NMA). The results of the effect of these model organic molecules onto the U(VI) retention showed a good agreement between the different techniques. Concerning the acetic acid, there are not differences in the sorption percentages of uranyl (see the figure). All these results indicate that the uranyl-acetate complexes stay in the aqueous solution rather than sorbing onto the silica. On the contrary, oxalic acid influences the sorption of U(VI) onto the silica surface. The sorption percentage of U(VI) in the ternary system (oxalic acid/silica/U(VI)) is lower than the binary system (U(VI)/silica) (see the figure). So, the presence of oxalic acid decreases the sorption of U(VI) onto the silica surface. (authors)

  14. Leucine-rich repeat-containing synaptic adhesion molecules as organizers of synaptic specificity and diversity.

    Schroeder, Anna; de Wit, Joris

    2018-04-09

    The brain harbors billions of neurons that form distinct neural circuits with exquisite specificity. Specific patterns of connectivity between distinct neuronal cell types permit the transfer and computation of information. The molecular correlates that give rise to synaptic specificity are incompletely understood. Recent studies indicate that cell-surface molecules are important determinants of cell type identity and suggest that these are essential players in the specification of synaptic connectivity. Leucine-rich repeat (LRR)-containing adhesion molecules in particular have emerged as key organizers of excitatory and inhibitory synapses. Here, we discuss emerging evidence that LRR proteins regulate the assembly of specific connectivity patterns across neural circuits, and contribute to the diverse structural and functional properties of synapses, two key features that are critical for the proper formation and function of neural circuits.

  15. RHFPPP, SCF-LCAO-MO Calculation for Closed Shell and Open Shell Organic Molecules

    Bieber, A.; Andre, J.J.

    1987-01-01

    1 - Nature of physical problem solved: Complete program performs SCF-LCAO-MO calculations for both closed and open-shell organic pi-molecules. The Pariser-Parr-People approximations are used with- in the framework of the restricted Hartree-Fock method. The SCF calculation is followed, if desired, by a variational configuration interaction (CI) calculation including singly excited configurations. 2 - Method of solution: A standard procedure is used; at each step a real symmetric matrix has to be diagonalized. The self-consistency is checked by comparing the eigenvectors between two consecutive steps. 3 - Restrictions on the complexity of the problem: i) The calculations are restricted to planar molecules. ii) In order to avoid accumulation of round-off errors, in the iterative procedure, double precision arithmetic is used. iii) The program is restricted to systems up to about 16 atoms; however the size of the systems can easily be modified if required

  16. A potentiometric titration method for the crystallization of drug-like organic molecules.

    Du-Cuny, Lei; Huwyler, Jörg; Fischer, Holger; Kansy, Manfred

    2007-09-05

    It is generally accepted, that crystalline solids representing a low energy polymorph should be selected for development of oral dosage forms. As a consequence, efficient and robust procedures are needed at an early stage during drug discovery to prepare crystals from drug-like organic molecules. In contrast to the use of supersaturated solutions, we present a potentiometric crystallization procedure where saturated solutions are prepared in a controlled manner by pH-titration. Crystallization is carried out under defined conditions using the sample concentration and experimental pK(a) values as input parameters. Crystals of high quality were obtained for 11 drugs selected to demonstrate the efficiency and applicability of the new method. Technical improvements are suggested to overcome practical limitations and to enhance the possibility of obtaining crystals from molecules in their uncharged form.

  17. Biotin conjugated organic molecules and proteins for cancer therapy: A review.

    Maiti, Santanu; Paira, Priyankar

    2018-02-10

    The main transporter for biotin is sodium dependent multivitamin transporter (SMVT), which is overexpressed in various aggressive cancer cell lines such as ovarian (OV 2008, ID8), leukemia (L1210FR), mastocytoma (P815), colon (Colo-26), breast (4T1, JC, MMT06056), renal (RENCA, RD0995), and lung (M109) cancer cell lines. Furthermore, its overexpression was found higher to that of folate receptor. Therefore, biotin demand in the rapidly growing tumors is higher than normal tissues. Several biotin conjugated organic molecules has been reported here for selective delivery of the drug in cancer cell. Biotin conjugated molecules are showing higher fold of cytotoxicity in biotin positive cancer cell lines than the normal cell. Nanoparticles and polymer surface modified drugs and biotin mediated cancer theranostic strategy was highlighted in this review. The cytotoxicity and selectivity of the drug in cancer cells has enhanced after biotin conjugation. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  18. Exploring the aqueous vertical ionization of organic molecules by molecular simulation and liquid microjet photoelectron spectroscopy.

    Tentscher, Peter R; Seidel, Robert; Winter, Bernd; Guerard, Jennifer J; Arey, J Samuel

    2015-01-08

    To study the influence of aqueous solvent on the electronic energy levels of dissolved organic molecules, we conducted liquid microjet photoelectron spectroscopy (PES) measurements of the aqueous vertical ionization energies (VIEaq) of aniline (7.49 eV), veratrole alcohol (7.68 eV), and imidazole (8.51 eV). We also reanalyzed previously reported experimental PES data for phenol, phenolate, thymidine, and protonated imidazolium cation. We then simulated PE spectra by means of QM/MM molecular dynamics and EOM-IP-CCSD calculations with effective fragment potentials, used to describe the aqueous vertical ionization energies for six molecules, including aniline, phenol, veratrole alcohol, imidazole, methoxybenzene, and dimethylsulfide. Experimental and computational data enable us to decompose the VIEaq into elementary processes. For neutral compounds, the shift in VIE upon solvation, ΔVIEaq, was found to range from ≈-0.5 to -0.91 eV. The ΔVIEaq was further explained in terms of the influence of deforming the gas phase solute into its solution phase conformation, the influence of solute hydrogen-bond donor and acceptor interactions with proximate solvent molecules, and the polarization of about 3000 outerlying solvent molecules. Among the neutral compounds, variability in ΔVIEaq appeared largely controlled by differences in solute-solvent hydrogen-bonding interactions. Detailed computational analysis of the flexible molecule veratrole alcohol reveals that the VIE is strongly dependent on molecular conformation in both gas and aqueous phases. Finally, aqueous reorganization energies of the oxidation half-cell ionization reaction were determined from experimental data or estimated from simulation for the six compounds aniline, phenol, phenolate, veratrole alcohol, dimethylsulfide, and methoxybenzene, revealing a surprising constancy of 2.06 to 2.35 eV.

  19. A Research Module for the Organic Chemistry Laboratory: Multistep Synthesis of a Fluorous Dye Molecule.

    Slade, Michael C; Raker, Jeffrey R; Kobilka, Brandon; Pohl, Nicola L B

    2014-01-14

    A multi-session research-like module has been developed for use in the undergraduate organic teaching laboratory curriculum. Students are tasked with planning and executing the synthesis of a novel fluorous dye molecule and using it to explore a fluorous affinity chromatography separation technique, which is the first implementation of this technique in a teaching laboratory. Key elements of the project include gradually introducing students to the use of the chemical literature to facilitate their searching, as well as deliberate constraints designed to force them to think critically about reaction design and optimization in organic chemistry. The project also introduces students to some advanced laboratory practices such as Schlenk techniques, degassing of reaction mixtures, affinity chromatography, and microwave-assisted chemistry. This provides students a teaching laboratory experience that closely mirrors authentic synthetic organic chemistry practice in laboratories throughout the world.

  20. Giant negative linear compression positively coupled to massive thermal expansion in a metal-organic framework.

    Cai, Weizhao; Katrusiak, Andrzej

    2014-07-04

    Materials with negative linear compressibility are sought for various technological applications. Such effects were reported mainly in framework materials. When heated, they typically contract in the same direction of negative linear compression. Here we show that this common inverse relationship rule does not apply to a three-dimensional metal-organic framework crystal, [Ag(ethylenediamine)]NO3. In this material, the direction of the largest intrinsic negative linear compression yet observed in metal-organic frameworks coincides with the strongest positive thermal expansion. In the perpendicular direction, the large linear negative thermal expansion and the strongest crystal compressibility are collinear. This seemingly irrational positive relationship of temperature and pressure effects is explained and the mechanism of coupling of compressibility with expansivity is presented. The positive coupling between compression and thermal expansion in this material enhances its piezo-mechanical response in adiabatic process, which may be used for designing new artificial composites and ultrasensitive measuring devices.

  1. Modification of mesoporous silica SBA-15 with different organic molecules to gain chemical sensors: a review

    Negar Lashgari

    2016-01-01

    Full Text Available The recognition of the biologically and environmentally important ions is of great interest in the field of chemical sensors in recent years. The fluorescent sensors as a powerful optical analytical technique for the detection of low level of various analytes such as anions and metal cations have been progressively developed due to the simplicity, cost effective, and selectivity for monitoring specific analytes in various systems. Organic-inorganic hybrid nanomaterials have important advantages as solid chemosensors and various innovative hybrid materials modified by fluorescence molecules were recently prepared. On the other hand, the homogeneous porosity and large surface area of mesoporous silica make it a promising inorganic support. SBA-15 as a two-dimensional hexagonal mesoporous silica material with stable structure, thick walls, tunable pore size, and high specific surface area is a valuable substrate for modification with different organic chelating groups. This review highlights the fluorescent chemosensors for ionic species based on modification of the mesoporous silica SBA-15 with different organic molecules, which have been recently developed from our laboratory.

  2. Designing small molecule polyaromatic p- and n-type semiconductor materials for organic electronics

    Collis, Gavin E.

    2015-12-22

    By combining computational aided design with synthetic chemistry, we are able to identify core 2D polyaromatic small molecule templates with the necessary optoelectronic properties for p- and n-type materials. By judicious selection of the functional groups, we can tune the physical properties of the material making them amenable to solution and vacuum deposition. In addition to solubility, we observe that the functional group can influence the thin film molecular packing. By developing structure-property relationships (SPRs) for these families of compounds we observe that some compounds are better suited for use in organic solar cells, while others, varying only slightly in structure, are favoured in organic field effect transistor devices. We also find that the processing conditions can have a dramatic impact on molecular packing (i.e. 1D vs 2D polymorphism) and charge mobility; this has implications for material and device long term stability. We have developed small molecule p- and n-type materials for organic solar cells with efficiencies exceeding 2%. Subtle variations in the functional groups of these materials produces p- and ntype materials with mobilities higher than 0.3 cm2/Vs. We are also interested in using our SPR approach to develop materials for sensor and bioelectronic applications.

  3. Density Functional Investigation of Graphene Doped with Amine-Based Organic Molecules

    Yeun Hee Hwang

    2015-01-01

    Full Text Available To improve the electronic properties of graphene, many doping techniques have been studied. Herein, we investigate the electronic and molecular structure of doped graphene using density functional theory, and we report the effects of amine-based benzene dopants adsorbed on graphene. Density functional theory (DFT calculations were performed to determine the role of amine-based aromatic compounds in graphene doping. These organic molecules bind to graphene through long-range interactions such as π-π interactions and C-H⋯π hydrogen bonding. We compared the electronic structures of pristine graphene and doped graphene to understand the electronic structure of doped graphene at the molecular level. Also, work functions of doped graphene were obtained from electrostatic potential calculations. A decrease in the work function was observed when the amine-based organic compounds were adsorbed onto graphene. Because these systems are based on physisorption, there was no obvious band structure change at point K at the Fermi level after doping. However, the amine-based organic dopants did change the absolute Fermi energy levels. In this study, we showed that the Fermi levels of the doped graphene were affected by the HOMO energy level of the dopants and by the intermolecular charge transfer between the adsorbed molecules and graphene.

  4. Hydrophilicity and Microsolvation of an Organic Molecule Resolved on the Sub-molecular Level by Scanning Tunneling Microscopy.

    Lucht, Karsten; Loose, Dirk; Ruschmeier, Maximilian; Strotkötter, Valerie; Dyker, Gerald; Morgenstern, Karina

    2018-01-26

    Low-temperature scanning tunneling microscopy was used to follow the formation of a solvation shell around an adsorbed functionalized azo dye from the attachment of the first water molecule to a fully solvated molecule. Specific functional groups bind initially one water molecule each, which act as anchor points for additional water molecules. Further water attachment occurs in areas close to these functional groups even when the functional groups themselves are already saturated. In contrast, water molecules surround the hydrophobic parts of the molecule only when the two-dimensional solvation shell closes around them. This study thus traces hydrophilic and hydrophobic properties of an organic molecule down to a sub-molecular length scale. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Selective adsorption and release of cationic organic dye molecules on mesoporous borosilicates

    Paul, Manidipa; Pal, Nabanita; Bhaumik, Asim

    2012-01-01

    Mesoporous materials can play a pivotal role as a host material for delivery application to a specific part of a system. In this work we explore the selective adsorption and release of cationic organic dye molecules such as safranine T (ST) and malachite green (MG) on mesoporous borosilicate materials. The mesoporous silica SBA-15 and borosilicate materials (MBS) were prepared using non-ionic surfactant Pluronic P123 as template via evaporation induced self-assembly (EISA) method. After template removal the materials show high surface areas and in some cases ordered mesopores of dimensions ca. 6–7 nm. High surface area, mesoporosity and the presence of heteroatom (boron) help this mesoporous borosilicate material to adsorb high amount of cationic dye molecules at its surface from the respective aqueous solutions. Furthermore, the mesoporous borosilicate samples containing higher percentage adsorbed dyes show excellent release of ST or MG dye in simulated body fluid (SBF) solution at physiological pH = 7.4 and temperature 310 K. The adsorption and release efficiency of mesoporous borosilicate samples are compared with reference boron-free mesoporous pure silica material to understand the nature of adsorbate–adsorbent interaction at the surfaces. - Graphical abstract: Highly ordered 2D-hexagonal mesoporous borosilicate materials have been synthesized by using Pluronic P123 as template. The materials show very good adsorption and release of organic cationic dye molecules under physiological conditions. Highlights: ► Highly ordered 2D-hexagonal mesoporous borosilicate. ► Nonionic Pluoronic P123 templated mesoporous material. ► Adsorption of organic dyes at the mesopore surface. ► Controlled release of dyes under physiological pH and temperature. ► Release of safranine T (ST) and malachite green (MG) dyes in simulated body fluids.

  6. Effect of organic small-molecule hole injection materials on the performance of inverted organic solar cells

    Li, Jie; Zheng, Yifan; Zheng, Ding; Yu, Junsheng

    2016-07-01

    In this study, the influence of small-molecule organic hole injection materials on the performance of organic solar cells (OSCs) as the hole transport layer (HTL) with an architecture of ITO/ZnO/P3HT:PC71BM/HTL/Ag has been investigated. A significant enhancement on the performance of OSCs from 1.06% to 2.63% is obtained by using N, N‧-bis(1-naphthalenyl)-N, N‧-bis-phenyl-(1, 1‧-biphenyl)-4, 4‧-diamine (NPB) HTL. Through the resistance simulation and space-charge limited current analysis, we found that NPB HTL cannot merely improve the hole mobility of the device but also form the Ohmic contact between the active layer and anode. Besides, when we apply mix HTL by depositing the NPB on the surface of molybdenum oxide, the power conversion efficiency of OSC are able to be further improved to 2.96%.

  7. Morphology versus Vertical Phase Segregation in Solvent Annealed Small Molecule Bulk Heterojunction Organic Solar Cells

    Alexander Kovalenko

    2015-01-01

    Full Text Available The deep study of solvent annealed small molecules bulk heterojunction organic solar cells based on DPP(TBFu2 : PC60BM blend is carried out. To reveal the reason of the solvent annealing advantage over the thermal one, capacitance-voltage measurements were applied. It was found that controlling the vertical phase segregation in the solar cells a high fullerene population in the vicinity of the cathode could be achieved. This results in increase of the shunt resistance of the cell, thus improving the light harvesting efficiency.

  8. Dual Function Additives: A Small Molecule Crosslinker for Enhanced Efficiency and Stability in Organic Solar Cells

    Rumer, Joseph W.; Ashraf, Raja S.; Eisenmenger, Nancy D.; Huang, Zhenggang; Meager, Iain; Nielsen, Christian B.; Schroeder, Bob C.; Chabinyc, Michael L.; McCulloch, Iain

    2015-01-01

    A bis-azide-based small molecule crosslinker is synthesized and evaluated as both a stabilizing and efficiency-boosting additive in bulk heterojunction organic photovoltaic cells. Activated by a noninvasive and scalable solution processing technique, polymer:fullerene blends exhibit improved thermal stability with suppressed polymer skin formation at the cathode and frustrated fullerene aggregation on ageing, with initial efficiency increased from 6% to 7%. © 2015 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Dual Function Additives: A Small Molecule Crosslinker for Enhanced Efficiency and Stability in Organic Solar Cells

    Rumer, Joseph W.

    2015-02-01

    A bis-azide-based small molecule crosslinker is synthesized and evaluated as both a stabilizing and efficiency-boosting additive in bulk heterojunction organic photovoltaic cells. Activated by a noninvasive and scalable solution processing technique, polymer:fullerene blends exhibit improved thermal stability with suppressed polymer skin formation at the cathode and frustrated fullerene aggregation on ageing, with initial efficiency increased from 6% to 7%. © 2015 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Theoretical studies on nuclear spin selective quantum dynamics of non-linear molecules; Theoretische Untersuchung zur Quantendynamik der Kernspinisomere nicht-linearer Molekuele

    Grohmann, Thomas

    2012-05-31

    In this thesis the wave packet dynamics of nuclear spin isomers of polyatomic molecules after interaction with static and time-dependent magnetic fields and moderate intense nonresonant laser pulses is investigated. In particular, the process of inducing (internal) molecular rotation as well as alignment of molecules by manipulating their rotational or rotational-torsional degrees of freedom is studied. In the first part of the thesis all theoretical concepts for identifying nuclear spin isomers and for describing their quantum dynamics will be discussed. Especially the symmetrization postulate and themolecular symmetry group will be introduced and illustrated for some examples of molecules. These concepts will be extended to the case of identifying nuclear spin isomers in the presence of an external field. In the second part it is shown for nitromethane that magnetic fields are able to induce unidirectional rotations in opposite directions for different nuclear spin isomers of molecules containing methyl groups if the dipolar interaction is included. Additionally, it is demonstrated that different nuclear spin isomers of a chemical compound may show different alignment after the interaction with a moderate intense laser pulse. As shown for the rigid symmetric top propadien and the rigid asymmetric tops ethene and analogues, distinct pairs of nuclear spin isomers show at certain points in time a complementary behavior: while one isomer is showing alignment the partner isomer is showing anti-alignment. Moreover, it is illustrated that not every nuclear spin isomer can be aligned equally efficient. The alignment of non-rigid molecules is considered as well. As an example for a molecule with feasible torsion in the electronic ground state, the alignment of diboron tetrafluoride is investigated. It becomes apparent that not only rotational but also the torsional dynamics of the molecules is nuclear spin selective; different nuclear spin isomers have at distinct points

  11. Investigation of linear accelerator pulse delivery using fast organic scintillator measurements

    Beierholm, Anders Ravnsborg; Andersen, Claus Erik; Lindvold, Lars René

    2010-01-01

    Fiber-coupled organic plastic scintillators present an attractive method for time-resolved dose measurements during radiotherapy. Most organic scintillators exhibit a fast response, making it possible to use them to measure individual high-energy X-ray pulses from a medical linear accelerator...... performed on Varian medical linear accelerators, delivering 6 MV X-ray beams. The dose delivery per radiation pulse was found to agree with expectations within roughly 1%, although minor discrepancies and transients were evident in the measurements....

  12. Vibronic coupling in ionized organic molecules: structural distortions and chemical reactions

    Williams, Ffrancon

    2003-01-01

    Ionized organic molecules (radical cations) in radiation chemistry are liable to undergo vibronic coupling whenever there is a relatively small energy gap (∼0.5-1.5 eV) between their ground and excited states. As a result of this mixing, the force constant for the symmetry-allowed vibrational mode that couples these states is lowered in the ground state of the radical cation so that deformation can take place more easily along this specific mode. This pseudo-Jahn-Teller effect can then result in a permanent structural distortion of the radical cation relative to the symmetry of the parent neutral molecule. It can also bring about an energetically favored pathway for a facile chemical rearrangement along a reaction coordinate defined by the coupling mode. Examples taken from matrix-isolation studies are used to illustrate these dramatic consequences of vibronic coupling in radical cations. Thus, the bicyclo[2.2.2]oct-2-ene and tetramethylurea radical cations are found to have twisted structures departing from the C 2v symmetry of their parent molecules, while the oxirane and bicyclo[1.1.1]pentane radical cations undergo ring-opening rearrangements along reaction coordinates that correspond to the deformational modes predicted by the pseudo-Jahn-Teller effect

  13. Solution-processed white organic light-emitting devices based on small-molecule materials

    Wang Dongdong; Wu Zhaoxin; Zhang Xinwen; Wang Dawei; Hou Xun

    2010-01-01

    We investigated solution-processed films of 4,4'-bis(2,2-diphenylvinyl)-1,1'-bibenyl (DPVBi) and its blends with N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) by atomic force microscopy (AFM). The AFM result shows that the solution-processed films are pin-free and their morphology is smooth enough to be used in OLEDs. We have developed a solution-processed white organic light-emitting device (WOLEDs) based on small-molecules, in which the light-emitting layer (EML) was formed by spin-coating the solution of small-molecules on top of the solution-processed hole-transporting layer. This WOLEDs, in which the EML consists of co-host (DPVBi and TPD), the blue dopant (4,4'-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl) and the yellow dye (5,6,11,12-tetraphenylnaphtacene), has a current efficiency of 6.0 cd/A at a practical luminance of 1000 cd/m 2 , a maximum luminance of 22500 cd/m 2 , and its color coordinates are quite stable. Our research shows a possible approach to achieve efficient and low-cost small-molecule-based WOLEDs, which avoids the complexities of the co-evaporation process of multiple dopants and host materials in vacuum depositions.

  14. On the nucleation and initial film growth of rod-like organic molecules

    Winkler, Adolf

    2016-10-01

    In this article, some fundamental topics related to the initial steps of organic film growth are reviewed. General conclusions will be drawn based on experimental results obtained for the film formation of oligophenylene and pentacene molecules on gold and mica substrates. Thin films were prepared via physical vapor deposition under ultrahigh-vacuum conditions and characterized in-situ mainly by thermal desorption spectroscopy, and ex-situ by X-ray diffraction and atomic force microscopy. In this short review article the following topics will be discussed: What are the necessary conditions to form island-like films which are either composed of flat-lying or of standing molecules? Does a wetting layer exist below and in between the islands? What is the reason behind the occasionally observed bimodal island size distribution? Can one describe the nucleation process with the diffusion-limited aggregation model? Do the impinging molecules directly adsorb on the surface or rather via a hot-precursor state? Finally, it will be described how the critical island size can be determined by an independent measurement of the deposition rate dependence of the island density and the capture-zone distribution via a universal relationship.

  15. Matrix effect on hydrogen-atom tunneling of organic molecules in cryogenic solids

    Ichikawa, Tsuneki

    2000-01-01

    Although the tunneling of atoms through potential energy barriers separating the reactant and reaction systems is not paid much attention in organic reactions, this plays an important role in reactions including the transfer of light atoms. Atomic tunneling is especially important for chemical reactions at low temperatures, since the thermal activation of reactant systems is very slow process in comparison with the tunneling. One of the typical reactions of atomic tunneling is hydrogen-atom abstraction from alkanes in cryogenic solids exposed to high-energy radiation. Irradiation of alkane molecules causes the homolytic cleavage of C-H bonds, which results in the pairwise formation of free hydrogen atoms and organic free radicals. Since the activation energies for the abstraction of hydrogen atoms from alkane molecules by free hydrogen atoms are higher than 5 kcal/mol, the lifetime of free hydrogen atoms at 77 K is estimated from the Arrhenius equation of k=vexp(-E a /RT) to be longer than 10 hrs. However, except for solid methane, free hydrogen atoms immediately convert to alkyl radicals even at 4.2 K by hydrogen-atom tunneling from alkane molecules to the free hydrogen atoms. The rate of hydrogen atom tunneling does not necessary increase with decreasing activation energy or the peak height of the potential energy barrier preventing the tunneling. Although the activation energy is the lowest at the tertiary carbon of alkanes, hydrogen atom tunneling from branched alkanes with tertiary carbon at the antepenultimate position of the carbon skeleton is the fastest at the secondary penultimate carbon. Based on our experimental results, we have proposed that the peculiarity of the hydrogen-atom abstraction in cryogenic solids comes from the steric hindrance by matrix molecules to the deformation of alkane molecules from the initial sp 3 to the final sp 2 configurations. The steric hindrance causes the increase of the height of the potential energy barrier for the

  16. Stability of metal organic frameworks and interaction of small gas molecules in these materials

    Tan, Kui

    The work in this dissertation combines spectroscopy ( in-situ infrared absorption and Raman), powder X-ray diffraction and DFT calculations to study the stability of metal organic frameworks materials (MOFs) in the presence of water vapor and other corrosive gases (e.g., SO 2, NO2 NO), and the interaction and competitive co-adsorption of several gases within MOFs by considering two types of prototypical MOFs: 1) a MOF with saturated metal centers based on paddlewheel secondary building units: M(bdc)(ted)0.5 [M=Cu, Zn, Ni, Co, bdc = 1,4-benzenedicarboxylate, ted = triethylenediamine], and 2) a MOF with unsaturated metal centers: M2(dobdc) [M=Mg2+, Zn2+, Ni2+, Co2+ and dobdc = 2,5-dihydroxybenzenedicarboxylate]. We find that the stability of MOFs to water vapor critically depends on their structure and the specific metal cation in the building units. For M(bdc)(ted)0.5, the metal-bdc bond is the most vulnerable for Cu(bdc)(ted)0.5, while the metal-ted bond is first attacked for the Zn and Co analogs. In contrast, Ni(bdc)(ted)0.5 remains stable under the same conditions. For M2(dobdc), or MOF-74, the weak link is the dobdc-metal bond. The water molecule is dissociatively adsorbed at the metal-oxygen group with OH adsorption directly on the metal center and H adsorption on the bridging O of the phenolate group in the dobdc linker. Other technologically important molecules besides water, such as NO, NO2, SO2, tend to poison M2(dobdc) through dissociative or molecular adsorption onto the open metal sites. A high uptake SO2 capacity was measured in M(bdc)(ted)0.5, attributed to multipoint interactions between the guest SO2 molecule and the MOF host. In the case of competitive co-adsorption between CO2 and other small molecules, we find that binding energy alone is not a good indicator of molecular site occupation within the MOF (i.e., it cannot successfully predict and evaluate the displacement of CO2 by other molecules). Instead, we show that the kinetic barrier for the

  17. Functionalized Self-Assembled InAs/GaAs Quantum-Dot Structures Hybridized with Organic Molecules

    Chen, Miaoxiang Max; Kobashi, K.; Chen, B.

    2010-01-01

    Low-dimensional III-V semiconductors have many advantages over other semiconductors; however, they are not particularly stable under physiological conditions. Hybridizing biocompatible organic molecules with advanced optical and electronic semiconductor devices based on quantum dots (QDs...

  18. Semiexperimental equilibrium structures for building blocks of organic and biological molecules: the B2PLYP route.

    Penocchio, Emanuele; Piccardo, Matteo; Barone, Vincenzo

    2015-10-13

    The B2PLYP double hybrid functional, coupled with the correlation-consistent triple-ζ cc-pVTZ (VTZ) basis set, has been validated in the framework of the semiexperimental (SE) approach for deriving accurate equilibrium structures of molecules containing up to 15 atoms. A systematic comparison between new B2PLYP/VTZ results and several equilibrium SE structures previously determined at other levels, in particular B3LYP/SNSD and CCSD(T) with various basis sets, has put in evidence the accuracy and the remarkable stability of such model chemistry for both equilibrium structures and vibrational corrections. New SE equilibrium structures for phenylacetylene, pyruvic acid, peroxyformic acid, and phenyl radical are discussed and compared with literature data. Particular attention has been devoted to the discussion of systems for which lack of sufficient experimental data prevents a complete SE determination. In order to obtain an accurate equilibrium SE structure for these situations, the so-called templating molecule approach is discussed and generalized with respect to our previous work. Important applications are those involving biological building blocks, like uracil and thiouracil. In addition, for more general situations the linear regression approach has been proposed and validated.

  19. Van Der Waals Heterostructures between Small Organic Molecules and Layered Substrates

    Han Huang

    2016-09-01

    Full Text Available Two dimensional atomic crystals, like grapheme (G and molybdenum disulfide (MoS2, exhibit great interest in electronic and optoelectronic applications. The excellent physical properties, such as transparency, semiconductivity, and flexibility, make them compatible with current organic electronics. Here, we review recent progress in the understanding of the interfaces of van der Waals (vdW heterostructures between small organic molecules (pentacene, copper phthalocyanine (CuPc, perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA, and dioctylbenzothienobenzothiophene (C8-BTBT and layered substrates (G, MoS2 and hexagonal boron nitride (h-BN. The influences of the underlying layered substrates on the molecular arrangement, electronic and vibrational properties will be addressed.

  20. Thermodynamic characteristics of the adsorption of organic molecules on modified MCM-41 adsorbents

    Gus'kov, V. Yu.; Sukhareva, D. A.; Salikhova, G. R.; Karpov, S. I.; Kudasheva, F. Kh.; Roessner, F.; Borodina, E. V.

    2017-07-01

    The adsorption of a number of organic molecules on samples of MCM-41 adsorbent modified with dichloromethylphenylsilane and subsequently treated with sulfuric acid (MDCS) and N-trimethoxysilylpropyl- N, N, N-trimethylammonium chloride (MNM) is studied. Specific retention volumes equal to the Henry constant are determined by means of inverse gas chromatography at infinite dilution. The thermodynamic characteristics of adsorption, the dispersive and specific components of the Helmholtz energy of adsorption, and the increment of the methyl group to the heat of adsorption are calculated. It is shown that the grafting of aminosilane and phenylsilane groups enhances the forces of dispersion and reduces specific interactions. A greater drop in polarity is observed for MDCS than for MNM, due to the stronger polarity of amoinosilane; the enthalpy factor makes the main contribution to the adsorption of organic compounds on the investigated adsorbents. It is found that the MNM sample is capable of the irreversible adsorption of alcohols.

  1. Focused Role of an Organic Small-Molecule PBD on Performance of the Bistable Resistive Switching.

    Li, Lei; Sun, Yanmei; Ai, Chunpeng; Lu, Junguo; Wen, Dianzhong; Bai, Xuduo

    2015-12-01

    An undoped organic small-molecule 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) and a kind of nanocomposite blending poly(methyl methacrylate) (PMMA) into PBD are employed to implement bistable resistive switching. For the bistable resistive switching indium tin oxide (ITO)/PBD/Al, its ON/OFF current ratio can touch 6. What is more, the ON/OFF current ratio, approaching to 10(4), is available due to the storage layer PBD:PMMA with the chemical composition 1:1 in the bistable resistive switching ITO/PBD:PMMA/Al. The capacity, data retention of more than 1 year and endurance performance (>10(4) cycles) of ITO/PBD:PMMA(1:1)/Al, exhibits better stability and reliability of the samples, which underpins the technique and application of organic nonvolatile memory.

  2. Multicolor emission from large-area porous thin films constructed of nanowires of small organic molecules

    Wang Zhechen; Ding Xunlei; Ma Yanping; Xue Wei; He Shenggui; Xiao Wenchang

    2008-01-01

    We describe a facile low-temperature physical vapor deposition approach to fabricate porous network thin films constructed of nanowires of small organic molecules on a large area. Supermolecular assemblies of pyrene nanowires based on a combination of van der Waals forces and π-π stacking tend to hierarchically self-assemble to form uniform porous films using our techniques. The morphology of the films is studied and we also study several reasons influencing the process of assembly such as evaporation temperature, deposition temperature, and different kinds of substrate. The deposition temperature is determined to be the main reason for hierarchical aggregation. Typically prepared films exhibit unique optical properties, that is, multicolor red-green-blue emissions. This novel method can be applied to other organic molecular systems and may be potentially used to place nanoscaled building blocks directly on solid surfaces for fabricating large-area nanostructure-based flat screens.

  3. Multicolor emission from large-area porous thin films constructed of nanowires of small organic molecules

    Wang, Zhe-Chen; Xiao, Wen-Chang; Ding, Xun-Lei; Ma, Yan-Ping; Xue, Wei; He, Sheng-Gui

    2008-12-01

    We describe a facile low-temperature physical vapor deposition approach to fabricate porous network thin films constructed of nanowires of small organic molecules on a large area. Supermolecular assemblies of pyrene nanowires based on a combination of van der Waals forces and π-π stacking tend to hierarchically self-assemble to form uniform porous films using our techniques. The morphology of the films is studied and we also study several reasons influencing the process of assembly such as evaporation temperature, deposition temperature, and different kinds of substrate. The deposition temperature is determined to be the main reason for hierarchical aggregation. Typically prepared films exhibit unique optical properties, that is, multicolor red-green-blue emissions. This novel method can be applied to other organic molecular systems and may be potentially used to place nanoscaled building blocks directly on solid surfaces for fabricating large-area nanostructure-based flat screens.

  4. Measurement of the conductance properties of single organic molecules using gold nanoparticles

    Gordin, Yoav

    In this work we describe the development and application of a new method for the electrical conductance measurement of single molecules. The issue of reliable theoretical modeling of molecular electronic transport is still very much in debate. The experimental methods used in the field are difficult to realize and interpret; most have very low yield, preventing proper statistical analysis and many have problems in the researchers' ability to characterize the system properly. We address this issue by using self assembly of gold nanoparticle-molecule-gold nanoparticle objects called dimers. This method allows fabrication of molecular junctions with greater ease; moreover it allows individual characterization of the various elements of the junction, removing much of the uncertainties that exist in this kind of measurements. We make use of home grown gold nanoparticles with a few tens of nanometer diameter to form the hybrid dimers. The dimers are large enough to connect between electrodes fabricated using electron beam lithography and to measure the electric properties of the molecule. We have invested significant effort in the characterization of the system, ensuring that the dimers are indeed bridged by the molecules, and that the chances that more than a single molecule exists in a dimer are negligibly small. We have made measurements on single gold nanoparticles, to characterize their properties separately from those of the molecule. These measurements have allowed us to observe single electron transistor (SET) behavior, resulting from the requirement that electrons charge the nanoparticle during transport. We have shown that the energy associated with this charging scales with nanoparticle size as expected. We have performed measurements on single organic molecules, showing that there is a very strong influence of molecular conjugation (the way electronic orbitals are spread along the molecular backbone) on its conductance. The molecules with broken conjugation

  5. Extensive TD-DFT Benchmark: Singlet-Excited States of Organic Molecules.

    Jacquemin, Denis; Wathelet, Valérie; Perpète, Eric A; Adamo, Carlo

    2009-09-08

    Extensive Time-Dependent Density Functional Theory (TD-DFT) calculations have been carried out in order to obtain a statistically meaningful analysis of the merits of a large number of functionals. To reach this goal, a very extended set of molecules (∼500 compounds, >700 excited states) covering a broad range of (bio)organic molecules and dyes have been investigated. Likewise, 29 functionals including LDA, GGA, meta-GGA, global hybrids, and long-range-corrected hybrids have been considered. Comparisons with both theoretical references and experimental measurements have been carried out. On average, the functionals providing the best match with reference data are, one the one hand, global hybrids containing between 22% and 25% of exact exchange (X3LYP, B98, PBE0, and mPW1PW91) and, on the other hand, a long-range-corrected hybrid with a less-rapidly increasing HF ratio, namely LC-ωPBE(20). Pure functionals tend to be less consistent, whereas functionals incorporating a larger fraction of exact exchange tend to underestimate significantly the transition energies. For most treated cases, the M05 and CAM-B3LYP schemes deliver fairly small deviations but do not outperform standard hybrids such as X3LYP or PBE0, at least within the vertical approximation. With the optimal functionals, one obtains mean absolute deviations smaller than 0.25 eV, though the errors significantly depend on the subset of molecules or states considered. As an illustration, PBE0 and LC-ωPBE(20) provide a mean absolute error of only 0.14 eV for the 228 states related to neutral organic dyes but are completely off target for cyanine-like derivatives. On the basis of comparisons with theoretical estimates, it also turned out that CC2 and TD-DFT errors are of the same order of magnitude, once the above-mentioned hybrids are selected.

  6. The census of complex organic molecules in the solar-type protostar IRAS16293-2422

    Jaber, Ali A.; Ceccarelli, C.; Kahane, C. [Université Grenoble Alpes, IPAG, F-38000 Grenoble (France); Caux, E. [Université de Toulouse, UPS-OMP, IRAP, F-31400 Toulouse (France)

    2014-08-10

    Complex organic molecules (COMs) are considered to be crucial molecules, since they are connected with organic chemistry, at the basis of terrestrial life. More pragmatically, they are molecules which in principle are difficult to synthesize in harsh interstellar environments and, therefore, are a crucial test for astrochemical models. Current models assume that several COMs are synthesized on lukewarm grain surfaces (≳30-40 K) and released in the gas phase at dust temperatures of ≳100 K. However, recent detections of COMs in ≲20 K gas demonstrate that we still need important pieces to complete the puzzle of COMs formation. Here, we present a complete census of the oxygen- and nitrogen-bearing COMs, previously detected in different Interstellar Medium (ISM) regions, toward the solar-type protostar IRAS16293-2422. The census was obtained from the millimeter-submillimeter unbiased spectral survey TIMASSS. Of the 29 COMs searched for, 6 were detected: methyl cyanide, ketene, acetaldehyde, formamide, dimethyl ether, and methyl formate. Multifrequency analysis of the last five COMs provides clear evidence that they are present in the cold (≲30 K) envelope of IRAS16293-2422, with abundances of 0.03-2 × 10{sup –10}. Our data do not allow us to support the hypothesis that the COMs abundance increases with increasing dust temperature in the cold envelope, as expected if COMs were predominately formed on lukewarm grain surfaces. Finally, when also considering other ISM sources, we find a strong correlation over five orders of magnitude between methyl formate and dimethyl ether, and methyl formate and formamide abundances, which may point to a link between these two couples of species in cold and warm gas.

  7. Dynamic Control of Synaptic Adhesion and Organizing Molecules in Synaptic Plasticity

    Rudenko, Gabby (Texas-MED)

    2017-01-01

    Synapses play a critical role in establishing and maintaining neural circuits, permitting targeted information transfer throughout the brain. A large portfolio of synaptic adhesion/organizing molecules (SAMs) exists in the mammalian brain involved in synapse development and maintenance. SAMs bind protein partners, formingtrans-complexes spanning the synaptic cleft orcis-complexes attached to the same synaptic membrane. SAMs play key roles in cell adhesion and in organizing protein interaction networks; they can also provide mechanisms of recognition, generate scaffolds onto which partners can dock, and likely take part in signaling processes as well. SAMs are regulated through a portfolio of different mechanisms that affect their protein levels, precise localization, stability, and the availability of their partners at synapses. Interaction of SAMs with their partners can further be strengthened or weakened through alternative splicing, competing protein partners, ectodomain shedding, or astrocytically secreted factors. Given that numerous SAMs appear altered by synaptic activity, in vivo, these molecules may be used to dynamically scale up or scale down synaptic communication. Many SAMs, including neurexins, neuroligins, cadherins, and contactins, are now implicated in neuropsychiatric and neurodevelopmental diseases, such as autism spectrum disorder, schizophrenia, and bipolar disorder and studying their molecular mechanisms holds promise for developing novel therapeutics.

  8. Anisotropic charge transport in large single crystals of π-conjugated organic molecules.

    Hourani, Wael; Rahimi, Khosrow; Botiz, Ioan; Koch, Felix Peter Vinzenz; Reiter, Günter; Lienerth, Peter; Heiser, Thomas; Bubendorff, Jean-Luc; Simon, Laurent

    2014-05-07

    The electronic properties of organic semiconductors depend strongly on the nature of the molecules, their conjugation and conformation, their mutual distance and the orientation between adjacent molecules. Variations of intramolecular distances and conformation disturb the conjugation and perturb the delocalization of charges. As a result, the mobility considerably decreases compared to that of a covalently well-organized crystal. Here, we present electrical characterization of large single crystals made of the regioregular octamer of 3-hexyl-thiophene (3HT)8 using a conductive-atomic force microscope (C-AFM) in air. We find a large anisotropy in the conduction with charge mobility values depending on the crystallographic orientation of the single crystal. The smaller conduction is in the direction of π-π stacking (along the long axis of the single crystal) with a mobility value in the order of 10(-3) cm(2) V(-1) s(-1), and the larger one is along the molecular axis (in the direction normal to the single crystal surface) with a mobility value in the order of 0.5 cm(2) V(-1) s(-1). The measured current-voltage (I-V) curves showed that along the molecular axis, the current followed an exponential dependence corresponding to an injection mode. In the π-π stacking direction, the current exhibits a space charge limited current (SCLC) behavior, which allows us to estimate the charge carrier mobility.

  9. Isotope-selective high-order interferometry with large organic molecules in free fall

    Rodewald, Jonas; Dörre, Nadine; Grimaldi, Andrea; Geyer, Philipp; Felix, Lukas; Mayor, Marcel; Shayeghi, Armin; Arndt, Markus

    2018-03-01

    Interferometry in the time domain has proven valuable for matter-wave based measurements. This concept has recently been generalized to cold molecular clusters using short-pulse standing light waves which realized photo-depletion gratings, arranged in a time-domain Talbot–Lau interferometer (OTIMA). Here we extend this idea further to large organic molecules and demonstrate a new scheme to scan the emerging molecular interferogram in position space. The capability of analyzing different isotopes of the same monomer under identical conditions opens perspectives for studying the interference fringe shift as a function of time in gravitational free fall. The universality of OTIMA interferometry allows one to handle a large variety of particles. In our present work, quasi-continuous laser evaporation allows transferring fragile organic molecules into the gas phase, covering more than an order of magnitude in mass between 614 amu and 6509 amu, i.e. 300% more massive than in previous OTIMA experiments. For all masses, we find about 30% fringe visibility.

  10. Visualizing electron dynamics in organic materials: Charge transport through molecules and angular resolved photoemission

    Kümmel, Stephan

    Being able to visualize the dynamics of electrons in organic materials is a fascinating perspective. Simulations based on time-dependent density functional theory allow to realize this hope, as they visualize the flow of charge through molecular structures in real-space and real-time. We here present results on two fundamental processes: Photoemission from organic semiconductor molecules and charge transport through molecular structures. In the first part we demonstrate that angular resolved photoemission intensities - from both theory and experiment - can often be interpreted as a visualization of molecular orbitals. However, counter-intuitive quantum-mechanical electron dynamics such as emission perpendicular to the direction of the electrical field can substantially alter the picture, adding surprising features to the molecular orbital interpretation. In a second study we calculate the flow of charge through conjugated molecules. The calculations show in real time how breaks in the conjugation can lead to a local buildup of charge and the formation of local electrical dipoles. These can interact with neighboring molecular chains. As a consequence, collections of ''molecular electrical wires'' can show distinctly different characteristics than ''classical electrical wires''. German Science Foundation GRK 1640.

  11. Ambipolar Small-Molecule:Polymer Blend Semiconductors for Solution-Processable Organic Field-Effect Transistors.

    Kang, Minji; Hwang, Hansu; Park, Won-Tae; Khim, Dongyoon; Yeo, Jun-Seok; Kim, Yunseul; Kim, Yeon-Ju; Noh, Yong-Young; Kim, Dong-Yu

    2017-01-25

    We report on the fabrication of an organic thin-film semiconductor formed using a blend solution of soluble ambipolar small molecules and an insulating polymer binder that exhibits vertical phase separation and uniform film formation. The semiconductor thin films are produced in a single step from a mixture containing a small molecular semiconductor, namely, quinoidal biselenophene (QBS), and a binder polymer, namely, poly(2-vinylnaphthalene) (PVN). Organic field-effect transistors (OFETs) based on QBS/PVN blend semiconductor are then assembled using top-gate/bottom-contact device configuration, which achieve almost four times higher mobility than the neat QBS semiconductor. Depth profile via secondary ion mass spectrometry and atomic force microscopy images indicate that the QBS domains in the films made from the blend are evenly distributed with a smooth morphology at the bottom of the PVN layer. Bias stress test and variable-temperature measurements on QBS-based OFETs reveal that the QBS/PVN blend semiconductor remarkably reduces the number of trap sites at the gate dielectric/semiconductor interface and the activation energy in the transistor channel. This work provides a one-step solution processing technique, which makes use of soluble ambipolar small molecules to form a thin-film semiconductor for application in high-performance OFETs.

  12. Biological response of HeLa cells to gold nanoparticles coated with organic molecules.

    Cardoso Avila, P E; Rangel Mendoza, A; Pichardo Molina, J L; Flores Villavicencio, L L; Castruita Dominguez, J P; Chilakapati, M K; Sabanero Lopez, M

    2017-08-01

    In this work, gold nanospheres functionalized with low weight organic molecules (4-aminothiphenol and cysteamine) were synthesized in a one-step method for their in vitro cytotoxic evaluation on HeLa cells. To enhance the biocompatibility of the cysteamine-capped GNPs, BSA was used due to its broad PH stability and high binding affinity to gold nanoparticles. Besides, the widely reported silica coated gold nanorods were tested here to contrast their toxic response against our nanoparticles coated with organic molecules. Our results shown, the viability measured at 1.9×10 -5 M did not show significant differences against negative controls for all the samples; however, the metabolic activity of HeLa cells dropped when they were exposed to silica gold nanorods in the range of concentrations from 2.9×10 -7 M to 3.0×10 -4 M, while in the cases of gold nanospheres, we found that only at concentrations below 1.9×10 -5 M metabolic activity was normal. Our preliminary results did not indicate any perceivable harmful toxicity to cell membrane, cytoskeleton or nucleus due to our nanospheres at 1.9×10 -5 M. Additional test should be conducted in order to ensure a safe use of them for biological applications, and to determine the extent of possible damage. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Complex organic molecules in the Galactic Centre: the N-bearing family

    Zeng, S.; Jiménez-Serra, I.; Rivilla, V. M.; Martín, S.; Martín-Pintado, J.; Requena-Torres, M. A.; Armijos-Abendaño, J.; Riquelme, D.; Aladro, R.

    2018-05-01

    We present an unbiased spectral line survey toward the Galactic Centre (GC) quiescent giant molecular cloud (QGMC), G+0.693 using the GBT and IRAM 30 telescopes. Our study highlights an extremely rich organic inventory of abundant amounts of nitrogen (N)-bearing species in a source without signatures of star formation. We report the detection of 17 N-bearing species in this source, of which 8 are complex organic molecules (COMs). A comparison of the derived abundances relative to H2 is made across various galactic and extragalactic environments. We conclude that the unique chemistry in this source is likely to be dominated by low-velocity shocks with X-rays/cosmic rays also playing an important role in the chemistry. Like previous findings obtained for O-bearing molecules, our results for N-bearing species suggest a more efficient hydrogenation of these species on dust grains in G+0.693 than in hot cores in the Galactic disk, as a consequence of the low dust temperatures coupled with energetic processing by X-ray/cosmic ray radiation in the GC.

  14. Functionalization of nanoparticle titanium dioxide with different bifunctional organic molecules and trimers of transition compounds for obtaining new materials

    Rivera Martinez, Maria Cinthya

    2012-01-01

    Functionalization of titanium dioxide in nanoporous anatase phase is investigated for obtaining new nanomaterials. Functionalizations were performed using two heating methods: the conventional of refluxing heating method and microwave irradiation with bifunctional organic molecules is used to study how to anchor molecules and the change in the wettability of the material. Besides, reactions with organic molecules were performed as the derived from nanoproxene. The growth layer by layer is performed using the bifunctional molecules previous for the immobilization of cobalt trimers. Functionalized molecules were characterized by infrared spectroscopy, X-ray diffraction, contact angle, scanning electron microscopy, x-ray elemental analysis, plasma atomic emission spectroscopy coupled inductively, x-ray photoelectron spectroscopy and thermogravimetric analysis. This type of functionalizations on nanoporous titanium dioxide could potentially improve optical sensitivity and activity of this nanomaterial in the visible region. (author) [es

  15. Metal-organic and supramolecular architectures based on mechanically interlocked molecules

    Fernando, Isurika Rosini

    The focus of this work is on mechanically interlocked molecules (MIMs), which have unusual physicochemical and mechanical properties with potential applications in nano-scale/molecular devices and high strength materials. Rotaxanes, for example, consist of an axle-like molecule threaded through a wheel-like molecule, with bulky groups at the two ends of the axle preventing the wheel from dissociating. The position of the wheel along the axle can be switched in a controllable and reversible manner by applying external stimuli, a feature that might lead to the next generation of computers. Molecularly woven materials (MWMs), another example of molecules with mechanically interlocked features, are predicted to be unprecedentedly strong while being lightweight and flexible. With the ultimate goal of achieving control over the functioning of molecular devices in the solid state, a variety of pseudorotaxane building blocks were prepared and characterized, including a novel, rare blue-colored motif. The temperature-dependent assembly/disassembly of pseudorotaxanes was exploited for the construction of single-wavelength colorimetric temperature sensors over a 100 °C window. Pseudorotaxanes based on aromatic crown ether wheels and disubstituted 4,4'-bipyridinium axles were converted into rotaxanes upon binding to metal complexes (zinc, cadmium, mercury, copper, cobalt), and the formation of ordered crystalline arrays was studied in the solid state. The columnar organization of pseudorotaxanes by Hg2X6 2-- complexes (X = Cl, Br, I), leading to unprecedented dichroic (blue/red) rotaxane crystals, was demonstrated for the first time. From the crystal structures studied it became apparent that negatively charged metal complexes are needed for successful assembly with the positively charged pseudorotaxane units. To be able to use the more common, positively charged metal ions for rotaxane framework construction, neutral and negatively charged pseudorotaxanes were synthesized

  16. Structural Design Principle of Small-Molecule Organic Semiconductors for Metal-Free, Visible-Light-Promoted Photocatalysis.

    Wang, Lei; Huang, Wei; Li, Run; Gehrig, Dominik; Blom, Paul W M; Landfester, Katharina; Zhang, Kai A I

    2016-08-08

    Herein, we report on the structural design principle of small-molecule organic semiconductors as metal-free, pure organic and visible light-active photocatalysts. Two series of electron-donor and acceptor-type organic semiconductor molecules were synthesized to meet crucial requirements, such as 1) absorption range in the visible region, 2) sufficient photoredox potential, and 3) long lifetime of photogenerated excitons. The photocatalytic activity was demonstrated in the intermolecular C-H functionalization of electron-rich heteroaromates with malonate derivatives. A mechanistic study of the light-induced electron transport between the organic photocatalyst, substrate, and the sacrificial agent are described. With their tunable absorption range and defined energy-band structure, the small-molecule organic semiconductors could offer a new class of metal-free and visible light-active photocatalysts for chemical reactions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. A-π-D-π-A Electron-Donating Small Molecules for Solution-Processed Organic Solar Cells: A Review.

    Wang, Zhen; Zhu, Lingyun; Shuai, Zhigang; Wei, Zhixiang

    2017-11-01

    Organic solar cells based on semiconducting polymers and small molecules have attracted considerable attention in the last two decades. Moreover, the power conversion efficiencies for solution-processed solar cells containing A-π-D-π-A-type small molecules and fullerenes have reached 11%. However, the method for designing high-performance, photovoltaic small molecules still remains unclear. In this review, recent studies on A-π-D-π-A electron-donating small molecules for organic solar cells are introduced. Moreover, the relationships between molecular properties and device performances are summarized, from which inspiration for the future design of high performance organic solar cells may be obtained. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Inorganics in Organics: Tracking down the Intrinsic Equilibriums between Organic Molecules and Trace Elements in Oceanic Waters

    Lechtenfeld, O. J.; Koch, B. P.; Kattner, G.

    2010-12-01

    Recent developments in analytical instrumentation enable to describe biogeochemical processes in oceanic waters on a molecular level. This is the prerequisite to integrate biological and geochemical parameters and to develop chemical cycles on a global perspective. The state-of-the-art Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) applications for dissolved organic matter (DOM) focus mainly on carbon, hydrogen, oxygen and nitrogen isotopes. Implementation of sulfur and especially phosphorus in the molecular formula assignment has been questionable because of ambiguous calculated elemental formulas. On the other hand, many compounds bearing these elements are well known to occur in the dissolved state as part of the permanent recycling processes (e.g. phospholipids, phosphonates) but analytics of dissolved organic phosphorus (DOP) and sulfur (DOS) are often hampered by the large inorganic P and S pools. Even less is known about complexation characteristics of the DOM moieties. Although electrochemical methods provide some information about trace metal speciation, the high amount of organic molecules and its insufficient description as chemical functional classes prevent the assignment of trace metals to ligand classes. Nevertheless, it is undoubtful that a varying but extensive amount of transition metals is bond in form of organic complexes. Hyphenation of reversed phase high performance liquid chromatography (RP-HPLC) with high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) is a valuable tool to study these metal-organic interactions in a qualitative and quantitative approach. We established a desolvation method that allows direct transfer of high organic solvent loads into the plasma. Thus, in combination with internal standardization and external calibration, the investigation of a broad polarity scale was possible. This approach overcomes previous restrictions to non-organic solvent separation techniques like size

  19. Intercalation of organic molecules into SnS{sub 2} single crystals

    Toh, M.L.; Tan, K.J.; Wei, F.X.; Zhang, K.K.; Jiang, H. [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Ave., Singapore 639798 (Singapore); Kloc, C., E-mail: ckloc@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Ave., Singapore 639798 (Singapore)

    2013-02-15

    SnS{sub 2} is a layered semiconductor with a van der Waals gap separating the covalently bonded layers. In this study, post-synthesis intercalation of donor organic amine molecules, such as ethylenediamine (en), into tin disulfide and secondary intercalation of p-phenylenediamine (PPD) and 1, 5-naphthalenediamine (NDA) into SnS{sub 2e}n have been verified with X-ray diffraction. PPD and NDA did not intercalate directly even during prolonged annealing but replaced en readily if en was already present in the van der Waals gap. The c-lattice dilation is proportional to the intercalant size. Unit cell lattices of intercalated products were determined from the positions of the X-ray diffraction peaks. Optical images taken during the intercalation showed that intercalation progressed from the periphery towards the interior of the crystal. TEM diffraction patterns in the [0 0 1] direction of SnS{sub 2} after intercalation revealed defects and stacking mismatches among the SnS{sub 2} layers caused by the intercalation. UV-Vis absorption studies showed a red shift in the band edge of the SnS{sub 2} material after intercalation. The band edge was 2.2 eV for pristine SnS{sub 2}; after intercalation with en or PPD, the absorbance spectra band edges shifted to approximately 0.7 eV or 0.5 eV, respectively. - Graphical Abstract: SnS{sub 2} single crystals were intercalated with organic amine molecules such as ethylenediamine, phenylenediamine and naphthalenediamine. Absorption studies showed red shift of band edge after intercalation, which was consistent with optical observations. X-ray diffraction indicated lattice dilation in the c-lattice of SnS{sub 2} after intercalation. Highlights: Black-Right-Pointing-Pointer Organic molecules intercalated inhomogenously between covalently bonded SnS{sub 2} layers. Black-Right-Pointing-Pointer Ethylenediamine (en) intercalate directly into SnS{sub 2}. Black-Right-Pointing-Pointer Phenylenediamine (PPD) and naphthalenediamine (NDA) can be

  20. Intercalation of organic molecules into SnS2 single crystals

    Toh, M.L.; Tan, K.J.; Wei, F.X.; Zhang, K.K.; Jiang, H.; Kloc, C.

    2013-01-01

    SnS 2 is a layered semiconductor with a van der Waals gap separating the covalently bonded layers. In this study, post-synthesis intercalation of donor organic amine molecules, such as ethylenediamine (en), into tin disulfide and secondary intercalation of p-phenylenediamine (PPD) and 1, 5-naphthalenediamine (NDA) into SnS 2e n have been verified with X-ray diffraction. PPD and NDA did not intercalate directly even during prolonged annealing but replaced en readily if en was already present in the van der Waals gap. The c-lattice dilation is proportional to the intercalant size. Unit cell lattices of intercalated products were determined from the positions of the X-ray diffraction peaks. Optical images taken during the intercalation showed that intercalation progressed from the periphery towards the interior of the crystal. TEM diffraction patterns in the [0 0 1] direction of SnS 2 after intercalation revealed defects and stacking mismatches among the SnS 2 layers caused by the intercalation. UV–Vis absorption studies showed a red shift in the band edge of the SnS 2 material after intercalation. The band edge was 2.2 eV for pristine SnS 2 ; after intercalation with en or PPD, the absorbance spectra band edges shifted to approximately 0.7 eV or 0.5 eV, respectively. - Graphical Abstract: SnS 2 single crystals were intercalated with organic amine molecules such as ethylenediamine, phenylenediamine and naphthalenediamine. Absorption studies showed red shift of band edge after intercalation, which was consistent with optical observations. X-ray diffraction indicated lattice dilation in the c-lattice of SnS 2 after intercalation. Highlights: ► Organic molecules intercalated inhomogenously between covalently bonded SnS 2 layers. ► Ethylenediamine (en) intercalate directly into SnS 2 . ► Phenylenediamine (PPD) and naphthalenediamine (NDA) can be intercalated into SnS 2 secondary. ► In a secondary intercalation the bonds between layers are weakened by direct

  1. Three dimensional extrusion printing induces polymer molecule alignment and cell organization within engineered cartilage.

    Guo, Ting; Ringel, Julia P; Lim, Casey G; Bracaglia, Laura G; Noshin, Maeesha; Baker, Hannah B; Powell, Douglas A; Fisher, John P

    2018-04-16

    Proper cell-material interactions are critical to remain cell function and thus successful tissue regeneration. Many fabrication processes have been developed to create microenvironments to control cell attachment and organization on a three-dimensional (3D) scaffold. However, these approaches often involve heavy engineering and only the surface layer can be patterned. We found that 3D extrusion based printing at high temperature and pressure will result an aligned effect on the polymer molecules, and this molecular arrangement will further induce the cell alignment and different differentiation capacities. In particular, articular cartilage tissue is known to have zonal collagen fiber and cell orientation to support different functions, where collagen fibers and chondrocytes align parallel, randomly, and perpendicular, respectively, to the surface of the joint. Therefore, cell alignment was evaluated in a cartilage model in this study. We used small angle X-ray scattering analysis to substantiate the polymer molecule alignment phenomenon. The cellular response was evaluated both in vitro and in vivo. Seeded mesenchymal stem cells (MSCs) showed different morphology and orientation on scaffolds, as a combined result of polymer molecule alignment and printed scaffold patterns. Gene expression results showed improved superficial zonal chondrogenic marker expression in parallel-aligned group. The cell alignment was successfully maintained in the animal model after 7 days with distinct MSC morphology between the casted and parallel printed scaffolds. This 3D printing induced polymer and cell alignment will have a significant impact on developing scaffold with controlled cell-material interactions for complex tissue engineering while avoiding complicated surface treatment, and therefore provides new concept for effective tissue repairing in future clinical applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2018. © 2018 Wiley Periodicals, Inc.

  2. Selected ion flow tube studies of S2+ reactions with a series of organic molecules

    Decker, Brian K.; Adams, Nigel G.

    1997-11-01

    A selected ion flow tube (SIFT) has been used to study the reactions of S2+ with a series of organic molecules (as well as H2, CO, NH3, NO and NO2). These include the hydrocarbons, C2H4, C2H6, CH2CCH2, CH3CHCH2 and C3H8; alcohols and thiols, CH3OH, C2H5OH, CH3SH and C2H5SH; ethers (CH3)2O and (C2H5)2O; aldehydes and ketones, CH3CHO, C2H5CHO and (CH3)2CO; and carboxylic acids and esters, HCO2H, HCO2CH3, HCO2C2H5, CH3CO2H, CH3CO2CH3, CH3CO2C2H5, C2H5CO2H, C2H5CO2CH3 and C2H5CO2C2H5. The rate coefficients are generally close to the collisional values, with exceptions among the reactions involving the smaller molecules. Most prevalent are abstraction reactions leading to formation of the thiosulfeno radical, HS2, or its protonated form; three-body associations; and channels leading to formation of the acetyl and propionyl cations, CH3CO+ and C2H5CO+, respectively. Only in reactions involving the alkenes is cleavage of the S---S bond of S2+ observed. The isomeric molecules in the data set generally react very differently, as would be expected from reactivity controlled by the position and complexity of the functional groups. The data are discussed in terms of reaction mechanisms, thermodynamics, and implications for interstellar chemistry.

  3. Elucidating Turnover Pathways of Bioactive Small Molecules by Isotopomer Analysis: The Persistent Organic Pollutant DDT

    Ehlers, Ina; Betson, Tatiana R.; Vetter, Walter; Schleucher, Jürgen

    2014-01-01

    The persistent organic pollutant DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) is still indispensable in the fight against malaria, although DDT and related compounds pose toxicological hazards. Technical DDT contains the dichloro congener DDD (1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethyl]benzene) as by-product, but DDD is also formed by reductive degradation of DDT in the environment. To differentiate between DDD formation pathways, we applied deuterium NMR spectroscopy to measure intramolecular deuterium distributions (2H isotopomer abundances) of DDT and DDD. DDD formed in the technical DDT synthesis was strongly deuterium-enriched at one intramolecular position, which we traced back to 2H/1H fractionation of a chlorination step in the technical synthesis. In contrast, DDD formed by reductive degradation was strongly depleted at the same position, which was due to the incorporation of 2H-depleted hydride equivalents during reductive degradation. Thus, intramolecular isotope distributions give mechanistic information on reaction pathways, and explain a puzzling difference in the whole-molecule 2H/1H ratio between DDT and DDD. In general, our results highlight that intramolecular isotope distributions are essential to interpret whole-molecule isotope ratios. Intramolecular isotope information allows distinguishing pathways of DDD formation, which is important to identify polluters or to assess DDT turnover in the environment. Because intramolecular isotope data directly reflect isotope fractionation of individual chemical reactions, they are broadly applicable to elucidate transformation pathways of small bioactive molecules in chemistry, physiology and environmental science. PMID:25350380

  4. Effect of molecular structure on fragmentation of isolated organic molecules in solid rare gas matrices

    Kobzarenko, A.V.; Sukhov, F.F.; Orlov, A.Yu.; Kovalev, G.V.; Baranova, I.A.; Feldman, V.I.

    2012-01-01

    The effect of excess energy on the primary radical cations of bifunctional carbonyl compounds and aliphatic alkynes was simulated by matrix isolation method using rare gas matrices with various ionization potentials. The formation of fragmentation products was monitored by EPR and FTIR spectroscopy. It was shown that the radical cations of bifunctional compounds (CH 3 OCH 2 COCH 3 and CH 3 COCOCH 3 ) dissociated effectively yielding · CH 3 radicals upon irradiation in solid argon matrix at T≤16 K. In addition to isolated methyl radicals, the radical pairs consisting of two methyl radicals separated by two CO molecules were detected in the case of diacetyl. The probability of fragmentation decreases with the decreasing excess energy by switching from Ar to Xe. In general, bifunctional molecules were found to be less stable to “hot” ionic fragmentation in low-temperature solids in comparison with simple prototype compounds. In the case of alkynes of the R--C≡CH type, a noticeable yield of fragmentation products was observed when R=–C(CH 3 ) 3 , but it was negligible for R=–CH 3 . The mechanisms of “hot” reactions and excess energy relaxation are discussed. - Highlights: ► Radiolysis of bifunctional organic compounds and alkynes. ► Dependence of “hot” fragmentation probability from molecular structure. ► Ions of bifunctional compounds are less stable than those of monofunctional ones. ► Alkynes are rather stable to “hot” fragmentation.

  5. Interplay between efficiency and device architecture for small molecule organic solar cells.

    Williams, Graeme; Sutty, Sibi; Aziz, Hany

    2014-06-21

    Small molecule organic solar cells (OSCs) have experienced a resurgence of interest over their polymer solar cell counterparts, owing to their improved batch-to-batch (thus, cell-to-cell) reliability. In this systematic study on OSC device architecture, we investigate five different small molecule OSC structures, including the simple planar heterojunction (PHJ) and bulk heterojunction (BHJ), as well as several planar-mixed structures. The different OSC structures are studied over a wide range of donor:acceptor mixing concentrations to gain a comprehensive understanding of their charge transport behavior. Transient photocurrent decay measurements provide crucial information regarding the interplay between charge sweep-out and charge recombination, and ultimately hint toward space charge effects in planar-mixed structures. Results show that the BHJ/acceptor architecture, comprising a BHJ layer with high C60 acceptor content, generates OSCs with the highest performance by balancing charge generation with charge collection. The performance of other device architectures is largely limited by hole transport, with associated hole accumulation and space charge effects.

  6. Triplet--Triplet Absorption Spectra of Organic Molecules in Condensed Phases

    Carmichael, I.; Hug, G.L.

    1986-01-01

    We present a compilation of spectral parameters associated with triplet--triplet absorption of organic molecules in condensed media. The wavelengths of maximum absorbance and the corresponding extinction coefficients, where known, have been critically evaluated. Other data, for example, lifetimes, energies and energy transfer rates, relevant to the triplet states of these molecules are included by way of comments but have not been subjected to a similar scrutiny. Work in the gas phase has been omitted, as have theoretical studies. We provide an introduction to triplet state processes in solution and solids, developing the conceptual background and offering an historical perspective on the detection and measurement of triplet state absorption. Techniques employed to populate the triplet state are reviewed and the various approaches to the estimation of the extinction coefficient of triplet--triplet absorption are critically discussed. A statistical analysis of the available data is presented and recommendations for a hierarchical choice of extinction coefficients are made. Data collection is expected to be complete through the end of 1984. Compound name, molecular formula and author indexes are appended

  7. Solution-Processed Organic Solar Cells from Dye Molecules: An Investigation of Diketopyrrolopyrrole:Vinazene Heterojunctions

    Walker, Bright

    2012-01-25

    Although one of the most attractive aspects of organic solar cells is their low cost and ease of fabrication, the active materials incorporated into the vast majority of reported bulk heterojunction (BHJ) solar cells include a semiconducting polymer and a fullerene derivative, classes of materials which are both typically difficult and expensive to prepare. In this study, we demonstrate that effective BHJs can be fabricated from two easily synthesized dye molecules. Solar cells incorporating a diketopyrrolopyrrole (DPP)-based molecule as a donor and a dicyanoimidazole (Vinazene) acceptor function as an active layer in BHJ solar cells, producing relatively high open circuit voltages and power conversion efficiencies (PCEs) up to 1.1%. Atomic force microscope images of the films show that active layers are rough and apparently have large donor and acceptor domains on the surface, whereas photoluminescence of the blends is incompletely quenched, suggesting that higher PCEs might be obtained if the morphology could be improved to yield smaller domain sizes and a larger interfacial area between donor and acceptor phases. © 2011 American Chemical Society.

  8. Nanoscale charge localization induced by random orientations of organic molecules in hybrid perovskite CH3NH3PbI3

    Ma, Jie; Wang, Lin-Wang

    2015-03-01

    Perovskite-based solar cells have achieved high solar-energy conversion efficiencies and attracted wide attentions nowadays. Despite the rapid progress in solar-cell devices, many fundamental issues of the hybrid perovskites have not been fully understood. Experimentally, it is well known that in CH3NH3PbI3, the organic molecules CH3NH3 are randomly orientated at the room temperature, but the impact of the random molecular orientation has not been investigated. Using linear-scaling ab-initiomethods, we have calculated the electronic structures of the tetragonal phase of CH3NH3PbI3 with randomly orientated organic molecules in large supercells up to ~20,000 atoms. Due to the dipole moment of the organic molecule, the random orientation creates a novel system with long-range potential fluctuations unlike alloys or other conventional disordered systems. We find that the charge densities of the conduction-band minimum and the valence-band maximum are localized separately in nanoscales due to the potential fluctuations. The charge localization causes electron-hole separation and reduces carrier recombination rates, which may contribute to the long carrier lifetime observed in experiments. We have also proposed a model to explain the charge localization.

  9. An immersion calorimetric study of the interactions between some organic molecules and functionalized carbon nanotube surfaces

    Castillejos-López, E.; Bachiller-Baeza, B.; Guerrero-Ruiz, A.; Rodriguez-Ramos, I.

    2013-01-01

    Highlights: ► The interaction of organic chemicals with the surface of modified CNTs was studied. ► Specific π–π interactions between graphitic CNTs and toluene have been considered. ► Confinement effects in CNTs increase the adsorption strength of aromatic compounds. ► Methanol molecules form H-bonds with the oxygen functional groups on CNT surfaces. - Abstract: The interaction of organic chemicals with the surface of carbon nanotubes has been studied by immersion calorimetry revealing significant differences in the properties when these materials are modified thermally or chemically. Therefore, multiwall carbon nanotubes have been synthesized using a chemical vapour deposition procedure and subsequently aliquots were treated with HNO 3 at reflux, maintaining the reaction during different times, in order to incorporate oxygen surface groups, or were treated at 2873 K under inert atmosphere. The aim of this thermal treatment is to eliminate structural defects of the carbon nanostructures and to graphitize the amorphous carbon phases. These features were confirmed by high-resolution transmission electron microscopy. The immersion in organic compounds, including toluene, methanol and methylcyclohexane, of all these carbon nanotubes samples reveals that the surface properties are remarkably modified. Thus, the formation of different types of interaction, depending on the surface, gives place to changes in the immersion enthalpies

  10. Coupling between diffusion and orientation of pentacene molecules on an organic surface.

    Rotter, Paul; Lechner, Barbara A J; Morherr, Antonia; Chisnall, David M; Ward, David J; Jardine, Andrew P; Ellis, John; Allison, William; Eckhardt, Bruno; Witte, Gregor

    2016-04-01

    The realization of efficient organic electronic devices requires the controlled preparation of molecular thin films and heterostructures. As top-down structuring methods such as lithography cannot be applied to van der Waals bound materials, surface diffusion becomes a structure-determining factor that requires microscopic understanding. Scanning probe techniques provide atomic resolution, but are limited to observations of slow movements, and therefore constrained to low temperatures. In contrast, the helium-3 spin-echo (HeSE) technique achieves spatial and time resolution on the nm and ps scale, respectively, thus enabling measurements at elevated temperatures. Here we use HeSE to unveil the intricate motion of pentacene admolecules diffusing on a chemisorbed monolayer of pentacene on Cu(110) that serves as a stable, well-ordered organic model surface. We find that pentacene moves along rails parallel and perpendicular to the surface molecules. The experimental data are explained by admolecule rotation that enables a switching between diffusion directions, which extends our molecular level understanding of diffusion in complex organic systems.

  11. Organic molecules in the polar ice: from chemical analysis to environmental proxies

    Barbante, Carlo; Zennaro, Piero; Giorio, Chiara; Kehrwald, Natalie; Benton, Alisa K.; Wolff, Eric W.; Kalberer, Markus; Kirchgeorg, Torben; Zangrando, Roberta; Barbaro, Elena; Gambaro, Andrea

    2015-04-01

    The molecular and isotopic compositions of organic matter buried in ice contains information that helps reconstruct past environmental conditions, evaluate histories of climate change, and assess impacts of humans on ecosystems. In recent years novel analytical techniques were developed to quantify molecular compounds in ice cores. As an example, biomass burning markers, including monosaccharide anhydrides, lightweight carboxylic acids, lignin and resin pyrolysis products, black carbon, and charcoal records help in reconstructing past fire activity across seasonal to millennial time scales. Terrestrial biomarkers, such as plant waxes (e.g. long-chain n-alkanes) are also a promising paleo vegetation proxy in ice core studies. Polycyclic aromatic hydrocarbons are ubiquitous pollutants recently detected in ice cores. These hydrocarbons primarily originate from incomplete combustion of organic matter and fossil fuels (e.g. diesel engines, domestic heating, industrial combustion) and therefore can be tracers of past combustion activities. In order to be suitable for paloeclimate purposes, organic molecular markers detected in ice cores should include the following important features. Markers have to be stable under oxidizing atmospheric conditions, and ideally should not react with hydroxyl radicals, during their transport to polar regions. Organic markers must be released in large amounts in order to be detected at remote distances from the sources. Proxies must be specific, in order to differentiate them from other markers with multiple sources. The extraction of glaciochemical information from ice cores is challenging due to the low concentrations of some impurities, thereby demanding rigorous control of external contamination sources and sensitive analytical techniques. Here, we review the analysis and use of organic molecules in ice as proxies of important environmental and climatic processes.

  12. Water and oxygen induced degradation of small molecule organic solar cells

    Hermenau, Martin; Riede, Moritz; Leo, Karl

    2011-01-01

    Small molecule organic solar cells were studied with respect to water and oxygen induced degradation by mapping the spatial distribution of reaction products in order to elucidate the degradation patterns and failure mechanisms. The active layers consist of a 30 nm bulk heterojunction formed......,4′-diamine p-doped with C60F36 (MeO-TPD:C60F36), which acted as hole transporting layer. Indium-tin-oxide (ITO) and aluminum served as hole and electron collecting electrode, respectively. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) in conjunction...... of aluminum oxide at the BPhen/Al interface, and diffusion of water into the ZnPc:C60 layer where ZnPc becomes oxidized. Finally, diffusion from the electrodes was found to have no or a negligible effect on the device lifetime....

  13. Accurate on-chip measurement of the Seebeck coefficient of high mobility small molecule organic semiconductors

    Warwick, C. N.; Venkateshvaran, D.; Sirringhaus, H.

    2015-09-01

    We present measurements of the Seebeck coefficient in two high mobility organic small molecules, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) and 2,9-didecyl-dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C10-DNTT). The measurements are performed in a field effect transistor structure with high field effect mobilities of approximately 3 cm2/V s. This allows us to observe both the charge concentration and temperature dependence of the Seebeck coefficient. We find a strong logarithmic dependence upon charge concentration and a temperature dependence within the measurement uncertainty. Despite performing the measurements on highly polycrystalline evaporated films, we see an agreement in the Seebeck coefficient with modelled values from Shi et al. [Chem. Mater. 26, 2669 (2014)] at high charge concentrations. We attribute deviations from the model at lower charge concentrations to charge trapping.

  14. Production of carbon-14 and preparation of some key precursors for labeling organic molecules

    Moriya, T.; Motoishi, S.

    1992-01-01

    Production of carbon-14 on 50 GBq scale has been performed by neutron irradiation of aluminium nitride target in the JMTR. This nuclide is separated in carbon dioxide form by combustion of the irradiated target at 1100degC with oxygen. The [ 14 C] carbon dioxide liberated thus is trapped in caustic solution and finally recovered as [ 14 C] barium carbonate. Some precursors useful for incorporating carbon-14 into a given organic molecule have been prepared. Precursors such as [1- 14 C] sodium acetate, [ 14 C] methanol and [ 14 C] potassium cyanide are prepared by rather conventional methods involving carbonation of methyl magnesium iodine, reduction of carbon dioxide with lithium aluminium hydride and reduction of carbonate with metallic potassium in the presence of ammonium salt, respectively. A catalytic polymerization of acetylene is used to prepare benzene. (author)

  15. Ion chemistry of some organic molecules studied by field ionization and field desorption mass spectrometry

    Greef, J. van der.

    1980-01-01

    The chemistry of isolated ions in the gas phase is strongly dependent on the internal energy which they have required upon formation. Since also the average lifetime of an ion depends on its internal energy, ion lifetime studies have been employed for many years to obtain a better insight in the relation between the chemistry and internal energy of gas phase ions. A very powerful tool for such studies is the field ionization kinetic (FIK) method, because it can provide a time-resolved picture of decompositions of ions with lifetimes varying from 10 -11 to 10 -5 s. The FIK method has been used in combination with 2 H, 13 C and 15 N labelling for mechanistic studies on the fragmentation of some selected ionised organic molecules. (Auth.)

  16. Nuclear magnetic resonance of laser-polarized noble gases in molecules, materials and organisms

    Goodson, Boyd M.

    1999-01-01

    Conventional nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) are fundamentally challenged by the insensitivity that stems from the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This dissertation is primarily concerned with the principles and practice of optically pumped nuclear magnetic resonance (OPNMR). The enormous sensitivity enhancement afforded by optical pumping noble gases can be exploited to permit a variety of novel NMR experiments across many disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, and zero-field NMR and MRI

  17. Nuclear magnetic resonance of laser-polarized noble gases in molecules, materials and organisms

    Goodson, Boyd McLean [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    Conventional nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) are fundamentally challenged by the insensitivity that stems from the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This dissertation is primarily concerned with the principles and practice of optically pumped nuclear magnetic resonance (OPNMR). The enormous sensitivity enhancement afforded by optical pumping noble gases can be exploited to permit a variety of novel NMR experiments across many disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, and zero-field NMR and MRI.

  18. Effect of substrate temperature on orientation of subphthalocyanine molecule in organic photovoltaic cells

    Chou, Chi-Ta; Tang, Wei-Li; Tai, Yian; Lin, Chien-Hung; Liu, Chin-Hsin J.; Chen, Li-Chyong; Chen, Kuei-Hsien

    2012-01-01

    This study investigates the effect of substrate temperature (T s ) on the boron subphthalocyanine chloride (SubPc) thin film and its power conversion efficiency in SubPc/C 60 heterojunction photovoltaic cells. The orientations of SubPc molecules in thin films determined by X-ray diffraction is strongly correlated with the electronic properties of the organic thin films, and can be controlled by the substrate temperature during the vapor deposition. An optimal substrate temperature of 120 °C has been concluded to induced (221) molecular orientation over the (122) orientation and significantly improve the carrier transport of the SubPc thin film. A SubPc/C 60 heterojunction photovoltaic cells thus fabricated shows higher open-circuit voltage and up to 1.55% conversion efficiency has been achieved, which is attributed to preferential (221) orientation of the SubPc deposited at the elevated temperature.

  19. Conjugated donor-acceptor-acceptor (D-A-A) molecule for organic nonvolatile resistor memory.

    Dong, Lei; Li, Guangwu; Yu, An-Dih; Bo, Zhishan; Liu, Cheng-Liang; Chen, Wen-Chang

    2014-12-01

    A new donor-acceptor-acceptor (D-A-A) type of conjugated molecule, N-(4-(N',N'-diphenyl)phenylamine)-4-(4'-(2,2-dicyanovinyl)phenyl) naphthalene-1,8-dicarboxylic monoimide (TPA-NI-DCN), consisting of triphenylamine (TPA) donors and naphthalimide (NI)/dicyanovinylene (DCN) acceptors was synthesized and characterized. In conjunction with previously reported D-A based materials, the additional DCN moiety attached as end group in the D-A-A configuration can result in a stable charge transfer (CT) and charge-separated state to maintain the ON state current. The vacuum-deposited TPA-NI-DCN device fabricated as an active memory layer was demonstrated to exhibit write-once-read-many (WORM) switching characteristics of organic nonvolatile memory due to the strong polarity of the TPA-NI-DCN moiety. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Strategies For Immobilization Of Bioactive Organic Molecules On Titanium Implant Surfaces – A Review

    Panayotov Ivan V.

    2015-03-01

    Full Text Available Numerous approaches have been used to improve the tissue-implant interface of titanium (Ti and titanium alloy (Ti6Al4V. They all aim at increasing cell migration and attachment to the metal, preventing unspecific protein adsorption and improving post-implantation healing process. Promising methods for titanium and titanium alloy surface modification are based on the immobilization of biologically active organic molecules. New and interesting biochemical approaches to such surface modification include layer-by-layer deposition of polyelectrolyte films, phage display-selected surface binding peptides and self-assembled DNA monolayer systems. The present review summarizes the scientific information about these methods, which are at in vitro or in vivo development stages, and hopes to promote their future application in dental implantology and in oral and maxillofacial surgery.

  1. Accurate on-chip measurement of the Seebeck coefficient of high mobility small molecule organic semiconductors

    C. N. Warwick

    2015-09-01

    Full Text Available We present measurements of the Seebeck coefficient in two high mobility organic small molecules, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT and 2,9-didecyl-dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (C10-DNTT. The measurements are performed in a field effect transistor structure with high field effect mobilities of approximately 3 cm2/V s. This allows us to observe both the charge concentration and temperature dependence of the Seebeck coefficient. We find a strong logarithmic dependence upon charge concentration and a temperature dependence within the measurement uncertainty. Despite performing the measurements on highly polycrystalline evaporated films, we see an agreement in the Seebeck coefficient with modelled values from Shi et al. [Chem. Mater. 26, 2669 (2014] at high charge concentrations. We attribute deviations from the model at lower charge concentrations to charge trapping.

  2. Physiological type I collagen organization induces the formation of a novel class of linear invadosomes

    Juin, Amélie; Billottet, Clotilde; Moreau, Violaine; Destaing, Olivier; Albiges-Rizo, Corinne; Rosenbaum, Jean; Génot, Elisabeth; Saltel, Frédéric

    2012-01-01

    Invadosomes are F-actin structures capable of degrading the matrix through the activation of matrix metalloproteases. As fibrillar type I collagen promotes pro-matrix metalloproteinase 2 activation by membrane type 1 matrix metalloproteinase, we aimed at investigating the functional relationships between collagen I organization and invadosome induction. We found that fibrillar collagen I induced linear F-actin structures, distributed along the fibrils, on endothelial cells, macrophages, fibroblasts, and tumor cells. These structures share features with conventional invadosomes, as they express cortactin and N-WASP and accumulate the scaffold protein Tks5, which proved essential for their formation. On the basis of their ability to degrade extracellular matrix elements and their original architecture, we named these structures “linear invadosomes.” Interestingly, podosomes or invadopodia were replaced by linear invadosomes upon contact of the cells with fibrillar collagen I. However, linear invadosomes clearly differ from classical invadosomes, as they do not contain paxillin, vinculin, and β1/β3 integrins. Using knockout mouse embryonic fibroblasts and RGD peptide, we demonstrate that linear invadosome formation and activity are independent of β1 and β3 integrins. Finally, linear invadosomes also formed in a three-dimensional collagen matrix. This study demonstrates that fibrillar collagen I is the physiological inducer of a novel class of invadosomes. PMID:22114353

  3. Detection and mapping of organic molecules in Titan's atmosphere using ALMA

    Cordiner, Martin

    2016-06-01

    Titan's atmospheric photochemistry results in the production of a wide range of organic molecules, including hydrocarbons, nitriles, aromatics and other complex species of possible pre-biotic relevance. Studies of Titan's atmospheric chemistry thus provide a unique opportunity to explore the origin and evolution of organic matter in primitive (terrestrial) planetary atmospheres. The Atacama Large Millimeter/submillimeter Array (ALMA) is a powerful new facility, well suited to the study of molecular emission from Titan's upper and middle-atmosphere. Results will be presented from our ongoing studies of Titan using ALMA data obtained during the period 2012-2014 [1,2], including detection and mapping of emission from C2H5CN, HNC, HC3N, CH3CN and CH3CCH. In addition, combining data from multiple ALMA Band 6 observations, we obtained high-resolution spectra with unprecedented sensitivity, enabling the first detection of C2H3CN (vinyl cyanide) on Titan, and derived a mean C2H3CN C2H5CN abundance ratio above 300 km of 0.3. Vinyl cyanide has recently been investigated as a possible constituent of (pre-biotic) vesicle membranes in Titan's liquid CH4 oceans [3]. Radiative transfer models and possible chemical formation pathways for the detected molecules will be discussed. ALMA observations provide instantaneous snapshot mapping of Titan's entire Earth-facing hemisphere for gases inaccessible to previous studies, and therefore provide new insights into photochemical production and transport, particularly at higher altitudes. Our maps show spatially resolved peaks in Titan's northern and southern hemispheres, consistent with the molecular distributions found in previous studies at infrared wavelengths by Voyager and Cassini, but high-altitude longitudinal asymmetries in our nitrile data indicate that the mesosphere may be more spatially variable than previously thought.

  4. FORMATION AND RECONDENSATION OF COMPLEX ORGANIC MOLECULES DURING PROTOSTELLAR LUMINOSITY OUTBURSTS

    Taquet, Vianney; Wirström, Eva S.; Charnley, Steven B.

    2016-01-01

    During the formation of stars, the accretion of surrounding material toward the central object is thought to undergo strong luminosity outbursts followed by long periods of relative quiescence, even at the early stages of star formation when the protostar is still embedded in a large envelope. We investigated the gas-phase formation and recondensation of the complex organic molecules (COMs) di-methyl ether and methyl formate, induced by sudden ice evaporation processes occurring during luminosity outbursts of different amplitudes in protostellar envelopes. For this purpose, we updated a gas-phase chemical network forming COMs in which ammonia plays a key role. The model calculations presented here demonstrate that ion–molecule reactions alone could account for the observed presence of di-methyl ether and methyl formate in a large fraction of protostellar cores without recourse to grain-surface chemistry, although they depend on uncertain ice abundances and gas-phase reaction branching ratios. In spite of the short outburst timescales of about 100 years, abundance ratios of the considered species higher than 10% with respect to methanol are predicted during outbursts due to their low binding energies relative to water and methanol which delay their recondensation during cooling. Although the current luminosity of most embedded protostars would be too low to produce complex organics in the hot-core regions that are observable with current sub-millimetric interferometers, previous luminosity outburst events would induce the formation of COMs in extended regions of protostellar envelopes with sizes increasing by up to one order of magnitude

  5. Formation and Recondensation of Complex Organic Molecules during Protostellar Luminosity Outbursts

    Taquet, Vianney; Wirström, Eva S.; Charnley, Steven B.

    2016-04-01

    During the formation of stars, the accretion of surrounding material toward the central object is thought to undergo strong luminosity outbursts followed by long periods of relative quiescence, even at the early stages of star formation when the protostar is still embedded in a large envelope. We investigated the gas-phase formation and recondensation of the complex organic molecules (COMs) di-methyl ether and methyl formate, induced by sudden ice evaporation processes occurring during luminosity outbursts of different amplitudes in protostellar envelopes. For this purpose, we updated a gas-phase chemical network forming COMs in which ammonia plays a key role. The model calculations presented here demonstrate that ion-molecule reactions alone could account for the observed presence of di-methyl ether and methyl formate in a large fraction of protostellar cores without recourse to grain-surface chemistry, although they depend on uncertain ice abundances and gas-phase reaction branching ratios. In spite of the short outburst timescales of about 100 years, abundance ratios of the considered species higher than 10% with respect to methanol are predicted during outbursts due to their low binding energies relative to water and methanol which delay their recondensation during cooling. Although the current luminosity of most embedded protostars would be too low to produce complex organics in the hot-core regions that are observable with current sub-millimetric interferometers, previous luminosity outburst events would induce the formation of COMs in extended regions of protostellar envelopes with sizes increasing by up to one order of magnitude.

  6. Vibronic coupling in ionized organic molecules. Structural distortions and chemical reactions

    Williams, F.

    2002-01-01

    Complete text of publication follows. Ionized organic molecules (radical cations, RC) are prone to undergo vibronic coupling whenever there is a relatively small energy gap ( 2v point group of the neutral parent molecule by twisting at the olefinic π bond to the lower C 2 symmetry in the RC (Chem. Eur. J. 2002, 8, 1074). These experiments clearly revealed a double minimum in the potential energy surface along the a 2 torsional mode. This is in accord with the coupling of the 2 B 1 and 2 B 2 Born-Oppenheimer states in C 2v symmetry, this mixing of the 2 B 1 π-ionized ground state and the 2 B 2 δ-ionized excited state being facilitated by the low (∼ 1.0 eV) gap between these states, as estimated from photoelectron spectroscopy. Turning to the second class of RC where unimolecular rearrangement reactions are promoted by vibronic interaction, several cases have emerged where the rearrangement would not be expected if it were based only on the ground-state properties of the RC. It was found (Chem. Phy. Lett. 1988, 143, 521) that the ethylene oxide RC undergoes C-C ring opening to the oxallyl species despite the fact that the ground state corresponds to ionization from the nonbonding oxygen π lone-pair orbital. The reaction develops excited-state character as a result of the vibronic mixing so that the activation barrier to ring opening is lowered. We will discuss the unusual rearrangements of the bicyclo[1.1.1.]pentane and [1.1.1]propellane RC from a similar perspective, emphasis being placed on the decisive role of symmetry in predicting the course of these rearrangements. We illustrate how this approach can reconcile conflicting considerations on some of the 'unexpected' reaction pathways followed by highly strained organic RC

  7. FORMATION AND RECONDENSATION OF COMPLEX ORGANIC MOLECULES DURING PROTOSTELLAR LUMINOSITY OUTBURSTS

    Taquet, Vianney [Leiden Observatory, Leiden University, P.O. Box 9513, 2300-RA Leiden (Netherlands); Wirström, Eva S. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala (Sweden); Charnley, Steven B. [Astrochemistry Laboratory and The Goddard Center for Astrobiology, Mailstop 691, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20770 (United States)

    2016-04-10

    During the formation of stars, the accretion of surrounding material toward the central object is thought to undergo strong luminosity outbursts followed by long periods of relative quiescence, even at the early stages of star formation when the protostar is still embedded in a large envelope. We investigated the gas-phase formation and recondensation of the complex organic molecules (COMs) di-methyl ether and methyl formate, induced by sudden ice evaporation processes occurring during luminosity outbursts of different amplitudes in protostellar envelopes. For this purpose, we updated a gas-phase chemical network forming COMs in which ammonia plays a key role. The model calculations presented here demonstrate that ion–molecule reactions alone could account for the observed presence of di-methyl ether and methyl formate in a large fraction of protostellar cores without recourse to grain-surface chemistry, although they depend on uncertain ice abundances and gas-phase reaction branching ratios. In spite of the short outburst timescales of about 100 years, abundance ratios of the considered species higher than 10% with respect to methanol are predicted during outbursts due to their low binding energies relative to water and methanol which delay their recondensation during cooling. Although the current luminosity of most embedded protostars would be too low to produce complex organics in the hot-core regions that are observable with current sub-millimetric interferometers, previous luminosity outburst events would induce the formation of COMs in extended regions of protostellar envelopes with sizes increasing by up to one order of magnitude.

  8. "Molecules-in-Medicine": Peer-Evaluated Presentations in a Fast-Paced Organic Chemistry Course for Medical Students

    Kadnikova, Ekaterina N.

    2013-01-01

    To accentuate the importance of organic chemistry in development of contemporary pharmaceuticals, a three-week unit entitled "Molecules-in-Medicine" was included in the curriculum of a comprehensive one-semester four-credit organic chemistry course. After a lecture on medicinal chemistry concepts and pharmaceutical practices, students…

  9. Late stage crystallization and healing during spin-coating enhance carrier transport in small-molecule organic semiconductors

    Chou, Kang Wei; Khan, Hadayat Ullah; Niazi, Muhammad Rizwan; Yan, Buyi; Li, Ruipeng; Payne, Marcia M.; Anthony, John Edward; Smilgies, Detlef Matthias; Amassian, Aram

    2014-01-01

    Spin-coating is currently the most widely used solution processing method in organic electronics. Here, we report, for the first time, a direct investigation of the formation process of the small-molecule organic semiconductor (OSC) 6,13-bis

  10. Study of two examples of non linear interaction of a laser wave with matter: laser-induced damage of dielectrics and non linear optical properties of organometallic molecules in solution

    Gaudry, Jean-Baptiste

    2000-01-01

    This research thesis reports the study of two mechanisms of non linear interaction of a laser wave with matter. More particularly, it reports the experimental investigation of non linear optical properties of organometallic molecules in solution, as well as the damage of perfect silica under laser irradiation by using simulation codes. As far as optical properties are concerned, the author highlights the influence of the electronic configuration of the metal present in the organometallic compound, and the influence of the ligand on the second-order non-linear response. As far as the simulation is concerned, some experimental results have been reproduced. This work can be useful for the investigation of the extrinsic damage of imperfect materials, and for the design of experiments of transient measurements of excited silica [fr

  11. Electronic coupling effects and charge transfer between organic molecules and metal surfaces

    Forker, Roman

    2010-07-01

    We employ a variant of optical absorption spectroscopy, namely in situ differential reflectance spectroscopy (DRS), for an analysis of the structure-properties relations of thin epitaxial organic films. Clear correlations between the spectra and the differently intense coupling to the respective substrates are found. While rather broad and almost structureless spectra are obtained for a quaterrylene (QT) monolayer on Au(111), the spectral shape resembles that of isolated molecules when QT is grown on graphite. We even achieve an efficient electronic decoupling from the subjacent Au(111) by inserting an atomically thin organic spacer layer consisting of hexa-peri-hexabenzocoronene (HBC) with a noticeably dissimilar electronic behavior. These observations are further consolidated by a systematic variation of the metal substrate (Au, Ag, and Al), ranging from inert to rather reactive. For this purpose, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) is chosen to ensure comparability of the molecular film structures on the different metals, and also because its electronic alignment on various metal surfaces has previously been studied with great intensity. We present evidence for ionized PTCDA at several interfaces and propose the charge transfer to be related to the electronic level alignment governed by interface dipole formation on the respective metals. (orig.)

  12. The Detection of Hot Cores and Complex Organic Molecules in the Large Magellanic Cloud

    Sewiło, Marta; Indebetouw, Remy; Charnley, Steven B.; Zahorecz, Sarolta; Oliveira, Joana M.; van Loon, Jacco Th.; Ward, Jacob L.; Chen, C.-H. Rosie; Wiseman, Jennifer; Fukui, Yasuo; Kawamura, Akiko; Meixner, Margaret; Onishi, Toshikazu; Schilke, Peter

    2018-02-01

    We report the first extragalactic detection of the complex organic molecules (COMs) dimethyl ether (CH3OCH3) and methyl formate (CH3OCHO) with the Atacama Large Millimeter/submillimeter Array (ALMA). These COMs, together with their parent species methanol (CH3OH), were detected toward two 1.3 mm continuum sources in the N 113 star-forming region in the low-metallicity Large Magellanic Cloud (LMC). Rotational temperatures ({T}{rot}∼ 130 K) and total column densities ({N}{rot}∼ {10}16 cm‑2) have been calculated for each source based on multiple transitions of CH3OH. We present the ALMA molecular emission maps for COMs and measured abundances for all detected species. The physical and chemical properties of two sources with COMs detection, and the association with H2O and OH maser emission, indicate that they are hot cores. The fractional abundances of COMs scaled by a factor of 2.5 to account for the lower metallicity in the LMC are comparable to those found at the lower end of the range in Galactic hot cores. Our results have important implications for studies of organic chemistry at higher redshift.

  13. Scanning transmission X-ray microscopy as a speciation tool for natural organic molecules

    Rothe, J.; Plaschke, M.; Denecke, M.A. [Inst. fuer Nukleare Entsorgung, Forschungszentrum Karlsruhe, Karlsruhe (Germany)

    2004-07-01

    A molecular-scale understanding of the basic processes affecting stability and transport behavior of actinide cations, complexes or hydroxide ('eigencolloid') species is prerequisite to performance assessment of nuclear waste disposal in geological formations. Depending on their functional group chemistry and macromolecular structure, naturally occurring organic molecules (NOM) possess a high tendency towards actinide complexation reactions. However, the compositional and structural heterogeneity of NOM and mixed aggregates with inorganic phases makes speciation by spectromicroscopy techniques highly desirable. The applicability of Scanning Transmission X-ray Microscopy (STXM) as a speciation tool for the characterization of NOM is demonstrated for a multifunctional natural organic acid (chlorogenic acid), Eu(III)-loaded humic acid (HA) aggregates and Eu(III)-oxo/hydroxide/HA hetero-aggregates. It is shown that in situ probing of HA functional group chemistry down to a spatial resolution < 100 nm (i.e., less than femto-liter sampled volumes) is feasible, at the same time revealing morphological details on NOM aggregates and NOM/mineral associations. (orig.)

  14. Study of the degradation of organic molecules complexing radionuclides by using Advanced Oxidation Processes

    Rekab, K.

    2014-01-01

    This research thesis reports the study of the application of two AOPs (Advanced Oxidation Processes) to degrade and mineralise organic molecules which are complexing radio-elements, and thus to allow their concentrations by trapping on mineral matrices. EDTA (ethylene diamine tetraacetic acid) is chosen as reference organic complexing agent for preliminary tests performed with inactive cobalt 59 before addressing actual nuclear effluents with active cobalt 60. The author first presents the industrial context (existing nuclear wastes, notably liquid effluents and their processing) and proposes an overview of the state of the art on adsorption and precipitation of cobalt (natural and radioactive isotope). Then, the author presents the characteristics of the various studied oxides, the photochemical reactor used to perform tests, experimental techniques and operational modes. Results are then presented regarding various issues: adsorption of EDTA and the Co-EDTA complex, and cobalt precipitation; determination of the lamp photon flow by chemical actinometry and by using the Keitz method; efficiency of different processes (UV, UV/TiO 2 , UV/H 2 O 2 ) to degrade EDTA and to degrade the Co-EDTA complex; processing of a nuclear effluent coming from La Hague pools with determination of decontamination factors

  15. Enantiomeric separation of complex organic molecules produced from irradiation of interstellar/circumstellar ice analogs

    Nuevo, M.; Meierhenrich, U. J.; D'Hendecourt, L.; Muñoz Caro, G. M.; Dartois, E.; Deboffle, D.; Thiemann, W. H.-P.; Bredehöft, J.-H.; Nahon, L.

    Irradiation of interstellar/circumstellar ice analogs by ultraviolet (UV) light followed by warm up in the laboratory leads to the formation of complex organic molecules, stable at room temperature. Hydrolysis of the room temperature residue releases amino acids, the building blocks of proteins. These amino acids exist in two different forms (L and D), but proteins encountered in living beings consist exclusively of L enantiomers. The origin of this property, called homochirality, is still unknown. Amino acids can be detected and quantified by chemical techniques such as chiral gas chromatography coupled with mass spectrometry (GC-MS). Enantiomers of chiral organics are also known to interact selectively with circularly polarized light (CPL), leading to a selective production or destruction of the final compounds. This paper describes how we settled an experiment where amino acids are formed by irradiation of interstellar/circumstellar ice analogs with ultraviolet (UV) CPL, produced by a synchrotron radiation beamline, which allowed us to quantify the effect of such polarized light on the production of amino acids. These results can be compared to the enantiomeric excesses measured in primitive meteorites such as Murchison.

  16. Functionalized organic semiconductor molecules to enhance charge carrier injection in electroluminescent cell

    Yalcin, Eyyup; Kara, Duygu Akin; Karakaya, Caner; Yigit, Mesude Zeliha; Havare, Ali Kemal; Can, Mustafa; Tozlu, Cem; Demic, Serafettin; Kus, Mahmut; Aboulouard, Abdelkhalk

    2017-07-01

    Organic semiconductor (OSC) materials as a charge carrier interface play an important role to improve the device performance of organic electroluminescent cells. In this study, 4,4″-bis(diphenyl amino)-1,1':3‧,1″-terphenyl-5'-carboxylic acid (TPA) and 4,4″-di-9H-carbazol-9-yl-1,1':3‧,1″-terphenyl-5'-carboxylic acid (CAR) has been designed and synthesized to modify indium tin oxide (ITO) layer as interface. Bare ITO and PEDOT:PSS coated on ITO was used as reference anode electrodes for comparison. Furthermore, PEDOT:PSS coated over CAR/ITO and TPA/ITO to observe stability of OSC molecules and to completely cover the ITO surface. Electrical, optical and surface characterizations were performed for each device. Almost all modified devices showed around 36% decrease at the turn on voltage with respect to bare ITO. The current density of bare ITO, ITO/CAR and ITO/TPA were measured as 288, 1525 and 1869 A/m2, respectively. By increasing current density, luminance of modified devices showed much better performance with respect to unmodified devices.

  17. Structural Ordering of Semiconducting Polymers and Small-Molecules for Organic Electronics

    O'Hara, Kathryn Allison

    Semiconducting polymers and small-molecules can be readily incorporated into electronic devices such as organic photovoltaics (OPVs), thermoelectrics (OTEs), organic light emitting diodes (OLEDs), and organic thin film transistors (OTFTs). Organic materials offer the advantage of being processable from solution to form flexible and lightweight thin films. The molecular design, processing, and resulting thin film morphology of semiconducting polymers drastically affect the optical and electronic properties. Charge transport within films of semiconducting polymers relies on the nanoscale organization to ensure electronic coupling through overlap of molecular orbitals and to provide continuous transport pathways. While the angstrom-scale packing details can be studied using X-ray scattering methods, an understanding of the mesoscale, or the length scale over which smaller ordered regions connect, is much harder to achieve. Grain boundaries play an important role in semiconducting polymer thin films where the average grain size is much smaller than the total distance which charges must traverse in order to reach the electrodes in a device. The majority of semiconducting polymers adopt a lamellar packing structure in which the conjugated backbones align in parallel pi-stacks separated by the alkyl side-chains. Only two directions of transport are possible--along the conjugated backbone and in the pi-stacking direction. Currently, the discussion of transport between crystallites is centered around the idea of tie-chains, or "bridging" polymer chains connecting two ordered regions. However, as molecular structures become increasingly complex with the development of new donor-acceptor copolymers, additional forms of connectivity between ordered domains should be considered. High resolution transmission electron microscopy (HRTEM) is a powerful tool for directly imaging the crystalline grain boundaries in polymer and small-molecule thin films. Recently, structures

  18. Multi-solution processes of small molecule for flexible white organic light-emitting diodes

    Tsai, Yu-Sheng, E-mail: ystsai@nfu.edu.tw [Institute of Electro-optical and Materials Science, National Formosa University, Yunlin 63201, Taiwan, ROC (China); Chittawanij, Apisit; Hong, Lin-Ann; Guo, Siou-Wei [Institute of Electro-optical and Materials Science, National Formosa University, Yunlin 63201, Taiwan, ROC (China); Wang, Ching-Chiun [Department of Solid State Lighting Technology, Mechanical and Systems Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan, ROC (China); Juang, Fuh-Shyang [Institute of Electro-optical and Materials Science, National Formosa University, Yunlin 63201, Taiwan, ROC (China); Lai, Shih-Hsiang [Department of Solid State Lighting Technology, Mechanical and Systems Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan, ROC (China); Lin, Yang-Ching [Institute of Electro-optical and Materials Science, National Formosa University, Yunlin 63201, Taiwan, ROC (China)

    2016-04-01

    Most small molecule organic light emitting diode (SM-OLED) device structures are made in one layer using solution-based processing because the solution is usually a high dissolvent material that easily attacks the layer below it. We demonstrate a simple and reliable stamping technique for fabricating multi-solution process flexible white SM-OLEDs. The structure is anode/spin-hole injection layer/spin-emitting layer/stamping-electron transport layer/cathode. Poly(di-methyl silane) (PDMS) stamp is used for transferring electron transport layer. An intermediate ultraviolet-ozone surface treatment is introduced to temporarily modify the PDMS stamp surface. Then, the solution-based electron transport layer film can therefore be uniformly formed on top of the PDMS surface. After that the electron transport layer film on the PDMS stamp is transfer-printed onto the emitting layer with suitable heating and pressing. A solution-based processing is successfully established to efficiently fabricate flexible white SM-OLEDs. The SM-OLEDs were obtained at the current density of 20 mA/cm{sup 2}, luminance of 1062 cd/m{sup 2}, current efficiency of 5.57 cd/A, and Commission internationale de l'éclairage coordinate of (0.32, 0.35). - Highlights: • All solution-processed small molecule materials (emitting layer, electron transport layer). • Poly(di-methylsilane) (PDMS) stamp is subsequently used for stamping transfer. • The flexible white SM-OLEDs are based on solution-processes with a low-cost method.

  19. Metal-Organic Frameworks for Resonant-Gravimetric Detection of Trace-Level Xylene Molecules.

    Xu, Tao; Xu, Pengcheng; Zheng, Dan; Yu, Haitao; Li, Xinxin

    2016-12-20

    As one of typical VOCs, xylene is seriously harmful to human health. Nowadays, however, there is really lack of portable sensing method to directly detect environmental xylene that has chemical inertness. Especially when the concentration of xylene is lower than the human olfactory threshold of 470 ppb, people are indeed hard to be aware of and avoid this harmful vapor. Herein the metal-organic framework (MOF) of HKUST-1 is first explored for sensing to the nonpolar molecule of p-xylene. And the sensing mechanism is identified that is via host-guest interaction of MOF with xylene molecule. By loading MOFs on mass-gravimetric resonant-cantilevers, sensing experiments for four MOFs of MOF-5, HKUST-1, ZIF-8, and MOF-177 approve that HKUST-1 has the highest sensitivity to p-xylene. The resonant-gravimetric sensing experiments with our HKUST-1 based sensors have demonstrated that trace-level p-xylene of 400 ppb can be detected that is lower than the human olfactory threshold of 470 ppb. We analyze that the specificity of HKUST-1 to xylene comes from Cu 2+ -induced moderate Lewis acidity and the "like dissolves like" interaction of the benzene ring. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is used to elucidate the adsorbing/sensing mechanism of HKUST-1 to p-xylene, where p-xylene adsorbing induced blue-shift phenomenon is observed that confirms the sensing mechanism. Our study also indicates that the sensor shows good selectivity to various kinds of common interfering gases. And the long-term repeatability and stability of the sensing material are also approved for the usage/storage period of two months. This research approves that the MOF materials exhibit potential usages for high performance chemical sensors applications.

  20. Multi-solution processes of small molecule for flexible white organic light-emitting diodes

    Tsai, Yu-Sheng; Chittawanij, Apisit; Hong, Lin-Ann; Guo, Siou-Wei; Wang, Ching-Chiun; Juang, Fuh-Shyang; Lai, Shih-Hsiang; Lin, Yang-Ching

    2016-01-01

    Most small molecule organic light emitting diode (SM-OLED) device structures are made in one layer using solution-based processing because the solution is usually a high dissolvent material that easily attacks the layer below it. We demonstrate a simple and reliable stamping technique for fabricating multi-solution process flexible white SM-OLEDs. The structure is anode/spin-hole injection layer/spin-emitting layer/stamping-electron transport layer/cathode. Poly(di-methyl silane) (PDMS) stamp is used for transferring electron transport layer. An intermediate ultraviolet-ozone surface treatment is introduced to temporarily modify the PDMS stamp surface. Then, the solution-based electron transport layer film can therefore be uniformly formed on top of the PDMS surface. After that the electron transport layer film on the PDMS stamp is transfer-printed onto the emitting layer with suitable heating and pressing. A solution-based processing is successfully established to efficiently fabricate flexible white SM-OLEDs. The SM-OLEDs were obtained at the current density of 20 mA/cm"2, luminance of 1062 cd/m"2, current efficiency of 5.57 cd/A, and Commission internationale de l'éclairage coordinate of (0.32, 0.35). - Highlights: • All solution-processed small molecule materials (emitting layer, electron transport layer). • Poly(di-methylsilane) (PDMS) stamp is subsequently used for stamping transfer. • The flexible white SM-OLEDs are based on solution-processes with a low-cost method.

  1. Prediction of octanol-water partition coefficients of organic compounds by multiple linear regression, partial least squares, and artificial neural network.

    Golmohammadi, Hassan

    2009-11-30

    A quantitative structure-property relationship (QSPR) study was performed to develop models those relate the structure of 141 organic compounds to their octanol-water partition coefficients (log P(o/w)). A genetic algorithm was applied as a variable selection tool. Modeling of log P(o/w) of these compounds as a function of theoretically derived descriptors was established by multiple linear regression (MLR), partial least squares (PLS), and artificial neural network (ANN). The best selected descriptors that appear in the models are: atomic charge weighted partial positively charged surface area (PPSA-3), fractional atomic charge weighted partial positive surface area (FPSA-3), minimum atomic partial charge (Qmin), molecular volume (MV), total dipole moment of molecule (mu), maximum antibonding contribution of a molecule orbital in the molecule (MAC), and maximum free valency of a C atom in the molecule (MFV). The result obtained showed the ability of developed artificial neural network to prediction of partition coefficients of organic compounds. Also, the results revealed the superiority of ANN over the MLR and PLS models. Copyright 2009 Wiley Periodicals, Inc.

  2. Linear Regression between CIE-Lab Color Parameters and Organic Matter in Soils of Tea Plantations

    Chen, Yonggen; Zhang, Min; Fan, Dongmei; Fan, Kai; Wang, Xiaochang

    2018-02-01

    To quantify the relationship between the soil organic matter and color parameters using the CIE-Lab system, 62 soil samples (0-10 cm, Ferralic Acrisols) from tea plantations were collected from southern China. After air-drying and sieving, numerical color information and reflectance spectra of soil samples were measured under laboratory conditions using an UltraScan VIS (HunterLab) spectrophotometer equipped with CIE-Lab color models. We found that soil total organic carbon (TOC) and nitrogen (TN) contents were negatively correlated with the L* value (lightness) ( r = -0.84 and -0.80, respectively), a* value (correlation coefficient r = -0.51 and -0.46, respectively) and b* value ( r = -0.76 and -0.70, respectively). There were also linear regressions between TOC and TN contents with the L* value and b* value. Results showed that color parameters from a spectrophotometer equipped with CIE-Lab color models can predict TOC contents well for soils in tea plantations. The linear regression model between color values and soil organic carbon contents showed it can be used as a rapid, cost-effective method to evaluate content of soil organic matter in Chinese tea plantations.

  3. A series of fluorene-based two-photon absorbing molecules: synthesis, linear and nonlinear characterization, and bioimaging

    Andrade, Carolina D.; Yanez, Ciceron O.; Rodriguez, Luis; Belfield, Kevin D.

    2010-01-01

    The synthesis, structural, and photophysical characterization of a series of new fluorescent donor–acceptor and acceptor-acceptor molecules, based on the fluorenyl ring system, with two-photon absorbing properties is described. These new compounds exhibited large Stokes shifts, high fluorescent quantum yields, and, significantly, high two-photon absorption cross sections, making them well suited for two-photon fluorescence microscopy (2PFM) imaging. Confocal and two-photon fluorescence microscopy imaging of COS-7 and HCT 116 cells incubated with probe I showed endosomal selectivity, demonstrating the potential of this class of fluorescent probes in multiphoton fluorescence microscopy. PMID:20481596

  4. Quantum coherent π-electron rotations in a non-planar chiral molecule induced by using a linearly polarized UV laser pulse

    Mineo, Hirobumi; Fujimura, Yuichi

    2015-06-01

    We propose an ultrafast quantum switching method of π-electron rotations, which are switched among four rotational patterns in a nonplanar chiral aromatic molecule (P)-2,2’- biphenol and perform the sequential switching among four rotational patterns which are performed by the overlapped pump-dump laser pulses. Coherent π-electron dynamics are generated by applying the linearly polarized UV pulse laser to create a pair of coherent quasidegenerated excited states. We also plot the time-dependent π-electron ring current, and discussed ring current transfer between two aromatic rings.

  5. Quantum switching of π-electron rotations in a nonplanar chiral molecule by using linearly polarized UV laser pulses.

    Mineo, Hirobumi; Yamaki, Masahiro; Teranishi, Yoshiaki; Hayashi, Michitoshi; Lin, Sheng Hsien; Fujimura, Yuichi

    2012-09-05

    Nonplanar chiral aromatic molecules are candidates for use as building blocks of multidimensional switching devices because the π electrons can generate ring currents with a variety of directions. We employed (P)-2,2'-biphenol because four patterns of π-electron rotations along the two phenol rings are possible and theoretically determine how quantum switching of the π-electron rotations can be realized. We found that each rotational pattern can be driven by a coherent excitation of two electronic states under two conditions: one is the symmetry of the electronic states and the other is their relative phase. On the basis of the results of quantum dynamics simulations, we propose a quantum control method for sequential switching among the four rotational patterns that can be performed by using ultrashort overlapped pump and dump pulses with properly selected relative phases and photon polarization directions. The results serve as a theoretical basis for the design of confined ultrafast switching of ring currents of nonplanar molecules and further current-induced magnetic fluxes of more sophisticated systems.

  6. Inversed linear dichroism in F K-edge NEXAFS spectra of fluorinated planar aromatic molecules

    de Oteyza, D. G.; Sakko, A.; El-Sayed, A.

    2012-01-01

    The symmetry and energy distribution of unoccupied molecular orbitals is addressed in this work by means of NEXAFS and density functional theory calculations for planar, fluorinated organic semiconductors (perfluorinated copper phthalocyanines and perfluoropentacene). We demonstrate how molecular...

  7. Efficient small-molecule organic solar cells incorporating a doped buffer layer

    Chou, Dei-Wei [Department of aviation and Communication Electronics, Air Force Institute of Technology, Kaohsiung 820, Taiwan (China); Chen, Kan-Lin [Department of Electronic Engineering, Fortune Institute of Technology, Kaohsiung 831, Taiwan (China); Huang, Chien-Jung, E-mail: chien@nuk.edu.tw [Department of Applied Physics, National University of Kaohsiung, Nanzih, Kaohsiung 811, Taiwan (China); Tsao, Yao-Jen [Department of Applied Physics, National University of Kaohsiung, Nanzih, Kaohsiung 811, Taiwan (China); Chen, Wen-Ray; Meen, Teen-Hang [Department of Electronic Engineering, National Formosa University, Hu-Wei, Yunlin 632, Taiwan (China)

    2013-06-01

    Small-molecule organic solar cells (OSCs) with an optimized structure of indium tin oxide/poly (3,4-ethylenedioxythioxythiophene):poly(styrenesulfonate)/copper phthalocyanine (CuPc) (10 nm)/CuPc: fullerene (C{sub 60}) mixed (20 nm)/C{sub 60} (20 nm)/4,7-diphenyl-1,10-phenanthroline (BPhen) (5 nm)/Ag were fabricated. In this study, the cesium carbonate-doped BPhen (Cs{sub 2}CO{sub 3}:BPhen) was adopted as the buffer layer to enhance the efficiency of the OSCs. The photovoltaic parameters of the OSCs, such as the short-circuit current density and fill factor, depend on the doping concentration of Cs{sub 2}CO{sub 3} in the BPhen layer. The cell with a Cs{sub 2}CO{sub 3}:BPhen (1:4) cathode buffer layer exhibits a power conversion efficiency (PCE) of 3.51%, compared to 3.37% for the device with the pristine BPhen layer. The enhancement of PCE was attributed to the energy-level alignment between the C{sub 60} layer and the Cs{sub 2}CO{sub 3}:BPhen layer. In addition, the characterization measured using atomic force microscopy shows that the Cs{sub 2}CO{sub 3}:BPhen layers have smoother surfaces. - Highlight: • Cs2CO3-doped 4,7-diphenyl-1,10-phenanthroline (BPhen) cathode buffer layer. • Cs2CO3:BPhen layer with different ratios affects organic solar cells performance. • Cell with 1:4 (Cs2CO3:BPhen) ratio shows 3.51% power conversion efficiency.

  8. Electron-molecule chemistry and charging processes on organic ices and Titan's icy aerosol surrogates

    Pirim, C.; Gann, R. D.; McLain, J. L.; Orlando, T. M.

    2015-09-01

    Electron-induced polymerization processes and charging events that can occur within Titan's atmosphere or on its surface were simulated using electron irradiation and dissociative electron attachment (DEA) studies of nitrogen-containing organic condensates. The DEA studies probe the desorption of H- from hydrogen cyanide (HCN), acetonitrile (CH3CN), and aminoacetonitrile (NH2CH2CN) ices, as well as from synthesized tholin materials condensed or deposited onto a graphite substrate maintained at low temperature (90-130 K). The peak cross sections for H- desorption during low-energy (3-15 eV) electron irradiation were measured and range from 3 × 10-21 to 2 × 10-18 cm2. Chemical and structural transformations of HCN ice upon 2 keV electron irradiation were investigated using X-ray photoelectron and Fourier-transform infrared spectroscopy techniques. The electron-beam processed materials displayed optical properties very similar to tholins produced by conventional discharge methods. Electron and negative ion trapping lead to 1011 charges cm-2 on a flat surface which, assuming a radius of 0.05 μm for Titan aerosols, is ∼628 charges/radius (in μm). The facile charge trapping indicates that electron interactions with nitriles and complex tholin-like molecules could affect the conductivity of Titan's atmosphere due to the formation of large negative ion complexes. These negatively charged complexes can also precipitate onto Titan's surface and possibly contribute to surface reactions and the formation of dunes.

  9. Improved Reliability of Small Molecule Organic Solar Cells by Double Anode Buffer Layers

    Pao-Hsun Huang

    2014-01-01

    Full Text Available An optimized hybrid planar heterojunction (PHJ of small molecule organic solar cells (SM-OSCs based on copper phthalocyanine (CuPc as donor and fullerene (C60 as acceptor was fabricated, which obviously enhanced the performance of device by sequentially using both MoO3 and pentacene as double anode buffer layers (ABL, also known as hole extraction layer (HEL. A series of the vacuum-deposited ABL, acting as an electron and exciton blocking layer, were examined for their characteristics in SM-OSCs. The performance and reliability were compared between conventional ITO/ABL/CuPc/C60/BCP/Ag cells and the new ITO/double ABL/CuPc/C60/BCP/Ag cells. The effect on the electrical properties of these materials was also investigated to obtain the optimal thickness of ABL. The comparison shows that the modified cell has an enhanced reliability compared to traditional cells. The improvement of lifetime was attributed to the idea of double layers to prevent humidity and oxygen from diffusing into the active layer. We demonstrated that the interfacial extraction layers are necessary to avoid degradation of device. That is to say, in normal temperature and pressure, a new avenue for the device within double buffer layers has exhibited the highest values of open circuit voltage (Voc, fill factor (FF, and lifetime in this work compared to monolayer of ABL.

  10. Raman studies of BEDT-TTF molecule-based organic superconductors

    Lin, Y.; Eldridge, J. E.; Schlueter, J.; Wang, H. H.; Kini, A. M.

    2001-01-01

    The temperature dependence of the frequencies of the Raman features due to ν 9 (A g ) and ν 60 (B 3g ) modes has been measured in the BEDT-TTF (ET) molecule-based organic superconductors κ-(ET) 2 Cu[N(CN) 2 ]Br, κ-(ET) 2 Cu[N(CN) 2 ]Cl, α t -(ET) 2 I 3 , and β-(ET) 2 AuI 2 . The frequency of the ν 9 (A g ) mode was observed to soften in κ-(ET) 2 Cu[N(CN) 2 ]Br and κ-(ET) 2 Cu[N(CN) 2 ]Cl at low temperatures where NMR data indicated antiferromagnetic fluctuations, providing evidence of spin-phonon interactions. The result is also compared with a very recent theory which deals with the effect of electronic correlations on the frequencies of the molecular phonon modes. We observed a peak splitting for the ν 60 (B 3g ) mode in α t -(ET) 2 I 3 below 190 K, where an incommensurate superstructure was reported, and a frequency decrease of 1.7±0.4 cm -1 for the upper component of the ν 60 (B 3g ) mode in the superconducting compound, demonstrating further the unusual properties of this mode

  11. Intercalated Water and Organic Molecules for Electrode Materials of Rechargeable Batteries.

    Lee, Hyeon Jeong; Shin, Jaeho; Choi, Jang Wook

    2018-03-24

    The intrinsic limitations of lithium-ion batteries (LIBs) with regard to safety, cost, and the availability of raw materials have promoted research on so-called "post-LIBs". The recent intense research of post-LIBs provides an invaluable lesson that existing electrode materials used in LIBs may not perform as well in post-LIBs, calling for new material designs compliant with emerging batteries based on new chemistries. One promising approach in this direction is the development of materials with intercalated water or organic molecules, as these materials demonstrate superior electrochemical performance in emerging battery systems. The enlarged ionic channel dimensions and effective shielding of the electrostatic interaction between carrier ions and the lattice host are the origins of the observed electrochemical performance. Moreover, these intercalants serve as interlayer pillars to sustain the framework for prolonged cycles. Representative examples of such intercalated materials applied to batteries based on Li + , Na + , Mg 2+ , and Zn 2+ ions and supercapacitors are considered, along with their impact in materials research. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Impact of Thermal Annealing on Organic Photovoltaic Cells Using Regioisomeric Donor-Acceptor-Acceptor Molecules.

    Zhang, Tao; Han, Han; Zou, Yunlong; Lee, Ying-Chi; Oshima, Hiroya; Wong, Ken-Tsung; Holmes, Russell J

    2017-08-02

    We report a promising set of donor-acceptor-acceptor (D-A-A) electron-donor materials based on coplanar thieno[3,2-b]/[2,3-b]indole, benzo[c][1,2,5]thiadiazole, and dicyanovinylene, which are found to show broadband absorption with high extinction coefficients. The role of the regioisomeric electron-donating thienoindole moiety on the physical and structural properties is examined. Bulk heterojunction (BHJ) organic photovoltaic cells (OPVs) based on the thieno[2,3-b]indole-based electron donor NTU-2, using C 70 as an electron acceptor, show a champion power conversion efficiency of 5.2% under AM 1.5G solar simulated illumination. This efficiency is limited by a low fill factor (FF), as has previously been the case in D-A-A systems. In order to identify the origin of the limited FF, further insight into donor layer charge-transport behavior is realized by examining planar heterojunction OPVs, with emphasis on the evolution of film morphology with thermal annealing. Compared to as-deposited OPVs that exhibit insufficient donor crystallinity, crystalline OPVs based on annealed thin films show an increase in the short-circuit current density, FF, and power conversion efficiency. These results suggest that that the crystallization of D-A-A molecules might not be realized spontaneously at room temperature and that further processing is needed to realize efficient charge transport in these materials.

  13. Reversible multi-electron redox chemistry of π-conjugated N-containing heteroaromatic molecule-based organic cathodes

    Peng, Chengxin; Ning, Guo-Hong; Su, Jie; Zhong, Guiming; Tang, Wei; Tian, Bingbing; Su, Chenliang; Yu, Dingyi; Zu, Lianhai; Yang, Jinhu; Ng, Man-Fai; Hu, Yong-Sheng; Yang, Yong; Armand, Michel; Loh, Kian Ping

    2017-07-01

    Even though organic molecules with well-designed functional groups can be programmed to have high electron density per unit mass, their poor electrical conductivity and low cycle stability limit their applications in batteries. Here we report a facile synthesis of π-conjugated quinoxaline-based heteroaromatic molecules (3Q) by condensation of cyclic carbonyl molecules with o-phenylenediamine. 3Q features a number of electron-deficient pyrazine sites, where multiple redox reactions take place. When hybridized with graphene and coupled with an ether-based electrolyte, an organic cathode based on 3Q molecules displays a discharge capacity of 395 mAh g-1 at 400 mA g-1 (1C) in the voltage range of 1.2-3.9 V and a nearly 70% capacity retention after 10,000 cycles at 8 A g-1. It also exhibits a capacity of 222 mAh g-1 at 20C, which corresponds to 60% of the initial specific capacity. Our results offer evidence that heteroaromatic molecules with multiple redox sites are promising in developing high-energy-density, long-cycle-life organic rechargeable batteries.

  14. Organized single-molecule magnets: direct observation of new Mn12 derivatives on gold

    Cornia, A.; Fabretti, A.C.; Pacchioni, M.; Zobbi, L.; Bonacchi, D.; Caneschi, A.; Gatteschi, D.; Biagi, R.; Del Pennino, U.; De Renzi, V.; Gurevich, L.; Zant, H.S.J. van der

    2004-01-01

    Gold adsorbates of the dodecamanganese(III,IV) single-molecule magnet (SMM) [Mn 12 O 12 (L) 16 (H 2 O) 4 ] where L=16-(acetylthio)hexadecanoate have been prepared and investigated by X-ray photoelectron spectroscopy and scanning tunneling microscopy (STM). The successful imaging of Mn 12 molecules by STM represents a first step toward the magnetic addressing of individual SMMs and the development of molecule-based devices for magnetic information storage

  15. NMR diffusion and relaxation measurements of organic molecules adsorbed in porous media

    Gjerdaaker, Lars

    2002-01-01

    The work in this thesis can be divided into two parts. The first part is focused on dynamic investigations of plastic crystals, both in bulk phases but also confined in porous materials (paper 1-3). This part was done together with professor Liudvikas Kimtys, Vilnius, Lithuania. The second part, with emphasis on diffusion, employed PFG NMR to measure the true intra-crystalline diffusivity, including development of a new pulse sequence with shorter effective diffusion time. This work was performed in collaboration with Dr. Geir H. Soerland, Trondheim, Norway and has resulted in three papers (paper 4-6). Paper 1-3: In these papers the dynamics of three organic compounds confined within mesoporous silica have been studied, and the results are discussed with reference to the bulk material. The three investigated compounds form disordered (plastic) phases of high symmetry on solidification (solid I). Thus, bulk cyclohexane exhibits a disordered phase between the solid-solid phase transition at 186 K and the melting point at 280 K. X-ray diffraction measurements have shown that solid I is face-centred cubic (Z=4, a=0.861 nm at 195 K), while the ordered solid II is monoclinic. Tert-butyl cyanide exhibits a plastic phase between the solid-solid transition point at 233 K and the melting point at 292 K. Neutron scattering techniques have established that solid I is tetragonal (Z=2, a=b=0.683 nm, c=0.674 nm, beta=90 deg at 234 K), while solid II is monoclinic. Finally, the disordered phase of pivalic acid melts at 310 K and undergoes a solid-solid phase transition at 280 K. The disordered phase is face-centred cubic, (Z=4, a=0.887 nm), while the low temperature phase (solid II) is triclinic. Paper 4-6; If one is aiming to measure true intra-crystallite diffusivities in porous media the distance travelled by the molecules during the pulse must be shorter than the size of the crystallite. The length of the diffusion time is therefore important. Working with heterogeneous media

  16. Lifetimes of organic photovoltaics: Design and synthesis of single oligomer molecules in order to study chemical degradation mechanisms

    Alstrup, J.; Norrman, K.; Jørgensen, M.

    2006-01-01

    Degradation mechanisms in organic and polymer photovoltaics are addressed through the study of an organic photovoltaic molecule based on a single phenylene-vinylene-type oligomer molecule. The synthesis of such a model compound with different end-groups is presented that allows for assignment...... of degradation products from different parts of the molecule. Photovoltaic devices with and without C(60) have been prepared and their characteristics under AM1.5 conditions are reported. The degradation of the active phenylene-vinylene compound in darkness and after 20h of illumination were investigated using...... a mass spectrometric technique (time-of-flight secondary ion mass spectrometry) allowing elucidation of the oxidative degradation pathways. (c) 2006 Elsevier B.V. All rights reserved....

  17. Structural, Linear, and Nonlinear Optical and Mechanical Properties of New Organic L-Serine Crystal

    K. Rajesh

    2014-01-01

    Full Text Available Nonlinear optical single crystal of organic amino acid L-Serine (LS was grown by slow evaporation technique. Solubility study of the compound was measured and metastable zone width was found. Single crystal X-ray diffraction study was carried out for the grown crystal. The linear and nonlinear optical properties of the crystal were confirmed by UV-Vis analysis and powder SHG tester. FT-IR spectrum was recorded and functional groups were analyzed. Vickers’ microhardness studies showed the mechanical strength of the grown crystal. Laser damage threshold value of the crystal was calculated. Photoconductivity studies reveal the conductivity of the crystal.

  18. Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated Mars surface UV radiation conditions

    Poch, Olivier; Dequaire, Tristan; Stalport, Fabien; Jaber, Maguy; Lambert, Jean-François; Szopa, Cyril; Coll, Patrice

    2015-04-01

    The search for organic carbon-containing molecules at the surface of Mars, as clues of past habitability or remnants of life, is a major scientific goal for Mars exploration. Several lines of evidence, including the detection of phyllosilicates, suggest that early Mars offered favorable conditions for long-term sustaining of water. As a consequence, we can assume that in those days, endogenous chemical processes, or even primitive life, may have produced organic matter on Mars. Moreover, exogenous delivery from small bodies or dust particles is likely to have brought fresh organic molecules to the surface of Mars up today. Organic matter is therefore expected to be present at the surface/subsurface of the planet. But the current environmental conditions at the surface - UV radiation, oxidants and energetic particles - generate physico-chemical processes that may affect organic molecules. On the other hand, on Earth, phyllosilicates are known to accumulate and preserve organic matter. But are phyllosilicates efficient at preserving organic molecules under the current environmental conditions at the surface of Mars? We have monitored the qualitative and quantitative evolutions of glycine, urea and adenine interacting with the Fe3+-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated Martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K) and pressure (6 ± 1 mbar) in a laboratory simulation setup. We have tested organic-rich samples which may be representative of the evaporation of a warm little pond of liquid water having concentrated organics on Mars. For each molecule, we have observed how the nontronite influences the quantum efficiency of its photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine: their efficiencies of photodecomposition are reduced by a factor

  19. Evolution of complex organic molecules in hot molecular cores. Synthetic spectra at (sub-)mm wavebands

    Choudhury, R.; Schilke, P.; Stéphan, G.; Bergin, E.; Möller, T.; Schmiedeke, A.; Zernickel, A.

    2015-03-01

    Context. Hot molecular cores (HMCs) are intermediate stages of high-mass star formation and are also known for their rich chemical reservoirs and emission line spectra at (sub-)mm wavebands. Complex organic molecules (COMs) such as methanol (CH3OH), ethanol (C2H5OH), dimethyl ether (CH3OCH3), and methyl formate (HCOOCH3) produce most of these observed lines. The observed spectral feature of HMCs such as total number of emission lines and associated line intensities are also found to vary with evolutionary stages. Aims: We aim to investigate the spectral evolution of these COMs to explore the initial evolutionary stages of high-mass star formation including HMCs. Methods: We developed various 3D models for HMCs guided by the evolutionary scenarios proposed by recent empirical and modeling studies. We then investigated the spatio-temporal variation of temperature and molecular abundances in HMCs by consistently coupling gas-grain chemical evolution with radiative transfer calculations. We explored the effects of varying physical conditions on molecular abundances including density distribution and luminosity evolution of the central protostar(s) among other parameters. Finally, we simulated the synthetic spectra for these models at different evolutionary timescales to compare with observations. Results: Temperature has a profound effect on the formation of COMs through the depletion and diffusion on grain surface to desorption and further gas-phase processing. The time-dependent temperature structure of the hot core models provides a realistic framework for investigating the spatial variation of ice mantle evaporation as a function of evolutionary timescales. We find that a slightly higher value (15 K) than the canonical dark cloud temperature (10 K) provides a more productive environment for COM formation on grain surface. With increasing protostellar luminosity, the water ice evaporation font (~100 K) expands and the spatial distribution of gas phase abundances of

  20. Inhibiting prolyl isomerase activity by hybrid organic-inorganic molecules containing rhodium(II) fragments.

    Coughlin, Jane M; Kundu, Rituparna; Cooper, Julian C; Ball, Zachary T

    2014-11-15

    A small molecule containing a rhodium(II) tetracarboxylate fragment is shown to be a potent inhibitor of the prolyl isomerase FKBP12. The use of small molecules conjugates of rhodium(II) is presented as a general strategy for developing new protein inhibitors based on distinct structural and sequence features of the enzyme active site. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Terminal moiety-driven electrical performance of asymmetric small-molecule-based organic solar cells

    Huang, Jianhua; Zhang, Shanlin; jiang, Bo

    2016-01-01

    With respect to the successes from symmetric small molecules, asymmetric ones have recently emerged as an alternative choice. In this paper, we present the synthesis and photovoltaic properties of four asymmetric small molecule donors. The benzo[1,2-b:4,5-b']dithiophene (BDT) end in the asymmetri...

  2. Chronic toxicity of sediment-associated linear alkylbenzene sulphonates (LAS) to freshwater benthic organisms

    Comber, S.D.W. [WRc-NSF, Henley Road, Medmenham, Marlow, Buckinghamshire, SL7 2HD (United Kingdom)]. E-mail: sean.comber@atkinsglobal.com; Conrad, A.U. [Weinberg Group, Blue Tower, Box 16, B-1050 Brussels (Belgium); Hoess, S. [ECOSSA, Thierschstrasser 43, 80538, Muenchen (Germany); Webb, S. [CEFIC, Ave E. Van Nieuwenhuyse 4, B-1160 Brussels (Belgium); Marshall, S. [Unilever Research, Environment Centre, Bebington, Wirral, Merseyside, L63 3JW (United Kingdom)

    2006-11-15

    The toxicity of linear alkylbenzene sulphonates (LAS), to freshwater benthic organisms was assessed during exposure to spiked sediment. Lethal and sub-lethal end-points were monitored for two organisms (oligochaete Lumbriculus variegatus and nematode Caenorhabditis elegans). Results demonstrated relatively low toxicity (LOECs >100 mg/kg dry weight). No observed effect concentrations (NOECs) of 81 mg/kg dw (Lumbriculus) and 100 mg/kg dw (Caenorhabditis) were determined. For the oligochaete, no specific endpoint was particularly sensitive to LAS. For the nematode, egg production was the most sensitive endpoint. Significant degradation was measured over the 28-day duration of the Lumbriculus study, equating to a half-life of 20 days in sediment. - This paper provides sediment toxicity data for LAS, essential for a detailed and accurate environment risk assessment.

  3. Chronic toxicity of sediment-associated linear alkylbenzene sulphonates (LAS) to freshwater benthic organisms

    Comber, S.D.W.; Conrad, A.U.; Hoess, S.; Webb, S.; Marshall, S.

    2006-01-01

    The toxicity of linear alkylbenzene sulphonates (LAS), to freshwater benthic organisms was assessed during exposure to spiked sediment. Lethal and sub-lethal end-points were monitored for two organisms (oligochaete Lumbriculus variegatus and nematode Caenorhabditis elegans). Results demonstrated relatively low toxicity (LOECs >100 mg/kg dry weight). No observed effect concentrations (NOECs) of 81 mg/kg dw (Lumbriculus) and 100 mg/kg dw (Caenorhabditis) were determined. For the oligochaete, no specific endpoint was particularly sensitive to LAS. For the nematode, egg production was the most sensitive endpoint. Significant degradation was measured over the 28-day duration of the Lumbriculus study, equating to a half-life of 20 days in sediment. - This paper provides sediment toxicity data for LAS, essential for a detailed and accurate environment risk assessment

  4. Formation and Atmosphere of Complex Organic Molecules of the HH 212 Protostellar Disk

    Lee, Chin-Fei; Ho, Paul T. P.; Hirano, Naomi; Shang, Hsien [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan (China); Li, Zhi-Yun [Astronomy Department, University of Virginia, Charlottesville, VA 22904 (United States); Zhang, Qizhou, E-mail: cflee@asiaa.sinica.edu.tw [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2017-07-01

    HH 212 is a nearby (400 pc) Class 0 protostellar system recently found to host a “hamburger”-shaped dusty disk with a radius of ∼60 au, deeply embedded in an infalling-rotating flattened envelope. We have spatially resolved this envelope-disk system with the Atacama Large Millimeter/submillimeter Array at up to ∼16 au (0.″04) resolution. The envelope is detected in HCO{sup +} J = 4–3 down to the dusty disk. Complex organic molecules (COMs) and doubly deuterated formaldehyde (D{sub 2}CO) are detected above and below the dusty disk within ∼40 au of the central protostar. The COMs are methanol (CH{sub 3}OH), deuterated methanol (CH{sub 2}DOH), methyl mercaptan (CH{sub 3}SH), and formamide (NH{sub 2}CHO, a prebiotic precursor). We have modeled the gas kinematics in HCO{sup +} and COMs and found a centrifugal barrier (CB) at a radius of ∼44 au, within which a Keplerian rotating disk is formed. This indicates that HCO{sup +} traces the infalling-rotating envelope down to the CB and COMs trace the atmosphere of a Keplerian rotating disk within the CB. The COMs are spatially resolved for the first time, both radially and vertically, in the atmosphere of a disk in the earliest, Class 0 phase of star formation. Our spatially resolved observations of COMs favor their formation in the disk rather than a rapidly infalling (warm) inner envelope. The abundances and spatial distributions of the COMs provide strong constraints on models of their formation and transport in low-mass star formation.

  5. THE SPATIAL DISTRIBUTION OF COMPLEX ORGANIC MOLECULES IN THE L1544 PRE-STELLAR CORE

    Jiménez-Serra, Izaskun [Astronomy Unit, School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Vasyunin, Anton I.; Caselli, Paola [Max-Planck-Institut für extraterrestrische Physik (MPE), Gießenbachstr., D-85741 Garching (Germany); Marcelino, Nuria [INAF, Osservatorio di Radioastronomia, Via P. Gobetti 101, I-40129 Bologna (Italy); Billot, Nicolas [Instituto de Radioastronomía Milimétrica, Avenida Divina Pastora 7, E-18012 Granada (Spain); Viti, Serena [Department of Physics and Astronomy, University College London, 132 Hampstead Road, London NW1 2PS (United Kingdom); Testi, Leonardo [European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany); Vastel, Charlotte [Université de Toulouse, UPS-OMP, IRAP, F-31400 Toulouse (France); Lefloch, Bertrand [Univ. Grenoble Alpes, IPAG, F-38000 Grenoble (France); Bachiller, Rafael, E-mail: i.jimenez-serra@qmul.ac.uk [Observatorio Astronómico Nacional (OAN, IGN), Calle Alfonso XII 3, E-28014 Madrid (Spain)

    2016-10-10

    The detection of complex organic molecules (COMs) toward cold sources such as pre-stellar cores (with T < 10 K) has challenged our understanding of the formation processes of COMs in the interstellar medium. Recent modeling on COM chemistry at low temperatures has provided new insight into these processes predicting that COM formation depends strongly on parameters such as visual extinction and the level of CO freeze out. We report deep observations of COMs toward two positions in the L1544 pre-stellar core: the dense, highly extinguished continuum peak with A{sub V}≥ 30 mag within the inner 2700 au; and a low-density shell with average A{sub V}∼ 7.5–8 mag located at 4000 au from the core’s center and bright in CH{sub 3}OH. Our observations show that CH{sub 3}O, CH{sub 3}OCH{sub 3}, and CH{sub 3}CHO are more abundant (by factors of ∼2–10) toward the low-density shell than toward the continuum peak. Other COMs such as CH{sub 3}OCHO, c-C{sub 3}H{sub 2}O, HCCCHO, CH{sub 2}CHCN, and HCCNC show slight enhancements (by factors ≤3), but the associated uncertainties are large. This suggests that COMs are actively formed and already present in the low-density shells of pre-stellar cores. The modeling of the chemistry of O-bearing COMs in L1544 indicates that these species are enhanced in this shell because (i) CO starts freezing out onto dust grains driving an active surface chemistry; (ii) the visual extinction is sufficiently high to prevent the UV photo-dissociation of COMs by the external interstellar radiation field; and (iii) the density is still moderate to prevent severe depletion of COMs onto grains.

  6. Two-photon Photoemission of Organic Semiconductor Molecules on Ag(111)

    Yang, Aram [Univ. of California, Berkeley, CA (United States)

    2008-05-01

    Angle- and time-resolved two-photon photoemission (2PPE) was used to study systems of organic semiconductors on Ag(111). The 2PPE studies focused on electronic behavior specific to interfaces and ultrathin films. Electron time dynamics and band dispersions were characterized for ultrathin films of a prototypical n-type planar aromatic hydrocarbon, PTCDA, and representatives from a family of p-type oligothiophenes.In PTCDA, electronic behavior was correlated with film morphology and growth modes. Within a fewmonolayers of the interface, image potential states and a LUMO+1 state were detected. The degree to which the LUMO+1 state exhibited a band mass less than a free electron mass depended on the crystallinity of the layer. Similarly, image potential states were measured to have free electron-like effective masses on ordered surfaces, and the effective masses increased with disorder within the thin film. Electron lifetimes were correlated with film growth modes, such that the lifetimes of electrons excited into systems created by layer-by-layer, amorphous film growth increased by orders of magnitude by only a few monolayers from the surface. Conversely, the decay dynamics of electrons in Stranski-Krastanov systems were limited by interaction with the exposed wetting layer, which limited the barrier to decay back into the metal.Oligothiophenes including monothiophene, quaterthiophene, and sexithiophene were deposited on Ag(111), and their electronic energy levels and effective masses were studied as a function of oligothiophene length. The energy gap between HOMO and LUMO decreased with increasing chain length, but effective mass was found to depend on domains from high- or low-temperature growth conditions rather than chain length. In addition, the geometry of the molecule on the surface, e.g., tilted or planar, substantially affected the electronic structure.

  7. THE SPATIAL DISTRIBUTION OF COMPLEX ORGANIC MOLECULES IN THE L1544 PRE-STELLAR CORE

    Jiménez-Serra, Izaskun; Vasyunin, Anton I.; Caselli, Paola; Marcelino, Nuria; Billot, Nicolas; Viti, Serena; Testi, Leonardo; Vastel, Charlotte; Lefloch, Bertrand; Bachiller, Rafael

    2016-01-01

    The detection of complex organic molecules (COMs) toward cold sources such as pre-stellar cores (with T < 10 K) has challenged our understanding of the formation processes of COMs in the interstellar medium. Recent modeling on COM chemistry at low temperatures has provided new insight into these processes predicting that COM formation depends strongly on parameters such as visual extinction and the level of CO freeze out. We report deep observations of COMs toward two positions in the L1544 pre-stellar core: the dense, highly extinguished continuum peak with A_V≥ 30 mag within the inner 2700 au; and a low-density shell with average A_V∼ 7.5–8 mag located at 4000 au from the core’s center and bright in CH_3OH. Our observations show that CH_3O, CH_3OCH_3, and CH_3CHO are more abundant (by factors of ∼2–10) toward the low-density shell than toward the continuum peak. Other COMs such as CH_3OCHO, c-C_3H_2O, HCCCHO, CH_2CHCN, and HCCNC show slight enhancements (by factors ≤3), but the associated uncertainties are large. This suggests that COMs are actively formed and already present in the low-density shells of pre-stellar cores. The modeling of the chemistry of O-bearing COMs in L1544 indicates that these species are enhanced in this shell because (i) CO starts freezing out onto dust grains driving an active surface chemistry; (ii) the visual extinction is sufficiently high to prevent the UV photo-dissociation of COMs by the external interstellar radiation field; and (iii) the density is still moderate to prevent severe depletion of COMs onto grains.

  8. Polymeric biomaterials for nerve regeneration applications: From promoting cellular organization to the delivery of bioactive molecules

    Delgado-Rivera, Roberto L.

    Thousands of new cases of injury to the central nervous system (CNS) occur each year in the USA and all over the world. However, despite recent advances, at present there is no cure for the resulting paraplegia or quadriplegia. This research is directed towards engineering biomaterial platforms to promote cellular organization at the surface of polymer scaffolds that will be conducive to proper regeneration of injured CNS. In addition, the formulation of a delivery system for neuroactive molecules using polymer-based materials will be evaluated to establish its potential to treat CNS disorders. Initial studies involved the chemical modification of an electrospun nonwoven matrix of nanofibers with fibroblast growth factor 2 (FGF-2). Nanofibers alone up-regulated FGF-2, albeit to a lesser extent than nanofibers covalently modified with FGF-2. These results underscore the importance of both surface topography and growth factor presentation on cellular function. Moreover, that FGF-2 modified nanofibrillar scaffolds may demonstrate utility in tissue engineering applications for replacement and regeneration of damaged tissue following CNS injury or disease. Subsequent research efforts focused on a novel micropatterning technique called microscale plasma-initiated patterning (microPIP). This patterning method uses a polydimethylsiloxane (PDMS) stamp to selectively protect regions of an underlying substrate from oxygen plasma treatment resulting in hydrophobic and hydrophilic regions. FGF-2 and laminin-1 were applied to an electrospun polyamide nanofibrillar matrix following plasma treatment. In this work it, was possible to demonstrate that textured surfaces, such as nanofibrillar scaffolds, can be micropatterned to provide external chemical cues for cellular organization. Finally, a microsphere system capable of encapsulating proteins while minimizing the mechanisms of protein degradation and providing a controlled release was investigated. Microspheres were comprised of

  9. Improved efficiency in organic/inorganic hybrid solar cells by interfacial modification of ZnO nanowires with small molecules

    Chang, Sehoon; Park, Hyesung; Cheng, Jayce J; Rekemeyer, Paul H; Gradečak, Silvija

    2014-01-01

    We demonstrate improved photovoltaic performance of ZnO nanowire/poly(3-hexylthiophene) (P3HT) nanofiber hybrid devices using an interfacial modification of ZnO nanowires. Formation of cascade energy levels between the ZnO nanowire and P3HT nanofiber was achieved by interfacial modification of ZnO nanowires using small molecules tetraphenyldibenzoperiflanthene (DBP) and 3,4,9,10-perylenetetracarboxylic bisbenzimidazole (PTCBI). The successful demonstration of improved device performance owing to the cascade energy levels by small molecule modification is a promising approach toward highly efficient organic/inorganic hybrid solar cells. (paper)

  10. Organized single-molecule magnets: direct observation of new Mn{sub 12} derivatives on gold

    Cornia, A.; Fabretti, A.C.; Pacchioni, M.; Zobbi, L. E-mail: lzobbi@unimo.it; Bonacchi, D.; Caneschi, A.; Gatteschi, D.; Biagi, R.; Del Pennino, U.; De Renzi, V.; Gurevich, L.; Zant, H.S.J. van der

    2004-05-01

    Gold adsorbates of the dodecamanganese(III,IV) single-molecule magnet (SMM) [Mn{sub 12}O{sub 12}(L){sub 16}(H{sub 2}O){sub 4}] where L=16-(acetylthio)hexadecanoate have been prepared and investigated by X-ray photoelectron spectroscopy and scanning tunneling microscopy (STM). The successful imaging of Mn{sub 12} molecules by STM represents a first step toward the magnetic addressing of individual SMMs and the development of molecule-based devices for magnetic information storage.

  11. Nonvolatile Memory Elements Based on the Intercalation of Organic Molecules Inside Carbon Nanotubes

    Meunier, Vincent; Kalinin, Sergei V.; Sumpter, Bobby G.

    2007-02-01

    We propose a novel class of nonvolatile memory elements based on the modification of the transport properties of a conducting carbon nanotube by the presence of an encapsulated molecule. The guest molecule has two stable orientational positions relative to the nanotube that correspond to conducting and nonconducting states. The mechanism, governed by a local gating effect of the molecule on the electronic properties of the nanotube host, is studied using density functional theory. The mechanisms of reversible reading and writing of information are illustrated with a F4TCNQ molecule encapsulated inside a metallic carbon nanotube. Our results suggest that this new type of nonvolatile memory element is robust, fatigue-free, and can operate at room temperature.

  12. Power-Law-Distributed Dark States are the Main Pathway for Photobleaching of Single Organic Molecules

    Hoogenboom, J.P.; Hoogenboom, Jacob; van Dijk, E.M.H.P.; Hernando Campos, J.; van Hulst, N.F.; Garcia Parajo, M.F.

    2005-01-01

    We exploit the strong excitonic coupling in a superradiant trimer molecule to distinguish between long-lived collective dark states and photobleaching events. The population and depopulation kinetics of the dark states in a single molecule follow power-law statistics over 5 orders of magnitude in time. This result is consistent with the formation of a radical unit via electron tunneling to a time-varying distribution of trapping sites in the surrounding polymer matrix. We furthermore demonstr...

  13. Computer software for linear and nonlinear regression in organic NMR; Programa de computador para regressao linear e nao linear em R.M.N. organica

    Canto, Eduardo Leite do; Rittner, Roberto [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica

    1992-12-31

    Calculation involving two variable linear regressions, require specific procedures generally not familiar to chemist. For attending the necessity of fast and efficient handling of NMR data, a self explained and Pc portable software has been developed, which allows user to produce and use diskette recorded tables, containing chemical shift or any other substituent physical-chemical measurements and constants ({sigma}{sub T}, {sigma}{sup o}{sub R}, E{sub s}, ...) 9 refs., 1 fig.

  14. CAL3JHH: a Java program to calculate the vicinal coupling constants (3J H,H) of organic molecules.

    Aguirre-Valderrama, Alonso; Dobado, José A

    2008-12-01

    Here, we present a free web-accessible application, developed in the JAVA programming language for the calculation of vicinal coupling constant (3J(H,H)) of organic molecules with the H-Csp3-Csp3-H fragment. This JAVA applet is oriented to assist chemists in structural and conformational analyses, allowing the user to calculate the averaged 3J(H,H) values among conformers, according to its Boltzmann populations. Thus, the CAL3JHH program uses the Haasnoot-Leeuw-Altona equation, and, by reading the molecule geometry from a protein data bank (PDB) file format or from multiple pdb files, automatically detects all the coupled hydrogens, evaluating the data needed for this equation. Moreover, a "Graphical viewer" menu allows the display of the results on the 3D molecule structure, as well as the plotting of the Newman projection for the couplings.

  15. "Trampoline" ejection of organic molecules from graphene and graphite via keV cluster ions impacts

    Verkhoturov, Stanislav V.; Gołuński, Mikołaj; Verkhoturov, Dmitriy S.; Geng, Sheng; Postawa, Zbigniew; Schweikert, Emile A.

    2018-04-01

    We present the data on ejection of molecules and emission of molecular ions caused by single impacts of 50 keV C602+ on a molecular layer of deuterated phenylalanine (D8Phe) deposited on free standing, 2-layer graphene. The projectile impacts on the graphene side stimulate the abundant ejection of intact molecules and the emission of molecular ions in the transmission direction. To gain insight into the mechanism of ejection, Molecular Dynamic simulations were performed. It was found that the projectile penetrates the thin layer of graphene, partially depositing the projectile's kinetic energy, and molecules are ejected from the hot area around the hole that is made by the projectile. The yield, Y, of negative ions of deprotonated phenylalanine, (D8Phe-H)-, emitted in the transmission direction is 0.1 ions per projectile impact. To characterize the ejection and ionization of molecules, we have performed the experiments on emission of (D8Phe-H)- from the surface of bulk D8Phe (Y = 0.13) and from the single molecular layer of D8Phe deposited on bulk pyrolytic graphite (Y = 0.15). We show that, despite the similar yields of molecular ions, the scenario of the energy deposition and ejection of molecules is different for the case of graphene due to the confined volume of projectile-analyte interaction. The projectile impact on the graphene-D8Phe sample stimulates the collective radial movement of analyte atoms, which compresses the D8Phe layer radially from the hole. At the same time, this compression bends and stretches the graphene membrane around the hole thus accumulating potential energy. The accumulated potential energy is transformed into the kinetic energy of correlated movement upward for membrane atoms, thus the membrane acts as a trampoline for the molecules. The ejected molecules are effectively ionized; the ionization probability is ˜30× higher compared to that obtained for the bulk D8Phe target. The proposed mechanism of ionization involves tunneling of

  16. "Trampoline" ejection of organic molecules from graphene and graphite via keV cluster ions impacts.

    Verkhoturov, Stanislav V; Gołuński, Mikołaj; Verkhoturov, Dmitriy S; Geng, Sheng; Postawa, Zbigniew; Schweikert, Emile A

    2018-04-14

    We present the data on ejection of molecules and emission of molecular ions caused by single impacts of 50 keV C 60 2+ on a molecular layer of deuterated phenylalanine (D8Phe) deposited on free standing, 2-layer graphene. The projectile impacts on the graphene side stimulate the abundant ejection of intact molecules and the emission of molecular ions in the transmission direction. To gain insight into the mechanism of ejection, Molecular Dynamic simulations were performed. It was found that the projectile penetrates the thin layer of graphene, partially depositing the projectile's kinetic energy, and molecules are ejected from the hot area around the hole that is made by the projectile. The yield, Y, of negative ions of deprotonated phenylalanine, (D8Phe-H) - , emitted in the transmission direction is 0.1 ions per projectile impact. To characterize the ejection and ionization of molecules, we have performed the experiments on emission of (D8Phe-H) - from the surface of bulk D8Phe (Y = 0.13) and from the single molecular layer of D8Phe deposited on bulk pyrolytic graphite (Y = 0.15). We show that, despite the similar yields of molecular ions, the scenario of the energy deposition and ejection of molecules is different for the case of graphene due to the confined volume of projectile-analyte interaction. The projectile impact on the graphene-D8Phe sample stimulates the collective radial movement of analyte atoms, which compresses the D8Phe layer radially from the hole. At the same time, this compression bends and stretches the graphene membrane around the hole thus accumulating potential energy. The accumulated potential energy is transformed into the kinetic energy of correlated movement upward for membrane atoms, thus the membrane acts as a trampoline for the molecules. The ejected molecules are effectively ionized; the ionization probability is ∼30× higher compared to that obtained for the bulk D8Phe target. The proposed mechanism of ionization involves

  17. Does Prigogine’s Non-linear Thermodynamics Support Popular Philosophical Discussions of Self-Organization?

    Alexander Pechenkin

    2015-10-01

    Full Text Available The article is concerned with the philosophical talks which became popular in the 1980s and have kept their popularity till now–the philosophical essays about self-organization. The author attempts to find out as to which extent are these essays founded on the scientific theory to which they regularly refer, that is, Ilya Prigogine’s non-linear thermodynamics. The author insists that the equivalent of self-organization in Prigogine’s theoretical physics is the concept of dissipative structure. The concept of selforganization, as it is used in philosophical literature, presupposes a sequence of extrapolations, the first extrapolation being conducted by Prigogine and his coauthors. They became to use the concept of dissipative structure beyond the rigorous theory of this phenomenon. The subsequent step was that the scientific term “dissipative structure” was replaced by the vague concept “self-organization” in many popular and semi-popular books and papers. The author also emphasizes that by placing the concept of self-organization into the framework of philosophical concepts (the picture of the world, the ideals of scientific thought, the contemporary scientific revolution, etc. a philosopher conducts the extrapolation of extrapolation and comes to a kind of what Edmund Husserl called Weltanschauung (‘worldview’ philosophy.

  18. Acquiring beam data for a flattening-filter free linear accelerator using organic scintillators

    Beierholm, A.R.; Behrens, C.F.; Hoffmann, L.; Andersen, C.E.

    2013-01-01

    Fibre-coupled organic scintillators have been proven a credible alternative to clinically implemented methods for radiotherapy dosimetry, primarily due to their water equivalence and good spatial resolution. Furthermore, the fast response of the scintillators can be exploited to perform time-resolved dosimetry on a highly detailed level. In this study, we present beam data for a Varian TrueBeam linear accelerator, which is capable of delivering flattening-filter free (FFF 1 ) clinical X-ray beams. The beam data have been acquired using an in-house developed dosimetry system based on fibre-coupled organic scintillators. The presented data exhibit high accuracy and precision when compared with data obtained using commercial dosimetry methods, and agree well with results published in the literature. -- Highlights: •A dosimetry system based on fibre-coupled organic scintillators is presented. •The system is used for radiotherapy beams with and without flattening filter. •Measurements show good agreement with various commercial dosimeters

  19. Tensor algebra-based geometric methodology to codify central chirality on organic molecules.

    García-Jacas, C R; Marrero-Ponce, Y; Hernández-Ortega, T; Martinez-Mayorga, K; Cabrera-Leyva, L; Ledesma-Romero, J C; Aguilera-Fernández, I; Rodríguez-León, A R

    2017-06-01

    A novel mathematical procedure to codify chiral features of organic molecules in the QuBiLS-MIDAS framework is introduced. This procedure constitutes a generalization to that commonly used to date, where the values 1 and -1 (correction factor) are employed to weight the molecular vectors when each atom is labelled as R (rectus) or S (sinister) according to the Cahn-Ingold-Prelog rules. Therefore, values in the range [Formula: see text] with steps equal to 0.25 may be accounted for. The atoms labelled R or S can have negative and positive values assigned (e.g. -3 for an R atom and 1 for an S atom, or vice versa), opposed values (e.g. -3 for an R atom and 3 for an S atom, or vice versa), positive values (e.g. 3 for an R atom and 1 for an S atom) or negative values (e.g. -3 for an R atom and -1 for an S atom). These proposed Chiral QuBiLS-MIDAS 3D-MDs are real numbers, non-symmetric and reduced to 'classical' (non-chiral) QuBiLS-MIDAS 3D-MDs when symmetry is not codified (correction factor equal to zero). In this report, only the factors with opposed values were considered with the purpose of demonstrating the feasibility of this proposal. From QSAR modelling carried out on four chemical datasets (Cramer's steroids, fenoterol stereoisomer derivatives, N-alkylated 3-(3-hydroxyphenyl)-piperidines, and perindoprilat stereoisomers), it was demonstrated that the use of several correction factors contributes to the building of models with greater robustness and predictive ability than those reported in the literature, as well as with respect to the models exclusively developed with QuBiLS-MIDAS 3D-MDs based on the factor 1 | -1. In conclusion, it can be stated that this novel strategy constitutes a suitable alternative to computed chirality-based descriptors, contributing to the development of good models to predict properties depending on symmetry.

  20. Organic molecules deposited on graphene: A computational investigation of self-assembly and electronic structure

    Oliveira, I. S. S. de; Miwa, R. H.

    2015-01-01

    We use ab initio simulations to investigate the adsorption and the self-assembly processes of tetracyanoquinodimethane (TCNQ), tetrafluoro-tetracyanoquinodimethane (F4-TCNQ), and tetrasodium 1,3,6,8-pyrenetetrasulfonic acid (TPA) on the graphene surface. We find that there are no chemical bonds at the molecule–graphene interface, even at the presence of grain boundaries on the graphene surface. The molecules bond to graphene through van der Waals interactions. In addition to the molecule–graphene interaction, we performed a detailed study of the role played by the (lateral) molecule–molecule interaction in the formation of the, experimentally verified, self-assembled layers of TCNQ and TPA on graphene. Regarding the electronic properties, we calculate the electronic charge transfer from the graphene sheet to the TCNQ and F4-TCNQ molecules, leading to a p-doping of graphene. Meanwhile, such charge transfer is reduced by an order of magnitude for TPA molecules on graphene. In this case, it is not expected a significant doping process upon the formation of self-assembled layer of TPA molecules on the graphene sheet

  1. Semi-automatic mapping of linear-trending bedforms using 'Self-Organizing Maps' algorithm

    Foroutan, M.; Zimbelman, J. R.

    2017-09-01

    Increased application of high resolution spatial data such as high resolution satellite or Unmanned Aerial Vehicle (UAV) images from Earth, as well as High Resolution Imaging Science Experiment (HiRISE) images from Mars, makes it necessary to increase automation techniques capable of extracting detailed geomorphologic elements from such large data sets. Model validation by repeated images in environmental management studies such as climate-related changes as well as increasing access to high-resolution satellite images underline the demand for detailed automatic image-processing techniques in remote sensing. This study presents a methodology based on an unsupervised Artificial Neural Network (ANN) algorithm, known as Self Organizing Maps (SOM), to achieve the semi-automatic extraction of linear features with small footprints on satellite images. SOM is based on competitive learning and is efficient for handling huge data sets. We applied the SOM algorithm to high resolution satellite images of Earth and Mars (Quickbird, Worldview and HiRISE) in order to facilitate and speed up image analysis along with the improvement of the accuracy of results. About 98% overall accuracy and 0.001 quantization error in the recognition of small linear-trending bedforms demonstrate a promising framework.

  2. Blending crystalline/liquid crystalline small molecule semiconductors: A strategy towards high performance organic thin film transistors

    He, Chao; He, Yaowu; Li, Aiyuan; Zhang, Dongwei; Meng, Hong

    2016-10-01

    Solution processed small molecule polycrystalline thin films often suffer from the problems of inhomogeneity and discontinuity. Here, we describe a strategy to solve these problems through deposition of the active layer from a blended solution of crystalline (2-phenyl[1]benzothieno[3,2-b][1]benzothiophene, Ph-BTBT) and liquid crystalline (2-(4-dodecylphenyl) [1]benzothieno[3,2-b]benzothiophene, C12-Ph-BTBT) small molecule semiconductors with the hot spin-coating method. Organic thin film transistors with average hole mobility approaching 1 cm2/V s, much higher than that of single component devices, have been demonstrated, mainly due to the improved uniformity, continuity, crystallinity, and stronger intermolecular π-π stacking in blend thin films. Our results indicate that the crystalline/liquid crystalline semiconductor blend method is an effective way to enhance the performance of organic transistors.

  3. Graphical prediction of quantum interference-induced transmission nodes in functionalized organic molecules

    Markussen, Troels; Stadler, Robert; Thygesen, Kristian Sommer

    2011-01-01

    Quantum interference (QI) in molecular transport junctions can lead to dramatic reductions of the electron transmission at certain energies. In a recent work [Markussen et al., Nano Lett., 2010, 10, 4260] we showed how the presence of such transmission nodes near the Fermi energy can be predicted...... solely from the structure of a conjugated molecule when the energies of the atomic pz orbitals do not vary too much. Here we relax the assumption of equal on-site energies and generalize the graphical scheme to molecules containing different atomic species. We use this diagrammatic scheme together......, the transmission functions of functionalized aromatic molecules generally display a rather complex nodal structure due to the interplay between molecular topology and the energy of the side group orbital....

  4. Steady-State Linear and Non-linear Optical Spectroscopy of Organic Chromophores and Bio-macromolecules.

    Marazzi, Marco; Gattuso, Hugo; Monari, Antonio; Assfeld, Xavier

    2018-01-01

    Bio-macromolecules as DNA, lipid membranes and (poly)peptides are essential compounds at the core of biological systems. The development of techniques and methodologies for their characterization is therefore necessary and of utmost interest, even though difficulties can be experienced due to their intrinsic complex nature. Among these methods, spectroscopies, relying on optical properties are especially important to determine their macromolecular structures and behaviors, as well as the possible interactions and reactivity with external dyes-often drugs or pollutants-that can (photo)sensitize the bio-macromolecule leading to eventual chemical modifications, thus damages. In this review, we will focus on the theoretical simulation of electronic spectroscopies of bio-macromolecules, considering their secondary structure and including their interaction with different kind of (photo)sensitizers. Namely, absorption, emission and electronic circular dichroism (CD) spectra are calculated and compared with the available experimental data. Non-linear properties will be also taken into account by two-photon absorption, a highly promising technique (i) to enhance absorption in the red and infra-red windows and (ii) to enhance spatial resolution. Methodologically, the implications of using implicit and explicit solvent, coupled to quantum and thermal samplings of the phase space, will be addressed. Especially, hybrid quantum mechanics/molecular mechanics (QM/MM) methods are explored for a comparison with solely QM methods, in order to address the necessity to consider an accurate description of environmental effects on spectroscopic properties of biological systems.

  5. Steady-State Linear and Non-linear Optical Spectroscopy of Organic Chromophores and Bio-macromolecules

    Marco Marazzi

    2018-04-01

    Full Text Available Bio-macromolecules as DNA, lipid membranes and (polypeptides are essential compounds at the core of biological systems. The development of techniques and methodologies for their characterization is therefore necessary and of utmost interest, even though difficulties can be experienced due to their intrinsic complex nature. Among these methods, spectroscopies, relying on optical properties are especially important to determine their macromolecular structures and behaviors, as well as the possible interactions and reactivity with external dyes—often drugs or pollutants—that can (photosensitize the bio-macromolecule leading to eventual chemical modifications, thus damages. In this review, we will focus on the theoretical simulation of electronic spectroscopies of bio-macromolecules, considering their secondary structure and including their interaction with different kind of (photosensitizers. Namely, absorption, emission and electronic circular dichroism (CD spectra are calculated and compared with the available experimental data. Non-linear properties will be also taken into account by two-photon absorption, a highly promising technique (i to enhance absorption in the red and infra-red windows and (ii to enhance spatial resolution. Methodologically, the implications of using implicit and explicit solvent, coupled to quantum and thermal samplings of the phase space, will be addressed. Especially, hybrid quantum mechanics/molecular mechanics (QM/MM methods are explored for a comparison with solely QM methods, in order to address the necessity to consider an accurate description of environmental effects on spectroscopic properties of biological systems.

  6. Steady-State Linear and Non-linear Optical Spectroscopy of Organic Chromophores and Bio-macromolecules

    Marazzi, Marco; Gattuso, Hugo; Monari, Antonio; Assfeld, Xavier

    2018-04-01

    Bio-macromolecules as DNA, lipid membranes and (poly)peptides are essential compounds at the core of biological systems. The development of techniques and methodologies for their characterization is therefore necessary and of utmost interest, even though difficulties can be experienced due to their intrinsic complex nature. Among these methods, spectroscopies, relying on optical properties are especially important to determine their macromolecular structures and behaviors, as well as the possible interactions and reactivity with external dyes – often drugs or pollutants – that can (photo)sensitize the bio-macromolecule leading to eventual chemical modifications, thus damages. In this review, we will focus on the theoretical simulation of electronic spectroscopies of bio-macromolecules, considering their secondary structure and including their interaction with different kind of (photo)sensitizers. Namely, absorption, emission and electronic circular dichroism (CD) spectra are calculated and compared with the available experimental data. Non-linear properties will be also taken into account by two-photon absorption, a highly promising technique (i) to enhance absorption in the red and infra-red windows and (ii) to enhance spatial resolution. Methodologically, the implications of using implicit and explicit solvent, coupled to quantum and thermal samplings of the phase space, will be addressed. Especially, hybrid quantum mechanics/ molecular mechanics (QM/MM) methods are explored for a comparison with solely QM methods, in order to address the necessity to consider an accurate description of environmental effects on spectroscopic properties of biological systems.

  7. Organic molecules based on dithienyl-2,1,3-benzothiadiazole as new donor materials for solution-processed organic photovoltaic cells

    Wu, Zhonglian; Fan, Benhu; Ouyang, Jianyong [Department of Materials Science and Engineering, National University of Singapore, Singapore 117574 (Singapore); Xue, Feng [Department of Chemistry, National University of Singapore, Singapore 117573 (Singapore); Adachi, Chihaya [Center for Future Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan)

    2010-12-15

    Polymers based on dithienyl-2,1,3-benzothiadiazole (TBT) have received strong attention as the donor materials of polymer photovoltaic cells (PVs), since they can have a low band gap. But soluble small organic molecules based on TBT have been rarely studied. This paper reports the synthesis of two small organic molecules based on TBT and their application as the donor materials of solution-processed bulk heterojunction organic photovoltaic cells (OPVs). These compounds were soluble in common organic solvents, such as chloroform, chlorobenzene and tetrahydrofuran. They have band gaps comparable to poly(3-hexylthiophene) (P3HT) and lower HOMO and LUMO (HOMO: highest occupied molecular orbital, LUMO: lowest unoccupied molecular orbital) levels than P3HT. These molecules and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were used as the donors and acceptor to fabricate bulk heterojunction OPVs through solution processing. After optimization of the experimental conditions, power conversion efficiency (PCE) of 0.66% was achieved on the solution-processed OPVs under AM 1.5G, 100 mW cm{sup -2} illumination. (author)

  8. Viscous properties of isotropic fluids composed of linear molecules: departure from the classical Navier-Stokes theory in nano-confined geometries.

    Hansen, J S; Daivis, Peter J; Todd, B D

    2009-10-01

    In this paper we present equilibrium molecular-dynamics results for the shear, rotational, and spin viscosities for fluids composed of linear molecules. The density dependence of the shear viscosity follows a stretched exponential function, whereas the rotational viscosity and the spin viscosities show approximately power-law dependencies. The frequency-dependent shear and spin viscosities are also studied. It is found that viscoelastic behavior is first manifested in the shear viscosity and that the real part of the spin viscosities features a maximum for nonzero frequency. The calculated transport coefficients are used together with the extended Navier-Stokes equations to investigate the effect of the coupling between the intrinsic angular momentum and linear momentum for highly confined fluids. Both steady and oscillatory flows are studied. It is shown, for example, that the fluid flow rate for Poiseuille flow is reduced by up to 10% in a 2 nm channel for a buta-triene fluid at density 236 kg m(-3) and temperature 306 K. The coupling effect may, therefore, become very important for nanofluidic applications.

  9. A Dual Source Ion Trap Mass Spectrometer for the Mars Organic Molecule Analyzer of ExoMars 2018

    Brickerhoff, William B.; vanAmerom, F. H. W.; Danell, R. M.; Arevalo, R.; Atanassova, M.; Hovmand, L.; Mahaffy, P. R.; Cotter, R. J.

    2011-01-01

    We present details on the objectives, requirements, design and operational approach of the core mass spectrometer of the Mars Organic Molecule Analyzer (MOMA) investigation on the 2018 ExoMars mission. The MOMA mass spectrometer enables the investigation to fulfill its objective of analyzing the chemical composition of organic compounds in solid samples obtained from the near surface of Mars. Two methods of ionization are realized, associated with different modes of MOMA operation, in a single compact ion trap mass spectrometer. The stringent mass and power constraints of the mission have led to features such as low voltage and low frequency RF operation [1] and pulse counting detection.

  10. Fluorescent molecule incorporated metal-organic framework for fluoride sensing in aqueous solution

    Zhao, Xudong, E-mail: zhaoxd_tykj@163.com; Wang, Yuanyang; Hao, Xiuli; Liu, Wen, E-mail: 13700509372@163.com

    2017-04-30

    Highlights: • Fluorescein sodium was successfully encapsulated in UiO-66 via in-situ synthesis. • FS@UiO-66 is one of the few Zr-MOF-based probes for fluoride so far. • FS@UiO-66 is a highly effective, fast-response and naked-eye sensor for fluoride. - Abstract: In this work, the fluorescent molecule (fluorescein sodium, FS) was successfully incorporated in the zirconium-based MOF (UiO-66) via in-situ synthesis method, which can be confirmed by FTIR spectra and fluorescence microscopic images. Based on this in-situ synthesis strategy, FS molecule can be immobilized tightly in the framework. Furthermore, the resulting FS@UiO-66 demonstrates to be a highly selective, real-time and naked-eye chemical sensor for fluoride in aqueous solution, which is mainly due to the release of FS molecule from FS@UiO-66 into the aqueous solution. Meanwhile, to the best of our knowledge, such Zr-MOF-based fluoride sensor is very rare so far. These results provide a promising approach to rationally design novel MOF-based fluorescent sensor for the target molecules.

  11. Characteristic contrast in Deltafmin maps of organic molecules using atomic force microscopy

    van der Heijden, N.J.; Hapala, Prokop; Rombouts, J.A.; van der Lit, J.; Smith, D.; Mutombo, Pingo; Švec, Martin; Jelínek, Pavel; Swart, I.

    2016-01-01

    Roč. 10, č. 9 (2016), 8517-8525 ISSN 1936-0851 R&D Projects: GA ČR(CZ) GC14-16963J Institutional support: RVO:68378271 Keywords : nc AFM * chemical contrast * DFT * molecules Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 13.942, year: 2016

  12. Small-molecule azomethines : Organic photovoltaics via Schiff base condensation chemistry

    Petrus, M.L.; Bouwer, R.K.M.; Lafont, U.; Athanasopoulos, S.; Greenham, N.C.; Dingemans, T.J.

    2014-01-01

    Conjugated small-molecule azomethines for photovoltaic applications were prepared via Schiff base condensation chemistry. Bulk heterojunction (BHJ) devices exhibit efficiencies of 1.2% with MoOx as the hole-transporting layer. The versatility and simplicity of the chemistry is illustrated by

  13. Small-molecule azomethines: Organic photovoltaics via Schiff base condensation chemistry

    Petrus, M.L.; Bouwer, R.K.M.; Lafont, U.; Athanasopoulos, S.; Greenham, N.C.; Dingemans, T.J.

    2014-01-01

    Conjugated small-molecule azomethines for photovoltaic applications were prepared via Schiff base condensation chemistry. Bulk heterojunction (BHJ) devices exhibit efficiencies of 1.2% with MoOx as the hole-transporting layer. The versatility and simplicity of the chemistry is illustrated by preparing a photovoltaic device directly from the reaction mixture without any form of workup.

  14. Perylene-Diimide Based Donor-Acceptor-Donor Type Small-Molecule Acceptors for Solution-Processable Organic Solar Cells

    Ganesamoorthy, Ramasamy; Vijayaraghavan, Rajagopalan; Sakthivel, Pachagounder

    2017-12-01

    Development of nonfullerene acceptors plays an important role in the commercial availability of plastic solar cells. We report herein synthesis of bay-substituted donor-acceptor-donor (D-A-D)-type perylene diimide (PDI)-based small molecules (SM-1 to SM-4) by Suzuki coupling method and their use as acceptors in bulk heterojunction organic solar cells (BHJ-OSCs) with poly(3-hexylthiophene) (P3HT) polymer donor. We varied the number of electron-rich thiophene units and the solubilizing side chains and also evaluated the optical and electrochemical properties of the small molecules. The synthesized small molecules were confirmed by Fourier-transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and high-resolution mass spectroscopy (HR-MS). The small molecules showed extensive and strong absorption in the ultraviolet-visible (UV-Vis) region up to 750 nm, with bandgap (E_{{g}}^{{opt}} ) reduced below use as electron-accepting materials. The small molecules showed good thermal stability up to 300°C. BHJ-OSCs with SM-1 and P3HT polymer donor showed maximum power conversion efficiency (PCE) of 0.19% with V oc of 0.30 V, J sc of 1.72 mA cm-2, and fill factor (FF) of 37%. The PCE decreased with the number of thiophene units. The PCE of SM-2 was lower than that of SM-1. This difference in PCE can be explained by the higher aggregation tendency of the bithiophene compared with the thiophene unit. Introduction of the solubilizing group in the bay position increased the aggregation property, leading to much lower PCE than for the small molecules without solubilizing group.

  15. Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

    Belloche, A.; Müller, H. S. P.; Menten, K. M.; Schilke, P.; Comito, C.

    2013-11-01

    Context. The discovery of amino acids in meteorites fallen to Earth and the detection of glycine, the simplest of them, in samples returned from a comet to Earth strongly suggest that the chemistry of the interstellar medium is capable of producing such complex organic molecules and that they may be widespread in our Galaxy. Aims: Our goal is to investigate the degree of chemical complexity that can be reached in the interstellar medium, in particular in dense star-forming regions. Methods: We performed an unbiased, spectral line survey toward Sgr B2(N) and (M), two regions where high-mass stars are formed, with the IRAM 30 m telescope in the 3 mm atmospheric transmission window. Partial surveys at 2 and 1.3 mm were performed in parallel. The spectra were analyzed with a simple radiative transfer model that assumes local thermodynamic equilibrium but takes optical depth effects into account. Results: About 3675 and 945 spectral lines with a peak signal-to-noise ratio higher than 4 are detected at 3 mm toward Sgr B2(N) and (M), i.e. about 102 and 26 lines per GHz, respectively. This represents an increase by about a factor of two over previous surveys of Sgr B2. About 70% and 47% of the lines detected toward Sgr B2(N) and (M) are identified and assigned to 56 and 46 distinct molecules as well as to 66 and 54 less abundant isotopologues of these molecules, respectively. In addition, we report the detection of transitions from 59 and 24 catalog entries corresponding to vibrationally or torsionally excited states of some of these molecules, respectively, up to a vibration energy of 1400 cm-1 (2000 K). Excitation temperatures and column densities were derived for each species but should be used with caution. The rotation temperatures of the detected complex molecules typically range from ~50 to 200 K. Among the detected molecules, aminoacetonitrile, n-propyl cyanide, and ethyl formate were reported for the first time in space based on this survey, as were five rare

  16. Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)

    Belloche, A.; Müller, H. S. P.; Garrod, R. T.; Menten, K. M.

    2016-03-01

    Context. Deuteration is a powerful tracer of the history of the cold prestellar phase in star-forming regions. Apart from methanol, little is known about deuterium fractionation of complex organic molecules in the interstellar medium, especially in regions forming high-mass stars. Aims: Our goal is to detect deuterated complex organic molecules toward the high mass star-forming region Sagittarius B2 (Sgr B2) and derive the level of deuteration for these molecules. Methods: We use a complete 3-mm spectral line survey performed with the Atacama Large Millimeter/submillimeter Array (ALMA) to search for deuterated complex organic molecules toward the hot molecular core Sgr B2(N2). We constructed population diagrams and integrated intensity maps to fit rotational temperatures and emission sizes for each molecule. Column densities are derived by modeling the full spectrum under the assumption of local thermodynamic equilibrium. We compare the results to predictions of two astrochemical models that treat the deuteration process. Results: We report the detection of CH2DCN toward Sgr B2(N2) with a deuteration level of 0.4%, and tentative detections of CH2DOH, CH2DCH2CN, the chiral molecule CH3CHDCN, and DC3N with levels in the range 0.05%-0.12%. A stringent deuteration upper limit is obtained for CH3OD (cyanide, the four deuterated species of ethanol, and CH2DOCHO. Ethyl cyanide is less deuterated than methyl cyanide by at least a factor five. The [CH2DOH]/[CH3OD] abundance ratio is higher than 1.8. It may still be consistent with the value obtained in Orion KL. Except for methyl cyanide, the measured deuteration levels lie at least a factor four below the predictions of current astrochemical models. The deuteration levels in Sgr B2(N2) are also lower than in Orion KL by a factor of a few up to a factor ten. Conclusions: The discrepancy between the deuteration levels of Sgr B2(N2) and the predictions of chemical models, and the difference between Sgr B2(N2) and Orion KL may

  17. From Molecules to Living Organisms : an Interplay between Biology and Physics : Lecture Notes of the Les Houches School of Physics

    Nury, Hughes; Parcy, François; Ruigrok, Rob W H; Ziegler, Christine; Cugliandolo, Leticia F; Session CII

    2016-01-01

    The aim of this book is to provide new ideas for studying living matter by a simultaneous understanding of behavior from molecules to the cell, to the whole organism in the light of physical concepts. Indeed, forces guide most biological phenomena. In some cases these forces can be well-described and thus used to model a particular biological phenomenon. This is exemplified here by the study of membranes, where their shapes and curvatures can be modeled using a limited number of parameters that are measured experimentally. The growth of plants is another example where the combination of physics, biology and mathematics leads to a predictive model. The laws of thermodynamics are essential, as they dictate the behavior of proteins, or more generally biological molecules, in an aqueous environment. Integrated studies from the molecule to a larger scale need a combination of cutting-edge approaches, such as the use of new X-ray sources, in-cell NMR, cryo-electron microscopy or single-molecule microscopy. Some are...

  18. A DFT and QTAIM study of the adsorption of organic molecules over the copper-doped coronene and circumcoronene

    Malček, Michal; Cordeiro, M. Natalia D. S.

    2018-01-01

    Graphene based materials are nowadays extensively studied because of their potential applications as gas sensors, biosensors or adsorbents. Doping the graphene surface with heteroatoms or transition metals can improve its electronic properties and chemical reactivity. Polyaromatic hydrocarbons coronene and circumcoronene can be used as models of tiny graphene quantum dots. The adsorption of a set of organic molecules (water, hydrogen peroxide, hydrogen sulfide, methanol, ethanol and oxygen molecule) over the copper-doped coronene and circumcoronene was theoretically studied using density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM). In the case of coronene, only one site was considered for the Cu-doping, whereas in the case of circumcoronene being a polyaromatic hydrocarbon composed of 54 carbon atoms, three different sites for Cu-doping were considered. For the systems under study, the adsorption of O2 was found energetically the most favorable, with energetic outcome ranging from -3.1 to -3.7 eV related to the position of dopant Cu atom. Changes in the topology of charge densities at Cu and in its vicinity after the adsorption of studied molecules were investigated in the framework of QTAIM. In addition, QTAIM analysis of bond critical points (BCP) was employed to study the character of the newly formed chemical bonds. The results of this study point out the suitability of Cu-doped graphene materials as sensors and/or adsorbents in practical applications.

  19. Organic Zeolite Analogues Based on Multi-Component Liquid Crystals: Recognition and Transformation of Molecules within Constrained Environments

    Yasuhiro Ishida

    2011-01-01

    Full Text Available In liquid crystals (LCs, molecules are confined in peculiar environments, where ordered alignment and certain mobility are realized at the same time. Considering these characteristics, the idea of “controlling molecular events within LC media” seems reasonable. As a suitable system for investigating this challenge, we have recently developed a new class of ionic LCs; the salts of amphiphilic carboxylic acids with 2-amino alcohols, or those of carboxylic acids with amphiphilic 2-amino alcohols, have a strong tendency to exhibit thermotropic LC phases. Because of the noncovalent nature of the interaction between molecules, one of the two components can easily be exchanged with, or transformed into, another molecule, without distorting the original LC architecture. In addition, both components are common organic molecules, and a variety of compounds are easily available. Taking advantage of these characteristics, we have succeeded in applying two‑component LCs as chiral media for molecular recognition and reactions. This review presents an overview of our recent studies, together with notable reports related to this field.

  20. Exploring Charge Transport in Guest Molecule Infiltrated Cu3(BTC)2 Metal Organic Framework

    Leonard, Francois Leonard [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Stavila, Vitalie [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Allendorf, Mark D. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2014-09-01

    The goal of this Exploratory Express project was to expand the understanding of the physical properties of our recently discovered class of materials consisting of metal-organic frameworks with electroactive ‘guest’ molecules that together form an electrically conducting charge-transfer complex (molecule@MOF). Thin films of Cu3(BTC)2 were grown on fused silica using solution step-by-step growth and were infiltrated with the molecule tetracyanoquinodimethane (TCNQ). The infiltrated MOF films were extensively characterized using optical microscopy, scanning electron microscopy, Raman spectroscopy, electrical conductivity, and thermoelectric properties. Thermopower measurements on TCNQ@Cu3(BTC)2 revealed a positive Seebeck coefficient of ~400 μV/k, indicating that holes are the primary carriers in this material. The high value of the Seebeck coefficient and the expected low thermal conductivity suggest that molecule@MOF materials may be attractive for thermoelectric power conversion applications requiring low cost, solution-processable, and non-toxic active materials.

  1. Multivariate Metal-Organic Frameworks for Dialing-in the Binding and Programming the Release of Drug Molecules.

    Dong, Zhiyue; Sun, Yangzesheng; Chu, Jun; Zhang, Xianzheng; Deng, Hexiang

    2017-10-11

    We report the control of guest release profiles by dialing-in desirable interactions between guest molecules and pores in metal-organic frameworks (MOFs). The interactions can be derived by the rate constants that were quantitatively correlated with the type of functional group and its proportion in the porous structure; thus the release of guest molecules can be predicted and programmed. Specifically, three probe molecules (ibuprofen, rhodamine B, and doxorubicin) were studied in a series of robust and mesoporous MOFs with multiple functional groups [MIL-101(Fe)-(NH 2 ) x , MIL-101(Fe)-(C 4 H 4 ) x , and MIL-101(Fe)-(C 4 H 4 ) x (NH 2 ) 1-x ]. The release rate can be adjusted by 32-fold [rhodamine from MIL-101(Fe)-(NH 2 ) x ], and the time of release peak can be shifted by up to 12 days over a 40-day release period [doxorubicin from MIL-101(Fe)-(C 4 H 4 ) x (NH 2 ) 1-x ], which was not obtained in the physical mixture of the single component MOF counterparts nor in other porous materials. The corelease of two pro-drug molecules (ibuprofen and doxorubicin) was also achieved.

  2. Influence of Oxychlorine Phases During the Pyrolysis of Organic Molecules: Implications for the Quest of Organics on Mars with the SAM Experiment Onboard the Curiosity Rover

    Millan, M.; Szopa, C.; Buch, A.; Belmahdi, I.; Glavin, D. P.; Freissinet, C.; Eigenbrode, J. L.; Archer, P. D., Jr,; Sutter, B.; Mahaffy, P.

    2017-01-01

    One among the main objectives of the Sample Analysis at Mars (SAM) experiment is the in situ molecular analysis of gases evolving from solid samples heated up to approximately 850 degrees Centigrade, and collected by Curiosity on Mars surface/sub-surface in Gale crater. With this aim, SAM uses a gas-chromatograph coupled to a quadrupole mass spectrometer (GC-QMS) devoted to separate, detect and identify both volatile inorganic and organic compounds. SAM detected chlorinated organic molecules produced in evolved gas analysis (EGA) experiments. Several of these were also detected by the Viking experiments in 1976. SAM also detected oxychlorine compounds that were present at the Phoenix landing site. The oxychlorines may be prevelant over much of the martian surface. The C1 to C3 aliphatic chlorohydrocarbons (chloromethane and di- and trichloromethane) detected by SAM were attributed to reaction products occurring between the oxychlorines phases and the organic compounds coming from SAM instrument background. But SAM also showed the presence of a large excess of chlorobenzene and C2 to C4 dichloroalkanes among the volatile species released by the Cumberland sample of the Sheepbed mudstone. For the first time in the history of the Mars exploration, this proved the presence of Mars indigenous organic material at the Mars' surface. However, the identification of the precursor organic compounds of these chlorohydrocarbons is difficult due to the complexity of the reactions occurring during the sample pyrolysis. Laboratory pyrolysis experiments have demonstrated that oxychlorines phases such as perchlorates and chlorates, decomposed into dioxygen and volatile chlorine bearing molecules (HCl and/or Cl2) during the pyrolysis. These chemical species can then react with the organic molecules present in the martian solid samples through oxidation, chlorination and oxychlorination processes.

  3. Use of a commercially available nucleating agent to control the morphological development of solution-processed small molecule bulk heterojunction organic solar cells

    Sharenko, Alexander; Treat, Neil D.; Love, John A.; Toney, Michael F.; Stingelin, Natalie; Nguyen, Thuc-Quyen

    2014-01-01

    © the Partner Organisations 2014. The nucleating agent DMDBS is used to modulate the crystallization of solution-processed small molecule donor molecules in bulk heterojunction organic photovoltaic (BHJ OPV) devices. This control over donor molecule crystallization leads to a reduction in optimized thermal annealing times as well as smaller donor molecule crystallites, and therefore more efficient devices, when using an excessive amount of solvent additive. We therefore demonstrate the use of nucleating agents as a powerful and versatile processing strategy for solution-processed, small molecule BHJ OPVs. This journal is

  4. Use of a commercially available nucleating agent to control the morphological development of solution-processed small molecule bulk heterojunction organic solar cells

    Sharenko, Alexander

    2014-08-12

    © the Partner Organisations 2014. The nucleating agent DMDBS is used to modulate the crystallization of solution-processed small molecule donor molecules in bulk heterojunction organic photovoltaic (BHJ OPV) devices. This control over donor molecule crystallization leads to a reduction in optimized thermal annealing times as well as smaller donor molecule crystallites, and therefore more efficient devices, when using an excessive amount of solvent additive. We therefore demonstrate the use of nucleating agents as a powerful and versatile processing strategy for solution-processed, small molecule BHJ OPVs. This journal is

  5. Band gap opening in α-graphyne by adsorption of organic molecule

    Majidi, R.; Karami, A. R.

    2014-09-01

    The lack of a band gap limits the application of graphyne in nanoelectronic devices. We have investigated possibility of opening a band gap in α-graphyne by adsorption of tetracyanoethylene. The electronic property of α-graphyne in the presence of different numbers of tetracyanoethylene has been studied using density functional theory. It is found that charge is transferred from graphyne sheet to tetracyanoethylene molecules. In the presence of this electron acceptor molecule, a semimetal α-graphyne shows semiconducting property. The energy band gap at the Dirac point is enhanced by increasing the number of tetracyanoethylene. Our results provide a simple method to create and control the band gap in α-graphyne.

  6. Enzyme Inhibitory and Molecular Docking Studies on Some Organic Molecules of Natural Occurrence

    Abbasi, M. A.; Hussain, G.; Rehman, A. U.; Shahwar, D.; Mohyuddin, A.; Ashraf, M.; Rahman, J.; Lodhi, M. A.; Khan, F. A.

    2016-01-01

    In the present study, in vitro enzyme inhibitory studies on cinchonidine (1), cinchonine (2), quinine (3), noscapine (narcotine, 4) and santonine (5) were carried out. The various enzymes included in the study were lipoxygenase, xanthine oxidase, acetyl cholinesterase, butyryl cholinesterase and protease. The results revealed that 2, 3, and 4 were moderate active against lipoxygenase and xanthine oxidase enzymes. The molecule 3 possessed weak activity against butyryl cholinesterase enzyme while remaining molecules were inactive against this enzyme. However, all these compounds were inactive against acetyl cholinestrase and protease enzymes. The synthesized compounds were computationally docked into the active site of lipoxygenase enzyme. The compounds 3 and 4 showed decent interactions, hence strengthening the observed results. (author)

  7. The hyaluronan and proteoglycan link proteins: Organizers of the brain extracellular matrix and key molecules for neuronal function and plasticity.

    Oohashi, Toshitaka; Edamatsu, Midori; Bekku, Yoko; Carulli, Daniela

    2015-12-01

    The hyaluronan and proteoglycanbinding link protein (Hapln) is a key molecule in the formation and control of hyaluronan-based condensed perineuronal matrix in the adult brain. This review summarizes the recent advances in understanding the role of Haplns in the formation and control of two distinct types of perineuronal matrices, one for "classical" PNN and the other for the specialized extracellular matrix (ECM) at the node of Ranvier in the central nervous system (CNS). We introduce the structural components of each ECM organization including the basic concept of supramolecular structure named "HLT model". We furthermore summarize the developmental and physiological role of perineuronal ECMs from the studies of Haplns and related molecules. Finally, we also discuss the potential mechanism modulating PNNs in the adult CNS. This layer of organized matrices may exert a direct effect via core protein or sugar moiety from the structure or by acting as a binding site for biologically active molecules, which are important for neuronal plasticity and saltatory conduction. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. The fabrication of small molecule organic light-emitting diode pixels by laser-induced forward transfer

    Shaw-Stewart, J. R. H.; Mattle, T.; Lippert, T. K.; Nagel, M.; Nüesch, F. A.; Wokaun, A.

    2013-01-01

    Laser-induced forward transfer (LIFT) is a versatile organic light-emitting diode (OLED) pixel deposition process, but has hitherto been applied exclusively to polymeric materials. Here, a modified LIFT process has been used to fabricate small molecule Alq3 organic light-emitting diodes (SMOLEDs). Small molecule thin films are considerably more mechanically brittle than polymeric thin films, which posed significant challenges for LIFT of these materials. The LIFT process presented here uses a polymeric dynamic release layer, a reduced environmental pressure, and a well-defined receiver-donor gap. The Alq3 pixels demonstrate good morphology and functionality, even when compared to conventionally fabricated OLEDs. The Alq3 SMOLED pixel performances show a significant amount of fluence dependence, not observed with polymerical OLED pixels made in previous studies. A layer of tetrabutyl ammonium hydroxide has been deposited on top of the aluminium cathode, as part of the donor substrate, to improve electron injection to the Alq3, by over 600%. These results demonstrate that this variant of LIFT is applicable for the deposition of functional small molecule OLEDs as well as polymeric OLEDs.

  9. Electron transport in disordered films of metal nanoparticles linked by organic molecules

    Mueller, K.H.; Wei, G.; Herrmann, J.; Raguse, B.; Baxter, G.

    2004-01-01

    Full text: We have investigated theoretically and experimentally the mechanism of electron transport in films made of ∼10 nm sized gold nanoparticles linked by alkanedithiol molecules. Conduction in these films is due to linker-molecule assisted single-electron tunnelling between neighbouring nanoparticles where electrons have to overcome the Coulomb blockade energy. Strong disorder in our films in the form of separation gap fluctuations between adjacent nanoparticles and variations in Coulomb blockade energies cause electron current percolation. We have found that the dependence of the conduction on the length of the alkanedithiol molecules is affected by the degree of disorder. In addition, we have observed that percolation leads to a non-Arrhenius-like temperature dependence of the conduction and to a film-thickness dependent conductivity. I-V characteristics at low temperatures reveal Coulomb blockade effects. The strong dependence of the electrical conduction on the separation gaps between adjacent nanoparticles can be utilized in strain gauge and gas sensor applications

  10. Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated martian surface ultraviolet radiation conditions.

    Poch, Olivier; Jaber, Maguy; Stalport, Fabien; Nowak, Sophie; Georgelin, Thomas; Lambert, Jean-François; Szopa, Cyril; Coll, Patrice

    2015-03-01

    Most of the phyllosilicates detected at the surface of Mars today are probably remnants of ancient environments that sustained long-term bodies of liquid water at the surface or subsurface and were possibly favorable for the emergence of life. Consequently, phyllosilicates have become the main mineral target in the search for organics on Mars. But are phyllosilicates efficient at preserving organic molecules under current environmental conditions at the surface of Mars? We monitored the qualitative and quantitative evolutions of glycine, urea, and adenine in interaction with the Fe(3+)-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K), and pressure (6 ± 1 mbar) in a laboratory simulation setup. We tested organic-rich samples that were representative of the evaporation of a small, warm pond of liquid water containing a high concentration of organics. For each molecule, we observed how the nontronite influences its quantum efficiency of photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine; their efficiencies of photodecomposition were reduced by a factor of 5 when mixed at a concentration of 2.6 × 10(-2) mol of molecules per gram of nontronite. Moreover, when the amount of nontronite in the sample of glycine was increased by a factor of 2, the gain of photoprotection was multiplied by a factor of 5. This indicates that the photoprotection provided by the nontronite is not a purely mechanical shielding effect but is also due to stabilizing interactions. No new evolution product was firmly identified, but the results obtained with urea suggest a particular reactivity in the presence of nontronite, leading to an increase of its dissociation rate.

  11. Analysis of functional organic molecules at noble metal surfaces by means of vibrational spectroscopies

    Leyssner, Felix

    2011-10-24

    The goal of this work is to optimize the efficiency of photoinduced molecular switching processes on surfaces via controlled variations of the adsorption and electronic properties of the switch. We investigated the influence of external stimuli, i.e. photons and thermal activation, on surface bound molecular switches undergoing trans/cis-isomerizations and ring-opening/closing-reactions, respectively. High resolution electron energy loss spectroscopy (HREELS) and sum-frequency generation (SFG) spectroscopy have been used as the main tools to investigate the adsorption behavior and the molecular switching properties. Two basic concepts of coupling the molecular switch to the surface have been studied: (i) physisorbed or weakly chemisorbed systems deposited on noble metal surfaces under UHV conditions and (ii) molecular switches bound covalently via anchor groups. In the HREELS study following concept (i), we investigated the adsorption geometry and isomerization behavior of various molecular switches on metal substrates which are able to undergo a photoinduced trans/cis-isomerization in solution. We investigated three isoelectronic molecules on Au where we systematically changed the photochemically active group from the diazo-group in an azobenzene-derivative (on Cu(111)) to the imine-group, and the vinylene-group, respectively. Finding the photoisomerization quenched for all systems we observed considerable differences in their thermal isomerization behavior. Comparable we find the photoinduced ring-opening/closing-reaction of spiropyran quenched on Au(111) but a thermally induced ring-opening reaction resulting in the open form being strongly stabilized by the metal. SFG spectroscopy is employed to investigate the reversible, photoinduced trans/cis-isomerization of an azobenzene-functionalized self-assembled monolayer (SAM) on gold using a tripodal linker system. In consequence of the decoupling provided by the tripodal linker, the switching behavior of the

  12. In-situ Evaluation of Soil Organic Molecules: Functional Group Chemistry Aggregate Structures, Metal and Surface Complexation Using Soft X-Ray

    Myneni, Satish C.

    2008-01-01

    Organic molecules are common in all Earth surface environments, and their composition and chemistry play an important role in a variety of biogeochemical reactions, such as mineral weathering, nutrient cycling and the solubility and transport of contaminants. However, most of what we know about the chemistry of these molecules comes from spectroscopy and microscopy studies of organic molecules extracted from different natural systems using either inorganic or organic solvents. Although all these methods gave us clues about the composition of these molecules, their composition and structure change with the extraction and the type of ex-situ analysis, their true behavior is less well understood. The goal of this project is to develop synchrotron instrumentation for studying natural organics, and to apply these recently developed synchrotron X-ray spectroscopy and microscopy techniques for understanding the: (1) functional group composition of naturally occurring organic molecules; (2) macromolecular structures of organic molecules; and (3) the nature of interactions of organic molecules with mineral surfaces in different environmental conditions.

  13. Classes of organic molecules targeted by a methanogenic microbial consortium grown on sedimentary rocks of various maturities

    Margaux eMesle

    2015-06-01

    Full Text Available Organic-rich shales are populated by methanogenic consortia that are able to degrade the fossilized organic matter into methane gas. To identify the organic fraction effectively degraded, we have sequentially depleted two types of organic-rich rocks, shales and coal, at two different maturities, by successive solvent extractions to remove the most soluble fractions (maltenes and asphaltenes and isolate kerogen. We show the ability of the consortia to produce methane from all rock samples, including those containing the most refractory organic matter, i.e. the kerogen. Shales yielded higher methane production than lignite and coal. Mature rocks yielded more methane than immature rocks. Surprisingly, the efficiency of the consortia was not influenced by the removal of the easily biodegradable fractions contained in the maltenes and asphaltenes. This suggests that one of the limitations of organic matter degradation in situ may be the accessibility of the carbon and energy source. Indeed, bitumen has a colloidal structure that may limit the accessibility to asphaltenes in the bulk rock. Solvent extractions might favor the access to asphaltenes and kerogen by modifying the spatial organization of the molecules in the rock matrix.

  14. New models for intermolecular repulsion and their application to Van Der Waals complexes and crystals of organic molecules

    Tsui, H.H.Y.

    2001-01-01

    Model intermolecular potentials are required for simulations of molecules in the gas, liquid, or solid phase. The widely used isotropic atom-atom model potentials are empirically fitted and based on the assumptions of transferability, combining rules and that atoms in molecules are spherical. This thesis develops a non-empirical method of modelling repulsion by applying the overlap model, which we show as a general non-empirical method of deriving repulsion potentials for a specific molecule. In this thesis, the repulsion parameters for an exponential atom-atom model potential are obtained from the ab initio charge density of a small organic molecule by making the assumption that the repulsion is proportional to the overlap of a pair of molecules. The proportionality constant is fixed by a limited number of intermolecular perturbation theory (IMPT) calculations. To complete the model potential, the electrostatic interaction is represented by a distributed multipole analysis, and the Slater-Kirkwood formula is used for the dispersion. These non-empirical potentials can reproduce experimental crystal structure when applied to crystal structure prediction of an oxyboryl derivative. A detailed study on further improving the overlap model was carried out for phenol-water, by including other minor intermolecular contributions of charge-transfer and penetration. High quality ab initio calculations on the complex were performed for use in comparison. To compare with experimental data, diffusion Monte Carlo simulations were performed with the potential, so that the effects of anharmonic zero-point motion on structure and energy of the system are included. When the system is too large for an IMPT calculation, the proportionality constant can be determined empirically by fitting the cell volume as shown in our study of crystal structures of chlorothalonil. This is used with an anisotropic repulsion model that has been derived for Cl and N atoms in chlorothalonil. This model

  15. Quantitative determination of the organ distribution of the cell adhesion molecule cell-CAM 105 by radioimmunoassay

    Odin, P.; Oebrink, B.

    1987-01-01

    The authors have previously identified a 105,000-Da plasma membrane glycoprotein, denoted cell-CAM 105, that is involved in intercellular adhesion of reaggregating rat hepatocytes. In this communication they report on the development of a radioimmunoassay for cell-CAM 105, employing purified cell-CAM 105, specific antisera against the molecule, and formalin-fixed protein A-containing staphylococci for precipitation of the immune complexes. The assay was shown to be sensitive, specific, precise, rapid, and easy to perform. They used this radioimmunoassay in investigations of the occurrence of cell-CAM 105 in different rat organs. Cell-CAM 105 was present in a wide spectrum of organs in varying amounts. The highest concentrations were found in the gastrointestinal tract, liver, some secretory glands, vagina, kidney, and lung. The results were confirmed by immunoblotting, which revealed one distinct protein component, corresponding to cell-CAM 105, in each positive organ

  16. X-ray topographic studies of organic and non-linear optical materials

    Halfpenny, P. J.; Sherwood, J. N.; Simpson, G. S.

    1997-01-01

    The flexible and non-destructive nature of X-ray topography is ideally suited to the study of large single crystals for both fundamental research and technological applications as well as the optimisation of crystal growth processes. Three examples are discussed, illustrating the application of X-ray topographic methods to non-linear optical (NLO) crystals. Synchrotron radiation section topography has been applied to the examination of large organic crystals. X-ray topography has been used to examine growth defects and the quality of crystals of m-nitroaniline (mNA) grown by the Bridgeman method. These studies allow evaluation of growth parameters together with their influence on defect density and show that in the case of mNA, remarkably low defect densities can be achieved under optimum growth conditions. Double-crystal reflection topography, with synchrotron radiation has been used to image defects intersecting the (011) faces of the inorganic NLO material potassium titanyl phosphate (KTP). X-ray images have been combined with optical microscopy and interferometry to provide valuable information on the crystal growth process

  17. Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules

    Schobesberger, Siegfried; Bianchi, Federico; Lönn, Gustaf; Ehn, Mikael; Lehtipalo, Katrianne; Dommen, Josef; Ehrhart, Sebastian; Ortega, Ismael K; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Hutterli, Manuel; Duplissy, Jonathan; Almeida, João; Amorim, Antonio; Breitenlechner, Martin; Downard, Andrew J; Dunne, Eimear M; Flagan, Richard C; Kajos, Maija; Keskinen, Helmi; Kirkby, Jasper; Kupc, Agnieszka; Kürten, Andreas; Kurtén, Theo; Laaksonen, Ari; Mathot, Serge; Onnela, Antti; Praplan, Arnaud P; Rondo, Linda; Santos, Filipe D; Schallhart, Simon; Schnitzhofer, Ralf; Sipilä, Mikko; Tomé, António; Tsagkogeorgas, Georgios; Vehkamäki, Hanna; Wimmer, Daniela; Baltensperger, Urs; Carslaw, Kenneth S; Curtius, Joachim; Hansel, Armin; Petäjä, Tuukka; Kulmala, Markku; Donahue, Neil M; Worsnop, Douglas R

    2013-01-01

    Atmospheric aerosols formed by nucleation of vapors affect radiative forcing and therefore climate. However, the underlying mechanisms of nucleation remain unclear, particularly the involvement of organic compounds. Here, we present high-resolution mass spectra of ion clusters observed during new particle formation experiments performed at the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research. The experiments involved sulfuric acid vapor and different stabilizing species, including ammonia and dimethylamine, as well as oxidation products of pinanediol, a surrogate for organic vapors formed from monoterpenes. A striking resemblance is revealed between the mass spectra from the chamber experiments with oxidized organics and ambient data obtained during new particle formation events at the Hyytiälä boreal forest research station. We observe that large oxidized organic compounds, arising from the oxidation of monoterpenes, cluster directly with single sulfuric acid molec...

  18. A three-dimensional tetrahedral-shaped conjugated small molecule for organic solar cells

    QIN Yang

    2014-04-01

    Full Text Available We report the synthesis of a novel three-dimensional tetrahedral-shaped small molecule,SO,containing a tetraphenylsilane core and cyanoester functionalized terthiophene arms.A deep lying HOMO energy level of -5.3 eV and a narrow bandgap of 1.9 eV were obtained from cyclic voltammetry measurements.Absorption,X-ray scattering and differential scanning calorimetry experiments all indicate high crystallinity of this compound.Solar cells employing SO were fabricated and evaluated.The relatively low performance was mainly ascribed to lack of appreciable phase separation,which is confirmed by optical microscopy.

  19. Manipulating the dipole layer of polar organic molecules on metal surfaces via different charge-transfer channels

    Lin, Meng-Kai; Nakayama, Yasuo; Zhuang, Ying-Jie; Wang, Chin-Yung; Pi, Tun-Wen; Ishii, Hisao; Tang, S.-J.

    The key properties of organic films such as energy level alignment (ELA), work functions, and injection barriers are closely linked to this dipole layer. Using angle resolved photoemission spectroscopy (ARPES), we systemically investigate the coverage-dependent work functions and spectra line shapes of occupied molecular orbital states of a polar molecule, chloroaluminium phthalocyanine (ClAlPc), grown on Ag(111) to show that the orientations of the first ClAlPc layer can be manipulated via the molecule deposition rate and post annealing, causing ELA at organic-metal interface to differ for about 0.3 eV between Cl-up and Cl-down configuration. Moreover, by comparing the experimental results with the calculations based on both gas-phase model and realistic model of ClAlPc on Ag(111) , we evidence that the different orientations of ClAlPc dipole layers lead to different charge-transfer channels between ClAlPc and Ag, a key factor that controls the ELA at organic-metal interface.

  20. A series of dithienobenzodithiophene based small molecules for highly efficient organic solar cells

    Huanran Feng; Miaomiao Li; Wang Ni; Bin Kan; Yunchuang Wang; Yamin Zhang; Hongtao Zhang; Xiangjian Wan; Yongsheng Chen

    2017-01-01

    Three acceptor-donor-acceptor(A-D-A) small molecules DCAODTBDT,DRDTBDT and DTBDTBDT using dithieno[2,3-d:2’,3’-d’]benzo[l,2-b:4,5-b’]dithiophene as the central building block,octyl cyanoacetate,3-octylrhodanine and thiobarbituric acid as the end groups were designed and synthesized as donor materials in solution-processed photovoltaic cells(OPVs).The impacts of these different electron withdrawing end groups on the photophysical properties,energy levels,charge carrier mobility,morphologies of blend films,and their photovoltaic properties have been systematically investigated.OPVs device based on DRDTBDT gave the best power conversion efficiency(PCE) of 8.34%,which was significantly higher than that based on DCAODTBDT(4.83%) or DTBDTBDT(3.39%).These results indicate that rather dedicated and balanced consideration of absorption,energy levels,morphology,mobility,etc.for the design of small-molecule-based OPVs(SM-OPVs)and systematic investigations are highly needed to achieve high performance for SM-OPVs.

  1. A series of dithienobenzodithiophene based small molecules for highly efficient organic solar cells

    Huanran Feng; Miaomiao Li; Wang Ni; Bin Kan; Yunchuang Wang; Yamin Zhang; Hongtao Zhang; Xiangjian Wan; Yongsheng Chen

    2017-01-01

    Three acceptor-donor-acceptor (A-D-A) small molecules DCAODTBDT,DRDTBDT and DTBDTBDT using dithieno[2,3-d∶2',3'-d']benzo[1,2-b∶4,5-b']dithiophene as the central building block,octyl cyanoacetate,3-octylrhodanine and thiobarbituric acid as the end groups were designed and synthesized as donor materials in solution-processed photovoltaic cells (OPVs).The impacts of these different electron withdrawing end groups on the photophysical properties,energy levels,charge carrier mobility,morphologies of blend films,and their photovoltaic properties have been systematically investigated.OPVs device based on DRDTBDT gave the best power conversion efficiency (PCE) of 8.34%,which was significantly higher than that based on DCAODTBDT (4.83%) or DTBDTBDT (3.39%).These results indicate that rather dedicated and balanced consideration of absorption,energy levels,morphology,mobility,etc.for the design of small-molecule-based OPVs (SM-OPVs) and systematic investigations are highly needed to achieve high performance for SM-OPVs.

  2. Exchange-correlation energy in the orbital occupancy method: electronic structure of organic molecules

    Oszwaldowski, R; Vazquez, H; Pou, P; Ortega, J; Perez, R; Flores, F

    2003-01-01

    A new DF-LCAO (density functional with local combination of atomic orbitals) method is used to calculate the electronic properties of 3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA), C 6 H 6 , CH 4 , and CO. The method, called the OO (orbital occupancy) method, is a DF-based theory, which uses the OOs instead of ρ(r) to calculate the exchange and correlation energies. In our calculations, we compare the OO method with the conventional local density approximation approach. Our results show that, using a minimal basis set, we obtain equilibrium bond lengths and binding energies for PTCDA, C 6 H 6 , and CH 4 which are respectively within 6, and 10-15% of the experimental values. We have also calculated the affinity and ionization levels, as well as the optical gap, for benzene and PTCDA and have found that a variant of Koopmans' theorem works well for these molecules. Using this theorem we calculate the Koopmans relaxation energies of the σ- and π-orbitals for PTCDA and have obtained this molecule's density of states which compares well with experimental evidence

  3. Solid state proton spin-lattice relaxation in four structurally related organic molecules

    Beckmann, Peter A.; Burbank, Kendra S.; Lau, Matty M.W.; Ree, Jessica N.; Weber, Tracy L.

    2003-01-01

    We report and interpret the temperature dependence of the proton spin-lattice relaxation rate at 8.50 and 22.5 MHz in four polycrystalline solids composed of structurally related molecules: 2-ethylanthracene, 2-t-butylanthracene, 2-ethylanthraquinone, and 2-t-butylanthraquinone. We have been unable to grow single crystals and therefore do not know the crystal structures. Hence, we use the NMR relaxometry data to make predictions about the solid state structures. As expected, we are able to conclude that the ethyl groups do not reorient in the solid state but that the t-butyl groups do. The anthraquinones have a ''simpler'' structure than the anthracenes. The best dynamical models suggest that there is a unique crystallographic site for the t-butyl groups in 2-t-butylanthraquinone and two sites, each with half the molecules, for the ethyl groups in 2-ethylanthraquinone. There are also two sites in 2-ethylanthracene, but with unequal weights, suggesting four sites in the unit cell with lower symmetry than the two anthraquinones. Finally, the observed relaxation rate data in 2-t-butylanthracene is very complex and its interpretation demonstrates the uniqueness problem that arises in interpreting relaxometry data without the knowledge of the crystal structure

  4. Band-selective excited ultrahigh resolution PSYCHE-TOCSY: fast screening of organic molecules and complex mixtures.

    Kakita, Veera Mohana Rao; Vemulapalli, Sahithya Phani Babu; Bharatam, Jagadeesh

    2016-04-01

    Precise assignments of (1) H atomic sites and establishment of their through-bond COSY or TOCSY connectivity are crucial for molecular structural characterization by using (1) H NMR spectroscopy. However, this exercise is often hampered by signal overlap, primarily because of (1) H-(1) H scalar coupling multiplets, even at typical high magnetic fields. The recent developments in homodecoupling strategies for effectively suppressing the coupling multiplets into nice singlets (pure-shift), particularly, Morris's advanced broadband pure-shift yielded by chirp excitation (PSYCHE) decoupling and ultrahigh resolution PSYCHE-TOCSY schemes, have shown new possibilities for unambiguous structural elucidation of complex organic molecules. The superior broadband PSYCHE-TOCSY exhibits enhanced performance over the earlier TOCSY methods, which however warrants prolonged experimental times due to the requirement of large number of dwell increments along the indirect dimension. Herein, we present fast and band-selective analog of the broadband PSYCHE-TOCSY, which is useful for analyzing complex organic molecules that exhibit characteristic yet crowded spectral regions. The simple pulse scheme relies on band-selective excitation (BSE) followed by PSYCHE homodecoupling in the indirect dimension. The BSE-PSYCHE-TOCSY has been exemplified for Estradiol and a complex carbohydrate mixture comprised of six constituents of closely comparable molecular weights. The experimental times are greatly reduced viz., ~20 fold for Estradiol and ~10 fold for carbohydrate mixture, with respect to the broadband PSYCHE-TOCSY. Furthermore, unlike the earlier homonuclear band-selective decoupling, the BSE-PSYCHE-decoupling provides fully decoupled pure-shift spectra for all the individual chemical sites within the excited band. The BSE-PSYCHE-TOCSY is expected to have significant potential for quick screening of complex organic molecules and mixtures at ultrahigh resolution. Copyright © 2015 John Wiley

  5. A harmonic approximation of intramolecular vibrations in a mixed quantum-classical methodology: Linear absorbance of a dissolved Pheophorbid-a molecule as an example

    Megow, Joerg; Kulesza, Alexander; Qu Zhengwang; Ronneberg, Thomas; Bonacic-Koutecky, Vlasta; May, Volkhard

    2010-01-01

    Graphical abstract: Structure of a single Pheo (green: C-atoms, blue: N-atoms, red; O-atoms, light grey: H-atoms). - Abstract: Linear absorption spectra of a single Pheophorbid-a molecule (Pheo) dissolved in ethanol are calculated in a mixed quantum-classical approach. In this computational scheme the absorbance is mainly determined by the time-dependent fluctuations of the energy gap between the Pheo ground and excited electronic state. The actual magnitude of the energy gap is caused by the electrostatic solvent solute coupling as well as by contributions due to intra Pheo vibrations. For the latter a new approach is proposed which is based on precalculated potential energy surfaces (PES) described in a harmonic approximation. To get the respective nuclear equilibrium configurations and Hessian matrices of the two involved electronic states we carried out the necessary electronic structure calculations in a DFT-framework. Since the Pheo changes its spatial orientation in the course of a MD run, the nuclear equilibrium configurations change their spatial position, too. Introducing a particular averaging procedure, these configurations are determined from the actual MD trajectories. The usability of the approach is underlined by a perfect reproduction of experimental data. This also demonstrates that our proposed method is suitable for the description of more complex systems in future investigations.

  6. A study on the electro-oxidation and electropolymerization of a new OPE linear molecule by EQCM and in situ FTIR spectroelectrochemistry

    Luo Jiao; Liu Meiling; Zhao Qiangqin; Zhao Jie; Zhang Youyu; Tan Liang; Tang Hao; Xie Qingji; Li Haitao; Yao Shouzhuo

    2010-01-01

    A novel symmetric conjugated oligo(phenylene-ethynylene) (OPE) linear molecule (1,4-bis(4-aminophenylethynyl)benzene); BAB) was synthesized by Sonogashira cross-coupling reactions. The structure and purity of the compound were confirmed by 1 H NMR, 13 C NMR and infrared (IR) and mass spectrometry (MS). The electrochemical oxidation process and mechanism of BAB were investigated via in situ Fourier transform infrared (FTIR) spectroelectrochemistry and electrochemical quartz crystal microbalance (EQCM). The electrochemical oxidation mechanism of BAB was proposed. The studies revealed that the BAB concentration and oxidation potential had a significant influence on the growth of the polymer film. A densely packed polymer film, which exhibited nonelectroactivity, was formed when a high monomer concentration and a high oxidation potential were used. When the electropolymerization of BAB was conducted at a lower concentration, a new pair of redox peaks appeared, and the resultant thin film had better electroactivity. The in situ FTIR studies confirmed that BAB could be electro-oxidized into radical cations and then electropolymerized via para (N-N) and/or ortho (N-C) coupling reactions to form polymers with a larger conjugated π-electron system. The surface morphology of the poly-BAB was also investigated with atomic force microscopy (AFM) and scanning electron microscopy (SEM).

  7. Assessment of oscillator strengths with multiconfigurational short-range density functional theory for electronic excitations in organic molecules

    Hedegård, Erik Donovan

    2017-01-01

    considered the large collection of organic molecules whose excited states were investigated with a range of electronic structure methods by Thiel et al. As a by-product of our calculations of oscillator strengths, we also obtain electronic excitation energies, which enable us to compare the performance......We have in a series of recent papers investigated electronic excited states with a hybrid between a complete active space self-consistent field (CASSCF) wave function and density functional theory (DFT). This method has been dubbed the CAS short-range DFT method (CAS–srDFT). The previous papers...

  8. Charge trapping at organic/self-assembly molecule interfaces studied by electrical switching behaviour in a crosspoint structure

    Li Yun; Pan Lijia; Pu Lin; Shi Yi; Liu Chuan; Tsukagoshi, Kazuhito

    2012-01-01

    Charge trapping at organic/self-assembly molecule (SAM) interfaces is studied by the electrical switching behaviour in a crosspoint structure, where interfacial charge trapping tunes the potential barrier of the SAM layer. The sample with rubrene exhibits the write-once read-many-times memory effect, which is due to the interfacial charges trapped at deep states. On the other hand, the sample with 2-amino-4,5-dicyanoimidazole presents recyclable conduction transition, which results from the trapped charges distributed at shallow states. Moreover, the percentage of the charges trapped at shallow states can be estimated from electrical transition levels. (paper)

  9. Charge trapping at organic/self-assembly molecule interfaces studied by electrical switching behaviour in a crosspoint structure

    Li, Yun; Liu, Chuan; Pan, Lijia; Pu, Lin; Tsukagoshi, Kazuhito; Shi, Yi

    2012-01-01

    Charge trapping at organic/self-assembly molecule (SAM) interfaces is studied by the electrical switching behaviour in a crosspoint structure, where interfacial charge trapping tunes the potential barrier of the SAM layer. The sample with rubrene exhibits the write-once read-many-times memory effect, which is due to the interfacial charges trapped at deep states. On the other hand, the sample with 2-amino-4,5-dicyanoimidazole presents recyclable conduction transition, which results from the trapped charges distributed at shallow states. Moreover, the percentage of the charges trapped at shallow states can be estimated from electrical transition levels.

  10. Solution-Processed Organic Solar Cells from Dye Molecules: An Investigation of Diketopyrrolopyrrole:Vinazene Heterojunctions

    Walker, Bright; Han, Xu; Kim, Chunki; Sellinger, Alan; Nguyen, Thuc-Quyen

    2012-01-01

    Although one of the most attractive aspects of organic solar cells is their low cost and ease of fabrication, the active materials incorporated into the vast majority of reported bulk heterojunction (BHJ) solar cells include a semiconducting polymer

  11. Organic molecule-based photothermal agents: an expanding photothermal therapy universe.

    Jung, Hyo Sung; Verwilst, Peter; Sharma, Amit; Shin, Jinwoo; Sessler, Jonathan L; Kim, Jong Seung

    2018-04-03

    Over the last decade, organic photothermal therapy (PTT) agents have attracted increasing attention as a potential complement for, or alternative to, classical drugs and sensitizers involving inorganic nanomaterials. In this tutorial review, we provide a structured description of the main classes of organic photothermal agents and their characteristics. Representative agents that have been studied in the context of photothermal therapy since 2000 are summarized and recent advances in using PTT agents to address various cancers indications are highlighted.

  12. Organic molecules as tools to control the growth, surface structure, and redox activity of colloidal quantum dots.

    Weiss, Emily A

    2013-11-19

    In order to achieve efficient and reliable technology that can harness solar energy, the behavior of electrons and energy at interfaces between different types or phases of materials must be understood. Conversion of light to chemical or electrical potential in condensed phase systems requires gradients in free energy that allow the movement of energy or charge carriers and facilitate redox reactions and dissociation of photoexcited states (excitons) into free charge carriers. Such free energy gradients are present at interfaces between solid and liquid phases or between inorganic and organic materials. Nanostructured materials have a higher density of these interfaces than bulk materials. Nanostructured materials, however, have a structural and chemical complexity that does not exist in bulk materials, which presents a difficult challenge: to lower or eliminate energy barriers to electron and energy flux that inevitably result from forcing different materials to meet in a spatial region of atomic dimensions. Chemical functionalization of nanostructured materials is perhaps the most versatile and powerful strategy for controlling the potential energy landscape of their interfaces and for minimizing losses in energy conversion efficiency due to interfacial structural and electronic defects. Colloidal quantum dots are semiconductor nanocrystals synthesized with wet-chemical methods and coated in organic molecules. Chemists can use these model systems to study the effects of chemical functionalization of nanoscale organic/inorganic interfaces on the optical and electronic properties of a nanostructured material, and the behavior of electrons and energy at interfaces. The optical and electronic properties of colloidal quantum dots have an intense sensitivity to their surface chemistry, and their organic adlayers make them dispersible in solvent. This allows researchers to use high signal-to-noise solution-phase spectroscopy to study processes at interfaces. In this

  13. Structure investigation of organic molecules on Au(111) surfaces; Strukturuntersuchung organischer Molekuele auf Au(111)-Oberflaechen

    Kazempoor, Michel

    2009-02-02

    The present work covers two topics namely the coadsorption of formic acid and water on Au(111) and the structure of biphenylalkanthiole SAMs on Au(111) surfaces. The coadsorption of formic acid and water on Au(111) surfaces has been investigated by means of vibrational and photoelectron spectroscopy (HREELS, XPS). Formic acid adsorbs at 90 K molecularly with vibrational modes characteristic for flat lying zig-zag chains in the mono- and multilayer regime, like in solid formic acid. The structure of the flat lying formic acid chains was determined by low energy electron diffraction (LEED) as a (2r3 x r19) unit cell. Annealing results in a complete desorption at 190 K. Sequential adsorption of formic acid and water at 90 K shows no significant chemical interaction. Upon annealing the coadsorbed layer to 140 K a hydrogenbonded cyclic complex of formic acid with one water molecule could be identified using isotopically labelled adsorbates. Upon further annealing this complex decomposes leaving molecularly adsorbed formic acid on the surface at 160 K, accompanied by a proton exchange between formic acid and water. The influence of the alkane spacer chain length on the structure of biphenylalkanethiols on Au(111) surfaces was investigated as well. A systematic study was done on BPn-SAMs deposited from the gas phase. For every chain length a structure was found by LEED. Furthermore the influence of temperature on the structure was investigated in the range from room temperature up to about 400 K. To obviate influences from different preparation methods BP3 and BP4 was deposited from gas phase and from solution. No LEED spots were observed on BP4 SAMs deposited from solution. For BP3 an influence of the preparation could be excluded. For all BPn-SAMs a good agreement between LEED and STM data's was found. Nevertheless different unit cells were determined by LEED and STM consistent structures could be suggested considering the unit cell size given by LEED and the

  14. Percolation model for electron conduction in films of metal nanoparticles linked by organic molecules

    Muller, K.H.; Herrmann, J.; Raguse, B.; Baxter, G.; Reda, T.

    2002-01-01

    Full text: We have investigated theoretically and experimentally the temperature dependence of the conductance of films of Au nanoparticles linked by alkane dithiol molecules in the temperature range between 5 K and 300 K. Conduction in these films is due to tunneling of single electrons between neighbouring metal nanoparticles. During tunnelling an electron has to overcome the Coulomb charging energy. We find that the observed temperature dependence of the conductance is non-Arrhenius like and can be described in terms of a percolation theory which takes account of disorder in the system. Disorder in our nanoparticle films is caused by variations in the nanoparticle size, fluctuations in the separation gaps between adjacent nanoparticles and by offset charges. To explain in detail our experimental data, a wide distribution of separation gaps and charging energies is needed. We find that a wide Coulomb charging energy distribution can arise from random offset charges even if the nanoparticle size distribution is narrow

  15. Desorption of organic molecules with fast incident atomic and polyatomic ions

    Hunt, J.E.; Salehpour, M.; Fishel, D.L.

    1989-01-01

    In 1974, Macfarlane and coworkers introduced a new mass spectrometric technique based on desorption-ionization of sample molecules from solid targets by the impact of fast heavy ions (fission fragments) from 252 Cf. The process of ion-induced desorption of molecular ions from surfaces is not yet fully understood, although a large amount of experimental data related to the mechanism has been published. This paper concerns the use of fast incident polyatomic ions to induce desorption of secondary molecular ions of valine and chlorophyll from surfaces. Polyatomic ions are unique in that they are a collection of temporally and spatially correlated atoms. The main finding in this study is that incident polyatomic ions produce drastic enhancements in the secondary ion yields over atomic ions. Also, two types of nonlinear effects in desorption have been observed and will be discussed

  16. The use of charge extraction by linearly increasing voltage in polar organic light-emitting diodes

    Züfle, Simon; Altazin, Stéphane; Hofmann, Alexander; Jäger, Lars; Neukom, Martin T.; Schmidt, Tobias D.; Brütting, Wolfgang; Ruhstaller, Beat

    2017-05-01

    We demonstrate the application of the CELIV (charge carrier extraction by linearly increasing voltage) technique to bilayer organic light-emitting devices (OLEDs) in order to selectively determine the hole mobility in N,N0-bis(1-naphthyl)-N,N0-diphenyl-1,10-biphenyl-4,40-diamine (α-NPD). In the CELIV technique, mobile charges in the active layer are extracted by applying a negative voltage ramp, leading to a peak superimposed to the measured displacement current whose temporal position is related to the charge carrier mobility. In fully operating devices, however, bipolar carrier transport and recombination complicate the analysis of CELIV transients as well as the assignment of the extracted mobility value to one charge carrier species. This has motivated a new approach of fabricating dedicated metal-insulator-semiconductor (MIS) devices, where the extraction current contains signatures of only one charge carrier type. In this work, we show that the MIS-CELIV concept can be employed in bilayer polar OLEDs as well, which are easy to fabricate using most common electron transport layers (ETLs), like Tris-(8-hydroxyquinoline)aluminum (Alq3). Due to the macroscopic polarization of the ETL, holes are already injected into the hole transport layer below the built-in voltage and accumulate at the internal interface with the ETL. This way, by a standard CELIV experiment only holes will be extracted, allowing us to determine their mobility. The approach can be established as a powerful way of selectively measuring charge mobilities in new materials in a standard device configuration.

  17. Sample Analysis at Mars (SAM) and Mars Organic Molecule Analyzer (MOMA) as Critical In Situ Investigation for Targeting Mars Returned Samples

    Freissinet, C.; Glavin, D. P.; Mahaffy, P. R.; Szopa, C.; Buch, A.; Goesmann, F.; Goetz, W.; Raulin, F.; SAM Science Team; MOMA Science Team

    2018-04-01

    SAM (Curiosity) and MOMA (ExoMars) Mars instruments, seeking for organics and biosignatures, are essential to establish taphonomic windows of preservation of molecules, in order to target the most interesting samples to return from Mars.

  18. A SIFT study of the reactions of H2ONO+ ions with several types of organic molecules

    Smith, David; Wang, Tianshu; Spanel, Patrik

    2003-11-01

    A selected ion flow tube (SIFT) study has been carried out of the reactions of hydrated nitrosonium ions, NO+H2O, which theory has equated to protonated nitrous acid ions, H2ONO+. One objective of this study was to investigate if this ion exhibits the properties of both a cluster ion and a protonated acid in their reactions with a variety of organic molecules. The chosen reactant molecules comprise two each of the following types--amines, terpenes, aromatic hydrocarbons, esters, carboxylic acids, ketones, aldehydes and alcohols. The reactant H2ONO+ (NO+H2O) ions are formed in a discharge ion source and injected into helium carrier gas where they are partially vibrationally excited and partially dissociated to NO+ ions. Hence, the reactions of the H2ONO+ ions had to be studies simultaneously with NO+ ions, the reactions of the latter ions readily being studied by selectively injecting NO+ ions into the carrier gas. The results of this study indicate that the H2ONO+ ions undergo a wide variety of reaction processes that depend on the properties of the reactant molecules such as their ionisation energies and proton affinities. These processes include charge transfer with compounds, M, that have low ionisation energies (producing M+), proton transfer with compounds possessing large proton affinities (MH+), hydride ion transfer (M---H+), alkyl radical (M---R+), alkoxide radical transfer (M---OR+), ion-molecule association (NO+H2OM) and ligand switching (NO+M), producing the ions given in parentheses.

  19. Tissue organization by cadherin adhesion molecules: dynamic molecular and cellular mechanisms of morphogenetic regulation

    Niessen, Carien M.; Leckband, Deborah; Yap, Alpha S.

    2013-01-01

    This review addresses the cellular and molecular mechanisms of cadherin-based tissue morphogenesis. Tissue physiology is profoundly influenced by the distinctive organizations of cells in organs and tissues. In metazoa, adhesion receptors of the classical cadherin family play important roles in establishing and maintaining such tissue organization. Indeed, it is apparent that cadherins participate in a range of morphogenetic events that range from support of tissue integrity to dynamic cellular rearrangements. A comprehensive understanding of cadherin-based morphogenesis must then define the molecular and cellular mechanisms that support these distinct cadherin biologies. Here we focus on four key mechanistic elements: the molecular basis for adhesion through cadherin ectodomains; the regulation of cadherin expression at the cell surface; cooperation between cadherins and the actin cytoskeleton; and regulation by cell signaling. We discuss current progress and outline issues for further research in these fields. PMID:21527735

  20. Ozonolysis and Subsequent Photolysis of unsaturated organic molecules: Model Systems for Photochemical Aging of Organic Aerosol Particles

    Park, J.; Gomez, A. L.; Walser, M. L.; Lin, A.; Nizkorodov, S. A.

    2005-12-01

    Chemical and photochemical aging of organic species adsorbed on aerosol particle surfaces is believed to have a significant effect on cloud condensation properties of atmospheric aerosols. Ozone initiated oxidation reactions of thin films of undecylenic acid and alkene-terminated self assembled monolayers (SAMs) on SiO2 surface were investigated using a combination of spectroscopic and mass spectrometric techniques. Photolysis of the oxidized film in the tropospheric actinic region (λ>290 nm) readily produces formaldehyde and formic acid as gas-phase products. Photodissociation action spectra of the oxidized film suggest that organic peroxides are responsible for the enhanced photochemical activity. The presence of peroxides in the oxidized sample was confirmed by mass-spectrometric analysis and by an iodometric test. Significant polymerization resulting from secondary reactions of Criegee radicals during ozonolysis of the film is also observed. The reaction mechanism and its implications for photochemical aging of atmospheric aerosol particles will be discussed.

  1. A GROMOS-Compatible Force Field for Small Organic Molecules in the Condensed Phase: The 2016H66 Parameter Set.

    Horta, Bruno A C; Merz, Pascal T; Fuchs, Patrick F J; Dolenc, Jozica; Riniker, Sereina; Hünenberger, Philippe H

    2016-08-09

    This article reports on the calibration and validation of a new GROMOS-compatible parameter set 2016H66 for small organic molecules in the condensed phase. The calibration is based on 62 organic molecules spanning the chemical functions alcohol, ether, aldehyde, ketone, carboxylic acid, ester, amine, amide, thiol, sulfide, and disulfide, as well as aromatic compounds and nucleic-acid bases. For 57 organic compounds, the calibration targets are the experimental pure-liquid density ρliq and the vaporization enthalpy ΔHvap, as well as the hydration free energy ΔGwat and the solvation free energy ΔGche in cyclohexane, at atmospheric pressure and at (or close to) room temperature. The final root-mean-square deviations (RMSD) for these four quantities over the set of compounds are 32.4 kg m(-3), 3.5 kJ mol(-1), 4.1 kJ mol(-1), and 2.1 kJ mol(-1), respectively, and the corresponding average deviations (AVED) are 1.0 kg m(-3), 0.2 kJ mol(-1), 2.6 kJ mol(-1), and 1.0 kJ mol(-1), respectively. For the five nucleic-acid bases, the parametrization is performed by transferring the final 2016H66 parameters from analogous organic compounds followed by a slight readjustment of the charges to reproduce the experimental water-to-chloroform transfer free energies ΔGtrn. The final RMSD for this quantity over the five bases is 1.7 kJ mol(-1), and the corresponding AVED is 0.8 kJ mol(-1). As an initial validation of the 2016H66 set, seven additional thermodynamic, transport, and dielectric properties are calculated for the 57 organic compounds in the liquid phase. The agreement with experiment in terms of these additional properties is found to be reasonable, with significant deviations typically affecting either a specific chemical function or a specific molecule. This suggests that in most cases, a classical force-field description along with a careful parametrization against ρliq, ΔHvap, ΔGwat, and ΔGche results in a model that appropriately describes the liquid in terms of

  2. High performance inkjet printed phosphorescent organic light emitting diodes based on small molecules commonly used in vacuum processes

    Jung, Sung-Hoon [Department of Materials Science and Engineering, Seoul National University, Seoul, 151-742 (Korea, Republic of); Kim, Jang-Joo, E-mail: jjkim@snu.ac.kr [Department of Materials Science and Engineering, Seoul National University, Seoul, 151-742 (Korea, Republic of); Kim, Hyong-Jun, E-mail: hkim@kongju.ac.kr [Department of Chemical Engineering, Kongju National University, Cheonan, 330-717 (Korea, Republic of)

    2012-09-30

    High efficiency phosphorescent organic light emitting diodes (OLEDs) are realized by inkjet printing based on small molecules commonly used in vacuum processes in spite of the limitation of the limited solubility. The OLEDs used the inkjet printed 5 wt.% tris(2-phenylpyridine)iridium(III) (Ir(ppy){sub 3}) doped in 4,4 Prime -Bis(carbazol-9-yl)biphenyl (CBP) as the light emitting layer on various small molecule based hole transporting layers, which are widely used in the fabrication of OLEDs by vacuum processes. The OLEDs resulted in the high power and the external quantum efficiencies of 29.9 lm/W and 11.7%, respectively, by inkjet printing the CBP:Ir(ppy){sub 3} on a 40 nm thick 4,4 Prime ,4 Double-Prime -tris(carbazol-9-yl)triphenylamine layer. The performance was very close to a vacuum deposited device with a similar structure. - Highlights: Black-Right-Pointing-Pointer Effective inkjet printed organic light emitting diode (OLED) technique is explored. Black-Right-Pointing-Pointer Solution process on commonly used hole transporting material (HTM) is demonstrated. Black-Right-Pointing-Pointer Triplet energy overlap of HTM and emitting material is the key to the performance. Black-Right-Pointing-Pointer Simple inkjet printed OLED provides the high current efficiency of 40 cd/A.

  3. Morphology versus vertical phase segregation in solvent annealed small molecule bulk heterojunction organic solar cells

    Kovalenko, A.; Stoyanova, V.; Pospisil, J.; Zhivkov, I.; Fekete, Ladislav; Karashanova, D.; Kratochvílová, Irena; Vala, M.; Weiter, M.

    2015-01-01

    Roč. 2015, Oct (2015), s. 238981 ISSN 1110-662X R&D Projects: GA ČR(CZ) GA15-05095S; GA TA ČR TA04020156; GA MŠk LO1409 Institutional support: RVO:68378271 Keywords : organic solar cells Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.226, year: 2015

  4. Processible conducting nanoscale cylinders due to self-organized polyaniline supra molecules

    Kosonen, H; Valkama, S; Ruokolainen, J; Knaapila, M; Torkkeli, M; Serimaa, R; Monkman, AP; ten Brinke, G; Ikkala, O

    2003-01-01

    Polyaniline sulphonates contain hydrogen bonding acceptor sites, which allow construction of supramolecules and self-organized structures. Here we have characterized the phase behavior of complexes of polyaniline, camphorsulphomc acid (CSA) and 4-hexylresorcinol (tires), PANI(CSA)(x)(Hres)(y), using

  5. Adsorption of Organic Electron Acceptors on Graphene-like Molecules: Quantum Chemical and Molecular Mechanical Study

    Haldar, Susanta; Kolář, Michal; Sedlák, Robert; Hobza, Pavel

    2012-01-01

    Roč. 116, č. 48 (2012), s. 25328-25336 ISSN 1932-7447 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : graphene * organic electron acceptors * interaction energies * base-pairs * hydrophobic association Subject RIV: CF - Physical ; The oretical Chemistry Impact factor: 4.814, year: 2012

  6. Laboratory simulation of interstellar grain chemistry and the production of complex organic molecules

    Allamandola, L. J.; Sandford, S. A.; Valero, G. J.

    1990-01-01

    During the past 15 years considerable progress in observational techniques has been achieved in the middle infrared (5000 to 500 cm(-1), 2 to 20 microns m), the spectral region most diagnostic of molecular vibrations. Spectra of many different astronomical infrared sources, some deeply embedded in dark molecular clouds, are now available. These spectra provide a powerful probe, not only for the identification of interstellar molecules in both the gas solid phases, but also of the physical and chemical conditions which prevail in these two very different domains. By comparing these astronomical spectra with the spectra of laboratory ices one can determine the composition and abundance of the icy materials frozen on the cold (10K) dust grains present in the interior of molecular clouds. These grains and their ice mantles may well be the building blocks from which comets are made. As an illustration of the processes which can take place as an ice is irradiated and subsequently warmed, researchers present the infrared spectra of the mixture H2O:CH3OH:CO:NH3:C6H14 (100:50:10:10:10). Apart from the last species, the ratio of these compounds is representative of the simplest ices found in interstellar clouds. The last component was incorporated into this particular experiment as a tracer of the behavior of a non-aromatic hydrocarbon. The change in the composition that results from ultraviolet photolysis of this ice mixture using a UV lamp to simulate the interstellar radiation field is shown. Photolysis produces CO, CO2, CH4, HCO, H2CO, as well as a family of moderately volatile hydrocarbons. Less volatile carbonaceous materials are also produced. The evolution of the infrared spectrum of the ice as the sample is warmed up to room temperature is illustrated. Researchers believe that the changes are similar to those which occur as ice is ejected from a comet and warmed up by solar radiation. The warm-up sequence shows that the nitrile or iso-nitrile bearing compound

  7. Synthesis of novel inorganic-organic hybrid materials for simultaneous adsorption of metal ions and organic molecules in aqueous solution

    Jin, Xinliang [State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Institute of Biochemical Engineering and Environmental Technology, Lanzhou University, Lanzhou 730000 (China); Li, Yanfeng, E-mail: liyf@lzu.edu.cn [State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Institute of Biochemical Engineering and Environmental Technology, Lanzhou University, Lanzhou 730000 (China); Yu, Cui; Ma, Yingxia; Yang, Liuqing; Hu, Huaiyuan [State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Institute of Biochemical Engineering and Environmental Technology, Lanzhou University, Lanzhou 730000 (China)

    2011-12-30

    Highlights: Black-Right-Pointing-Pointer Novel hybrid materials were synthesized and employed in the absorption of heavy metal and organic pollutants. Black-Right-Pointing-Pointer A novel method for amphiphilic adsorbent material synthesis was first reported in this paper. Black-Right-Pointing-Pointer The adsorbent material showed excellent adsorption capacity to Pb(II) and phenol. - Abstract: In this paper, atom transfer radical polymerization (ATRP) and radical grafting polymerization were combined to synthesize a novel amphiphilic hybrid material, meanwhile, the amphiphilic hybrid material was employed in the absorption of heavy metal and organic pollutants. After the formation of attapulgite (ATP) ATRP initiator, ATRP block copolymers of styrene (St) and divinylbenzene (DVB) were grafted from it as ATP-P(S-b-DVB). Then radical polymerization of acrylonitrile (AN) was carried out with pendent double bonds in the DVD units successfully, finally we got the inorganic-organic hybrid materials ATP-P(S-b-DVB-g-AN). A novel amphiphilic hybrid material ATP-P(S-b-DVB-g-AO) (ASDO) was obtained after transforming acrylonitrile (AN) units into acrylamide oxime (AO) as hydrophilic segment. The adsorption capacity of ASDO for Pb(II) could achieve 131.6 mg/g, and the maximum removal capacity of ASDO towards phenol was found to be 18.18 mg/g in the case of monolayer adsorption at 30 Degree-Sign C. The optimum pH was 5 for both lead and phenol adsorption. The adsorption kinetic suited pseudo-second-order equation and the equilibrium fitted the Freundlich model very well under optimal conditions. At the same time FT-IR, TEM and TGA were also used to study its structure and property.

  8. Probing Zeolite Crystal Architecture and Structural Imperfections using Differently Sized Fluorescent Organic Probe Molecules.

    Hendriks, Frank C; Schmidt, Joel E; Rombouts, Jeroen A; Lammertsma, Koop; Bruijnincx, Pieter C A; Weckhuysen, Bert M

    2017-05-05

    A micro-spectroscopic method has been developed to probe the accessibility of zeolite crystals using a series of fluorescent 4-(4-diethylaminostyryl)-1-methylpyridinium iodide (DAMPI) probes of increasing molecular size. Staining large zeolite crystals with MFI (ZSM-5) topology and subsequent mapping of the resulting fluorescence using confocal fluorescence microscopy reveal differences in structural integrity: the 90° intergrowth sections of MFI crystals are prone to develop structural imperfections, which act as entrance routes for the probes into the zeolite crystal. Polarization-dependent measurements provide evidence for the probe molecule's alignment within the MFI zeolite pore system. The developed method was extended to BEA (Beta) crystals, showing that the previously observed hourglass pattern is a general feature of BEA crystals with this morphology. Furthermore, the probes can accurately identify at which crystal faces of BEA straight or sinusoidal pores open to the surface. The results show this method can spatially resolve the architecture-dependent internal pore structure of microporous materials, which is difficult to assess using other characterization techniques such as X-ray diffraction. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  9. Isotopic compositions and probable origins of organic molecules in the Eocene Messel shale

    Hayes, J. M.; Takigiku, Ray; Ocampo, Ruben; Callot, Enry J.; Albrecht, Pierre

    1987-01-01

    It is shown here that the carbon isotopic compositions of biomarkers from the Eocene Messel shale, accumulated 47 + or - 2 million years ago in anaerobic waters at the bottom of a lake, allow identification of specific sources for some materials and reconstruction of carbon flows within the lake and its sediments. The C-13 content of organic matter synthesized by lacustrine primary producers can be estimated from the observed C-13 content of the geoporphyrins derived from their chlorophylls. Total organic material in the shale is depleted in C-13 by six parts per thousand relative to that input. This difference cannot be explained by selective loss of components enriched in C-13, nor, as shown by isotopic compositions of other biomarkers, by inputs from land plants surrounding the lake or from methanogenic bacteria.

  10. Electronic sputtering of large organic molecules and its application in bio molecular mass spectrometry

    Sundqvist, B.U.R.

    1992-01-01

    This is a review of research which has its origin in the discovery of Plasma Desorption Mass Spectrometry (PDMS). Two main fields of research have developed, namely fundamental studies of the ejection process at fast ion impact and studies of applications of the new mass spectrometric technique. In this review the emphasis will be on the process of electronic sputtering of organic solids but also applications of this process in bio molecular mass spectrometry will be discussed. (author)

  11. Two Dimensional Symmetric Correlation Functions of the S Operator and Two Dimensional Fourier Transforms: Considering the Line Coupling for P and R Lines of Linear Molecules

    Ma, Q.; Boulet, C.; Tipping, R. H.

    2014-01-01

    The refinement of the Robert-Bonamy (RB) formalism by considering the line coupling for isotropic Raman Q lines of linear molecules developed in our previous study [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)] has been extended to infrared P and R lines. In these calculations, the main task is to derive diagonal and off-diagonal matrix elements of the Liouville operator iS1 - S2 introduced in the formalism. When one considers the line coupling for isotropic Raman Q lines where their initial and final rotational quantum numbers are identical, the derivations of off-diagonal elements do not require extra correlation functions of the ^S operator and their Fourier transforms except for those used in deriving diagonal elements. In contrast, the derivations for infrared P and R lines become more difficult because they require a lot of new correlation functions and their Fourier transforms. By introducing two dimensional correlation functions labeled by two tensor ranks and making variable changes to become even functions, the derivations only require the latters' two dimensional Fourier transforms evaluated at two modulation frequencies characterizing the averaged energy gap and the frequency detuning between the two coupled transitions. With the coordinate representation, it is easy to accurately derive these two dimensional correlation functions. Meanwhile, by using the sampling theory one is able to effectively evaluate their two dimensional Fourier transforms. Thus, the obstacles in considering the line coupling for P and R lines have been overcome. Numerical calculations have been carried out for the half-widths of both the isotropic Raman Q lines and the infrared P and R lines of C2H2 broadened by N2. In comparison with values derived from the RB formalism, new calculated values are significantly reduced and become closer to measurements.

  12. Advances in Electrocatalysis for Energy Conversion and Synthesis of Organic Molecules.

    Holade, Yaovi; Servat, Karine; Tingry, Sophie; Napporn, Teko W; Remita, Hynd; Cornu, David; Kokoh, K Boniface

    2017-10-06

    Ubiquitous electrochemistry is expected to play a major role for reliable energy supply as well as for production of sustainable fuels and chemicals. The fundamental understanding of organics-based electrocatalysis in alkaline media at the solid-liquid interface involves complex mechanisms and performance descriptors (from the electrolyte and reaction intermediates), which undermine the roads towards advance and breakthroughs. Here, we review and diagnose recently designed strategies for the electrochemical conversion of organics into electricity and/or higher-value chemicals. To tune the mysterious workings of nanocatalysts in electrochemical devices, we examine the guiding principles by which the performance of a particular electrode material is governed, thus highlighting various tactics for the development of synthesis methods for nanomaterials with specific properties. We end by examining the production of chemicals by using electrochemical methods, from selective oxidation to reduction reactions. The intricate relationship between electrode and selectivity encourages both of the communities of electrocatalysis and organic synthesis to move forward together toward the renaissance of electrosynthesis methods. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. The monomeric, tetrameric, and fibrillar organization of Fib: the dynamic building block of the bacterial linear motor of Spiroplasma melliferum BC3.

    Cohen-Krausz, Sara; Cabahug, Pamela C; Trachtenberg, Shlomo

    2011-07-08

    Spiroplasmas belong to the class Mollicutes, representing the minimal, free-living, and self-replicating forms of life. Spiroplasmas are helical wall-less bacteria and the only ones known to swim by means of a linear motor (rather than the near-universal rotary bacterial motor). The linear motor follows the shortest path along the cell's helical membranal tube. The motor is composed of a flat monolayered ribbon of seven parallel fibrils and is believed to function in controlling cell helicity and motility through dynamic, coordinated, differential length changes in the fibrils. The latter cause local perturbations of helical symmetry, which are essential for net directional displacement in environments with a low Reynolds number. The underlying fibrils' core building block is a circular tetramer of the 59-kDa protein Fib. The fibrils' differential length changes are believed to be driven by molecular switching of Fib, leading consequently to axial ratio and length changes in tetrameric rings. Using cryo electron microscopy, diffractometry, single-particle analysis of isolated ribbons, and sequence analyses of Fib, we determined the overall molecular organization of the Fib monomer, tetramer, fibril, and linear motor of Spiroplasma melliferum BC3 that underlies cell geometry and motility. Fib appears to be a bidomained molecule, of which the N-terminal half is apparently a globular phosphorylase. By a combination of reversible rotation and diagonal shift of Fib monomers, the tetramer adopts either a cross-like nonhanded conformation or a ring-like handed conformation. The sense of Fib rotation may determine the handedness of the linear motor and, eventually, of the cell. A further change in the axial ratio of the ring-like tetramers controls fibril lengths and the consequent helical geometry. Analysis of tetramer quadrants from adjacent fibrils clearly demonstrates local differential fibril lengths. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Influence of organic molecules on the aggregation of TiO{sub 2} nanoparticles in acidic conditions

    Danielsson, Karin, E-mail: karin.danielsson@chem.gu.se [University of Gothenburg, Department of Chemistry and Molecular Biology (Sweden); Gallego-Urrea, Julián A.; Hassellov, Martin [University of Gothenburg, Department of Marine Sciences (Sweden); Gustafsson, Stefan [Chalmers University of Technology, Department of Applied Physics (Sweden); Jonsson, Caroline M. [University of Gothenburg, Department of Chemistry and Molecular Biology (Sweden)

    2017-04-15

    Engineered nanoparticles released into the environment may interact with natural organic matter (NOM). Surface complexation affects the surface potential, which in turn may lead to aggregation of the particles. Aggregation of synthetic TiO{sub 2} (anatase) nanoparticles in aqueous suspension was investigated at pH 2.8 as a function of time in the presence of various organic molecules and Suwannee River fulvic acid (SRFA), using dynamic light scattering (DLS) and high-resolution transmission electron microscopy (TEM). Results showed that the average hydrodynamic diameter and ζ-potential were dependent on both concentration and molecular structure of the organic molecule. Results were also compared with those of quantitative batch adsorption experiments. Further, a time study of the aggregation of TiO{sub 2} nanoparticles in the presence of 2,3-dihydroxybenzoic acid (2,3-DHBA) and SRFA, respectively, was performed in order to observe changes in ζ-potential and particle size over a time period of 9 months. In the 2,3-DHBA-TiO{sub 2} system, ζ-potentials decreased with time resulting in charge neutralization and/or inversion depending on ligand concentration. Aggregate sizes increased initially to the micrometer size range, followed by disaggregation after several months. No or very little interaction between SRFA and TiO{sub 2} occurred at the lowest concentrations tested. However, at the higher concentrations of SRFA, there was an increase in both aggregate size and the amount of SRFA adsorbed to the TiO{sub 2} surface. This was in correlation with the ζ-potential that decreased with increased SRFA concentration, leading to destabilization of the system. These results stress the importance of performing studies over both short and long time periods to better understand and predict the long-term effects of nanoparticles in the environment.

  15. Self-organized structures in a superorganism: do ants “behave” like molecules?

    Detrain, Claire; Deneubourg, Jean-Louis

    2006-09-01

    While the striking structures (e.g. nest architecture, trail networks) of insect societies may seem familiar to many of us, the understanding of pattern formation still constitutes a challenging problem. Over the last two decades, self-organization has dramatically changed our view on how collective decision-making and structures may emerge out of a population of ant workers having each their own individuality as well as a limited access to information. A variety of collective behaviour spontaneously outcome from multiple interactions between nestmates, even when there is no directing influence imposed by an external template, a pacemaker or a leader. By focussing this review on foraging structures, we show that ant societies display some properties which are usually considered in physico-chemical systems, as typical signatures of self-organization. We detail the key role played by feed-back loops, fluctuations, number of interacting units and sensitivity to environmental factors in the emergence of a structured collective behaviour. Nonetheless, going beyond simple analogies with non-living self-organized patterns, we stress on the specificities of social structures made of complex living units of which the biological features have been selected throughout the evolution depending on their adaptive value. In particular, we consider the ability of each ant individual to process information about environmental and social parameters, to accordingly tune its interactions with nestmates and ultimately to determine the final pattern emerging at the collective level. We emphasize on the parsimony and simplicity of behavioural rules at the individual level which allow an efficient processing of information, energy and matter within the whole colony.

  16. Critical analysis of radioiodination techniques for micro and macro organic molecules

    Sajid Mushtaq; Jongho Jeon; Beom Su Jang; Sang Hyun Park; Korea University of Science and Technology, Daejeon; Aqeela Shaheen

    2016-01-01

    A variety of radioiodination methods is available in the literature depending upon the nature of organic compound to be labeled, however only few can completely fulfill manufacturing requirements.Ideally a selected method should be one which offers maximum benefits like regioselectivity, minimum reaction steps, minimum reaction time, high radiochemical yield and high specific activity. In this review radioiodination techniques were critically analyzed. Advantages, drawbacks, possible mode of action and special reaction conditions required to get high radiochemical yield were taken into account. The influence of iodine introduction on physicochemical properties, in vivo or in vitro pharmacological properties of pharmaceutical due to increase of lipophilicity were discussed along with examples. (author)

  17. Nanostructured Silver Substrates With Stable and Universal SERS Properties: Application to Organic Molecules and Semiconductor Nanoparticles

    Waurisch C

    2009-01-01

    Full Text Available Abstract Nanostructured silver films have been prepared by thermal deposition on silicon, and their properties as SERS substrates investigated. The optimal conditions of the post-growth annealing of the substrates were established. Atomic force microscopy study revealed that the silver films with relatively dense and homogeneous arrays of 60–80-nm high pyramidal nanoislands are the most efficient for SERS of both organic dye and inorganic nanoparticles analytes. The noticeable enhancement of the Raman signal from colloidal nanoparticles with the help of silver island films is reported for the first time.

  18. Printed 2 V-operating organic inverter arrays employing a small-molecule/polymer blend

    Shiwaku, Rei; Takeda, Yasunori; Fukuda, Takashi; Fukuda, Kenjiro; Matsui, Hiroyuki; Kumaki, Daisuke; Tokito, Shizuo

    2016-10-01

    Printed organic thin-film transistors (OTFTs) are well suited for low-cost electronic applications, such as radio frequency identification (RFID) tags and sensors. Achieving both high carrier mobility and uniform electrical characteristics in printed OTFT devices is essential in these applications. Here, we report on printed high-performance OTFTs and circuits using silver nanoparticle inks for the source/drain electrodes and a blend of dithieno[2,3-d2‧,3‧-d‧]benzo[1,2-b4,5-b‧]dithiophene (DTBDT-C6) and polystyrene for the organic semiconducting layer. A high saturation region mobility of 1.0 cm2 V-1 s-1 at low operation voltage of -5 V was obtained for relatively short channel lengths of 9 μm. All fifteen of the printed pseudo-CMOS inverter circuits were formed on a common substrate and operated at low operation voltage of 2 V with the total variation in threshold voltage of 0.35 V. Consequently, the printed OTFT devices can be used in more complex integrated circuit applications requiring low manufacturing cost over large areas.

  19. Printed 2 V-operating organic inverter arrays employing a small-molecule/polymer blend.

    Shiwaku, Rei; Takeda, Yasunori; Fukuda, Takashi; Fukuda, Kenjiro; Matsui, Hiroyuki; Kumaki, Daisuke; Tokito, Shizuo

    2016-10-04

    Printed organic thin-film transistors (OTFTs) are well suited for low-cost electronic applications, such as radio frequency identification (RFID) tags and sensors. Achieving both high carrier mobility and uniform electrical characteristics in printed OTFT devices is essential in these applications. Here, we report on printed high-performance OTFTs and circuits using silver nanoparticle inks for the source/drain electrodes and a blend of dithieno[2,3-d;2',3'-d']benzo[1,2-b;4,5-b']dithiophene (DTBDT-C 6 ) and polystyrene for the organic semiconducting layer. A high saturation region mobility of 1.0 cm 2  V -1  s -1 at low operation voltage of -5 V was obtained for relatively short channel lengths of 9 μm. All fifteen of the printed pseudo-CMOS inverter circuits were formed on a common substrate and operated at low operation voltage of 2 V with the total variation in threshold voltage of 0.35 V. Consequently, the printed OTFT devices can be used in more complex integrated circuit applications requiring low manufacturing cost over large areas.

  20. Magneto-transport and optical control of magnetization in organic systems: From polymers to molecule-based magnets

    Bozdag, Kadriye Deniz

    Organic systems can be synthesized to have various impressive properties such as room temperature magnetism, electrical conductivity as high as conventional metals and magnetic field dependent transport. In this dissertation, we report comprehensive experimental studies in two different classes of organic systems, V-Cr Prussian blue molecule-based magnets and polyaniline nanofiber networks. The first system, V-Cr Prussian blue magnets, belongs to a family of cyano-bridged bi-metallic compounds which display a broad range of interesting photoinduced magnetic properties. A notable example for optically controllable molecule-based magnets is Co-Fe Prussian blue magnet (Tc ˜ 12 K), which exhibits light-induced changes in between magnetic states together with glassy behavior. In this dissertation, the first reports of reversible photoinduced magnetic phenomena in V-Cr Prussian blue analogs and the analysis of its AC and DC magnetization behavior are presented. Optical excitation of V-Cr Prussian blue, one of the few room temperature molecule-based magnets, with UV light (lambda = 350 nm) suppresses magnetization, whereas subsequent excitation with green light (lambda = 514 nm) increases magnetization. The partial recovery effect of green light is observed only when the sample is previously UV-irradiated. Moreover the photoinduced state has a long lifetime at low temperatures (tau > 106 s at T = 10 K) indicating that V-Cr Prussian blue reaches a hidden metastable state upon illumination with UV light. The effects of optical excitation are maintained up to 200 K and completely erased when the sample is warmed above 250 K. Results of detailed magnetic studies and the likely microscopic mechanisms for the photo illumination effects on magnetic properties are discussed. The second organic system, polyaniline nanofiber networks, was synthesized via dilute polymerization and studied at low and high electric and magnetic fields for temperatures 2 K--250 K for their magneto

  1. High Resolution Millimeter Wave Absorption Spectroscopy of Flexi- Ble Complex Organic Molecules: Laboratory Spectrum of 1, 2-Butanediol

    Maris, Assimo

    2017-11-01

    The enhancing sensibility of radioastronomical observations allows for detec- tion of complex organic molecules (COMs) with increasing size. Observations performed by the Atacama Large Millimeter Array (ALMA) open up new oppor- tunities to reveal the COMs, at the same time, the huge amount of data collected and the extremely rich surveys represent a challenge for the astrochemistry community. Among all the detected molecules, the diols are object of chemical interest, because of their similarity with important biological building block molecules such as sugar alcohols. The simplest of them, ethylene glycol (EG), is one of the largest COMs detected in space thus far. Lines attributable to the most stable conformer of EG were detected in different environments and recently also the higher energy conformer has been observed both towards IRAS 16293-2422 and the Orion KL. Observations of 1, 2- and 1, 3-propanediol toward Sgr B2 (N-LMH) were attempted as part of the GBT Prebiotic Interstellar Molecule Sur- vey Legacy Project, but no transitions were detected. Although up to now, due the fact that the column densities of molecules tend to decrease with increasing molecular weight, no large diols have been observed in interstellar space, owing to the raising sensitivity of the radioastronomy observations, their future detection can not be excluded. In this context we report, for the first time, the laboratory millimeter spectrum of 1, 2-butanediol (BD) recorded in the 59.6-103.6 GHz frequency region (5.03-2.89 mm). BD (the ethylated form of EG) is a flexible molecule characterized by a great conformational complexity, thus at room condi- tions the population is distributed in a large number of species, leading to a very congested spectrum. This problem has been overcome exploiting the rotational and conformational cooling produced by the supersonic expansion technique. Six conformers of BD, including the global minimum, have been assigned yielding the rotational constants

  2. The CP molecule labyrinth: a paradigm of how endeavors in total synthesis lead to discoveries and inventions in organic synthesis.

    Nicolaou, K C; Baran, Phil S

    2002-08-02

    Imagine an artist carving a sculpture from a marble slab and finding gold nuggets in the process. This thought is not a far-fetched description of the work of a synthetic chemist pursuing the total synthesis of a natural product. At the end of the day, he or she will be judged by the artistry of the final work and the weight of the gold discovered in the process. However, as colorful as this description of total synthesis may be, it does not entirely capture the essence of the endeavor, for there is much more to be told, especially with regard to the contrast of frustrating failures and exhilarating moments of discovery. To fully appreciate the often Herculean nature of the task and the rewards that accompany it, one must sense the details of the enterprise behind the scenes. A more vivid description of total synthesis as a struggle against a tough opponent is perhaps appropriate to dramatize these elements of the experience. In this article we describe one such endeavor of total synthesis which, in addition to reaching the target molecule, resulted in a wealth of new synthetic strategies and technologies for chemical synthesis. The total synthesis of the CP molecules is compared to Theseus' most celebrated athlos (Greek for exploit, accomplishment): the conquest of the dreaded Minotaur, which he accomplished through brilliance, skill, and bravery having traversed the famous labyrinth with the help of Ariadne. This story from Greek mythology comes alive in modern synthetic expeditions toward natural products as exemplified by the total synthesis of the CP molecules which serve as a paradigm for modern total synthesis endeavors, where the objectives are discovery and invention in the broader sense of organic synthesis.

  3. Efficient synthetic methods for the installation of boron-nitrogen bonds in conjugated organic molecules.

    Morgan, Matthew M; Piers, Warren E

    2016-04-14

    Polycyclic aromatic hydrocarbons in which one or more CC units have been replaced by isoelectronic BN units have attracted interest as potentially improved organic materials in various devices. This promise has been hampered by a lack of access to gram quantities of these materials. However, the exploitation of keystone reactions such as ring closing metathesis, borylative cyclization of amino styrenes and electrophilic borylation has lead to strategies for access to workable amounts of material. These strategies can be augmented by judicious postfunctionalization reactions to diversify the library of materials available. This Frontier article highlights some of the recent successes and shows that the long promised applications of BN-doped PAHs are beginning to be explored in a meaningful way.

  4. Search for biochemical fossils on earth and non-biological organic molecules on Jupiter, Saturn and Titan

    Nagy, Bartholomew

    1982-07-01

    Recognizable remnants of ancient biochemicals may survive under mild/moderate geological environments. Acyclic isoprenoid hydrocarbons, cyclic hydrocarbons with terpenoid carbon skeletons (e.g. hopanes) and vanadyl and nickel porphyrins have been isolated from organic matter, including petroleum, in Phanerozoic sedimentary rocks. Remnants of lignin have also been found. Usually, carbohydrates do not survive long; they degrade and/or react with other organic substances to form macromolecular matter. Proteins, e.g. apparently those in dinosaur bone collagen, break down relatively rapidly. Life arose during the Precambrian and potential biochemical fossils, e.g. n-alkanes, 2,5-dimethylfuran have been isolated from Precambrian kerogens. Traces of hydrocarbons, NH3, PH3 occur on Jupiter and Saturn. Hydrocarbons, N2 and HCN, the latter a key intermediary in the laboratory abiological syntheses of amino acids and nucleic acid bases, are present on Titan where life could not have evolved. Precursor abiological organic molecules of some complexity may have been synthesized on Titan and the Jovian planets.

  5. Engineering of Porphyrin Molecules for Use as Effective Cathode Interfacial Modifiers in Organic Solar Cells of Enhanced Efficiency and Stability.

    Tountas, Marinos; Verykios, Apostolis; Polydorou, Ermioni; Kaltzoglou, Andreas; Soultati, Anastasia; Balis, Nikolaos; Angaridis, Panagiotis A; Papadakis, Michael; Nikolaou, Vasilis; Auras, Florian; Palilis, Leonidas C; Tsikritzis, Dimitris; Evangelou, Evangelos K; Gardelis, Spyros; Koutsoureli, Matroni; Papaioannou, George; Petsalakis, Ioannis D; Kennou, Stella; Davazoglou, Dimitris; Argitis, Panagiotis; Falaras, Polycarpos; Coutsolelos, Athanassios G; Vasilopoulou, Maria

    2018-06-06

    In the present work, we effectively modify the TiO 2 electron transport layer of organic solar cells with an inverted architecture using appropriately engineered porphyrin molecules. The results show that the optimized porphyrin modifier bearing two carboxylic acids as the anchoring groups and a triazine electron-withdrawing spacer significantly reduces the work function of TiO 2 , thereby reducing the electron extraction barrier. Moreover, the lower surface energy of the porphyrin-modified substrate results in better physical compatibility between the latter and the photoactive blend. Upon employing porphyrin-modified TiO 2 electron transport layers in PTB7:PC 71 BM-based organic solar cells we obtained an improved average power conversion efficiency up to 8.73%. Importantly, porphyrin modification significantly increased the lifetime of the devices, which retained 80% of their initial efficiency after 500 h of storage in the dark. Because of its simplicity and efficacy, this approach should give tantalizing glimpses and generate an impact into the potential of porphyrins to facilitate electron transfer in organic solar cells and related devices.

  6. Thermodynamics of organic molecule adsorption on sorbents modified with 5-hydroxy-6-methyluracil by inverse gas chromatography.

    Gus'kov, Vladimir Yu; Gainullina, Yulia Yu; Ivanov, Sergey P; Kudasheva, Florida Kh

    2014-08-22

    The thermodynamic features of organic molecule adsorption from the gaseous phase of sorbents modified with 5-hydroxy-6-methyluracil (HMU) were studied. Molar internal energy and entropy of adsorption variation analyses showed that with every type surface, except for silica gel, layers of supramolecular structure have cavities equal in size with the ones revealed in HMU crystals by X-ray diffraction. Adsorption thermodynamics on HMU-modified sorbents depended on the amount of impregnated HMU and on the polarity, but not the porosity, of the initial sorbent. Polarity of the modified surface increased as a function of HMU quantity and initial sorbent mean pore size, but become appreciably lower if the initial surface is capable of hydrogen bonding. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Theoretical characterization and design of small molecule donor material containing naphthodithiophene central unit for efficient organic solar cells.

    Duan, Yu-Ai; Geng, Yun; Li, Hai-Bin; Jin, Jun-Ling; Wu, Yong; Su, Zhong-Min

    2013-07-15

    To seek for high-performance small molecule donor materials used in heterojunction solar cell, six acceptor-donor-acceptor small molecules based on naphtho[2,3-b:6,7-b']dithiophene (NDT) units with different acceptor units were designed and characterized using density functional theory and time-dependent density functional theory. Their geometries, electronic structures, photophysical, and charge transport properties have been scrutinized comparing with the reported donor material NDT(TDPP)2 (TDPP  =  thiophene-capped diketopyrrolopyrrole). The open circuit voltage (V(oc)), energetic driving force(ΔE(L-L)), and exciton binding energy (E(b)) were also provided to give an elementary understanding on their cell performance. The results reveal that the frontier molecular orbitals of 3-7 match well with the acceptor material PC61 BM, and compounds 3-5 were found to exhibit the comparable performances to 1 and show promising potential in organic solar cells. In particular, comparing with 1, system 7 with naphthobisthiadiazole acceptor unit displays broader absorption spectrum, higher V(oc), lower E(b), and similar carrier mobility. An in-depth insight into the nature of the involved excited states based on transition density matrix and charge density difference indicates that all S1 states are mainly intramolecular charge transfer states with the charge transfer from central NDT unit to bilateral acceptor units, and also imply that the exciton of 7 can be dissociated easily due to its large extent of the charge transfer. In a word, 7 maybe superior to 1 and may act as a promising donor candidate for organic solar cell. Copyright © 2013 Wiley Periodicals, Inc.

  8. How to compute isomerization energies of organic molecules with quantum chemical methods.

    Grimme, Stefan; Steinmetz, Marc; Korth, Martin

    2007-03-16

    The reaction energies for 34 typical organic isomerizations including oxygen and nitrogen heteroatoms are investigated with modern quantum chemical methods that have the perspective of also being applicable to large systems. The experimental reaction enthalpies are corrected for vibrational and thermal effects, and the thus derived "experimental" reaction energies are compared to corresponding theoretical data. A series of standard AO basis sets in combination with second-order perturbation theory (MP2, SCS-MP2), conventional density functionals (e.g., PBE, TPSS, B3-LYP, MPW1K, BMK), and new perturbative functionals (B2-PLYP, mPW2-PLYP) are tested. In three cases, obvious errors of the experimental values could be detected, and accurate coupled-cluster [CCSD(T)] reference values have been used instead. It is found that only triple-zeta quality AO basis sets provide results close enough to the basis set limit and that sets like the popular 6-31G(d) should be avoided in accurate work. Augmentation of small basis sets with diffuse functions has a notable effect in B3-LYP calculations that is attributed to intramolecular basis set superposition error and covers basic deficiencies of the functional. The new methods based on perturbation theory (SCS-MP2, X2-PLYP) are found to be clearly superior to many other approaches; that is, they provide mean absolute deviations of less than 1.2 kcal mol-1 and only a few (computational thermochemistry methods.

  9. Method for linearizing the potentiometric curves of precipitation titration in nonaqueous and aqueous-organic solutions

    Bykova, L.N.; Chesnokova, O.Ya.; Orlova, M.V.

    1995-01-01

    The method for linearizing the potentiometric curves of precipitation titration is studied for its application in the determination of halide ions (Cl - , Br - , I - ) in dimethylacetamide, dimethylformamide, in which titration is complicated by additional equilibrium processes. It is found that the method of linearization permits the determination of the titrant volume at the end point of titration to high accuracy in the case of titration curves without a potential jump in the proximity of the equivalent point (5 x 10 -5 M). 3 refs., 2 figs., 3 tabs

  10. Linear and nonlinear methods in modeling the aqueous solubility of organic compounds.

    Catana, Cornel; Gao, Hua; Orrenius, Christian; Stouten, Pieter F W

    2005-01-01

    Solubility data for 930 diverse compounds have been analyzed using linear Partial Least Square (PLS) and nonlinear PLS methods, Continuum Regression (CR), and Neural Networks (NN). 1D and 2D descriptors from MOE package in combination with E-state or ISIS keys have been used. The best model was obtained using linear PLS for a combination between 22 MOE descriptors and 65 ISIS keys. It has a correlation coefficient (r2) of 0.935 and a root-mean-square error (RMSE) of 0.468 log molar solubility (log S(w)). The model validated on a test set of 177 compounds not included in the training set has r2 0.911 and RMSE 0.475 log S(w). The descriptors were ranked according to their importance, and at the top of the list have been found the 22 MOE descriptors. The CR model produced results as good as PLS, and because of the way in which cross-validation has been done it is expected to be a valuable tool in prediction besides PLS model. The statistics obtained using nonlinear methods did not surpass those got with linear ones. The good statistic obtained for linear PLS and CR recommends these models to be used in prediction when it is difficult or impossible to make experimental measurements, for virtual screening, combinatorial library design, and efficient leads optimization.

  11. Weights and linear measurements of the body and some organs of ...

    The absolute weights of the body, heart, kidneys, spleen, pancreas, liver, gonads, digestive tract and adrenal glands, as well as the absolute linear measurements of the body, digestive tract and oviduct were determined in adult female and male African white-bellied tree pangolins. The relative weights, relative lengths and ...

  12. Linear programming model to construct phylogenetic network for 16S rRNA sequences of photosynthetic organisms and influenza viruses.

    Mathur, Rinku; Adlakha, Neeru

    2014-06-01

    Phylogenetic trees give the information about the vertical relationships of ancestors and descendants but phylogenetic networks are used to visualize the horizontal relationships among the different organisms. In order to predict reticulate events there is a need to construct phylogenetic networks. Here, a Linear Programming (LP) model has been developed for the construction of phylogenetic network. The model is validated by using data sets of chloroplast of 16S rRNA sequences of photosynthetic organisms and Influenza A/H5N1 viruses. Results obtained are in agreement with those obtained by earlier researchers.

  13. New Linear Partitioning Models Based on Experimental Water: Supercritical CO2 Partitioning Data of Selected Organic Compounds.

    Burant, Aniela; Thompson, Christopher; Lowry, Gregory V; Karamalidis, Athanasios K

    2016-05-17

    Partitioning coefficients of organic compounds between water and supercritical CO2 (sc-CO2) are necessary to assess the risk of migration of these chemicals from subsurface CO2 storage sites. Despite the large number of potential organic contaminants, the current data set of published water-sc-CO2 partitioning coefficients is very limited. Here, the partitioning coefficients of thiophene, pyrrole, and anisole were measured in situ over a range of temperatures and pressures using a novel pressurized batch-reactor system with dual spectroscopic detectors: a near-infrared spectrometer for measuring the organic analyte in the CO2 phase and a UV detector for quantifying the analyte in the aqueous phase. Our measured partitioning coefficients followed expected trends based on volatility and aqueous solubility. The partitioning coefficients and literature data were then used to update a published poly parameter linear free-energy relationship and to develop five new linear free-energy relationships for predicting water-sc-CO2 partitioning coefficients. A total of four of the models targeted a single class of organic compounds. Unlike models that utilize Abraham solvation parameters, the new relationships use vapor pressure and aqueous solubility of the organic compound at 25 °C and CO2 density to predict partitioning coefficients over a range of temperature and pressure conditions. The compound class models provide better estimates of partitioning behavior for compounds in that class than does the model built for the entire data set.

  14. Selective transformation of carbonyl ligands to organic molecules. Progress report, September 1, 1989--November 14, 1992

    Cutler, A.R.

    1992-05-12

    Studies on the carbonylation of ({eta}{sup 5}-indenyl)(L)(CO)Ru-R complexes (L = CO, PPh{sub 3}; R = CH{sub 2}OMe, CH{sub 3}) have been completed. Particularly noteworthy is that the methoxymethyl complexes readily transform to their acyl derivatives under mild conditions that leave their iron congeners inert towards CO. Surprisingly, even ({eta}{sup 5}-indenyl)(PPh{sub 3}){sub 2}Ru-CH{sub 3} carbonylates and gives ({eta}{sup 5}-indenyl)(PPh{sub 3})(CO)Ru-C(O)CH{sub 3}. Mechanistic studies on the ``non catalyzed`` hydrosilation of the manganese acyls (CO){sub 5}Mn-C(O)CH{sub 2}R (R = H, OCH{sub 3}, CH{sub 3}) with Et{sub 3}SiH and of cobalt acetyls (CO){sub 3}(PR{sub 3})CoC(O)CH{sub 3} with several monohydrosilanes have been completed. The cobalt acetyls cleanly give ethoxysilanes (not acetaldehyde), and the manganese acyls provide {alpha}-siloxyvinyl complexes Z-(CO){sub 5}Mn-C(OSiEt{sub 3})=CHR (R = H, CH{sub 3}, OCH{sub 3}). Carbonylation and protolytic cleavage of the latter generate pyruvoyl complexes (CO){sub 5}Mn-COCOR (R = CH{sub 3}, CH{sub 2}CH{sub 3}), formally the products of net ``double carbonylation`` sequences. Studies in progress are concerned with how manganese complexes as diverse as (CO){sub 5}Mn-Y [Y = C(O)R, R, BR - but not SiMe{sub 3} or Mn(CO){sub 5}] and ({eta}{sup 3}-C{sub 3}H{sub 5})Mn(CO){sub 2}L [but not CpMn(CO){sub 3} or CpMn(CO){sub 2}({eta}{sup 2}HSiR{sub 3})] function as efficient hydrosilation catalysts towards Cp(CO){sub 2}FeC(O)CH{sub 3}, for example. These reactions cleanly afford fully characterized {alpha}-siloxyethyl complexes Fp-CH(OSiR{sub 3})CH{sub 3} under conditions where typically Rh(1) hydrosilation catalysts are inactive. Several of these manganese complexes also catalytically hydrosilate organic esters, including lactones, to their ethers R-CH{sub 2}OR; these novel ester reductions occur quantitatively at room temperature and appear to be general in scope.

  15. Late stage crystallization and healing during spin-coating enhance carrier transport in small-molecule organic semiconductors

    Chou, Kang Wei

    2014-01-01

    Spin-coating is currently the most widely used solution processing method in organic electronics. Here, we report, for the first time, a direct investigation of the formation process of the small-molecule organic semiconductor (OSC) 6,13-bis(triisopropylsilylethynyl) (TIPS)-pentacene during spin-coating in the context of an organic thin film transistor (OTFT) application. The solution thinning and thin film formation were monitored in situ by optical reflectometry and grazing incidence wide angle X-ray scattering, respectively, both of which were performed during spin-coating. We find that OSC thin film formation is akin to a quenching process, marked by a deposition rate of ∼100 nm s-1, nearly three orders of magnitude faster than drop-casting. This is then followed by a more gradual crystallization and healing step which depends upon the spinning speed. We associate this to further crystallization and healing of defects by residency of the residual solvent trapped inside the kinetically trapped film. The residency time of the trapped solvent is extended to several seconds by slowing the rotational speed of the substrate and is credited with improving the carrier mobility by nearly two orders of magnitude. Based on this insight, we deliberately slow down the solvent evaporation further and increase the carrier mobility by an additional order of magnitude. These results demonstrate how spin-coating conditions can be used as a handle over the crystallinity of organic semiconductors otherwise quenched during initial formation only to recrystallize and heal during extended interaction with the trapped solvent. This journal is © the Partner Organisations 2014.

  16. Atomic-Resolution Transmission Electron Microscopic Movies for Study of Organic Molecules, Assemblies, and Reactions: The First 10 Years of Development.

    Nakamura, Eiichi

    2017-06-20

    A molecule is a quantum mechanical entity. "Watching motions and reactions of a molecule with our eyes" has therefore been a dream of chemists for a century. This dream has come true with the aid of the movies of atomic-resolution transmission electron microscopic (AR-TEM) molecular images through real-time observation of dynamic motions of single organic molecules (denoted hereafter as single-molecule atomic-resolution real-time (SMART) TEM imaging). Since 2007, we have reported movies of a variety of single organic molecules, organometallic molecules, and their assemblies, which are rotating, stretching, and reacting. Like movies in the theater, the atomic-resolution molecular movies provide us information on the 3-D structures of the molecules and also their time evolution. The success of the SMART-TEM imaging crucially depends on the development of "chemical fishhooks" with which fish (organic molecules) in solution can be captured on a single-walled carbon nanotube (CNT, serving as a "fishing rod"). The captured molecules are connected to a slowly vibrating CNT, and their motions are displayed on a monitor in real time. A "fishing line" connecting the fish and the rod may be a σ-bond, a van der Waals force, or other weak connections. Here, the molecule/CNT system behaves as a coupled oscillator, where the low-frequency anisotropic vibration of the CNT is transmitted to the molecules via the weak chemical connections that act as an energy filter. Interpretation of the observed motions of the molecules at atomic resolution needs us to consider the quantum mechanical nature of electrons as well as bond rotation, letting us deviate from the conventional statistical world of chemistry. What new horizons can we explore? We have so far carried out conformational studies of individual molecules, assigning anti or gauche conformations to each C-C bond in conformers that we saw. We can also determine the structures of van der Waals assemblies of organic molecules

  17. Calculation of 0-0 excitation energies of organic molecules by CIS(D) quantum chemical methods

    Grimme, Stefan; Izgorodina, Ekaterina I.

    2004-01-01

    The accuracy and reliability of the CIS(D) quantum chemical method and a spin-component scaled variant (SCS-CIS(D)) are tested for calculating 0-0 excitation energies of organic molecules. The ground and excited state geometries and the vibrational zero-point corrections are taken from (TD)DFT-B3LYP calculations. In total 32 valence excited states of different character are studied: π → π* states of polycyclic aromatic compounds/polyenes and n → π* states of carbonyl, thiocarbonyl and aza(azo)-aromatic compounds. This set is augmented by two systems of special interest, i.e., indole and the TICT state of dimethylaminbenzonitrile (DMABN). Both methods predict excitation energies that are on average higher than experiment by about 0.2 eV. The errors are found to be quite systematic (with a standard deviation of about 0.15 eV) and especially SCS-CIS(D) provides a more balanced treatment of π → π* vs. n → π* states. For the test suite of states, both methods clearly outperform the (TD)DFT-B3LYP approach. Opposed to previous conclusions about the performance of CIS(D), these methods can be recommended as reliable and efficient tools for computational studies of excited state problems in organic chemistry. In order to obtain conclusive results, however, the use of optimized excited state geometries and comparison with observables (0-0 excitation energies) are necessary

  18. Vertical Phase Separation in Small Molecule:Polymer Blend Organic Thin Film Transistors Can Be Dynamically Controlled

    Zhao, Kui

    2016-02-03

    © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Blending of small-molecule organic semiconductors (OSCs) with amorphous polymers is known to yield high performance organic thin film transistors (OTFTs). Vertical stratification of the OSC and polymer binder into well-defined layers is crucial in such systems and their vertical order determines whether the coating is compatible with a top and/or a bottom gate OTFT configuration. Here, we investigate the formation of blends prepared via spin-coating in conditions which yield bilayer and trilayer stratifications. We use a combination of in situ experimental and computational tools to study the competing effects of formulation thermodynamics and process kinetics in mediating the final vertical stratification. It is shown that trilayer stratification (OSC/polymer/OSC) is the thermodynamically favored configuration and that formation of the buried OSC layer can be kinetically inhibited in certain conditions of spin-coating, resulting in a bilayer stack instead. The analysis reveals here that preferential loss of the OSC, combined with early aggregation of the polymer phase due to rapid drying, inhibit the formation of the buried OSC layer. The fluid dynamics and drying kinetics are then moderated during spin-coating to promote trilayer stratification with a high quality buried OSC layer which yields unusually high mobility >2 cm2 V-1 s-1 in the bottom-gate top-contact configuration.

  19. Linear electro-optic coefficient in multilayer self-organized InAs quantum dot structures

    Akca, I.B.; Dana, A.; Aydinli, A.; Rossetti, M.; Li, L.; Dagli, N.; Fiore, A.

    2007-01-01

    The electro-optic coefficients of self-organized InAs quantum dot layers in molecular beam epitaxy grown laser structures in reverse bias have been investigated. Enhanced electrooptic coefficients compared to bulk GaAs were observed.

  20. Reaction of N,N’-dimethylformamide and divalent viologen molecule to generate an organic dopant for molybdenum disulfide

    A. Fukui

    2018-05-01

    Full Text Available Tuning the carrier concentration is essential for semiconducting materials to apply optoelectronic devices. Molybdenum disulfide (MoS2 is a semiconducting material composed of atomically thin (∼0.7 nm thickness layers. To dope thin MoS2, instead of using conventional atom/ion injection processes, a surface charge transfer method was successfully applied. In this study, we report a simple preparation method of a molecular dopant applicable to the doping process. The method follows a previous report for producing a molecular dopant, benzyl viologen (BV which shows electron doping to MoS2. To prepare dopant BV molecules, a reduction process with a commercially available divalent BV by sodium borohydride (NaBH4 is required; however, the reaction requires a large consumption of NaBH4. NaBH4 drastically reacts with the solvent water itself. We found a reaction process of BV in an organic solvent, N,N’-dimethylformamide (DMF, by adding a small amount of water dissolving the divalent BV. The reaction is mild (at room temperature and is autonomous once DMF comes into contact with the divalent BV aqueous solution. The reaction can be monitored with a UV-Vis spectrometer, and kinetic analysis indicates two reaction steps between divalent/monovalent/neutral viologen isomers. The product was soluble in toluene and did not dissolve in water, indicating it is similar to the reported dopant BV. The synthesized molecule was found to act as a dopant for MoS2 by applying a metal-oxide-semiconductor field-effect-transistor (MOSFET structure. The process is a general method and applicable to other viologen-related dopants to tune the electronic structure of 2D materials to facilitate generating atomically thin devices.

  1. A multifunctional setup to record FTIR and UV-vis spectra of organic molecules and their photoproducts in astronomical ices.

    Kofman, V; Witlox, M J A; Bouwman, J; Ten Kate, I L; Linnartz, H

    2018-05-01

    This article describes a new, multi-functional, high-vacuum ice setup that allows to record the in situ and real-time spectra of vacuum UV (VUV)-irradiated non-volatile molecules embedded in a low-temperature (10 K) amorphous solid water environment. Three complementary diagnostic tools-UV-visible (UV-vis) and Fourier Transform Infrared (FTIR) spectroscopy and temperature-programmed desorption quadrupole mass spectrometry-can be used to simultaneously study the physical and chemical behavior of the organic molecules in the ice upon VUV irradiation. The setup is equipped with a temperature-controlled sublimation oven that enables the controlled homogeneous deposition of solid species such as amino acids, nucleobases, and polycyclic aromatic hydrocarbons (PAHs) in ice mixtures prepared from precursor gases and/or liquids. The resulting ice is photo-processed with a microwave discharge hydrogen lamp, generating VUV radiation with a spectral energy distribution representative for the interstellar medium. The characteristics, performance, and future potential of the system are discussed by describing three different applications. First, a new method is introduced, which uses broadband interference transmission fringes recorded during ice deposition, to determine the wavelength-dependent refractive index, n λ , of amorphous solid water. This approach is also applicable to other solids, pure and mixed. Second, the UV-vis and FTIR spectroscopy of an VUV-irradiated triphenylene:water ice mixture is discussed, monitoring the ionization efficiency of PAHs in interstellar ice environments. The third and final example investigates the stability of solid glycine upon VUV irradiation by monitoring the formation of dissociation products in real time.

  2. Infrared spectra of complex organic molecules in astronomically relevant ice matrices. I. Acetaldehyde, ethanol, and dimethyl ether

    Terwisscha van Scheltinga, J.; Ligterink, N. F. W.; Boogert, A. C. A.; van Dishoeck, E. F.; Linnartz, H.

    2018-03-01

    Context. The number of identified complex organic molecules (COMs) in inter- and circumstellar gas-phase environments is steadily increasing. Recent laboratory studies show that many such species form on icy dust grains. At present only smaller molecular species have been directly identified in space in the solid state. Accurate spectroscopic laboratory data of frozen COMs, embedded in ice matrices containing ingredients related to their formation scheme, are still largely lacking. Aim. This work provides infrared reference spectra of acetaldehyde (CH3CHO), ethanol (CH3CH2OH), and dimethyl ether (CH3OCH3) recorded in a variety of ice environments and for astronomically relevant temperatures, as needed to guide or interpret astronomical observations, specifically for upcoming James Webb Space Telescope observations. Methods: Fourier transform transmission spectroscopy (500-4000 cm-1/20-2.5 μm, 1.0 cm-1 resolution) was used to investigate solid acetaldehyde, ethanol and dimethyl ether, pure or mixed with water, CO, methanol, or CO:methanol. These species were deposited on a cryogenically cooled infrared transmissive window at 15 K. A heating ramp was applied, during which IR spectra were recorded until all ice constituents were thermally desorbed. Results: We present a large number of reference spectra that can be compared with astronomical data. Accurate band positions and band widths are provided for the studied ice mixtures and temperatures. Special efforts have been put into those bands of each molecule that are best suited for identification. For acetaldehyde the 7.427 and 5.803 μm bands are recommended, for ethanol the 11.36 and 7.240 μm bands are good candidates, and for dimethyl ether bands at 9.141 and 8.011 μm can be used. All spectra are publicly available in the Leiden Database for Ice.

  3. Reaction of N,N'-dimethylformamide and divalent viologen molecule to generate an organic dopant for molybdenum disulfide

    Fukui, A.; Miura, K.; Ichimiya, H.; Tsurusaki, A.; Kariya, K.; Yoshimura, T.; Ashida, A.; Fujimura, N.; Kiriya, D.

    2018-05-01

    Tuning the carrier concentration is essential for semiconducting materials to apply optoelectronic devices. Molybdenum disulfide (MoS2) is a semiconducting material composed of atomically thin (˜0.7 nm thickness) layers. To dope thin MoS2, instead of using conventional atom/ion injection processes, a surface charge transfer method was successfully applied. In this study, we report a simple preparation method of a molecular dopant applicable to the doping process. The method follows a previous report for producing a molecular dopant, benzyl viologen (BV) which shows electron doping to MoS2. To prepare dopant BV molecules, a reduction process with a commercially available divalent BV by sodium borohydride (NaBH4) is required; however, the reaction requires a large consumption of NaBH4. NaBH4 drastically reacts with the solvent water itself. We found a reaction process of BV in an organic solvent, N,N'-dimethylformamide (DMF), by adding a small amount of water dissolving the divalent BV. The reaction is mild (at room temperature) and is autonomous once DMF comes into contact with the divalent BV aqueous solution. The reaction can be monitored with a UV-Vis spectrometer, and kinetic analysis indicates two reaction steps between divalent/monovalent/neutral viologen isomers. The product was soluble in toluene and did not dissolve in water, indicating it is similar to the reported dopant BV. The synthesized molecule was found to act as a dopant for MoS2 by applying a metal-oxide-semiconductor field-effect-transistor (MOSFET) structure. The process is a general method and applicable to other viologen-related dopants to tune the electronic structure of 2D materials to facilitate generating atomically thin devices.

  4. A multifunctional setup to record FTIR and UV-vis spectra of organic molecules and their photoproducts in astronomical ices

    Kofman, V.; Witlox, M. J. A.; Bouwman, J.; ten Kate, I. L.; Linnartz, H.

    2018-05-01

    This article describes a new, multi-functional, high-vacuum ice setup that allows to record the in situ and real-time spectra of vacuum UV (VUV)-irradiated non-volatile molecules embedded in a low-temperature (10 K) amorphous solid water environment. Three complementary diagnostic tools—UV-visible (UV-vis) and Fourier Transform Infrared (FTIR) spectroscopy and temperature-programmed desorption quadrupole mass spectrometry—can be used to simultaneously study the physical and chemical behavior of the organic molecules in the ice upon VUV irradiation. The setup is equipped with a temperature-controlled sublimation oven that enables the controlled homogeneous deposition of solid species such as amino acids, nucleobases, and polycyclic aromatic hydrocarbons (PAHs) in ice mixtures prepared from precursor gases and/or liquids. The resulting ice is photo-processed with a microwave discharge hydrogen lamp, generating VUV radiation with a spectral energy distribution representative for the interstellar medium. The characteristics, performance, and future potential of the system are discussed by describing three different applications. First, a new method is introduced, which uses broadband interference transmission fringes recorded during ice deposition, to determine the wavelength-dependent refractive index, nλ, of amorphous solid water. This approach is also applicable to other solids, pure and mixed. Second, the UV-vis and FTIR spectroscopy of an VUV-irradiated triphenylene:water ice mixture is discussed, monitoring the ionization efficiency of PAHs in interstellar ice environments. The third and final example investigates the stability of solid glycine upon VUV irradiation by monitoring the formation of dissociation products in real time.

  5. Linear and nonlinear surface spectroscopy of supported size selected metal clusters and organic adsorbates

    Thaemer, Martin Georg

    2012-03-08

    The spectroscopic investigation of supported size selected metal clusters over a wide wavelength range plays an important role for understanding their outstanding catalytic properties. The challenge which must be overcome to perform such measurements is the difficult detection of the weak spectroscopic signals from these samples. As a consequence, highly sensitive spectroscopic methods are applied, such as surface Cavity Ringdown Spectroscopy and surface Second Harmonic Generation Spectroscopy. The spectroscopic apparatus developed is shown to have a sensitivity which is high enough to detect sub-monolayer coverages of adsorbates on surfaces. In the measured spectra of small supported silver clusters of the sizes Ag{sub 4}2, Ag{sub 2}1, Ag{sub 9}, and Ag atoms a stepwise transition from particles with purely metallic character to particles with molecule-like properties can be observed within this size range.

  6. The HIFI spectral survey of AFGL 2591 (CHESS). I. Highly excited linear rotor molecules in the high-mass protostellar envelope

    van der Wiel, M. H. D.; Pagani, L.; van der Tak, F. F. S.; Kaźmierczak, M.; Ceccarelli, C.

    2013-05-01

    Context. Linear rotor molecules such as CO, HCO+ and HCN are important probes of star-forming gas. For these species, temperatures of ≲ 50 K are sufficient to produce emission lines that are observable from the ground at (sub)millimeter wavelengths. Molecular gas in the environment of massive protostellar objects, however, is known to reach temperatures of several hundred K. To probe this, space-based far-infrared observations are required. Aims: We aim to reveal the gas energetics in the circumstellar environment of the prototypical high-mass protostellar object AFGL 2591. Methods: Rotational spectral line signatures of CO species, HCO+, CS, HCN and HNC from a 490-1240 GHz survey with Herschel/HIFI, complemented by ground-based JCMT and IRAM 30 m spectra, cover transitions in the energy range (Eup/k) between 5 K and ~ 300 K. Selected frequency settings in the highest frequency HIFI bands (up to 1850 GHz) extend this range to 750 K for 12C16O. The resolved spectral line profiles are used to separate and study various kinematic components. Observed line intensities are compared with a numerical model that calculates excitation balance and radiative transfer based on spherical geometry. Results: The line profiles show two emission components, the widest and bluest of which is attributed to an approaching outflow and the other to the envelope. We find evidence for progressively more redshifted and wider line profiles from the envelope gas with increasing energy level. This trend is qualitatively explained by residual outflow contribution picked up in the systematically decreasing beam size. Integrated line intensities for each species decrease as Eup/k increases from ≲ 50 to ~700 K. The H2 density and temperature of the outflow gas are constrained to ~105-106 cm-3 and 60-200 K. In addition, we derive a temperature between 9 and 17 K and N(H2) ~ 3 × 1021 cm-2 for a known foreground cloud seen in absorption, and N(H2) ≲ 1019 cm-2 for a second foreground component

  7. Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

    Maurizio Selva

    2016-08-01

    Full Text Available The use of ionic liquids (ILs as organocatalysts is reviewed for transesterification reactions, specifically for the conversion of nontoxic compounds such as dialkyl carbonates to both linear mono-transesterification products or alkylene carbonates. An introductory survey compares pros and cons of classic catalysts based on both acidic and basic systems, to ionic liquids. Then, innovative green syntheses of task-specific ILs and their representative applications are introduced to detail the efficiency and highly selective outcome of ILs-catalyzed transesterification reactions. A mechanistic hypothesis is discussed by the concept of cooperative catalysis based on the dual (electrophilic/nucleophilic activation of reactants.

  8. Estimation of biological parameters of marine organisms using linear and nonlinear acoustic scattering model-based inversion methods.

    Chu, Dezhang; Lawson, Gareth L; Wiebe, Peter H

    2016-05-01

    The linear inversion commonly used in fisheries and zooplankton acoustics assumes a constant inversion kernel and ignores the uncertainties associated with the shape and behavior of the scattering targets, as well as other relevant animal parameters. Here, errors of the linear inversion due to uncertainty associated with the inversion kernel are quantified. A scattering model-based nonlinear inversion method is presented that takes into account the nonlinearity of the inverse problem and is able to estimate simultaneously animal abundance and the parameters associated with the scattering model inherent to the kernel. It uses sophisticated scattering models to estimate first, the abundance, and second, the relevant shape and behavioral parameters of the target organisms. Numerical simulations demonstrate that the abundance, size, and behavior (tilt angle) parameters of marine animals (fish or zooplankton) can be accurately inferred from the inversion by using multi-frequency acoustic data. The influence of the singularity and uncertainty in the inversion kernel on the inversion results can be mitigated by examining the singular values for linear inverse problems and employing a non-linear inversion involving a scattering model-based kernel.

  9. Effects of gamma radiation from 60Co on dilute aqueous solutions of Linear Alkyl Sulfonate Surfactants and other organic pollutants

    Rohrer, D.M.

    1975-01-01

    This study is the result of research findings and operational experiences gained by the author in over four years of work associated with the use of 60 Co for the treatment of waste-water. The effects of 60 Co are discussed with regard to radiochemical destruction of specific organic pollutant species. The study deals specifically with the effects of gamma radiation from a 30,000 Ci 60 Co source upon aqueous solutions of Linear Alkyl Sulfonate Surfactants. The new Linear Alkyl Sulfonate (LAS) Surfactants, the major surfactant produced in the United States of America since June 1965, was developed to replace the old Alkyl Benzene Sulfonate (ABS) Surfactants. The reason for the removal of Alkyl Benzene Sulfonate Surfactants was their extreme environmental stability and the associated appearance of foam in waste-water treatment plants and receiving streams. Although the Linear Alkyl Sulfonate Surfactants are considered 'bio-degradable', the time required for 'bio-degradation' is impractical within the present environmental guidelines. This led to research into alternate techniques of treatment for the destruction of Linear Alkyl Sulfonate Surfactants. Consideration is also given to similar effects of gamma radiation upon pesticides and to the practical aspects of the use of gamma radiation for the treatment of waste-water. Included are discussions of the general experimental procedures used, the sources and their calibration, and sampling techniques to ensure the accuracy of the data. (author)

  10. Probing into hybrid organic-molecule and InAs quantum-dots nanosystem with multistacked dots-in-a-well units

    Chen, Miaoxiang Max; Kobashi, Kazufumi

    2012-01-01

    Hybridizing air-stable organic-molecules with advanced III-V semiconductor quantum-dots (QDs) structures can be utilized to create a new generation of biochemical sensing devices. In order to enhance their optical performances, the active regions in these QDs structures commonly consist of multis......Hybridizing air-stable organic-molecules with advanced III-V semiconductor quantum-dots (QDs) structures can be utilized to create a new generation of biochemical sensing devices. In order to enhance their optical performances, the active regions in these QDs structures commonly consist...

  11. Tuning crystal polymorphs of a Π-extended tetrathiafulvalene-based cruciform molecule towards high-performance organic field-effect transistors

    Feng, Linlin; Dong, Huanli; Li, Qingyuan

    2017-01-01

    It is a common phenomenon for organic semiconductors to crystallize in two or more polymorphs, leading to various molecular packings and different charge transport properties. Therefore, it is a crucial issue of tuning molecular crystal polymorphs (i.e., adjusting the same molecule with different......)-based cruciform molecule, named as IF-TTF. The charge carrier mobility of the α-phase IF-TTF crystals was more than one order of magnitude higher than that of β-phase crystals, suggesting the importance of reasonably tuning molecular packing in solid state for the improvement of charge transport in organic...... semiconductors...

  12. Acquiring beam data for a flattening-filter free linear accelerator using organic scintillators

    Beierholm, Anders Ravnsborg; Behrens, C.F.; Hoffmann, L.

    2013-01-01

    Fibre-coupled organic scintillators have been proven a credible alternative to clinically implemented methods for radiotherapy dosimetry, primarily due to their water equivalence and good spatial resolution. Furthermore, the fast response of the scintillators can be exploited to perform time-reso...

  13. Transformation of Graphitic and Amorphous Carbon Dust to Complex Organic Molecules in a Massive Carbon Cycle in Protostellar Nebulae

    Nuth, Joseph A., III; Johnson, Natasha M.

    2012-01-01

    relatively inert carbonaceous dust from the ISM into the vital organic precursors to life such as amino acids and sugars intimately mixed with dust and ice in primitive planetesimals. Since the number of carbon atoms entering the Solar Nebula as dust exceeds the number of atoms entering the nebula as oxide grains. the formation of large quantities of complex organic molecules may represent the largest single chemical cycle in the nebula.

  14. Versatile piezoelectric pulsed molecular beam source for gaseous compounds and organic molecules with femtomole accuracy for UHV and surface science applications

    Schiesser, Alexander; Schaefer, Rolf

    2009-01-01

    This note describes the construction of a piezoelectric pulsed molecular beam source based upon a design presented in an earlier work [D. Proch and T. Trickl, Rev. Sci. Instrum. 60, 713 (1988)]. The design features significant modifications that permit the determination of the number of molecules in a beam pulse with an accuracy of 1x10 11 molecules per pulse. The 21 cm long plunger-nozzle setup allows the molecules to be brought to any point of the UHV chamber with very high intensity. Furthermore, besides typical gaseous compounds, also smaller organic molecules with a vapor pressure higher than 0.1 mbar at room temperature may serve as feed material. This makes the new design suitable for various applications in chemical and surface science studies.

  15. Mild Conditions for Deuteration of Primary and Secondary Arylamines for the Synthesis of Deuterated Optoelectronic Organic Molecules

    Anwen M. Krause-Heuer

    2014-11-01

    Full Text Available Deuterated arylamines demonstrate great potential for use in optoelectronic devices, but their widespread utility requires a method for large-scale synthesis. The incorporation of these deuterated materials into optoelectronic devices also provides the opportunity for studies of the functioning device using neutron reflectometry based on the difference in the scattering length density between protonated and deuterated compounds. Here we report mild deuteration conditions utilising standard laboratory glassware for the deuteration of: diphenylamine, N-phenylnaphthylamine, N-phenyl-o-phenylenediamine and 1-naphthylamine (via H/D exchange in D2O at 80 °C, catalysed by Pt/C and Pd/C. These conditions were not successful in the deuteration of triphenylamine or N,N-dimethylaniline, suggesting that these mild conditions are not suitable for the deuteration of tertiary arylamines, but are likely to be applicable for the deuteration of other primary and secondary arylamines. The deuterated arylamines can then be used for synthesis of larger organic molecules or polymers with optoelectronic applications.

  16. Influence of the replacement of alkoxyl with alkylthienyl on photovoltaic properties of two small molecule donors for organic solar cells

    Shaoqing Zhang; Liyan Yang; Delong Liu; Chang He; Jianqi Zhang; Yun Zhang; Jianhui Hou

    2017-01-01

    Two benzo[1,2-b:4,5-b']dithiophene (BDT)-based small molecule (SM) donor materials with identical conjugated backbones but different substitution groups,named as DRTB-O and DRTB-T,were well explored to demonstrate the influence of the replacement of alkoxy with alkylthienyl on their photovoltaic properties in fullerene-based and fullerene-free organic solar cells (OSCs).The study shows that the two SM donors possess similar absorption spectra and energy levels but different crystalline structures in solid films.The carrier transport property and phase separation morphologies of the blend films have also been fully investigated.By employing PC71BM as the acceptor,the power conversion efficiency (PCE) of DRTB-O:PC71BM and DRTB-T:PC71BM based devices were 4.91% and 7.08%,respectively.However,by blending with IDIC,the two SM donors exhibited distinctly different photovoltaic properties in fullerene-free OSCs,and the PCE of DRTB-O:IDIC and DRTB-T:IDIC based devices were 0.15% and 9.06%,respectively.These results indicate that the replacement of alkoxyl with alkylthienyl in designing SM donor materials plays an important role in the application of fullerene-free OSCs.

  17. Electron-rich anthracene semiconductors containing triarylamine for solution-processed small-molecule organic solar cells.

    Choi, Hyeju; Ko, Haye Min; Cho, Nara; Song, Kihyung; Lee, Jae Kwan; Ko, Jaejung

    2012-10-01

    New electron-rich anthracene derivatives containing triarylamine hole stabilizers, 2,6-bis[5,5'-bis(N,N'-diphenylaniline)-2,2'-bithiophen-5-yl]-9,10-bis-[(triisopropylsilyl)ethynyl]anthracene (TIPSAntBT-TPA) and 2,6-bis(5,5'-bis{4-[bis(9,9-dimethyl-9H-fluoren-2-yl)amino]phenyl}-2,2'-bithiophen-5-yl)-9,10-bis-[(triisopropylsilyl)ethynyl]anthracene (TIPSAntBT-bisDMFA), linked with π-conjugated bithiophene bridges, were synthesized and their photovoltaic characteristics were investigated in solution-processed small-molecule organic solar cells (SMOSCs). These new materials exhibited superior intramolecular charge transfer from triarylamine to anthracene, leading to a more electron-rich anthracene core that facilitated electron transfer into phenyl-C(61)-butyric acid methyl ester. Compared with TIPSAntBT and triarylamine, these materials show a threefold improvement in hole-transporting properties and better photovoltaic performance in solution-processed SMOSCs, with the best power conversion efficiency being 2.96 % at a high open-circuit voltage of 0.85 V. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Highly selective sieving of small gas molecules by using an ultra-microporous metal–organic framework membrane

    Kang, Zixi; Xue, Ming; Fan, Lili; Huang, Lin; Guo, Lijia; Wei, Guoying; Chen, Banglin; Qiu, Shilun

    2014-01-01

    © 2014 The Royal Society of Chemistry. Two tailor-made microporous metal-organic framework (MOF) membranes were successfully fabricated on nickel screens by secondary growth. The effect of pore structures on gas separation was examined by means of single and binary gas permeation tests. The MOF JUC-150 membrane with its ultra-micropores showed marked preferential permeance to H2 relative to other gas molecules. The selectivity factors of this membrane were 26.3, 17.1 and 38.7 for H2/CH4, H2/N2 and H2/CO2, respectively, at room temperature. To the best of our knowledge, these values represent unprecedentedly high separation selectivity among those for all MOF membranes reported to date. The JUC-150 membrane also shows high thermal stability and outstanding separation performance at a high temperature of 200 °C. The separation performance of these membranes persists even after more than 1 year exposure to air. The superiority of the tailored pore size, high selectivity for H2 over other gases, significant stability and recyclability make these materials potential candidates for industrial H2 recycling applications.

  19. Origin of the Strong Interaction between Polar Molecules and Copper(II) Paddle-Wheels in Metal Organic Frameworks.

    Ongari, Daniele; Tiana, Davide; Stoneburner, Samuel J; Gagliardi, Laura; Smit, Berend

    2017-07-20

    The copper paddle-wheel is the building unit of many metal organic frameworks. Because of the ability of the copper cations to attract polar molecules, copper paddle-wheels are promising for carbon dioxide adsorption and separation. They have therefore been studied extensively, both experimentally and computationally. In this work we investigate the copper-CO 2 interaction in HKUST-1 and in two different cluster models of HKUST-1: monocopper Cu(formate) 2 and dicopper Cu 2 (formate) 4 . We show that density functional theory methods severely underestimate the interaction energy between copper paddle-wheels and CO 2 , even including corrections for the dispersion forces. In contrast, a multireference wave function followed by perturbation theory to second order using the CASPT2 method correctly describes this interaction. The restricted open-shell Møller-Plesset 2 method (ROS-MP2, equivalent to (2,2) CASPT2) was also found to be adequate in describing the system and used to develop a novel force field. Our parametrization is able to predict the experimental CO 2 adsorption isotherms in HKUST-1, and it is shown to be transferable to other copper paddle-wheel systems.

  20. Highly selective sieving of small gas molecules by using an ultra-microporous metal–organic framework membrane

    Kang, Zixi

    2014-09-12

    © 2014 The Royal Society of Chemistry. Two tailor-made microporous metal-organic framework (MOF) membranes were successfully fabricated on nickel screens by secondary growth. The effect of pore structures on gas separation was examined by means of single and binary gas permeation tests. The MOF JUC-150 membrane with its ultra-micropores showed marked preferential permeance to H2 relative to other gas molecules. The selectivity factors of this membrane were 26.3, 17.1 and 38.7 for H2/CH4, H2/N2 and H2/CO2, respectively, at room temperature. To the best of our knowledge, these values represent unprecedentedly high separation selectivity among those for all MOF membranes reported to date. The JUC-150 membrane also shows high thermal stability and outstanding separation performance at a high temperature of 200 °C. The separation performance of these membranes persists even after more than 1 year exposure to air. The superiority of the tailored pore size, high selectivity for H2 over other gases, significant stability and recyclability make these materials potential candidates for industrial H2 recycling applications.

  1. Systematic Investigation of Controlled Nanostructuring of Mn 12 Single-Molecule Magnets Templated by Metal–Organic Frameworks

    Aulakh, Darpandeep [Department of Chemistry; amp, Biomolecular Science, Clarkson University, Potsdam, New York 13699, United States; Xie, Haomiao [Department of Chemistry, Texas A& amp,M University, College Station, Texas 77845, United States; Shen, Zhe [Department of Chemistry, Texas A& amp,M University, College Station, Texas 77845, United States; Harley, Alexander [Department of Chemistry; amp, Biomolecular Science, Clarkson University, Potsdam, New York 13699, United States; Zhang, Xuan [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States; Yakovenko, Andrey A. [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States; Dunbar, Kim R. [Department of Chemistry, Texas A& amp,M University, College Station, Texas 77845, United States; Wriedt, Mario [Department of Chemistry; amp, Biomolecular Science, Clarkson University, Potsdam, New York 13699, United States

    2017-05-25

    This is the first systematic study exploring metal–organic frameworks (MOFs) as platforms for the controlled nanostructuring of molecular magnets. We report the incorporation of seven single-molecule magnets (SMMs) of general composition [Mn12O12(O2CR)16(OH2)4], with R = CF3 (1), (CH3)CCH2 (2), CH2Cl (3), CH2Br (4), CHCl2 (5), CH2But (6), and C6H5 (7), into the hexagonal channel pores of a mesoporous MOF host. The resulting nanostructured composites combine the key SMM properties with the functional properties of the MOF. Synchrotron-based powder diffraction with difference envelope density analysis, physisorption analysis (surface area and pore size distribution), and thermal analyses reveal that the well-ordered hexagonal structure of the host framework is preserved, and magnetic measurements indicate that slow relaxation of the magnetization, characteristic of the corresponding Mn12 derivative guests, occurs inside the MOF pores. Structural host–guest correlations including the bulkiness and polarity of peripheral SMM ligands are discussed as fundamental parameters influencing the global SMM@MOF loading capacities. These results demonstrate that employing MOFs as platforms for the nanostructuration of SMMs is not limited to a particular host–guest system but potentially applicable to a multitude of other molecular magnets. Such fundamental findings will assist in paving the way for the development of novel advanced spintronic devices.

  2. Linear correlation of interfacial tension at water-solvent interface, solubility of water in organic solvents, and SE* scale parameters

    Mezhov, E.A.; Khananashvili, N.L.; Shmidt, V.S.

    1988-01-01

    A linear correlation has been established between the solubility of water in water-immiscible organic solvents and the interfacial tension at the water-solvent interface on the one hand and the parameters of the SE* and π* scales for these solvents on the other hand. This allows us, using the known tabulated SE* or π* parameters for each solvent, to predict the values of the interfacial tension and the solubility of water for the corresponding systems. We have shown that the SE* scale allows us to predict these values more accurately than other known solvent scales, since in contrast to other scales it characterizes solvents found in equilibrium with water

  3. Below a Historic Mercury Mine: Non-linear Patterns of Mercury Bioaccumulation in Aquatic Organisms

    Haas, J.; Ichikawa, G.; Ode, P.; Salsbery, D.; Abel, J.

    2001-12-01

    Unlike most heavy metals, mercury is capable of bioaccumulating in aquatic food-chains, primarily because it is methylated by bacteria in sediment to the more toxic methylmercury form. Mercury concentrations in a number of riparian systems in California are highly elevated as a result of historic mining activities. These activities included both the mining of cinnabar in the coastal ranges to recover elemental mercury and the use of elemental mercury in the gold fields of the Sierra Nevada Mountains. The most productive mercury mining area was the New Almaden District, now a county park, located in the Guadalupe River drainage of Santa Clara County, where cinnabar was mined and retorted for over 100 years. As a consequence, riparian systems in several subwatersheds of the Guadalupe River drainage are contaminated with total mercury concentrations that exceed state hazardous waste criteria. Mercury concentrations in fish tissue frequently exceed human health guidelines. However, the potential ecological effects of these elevated mercury concentrations have not been thoroughly evaluated. One difficulty is in extrapolating sediment concentrations to fish tissue concentrations without accounting for physical and biological processes that determine bioaccumulation patterns. Many processes, such as methylation and demethylation of mercury by bacteria, assimilation efficiency in invertebrates, and metabolic rates in fish, are nonlinear, a factor that often confounds attempts to evaluate the effects of mercury contamination on aquatic food webs. Sediment, benthic macroinvertebrate, and fish tissue samples were collected in 1998 from the Guadalupe River drainage in Santa Clara County at 13 sites upstream and downstream from the historic mining district. Sediment and macroinvertebrate samples were analyzed for total mercury and methylmercury. Fish samples were analyzed for total mercury as whole bodies, composited by species and size. While linear correlations of sediment

  4. Influence of the crystallographic structure of the electrode surface on the structure of the electrical double layer and adsorption of organic molecules

    Kochorovski, Z.; Zagorska, I.; Pruzhkovska-Drakhal, R.; Trasatti, S.

    1995-01-01

    The results of systematic investigation of influence of crystal structure of Bi-, Sb- and Cd-electrode surfaces on regularities of double electric layer structure in aqueous and nonaqueous solutions of surface-nonactive electrolyte are given. Influence of electrode surface characteristics on adsorptive behaviour of different organic molecules has been studied. General regularities of of chemical nature influence and surface crystallographic structure on the double layer structure and on organic compounds adsorption have been established. 57 refs., 7 figs., 4 tabs

  5. Cyclodextrin-supported organic matrix for application of MALDI-MS for forensics. Soft-ionization to obtain protonated molecules of low molecular weight compounds

    Yonezawa, Tetsu, E-mail: tetsu@eng.hokudai.ac.jp [Division of Materials Science and Engineering, Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628 (Japan); Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Asano, Takashi [Division of Materials Science and Engineering, Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628 (Japan); Criminal Investigation Laboratory, Metropolitan Police Department, 2-1-1 Kasumigaseki, Chiyoda-ku, Tokyo 100-8929 (Japan); Fujino, Tatsuya [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan); Nishihara, Hiroshi [Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2013-06-20

    Highlights: ► MALDI-MS applications for drug identification in forensic science is investigated. ► Cyclodextrin-supported organic matrices strongly suppress the obstacle peaks of organic matrix compounds. ► Cyclodextrin-supported organic matrices also suppress the alkali adducted molecule peaks. ► Sugar units of cyclodextrins work for this specific features. - Abstract: A mass measurement technique for detecting low-molecular-weight drugs with a cyclodextrin-supported organic matrix was investigated. By using cyclodextrin-supported 2,4,6-trihydroxyacetophenone (THAP), the matrix-related peaks of drugs were suppressed. The peaks of protonated molecules of the sample and THAP were mainly observed, and small fragments were detected in a few cases. Despite the Na{sup +} and K{sup +} peaks were observed in the spectrum, Na{sup +} or K{sup +} adduct sample molecules were undetected, owing to the sugar units of cyclodextrin. The advantages of MALDI-MS with cyclodextrin-supported matrices as an analytical tool for forensic samples are discussed. The suppression of alkali adducted molecules and desorption process are also discussed.

  6. Quantitative Study of Ether Group Molecules in Insoluble Organic Matter from Carbonaceous Chondrites by CuO-NaOH Selective Degradation

    Yabuta, H.; Cody, G. D.; Alexander, C. M. O'd.

    2006-03-01

    CuO-NaOH degradation of the insoluble organic matter (IOM) from the Murchison meteorite was conducted. A variety of carboxylic acids were indentified. Oxalic acid was most abundant. It was estimated that approximately ~30% of the IOM included ether groups containing molecules.

  7. Cyclodextrin-supported organic matrix for application of MALDI-MS for forensics. Soft-ionization to obtain protonated molecules of low molecular weight compounds

    Yonezawa, Tetsu; Asano, Takashi; Fujino, Tatsuya; Nishihara, Hiroshi

    2013-01-01

    Highlights: ► MALDI-MS applications for drug identification in forensic science is investigated. ► Cyclodextrin-supported organic matrices strongly suppress the obstacle peaks of organic matrix compounds. ► Cyclodextrin-supported organic matrices also suppress the alkali adducted molecule peaks. ► Sugar units of cyclodextrins work for this specific features. - Abstract: A mass measurement technique for detecting low-molecular-weight drugs with a cyclodextrin-supported organic matrix was investigated. By using cyclodextrin-supported 2,4,6-trihydroxyacetophenone (THAP), the matrix-related peaks of drugs were suppressed. The peaks of protonated molecules of the sample and THAP were mainly observed, and small fragments were detected in a few cases. Despite the Na + and K + peaks were observed in the spectrum, Na + or K + adduct sample molecules were undetected, owing to the sugar units of cyclodextrin. The advantages of MALDI-MS with cyclodextrin-supported matrices as an analytical tool for forensic samples are discussed. The suppression of alkali adducted molecules and desorption process are also discussed

  8. Synthesis of Conjugated Small Molecules and Polymers by a Palladium Catalyzed Cyclopentannulation Strategy: Towards New Organic Semiconductors

    Bheemireddy, Sambasiva Reddy

    The utility of conjugated small molecules and polymers as organic semiconductors have seen a tremendous growth in research and development in academia as well as industry because of their processability and flexibility advantages in comparison to inorganic semiconductors. The extensive research over the years has produced a large number of p-type (hole conducting) and n-type (electron conducting) semiconductors that can be used to construct organic electronic devices. Of these materials, p-type semiconductors are more established and extensively studied because of the ease of preparation as well as their better general stability in comparison to n-type materials. Despite recent research into the development of n-type materials, fullerene (C60 and C 70) and its derivatives are still the predominant materials used as electron acceptors for OPV applications. By taking advantage of the electron accepting behavior of cyclopenta[hi]aceanthrylene fragment of C70, we have designed and synthesized new materials based on cyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs). By using a newly developed palladium catalyzed cyclopentannulation methodology, 1,2,6,7- tetraarylcyclopenta[hi]aceanthrylenes were prepared by treating diarylethynylenes with 9,10-dibromoanthracene. Scholl cyclodehydrogenation was used to close the externally fused aryl groups to provide access to contorted 2,7,13,18- tetraalkoxytetrabenzo[f,h,r,t]rubicenes. The contortion provides access to more soluble materials than their planar counterparts but still ii allows significant pi-pi stacking between molecules. Using a modified palladium catalyzed cyclopentannulation polymerization followed by a cyclodehydrogenation reaction, a nonconventional synthesis of CP-PAH embedded ladder polymers was also achieved. These ladder polymers possess broad UV-Vis absorptions and narrow optical gaps of 1.17-1.29 eV. The synthesis of new donor-acceptor copolymers incorporating electron accepting 1,2,6,7- tetra(4

  9. Linear solvation energy relationships for toxicity of selected organic chemicals to Daphnia pulex and Daphnia magna

    Passino, Dora R.M.; Hickey, James P.; Frank, Anthony M.

    1988-01-01

    In the Laurentian Great Lakes, more than 300 contaminants have been identified in fish, other biota, water, and sediment. Current hazard assessment of these chemicals by the National Fisheries Research Center-Great Lakes is based on their toxicity, occurrence in the environment, and source. Although scientists at the Center have tested over 70 chemicals with the crustacean Daphnia pulex, the number of experimental data needed to screen the huge array of chemicals in the Great Lakes exceeds the practical capabilities of conducting bioassays. This limitation can be partly circumvented, however, by using mathematical models based on quantitative structure-activity relationships (QSAR) to provide rapid, inexpensive estimates of toxicity. Many properties of chemicals, including toxicity, bioaccumulation and water solubility are well correlated and can be predicted by equations of the generalized linear solvation energy relationships (LSER). The equation we used to model solute toxicity is Toxicity = constant + mVI/100 + s (π* + dδ) + bβm + aαm where VI = intrinsic (Van der Waals) molar volume; π* = molecular dipolarity/polarizability; δ = polarizability 'correction term'; βm = solute hydrogen bond acceptor basicity; and αm = solute hydrogen bond donor acidity. The subscript m designates solute monomer values for α and β. We applied the LSER model to 48-h acute toxicity data (measured as immobilization) for six classes of chemicals detected in Great Lakes fish. The following regression was obtained for Daphnia pulex (concentration = μM): log EC50 = 4.86 - 4.35 VI/100; N = 38, r2 = 0.867, sd = 0.403 We also used the LSER modeling approach to analyze to a large published data set of 24-h acute toxicity for Daphnia magna; the following regression resulted, for eight classes of compounds (concentration = mM): log EC50 = 3.88 - 4.52 VI/100 - 1.62 π* + 1.66 βm - 0.916 αm; N = 62, r2 = 0.859, sd = 0.375 In addition we developed computer software that identifies

  10. Synchrotron far-IR RAIRS studies of interfaces created by polyfunctional organic molecules at defined metal surfaces

    Raval, R.; Williams, J.; Roberts, A.J.; Nunney, T.S.; Surman, M.

    1998-01-01

    Far-IR Reflection Absorption Infrared Spectroscopy (RAIRS) has been used to probe sub monolayers and multilayers of polyfunctional organic ad layers deposited under clean controlled conditions on small-area single-crystal surfaces, using the newly commissioned Daresbury 13.3 far-IR synchrotron beamline. It's shown that the current performance of the beamline allows to monitor fractions of monolayers of formate species on Cu(110), formed at 300 K from the deprotonation of formic acid. Two distinct vCu-O vibrations are observed for coverages up to 0.25 monolayer. The paper attributes the two bands to at least two chemically distinct species, each possessing a local site symmetry of C 2v and bonded to the metal surface via the two oxygen atoms. The two types of formate species are thought to arise from local density fluctuations in formate coverage across the ad layer which leads to local changes in the Cu-O bond. In additions, it's reported far-IR RAIRS spectra of bio molecule/metal interfaces created by depositing thin films (3-10 layers) of the chiral amino-acid, L-methionine, on Cu(110) at 300 K. The multilayer spectra closely resemble the far-IR spectra obtained from crystalline L-methionine, suggesting that the thin layer consists of the zwitterionic species. These thin bio films are stable on the surface to >330 K. No growth of metal-ligand vibrations in the multilayer phase is observed, demonstrating that corrosive chemisorption processes that create Cu-methionine complexes in the multilayer by leaching of surface Cu atoms do not occur in these conditions

  11. Solution-processed small molecules as mixed host for highly efficient blue and white phosphorescent organic light-emitting diodes.

    Fu, Qiang; Chen, Jiangshan; Shi, Changsheng; Ma, Dongge

    2012-12-01

    The widely used hole-transporting host 4,4',4″-tris(N-carbazolyl)-triphenylamine (TCTA) blended with either a hole-transporting or an electron-transporting small-molecule material as a mixed-host was investigated in the phosphorescent organic light-emitting diodes (OLEDs) fabricated by the low-cost solution-process. The performance of the solution-processed OLEDs was found to be very sensitive to the composition of the mixed-host systems. The incorporation of the hole-transporting 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) into TCTA as the mixed-host was demonstrated to greatly reduce the driving voltage and thus enhance the efficiency due to the improvement of hole injection and transport. On the basis of the mixed-host of TCTA:TAPC, we successfully fabricated low driving voltage and high efficiency blue and white phosphorescent OLEDs. A maximum forward viewing current efficiency of 32.0 cd/A and power efficiency of 25.9 lm/W were obtained in the optimized mixed-host blue OLED, which remained at 29.6 cd/A and 19.1 lm/W at the luminance of 1000 cd/m(2) with a driving voltage as low as 4.9 V. The maximum efficiencies of 37.1 cd/A and 32.1 lm/W were achieved in a single emissive layer white OLED based on the TCTA:TAPC mixed-host. Even at 1000 cd/m(2), the efficiencies still reach 34.2 cd/A and 23.3 lm/W and the driving voltage is only 4.6 V, which is comparable to those reported from the state-of-the-art vacuum-evaporation deposited white OLEDs.

  12. Determination of local concentration of H2O molecules and gas temperature in the process of hydrogen – oxygen gas mixture heating by means of linear and nonlinear laser spectroscopy

    Kozlov, D N; Kobtsev, V D; Stel'makh, O M; Smirnov, Valery V; Stepanov, E V

    2013-01-01

    Employing the methods of linear absorption spectroscopy and nonlinear four-wave mixing spectroscopy using laserinduced gratings we have simultaneously measured the local concentrations of H 2 O molecules and the gas temperature in the process of the H 2 – O 2 mixture heating. During the measurements of the deactivation rates of pulsed-laser excited singlet oxygen O 2 (b 1 Σ + g ) in collisions with H 2 in the range 294 – 850 K, the joint use of the two methods made it possible to determine the degree of hydrogen oxidation at a given temperature. As the mixture is heated, H 2 O molecules are formed by 'dark' reactions of H 2 with O 2 in the ground state. The experiments have shown that the measurements of tunable diode laser radiation absorption along an optical path through the inhomogeneously heated gas mixture in a cell allows high-accuracy determination of the local H 2 O concentration in the O 2 laser excitation volume, if the gas temperature in this volume is known. When studying the collisional deactivation of O 2 (b 1 Σ + g ) molecules, the necessary measurements of the local temperature can be implemented using laser-induced gratings, arising due to spatially periodic excitation of O 2 (X 3 Σ - g ) molecules to the b 1 Σ + g state by radiation of the pump laser of the four-wave mixing spectrometer. (laser spectroscopy)

  13. Optimized pulsed write schemes improve linearity and write speed for low-power organic neuromorphic devices

    Keene, Scott T.; Melianas, Armantas; Fuller, Elliot J.; van de Burgt, Yoeri; Talin, A. Alec; Salleo, Alberto

    2018-06-01

    Neuromorphic devices are becoming increasingly appealing as efficient emulators of neural networks used to model real world problems. However, no hardware to date has demonstrated the necessary high accuracy and energy efficiency gain over CMOS in both (1) training via backpropagation and (2) in read via vector matrix multiplication. Such shortcomings are due to device non-idealities, particularly asymmetric conductance tuning in response to uniform voltage pulse inputs. Here, by formulating a general circuit model for capacitive ion-exchange neuromorphic devices, we show that asymmetric nonlinearity in organic electrochemical neuromorphic devices (ENODes) can be suppressed by an appropriately chosen write scheme. Simulations based upon our model suggest that a nonlinear write-selector could reduce the switching voltage and energy, enabling analog tuning via a continuous set of resistance states (100 states) with extremely low switching energy (~170 fJ · µm‑2). This work clarifies the pathway to neural algorithm accelerators capable of parallelism during both read and write operations.

  14. Comparison of Linear and Cyclic His-Ala-Val Peptides in Modulating the Blood-Brain Barrier Permeability: Impact on Delivery of Molecules to the Brain.

    Alaofi, Ahmed; On, Ngoc; Kiptoo, Paul; Williams, Todd D; Miller, Donald W; Siahaan, Teruna J

    2016-02-01

    The aim of this study is to evaluate the effect of peptide cyclization on the blood-brain barrier (BBB) modulatory activity and plasma stability of His-Ala-Val peptides, which are derived from the extracellular 1 domain of human E-cadherin. The activities to modulate the intercellular junctions by linear HAV4 (Ac-SHAVAS-NH2), cyclic cHAVc1 (Cyclo(1,8)Ac-CSHAVASC-NH2), and cyclic cHAVc3 (Cyclo(1,6)Ac-CSHAVC-NH2) were compared in in vitro and in vivo BBB models. Linear HAV4 and cyclic cHAVc1 have the same junction modulatory activities as assessed by in vitro MDCK monolayer model and in situ rat brain perfusion model. In contrast, cyclic cHAVc3 was more effective than linear HAV4 in modulating MDCK cell monolayers and in improving in vivo brain delivery of Gd-DTPA on i.v. administration in Balb/c mice. Cyclic cHAVc3 (t1/2 = 12.95 h) has better plasma stability compared with linear HAV4 (t1/2 = 2.4 h). The duration of the BBB modulation was longer using cHAVc3 (2-4 h) compared with HAV4 (brain delivery of IRdye800cw-PEG (25 kDa) as detected by near IR imaging. The result showed that cyclic cHAVc3 peptide had better activity and plasma stability than linear HAV4 peptide. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  15. Probing the emitter site of Renilla luciferase using small organic molecules; an attempt to understand the molecular architecture of the emitter site.

    Salehi, Farajollah; Emamzadeh, Rahman; Nazari, Mahboobeh; Rasa, Seyed Mohammad Mahdi

    2016-12-01

    Renilla luciferase is a sensitive enzyme and has wide applications in biotechnology such as drug screening. Previous studies have tried to show the catalytic residues, nevertheless, the accurate architecture and molecular behavior of its emitter site remains uncharacterized. In this study, the activity of Renilla luciferase, in the presence of two small organic molecules including dimethyl sulfoxide (DMSO) and isopropanol was considered and the structure was studied by circular dichroism (CD) and fluorescence spectroscopy. Moreover, the interaction of small organic molecules with the Renilla luciferase was studied using molecular dynamics simulations. Kinetics studies showed that at low concentration of DMSO (16.6-66mM) and isopropanol (19.3-76mM) the K m changed and a competitive inhibition pattern was observed. Moreover, spectroscopy studies reveled that the changes of activity of Renilla luciferase in the presence of low concentrations of small organic molecules was not associated with structural collapse or severe changes in the enzyme conformation. Molecular dynamics simulations indicated that DMSO and isopropanol, as probing molecules, were both able to bind to the emitter site and remained with the residues of the emitter site. Based on the probing data, the architecture of the emitter site in the "non-binding" model was proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Molecular polarizability of organic molecules and their complexes. Communication LIV. Molar volumes of polyaryl organoelement compounds in solutions, extrapolated to infinite dilution, and steric structure of the molecules

    Bulgarevich, S.B.; Burdastykh, T.V.

    2008-01-01

    Molar volumes in various solvents were determined for organic derivatives of silicon, phosphorus, arsenic, sulfur, and tellurium, containing aryl nuclei capable to internal rotation about single bonds between them and bridging groups. Additive analysis of the molar volumes of these compounds showed that the aryl nuclei are acoplanar with respect to the bridging groups. Most probable is a conrotatory mutual orientation of the aromatic rings. Molar volumes were also determined for a series of compounds with two bridging groups, which can serve as models of an extreme case of mutual proximity of aryl ring planes in diaryl systems with one bridging group. A possibility for considerably simplifying the methods for determination of dipole moments and Kerr constants for compounds whose molar volumes can be calculated by our developed additive scheme is demonstrated [ru

  17. Immunological detection of small organic molecules in the presence of perchlorates: relevance to the life marker chip and life detection on Mars.

    Rix, Catherine S; Sims, Mark R; Cullen, David C

    2011-11-01

    The proposed ExoMars mission, due to launch in 2018, aims to look for evidence of extant and extinct life in martian rocks and regolith. Previous attempts to detect organic molecules of biological or abiotic origin on Mars have been unsuccessful, which may be attributable to destruction of these molecules by perchlorate salts during pyrolysis sample extraction techniques. Organic molecules can also be extracted and measured with solvent-based systems. The ExoMars payload includes the Life Marker Chip (LMC) instrument, capable of detecting biomarker molecules of extant and extinct Earth-like life in liquid extracts of martian samples with an antibody microarray assay. The aim of the work reported here was to investigate whether the presence of perchlorate salts, at levels similar to those at the NASA Phoenix landing site, would compromise the LMC extraction and detection method. To test this, we implemented an LMC-representative sample extraction process with an LMC-representative antibody assay and used these to extract and analyze a model sample that consisted of a Mars analog sample matrix (JSC Mars-1) spiked with a representative organic molecular target (pyrene, an example of abiotic meteoritic infall targets) in the presence of perchlorate salts. We found no significant change in immunoassay function when using pyrene standards with added perchlorate salts. When model samples spiked with perchlorate salts were subjected to an LMC-representative liquid extraction, immunoassays functioned in a liquid extract and detected extracted pyrene. For the same model sample matrix without perchlorate salts, we observed anomalous assay signals that coincided with yellow coloration of the extracts. This unexpected observation is being studied further. This initial study indicates that the presence of perchlorate salts, at levels similar to those detected at the NASA Phoenix landing site, is unlikely to prevent the LMC from extracting and detecting organic molecules from

  18. Geometric phase effects in excited state dynamics through a conical intersection in large molecules: N-dimensional linear vibronic coupling model study

    Li, Jiaru; Joubert-Doriol, Loïc; Izmaylov, Artur F.

    2017-08-01

    We investigate geometric phase (GP) effects in nonadiabatic transitions through a conical intersection (CI) in an N-dimensional linear vibronic coupling (ND-LVC) model. This model allows for the coordinate transformation encompassing all nonadiabatic effects within a two-dimensional (2D) subsystem, while the other N - 2 dimensions form a system of uncoupled harmonic oscillators identical for both electronic states and coupled bi-linearly with the subsystem coordinates. The 2D subsystem governs ultra-fast nonadiabatic dynamics through the CI and provides a convenient model for studying GP effects. Parameters of the original ND-LVC model define the Hamiltonian of the transformed 2D subsystem and thus influence GP effects directly. Our analysis reveals what values of ND-LVC parameters can introduce symmetry breaking in the 2D subsystem that diminishes GP effects.

  19. Inkjet-Printed Small-Molecule Organic Light-Emitting Diodes: Halogen-Free Inks, Printing Optimization, and Large-Area Patterning.

    Zhou, Lu; Yang, Lei; Yu, Mengjie; Jiang, Yi; Liu, Cheng-Fang; Lai, Wen-Yong; Huang, Wei

    2017-11-22

    Manufacturing small-molecule organic light-emitting diodes (OLEDs) via inkjet printing is rather attractive for realizing high-efficiency and long-life-span devices, yet it is challenging. In this paper, we present our efforts on systematical investigation and optimization of the ink properties and the printing process to enable facile inkjet printing of conjugated light-emitting small molecules. Various factors on influencing the inkjet-printed film quality during the droplet generation, the ink spreading on the substrates, and its solidification processes have been systematically investigated and optimized. Consequently, halogen-free inks have been developed and large-area patterning inkjet printing on flexible substrates with efficient blue emission has been successfully demonstrated. Moreover, OLEDs manufactured by inkjet printing the light-emitting small molecules manifested superior performance as compared with their corresponding spin-cast counterparts.

  20. Synthesis of an A-D-A type of molecule used as electron acceptor for improving charge transfer in organic solar cells

    Zhang, Chao-Zhi, E-mail: chzhzhang@sohu.com [Department of Chemistry, Nanjing University of Information Science & Technology, Nanjing 210044 (China); Gu, Shu-Duo; Shen, Dan; Yuan, Yang [Department of Chemistry, Nanjing University of Information Science & Technology, Nanjing 210044 (China); Zhang, Mingdao, E-mail: matchlessjimmy@163.com [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Nanjing University of Information Science & Technology, Nanjing 210044 (China)

    2016-08-22

    Electron-accepting molecules play an important role in developing organic solar cells. A new type of A-D-A molecule, 3,6-di([7-(5-bromothiophen-2-yl)-1,5,2,4,6,8-dithiotetrazocin-3-yl]thiophen -2-yl)-9-(2-ethylhexyl)carbazole, was synthesized. The lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels are −3.55 and −5.85 eV, respectively. Therefore, the A-D-A type of compound could be used as electron acceptor for fabricating organic solar cell with a high open circuit voltage. Gibbs free energy (−49.2 kJ/mol) reveals that the process of A-D-A acceptor accepting an electron from poly(3-hexylthiophene) at excited state is spontaneous. The value of entropy (118 J/mol) in the process of an electron transferring from P3HT to the A-D-A acceptor at organic interface suggests that electrons generated from separation of electron-hole pairs at donor/acceptor interface would be delocalized efficiently. Therefore, the A-D-A molecule would be a potential acceptor for efficient organic BHJ solar cells.

  1. Characteristics of ITO electrode grown by linear facing target sputtering with ladder type magnetic arrangement for organic light emitting diodes

    Jeong, Jin-A; Kim, Han-Ki; Lee, Jae-Young; Lee, Jung-Hwan; Bae, Hyo-Dae; Tak, Yoon-Heung

    2009-01-01

    The preparation and characteristics of indium tin oxide (ITO) electrodes grown using a specially designed linear facing target sputtering (LFTS) system with a ladder type magnet arrangement for organic light emitting diodes (OLED) are described. It was found that the electrical and optical properties of the ITO electrode were critically dependent on the Ar/O 2 flow ratio, while its structural and surface properties remained fairly constant regardless of the Ar/O 2 flow ratio, due to the low substrate temperature during the plasma damage-free sputtering. Under the optimized conditions, we obtained an ITO electrode with the lowest sheet resistance of 39.4 Ω/sq and high transmittance of 90.1% (550 nm wavelength) at room temperature. This suggests that LFTS is a promising low temperature and plasma damage free sputtering technology for preparing high-quality ITO electrodes for OLEDs and flexible OLEDs at room temperature.

  2. Comparison of light out-coupling enhancements in single-layer blue-phosphorescent organic light emitting diodes using small-molecule or polymer hosts

    Chang, Yung-Ting [Institute of Chemistry, Academia Sinica, Taipei, Taiwan 11529, Taiwan (China); Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan 10617, Taiwan (China); Liu, Shun-Wei [Department of Electronic Engineering, Mingchi University of Technology, New Taipei, Taiwan 24301, Taiwan (China); Yuan, Chih-Hsien; Lee, Chih-Chien [Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan 10607, Taiwan (China); Ho, Yu-Hsuan; Wei, Pei-Kuen [Research Center for Applied Science Academia Sinica, Taipei, Taiwan 11527, Taiwan (China); Chen, Kuan-Yu [Chilin Technology Co., LTD, Tainan City, Taiwan 71758, Taiwan (China); Lee, Yi-Ting; Wu, Min-Fei; Chen, Chin-Ti, E-mail: cchen@chem.sinica.edu.tw, E-mail: chihiwu@cc.ee.ntu.edu.tw [Institute of Chemistry, Academia Sinica, Taipei, Taiwan 11529, Taiwan (China); Wu, Chih-I, E-mail: cchen@chem.sinica.edu.tw, E-mail: chihiwu@cc.ee.ntu.edu.tw [Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan 10617, Taiwan (China)

    2013-11-07

    Single-layer blue phosphorescence organic light emitting diodes (OLEDs) with either small-molecule or polymer hosts are fabricated using solution process and the performances of devices with different hosts are investigated. The small-molecule device exhibits luminous efficiency of 14.7 cd/A and maximum power efficiency of 8.39 lm/W, which is the highest among blue phosphorescence OLEDs with single-layer solution process and small molecular hosts. Using the same solution process for all devices, comparison of light out-coupling enhancement, with brightness enhancement film (BEF), between small-molecule and polymer based OLEDs is realized. Due to different dipole orientation and anisotropic refractive index, polymer-based OLEDs would trap less light than small molecule-based OLEDs internally, about 37% better based simulation results. In spite of better electrical and spectroscopic characteristics, including ambipolar characteristics, higher carrier mobility, higher photoluminescence quantum yield, and larger triplet state energy, the overall light out-coupling efficiency of small molecule-based devices is worse than that of polymer-based devices without BEF. However, with BEF for light out-coupling enhancement, the improved ratio in luminous flux and luminous efficiency for small molecule based device is 1.64 and 1.57, respectively, which are significantly better than those of PVK (poly-9-vinylcarbazole) devices. In addition to the theoretical optical simulation, the experimental data also confirm the origins of differential light-outcoupling enhancement. The maximum luminous efficiency and power efficiency are enhanced from 14.7 cd/A and 8.39 lm/W to 23 cd/A and 13.2 lm/W, respectively, with laminated BEF, which are both the highest so far for single-layer solution-process blue phosphorescence OLEDs with small molecule hosts.

  3. Comparison of light out-coupling enhancements in single-layer blue-phosphorescent organic light emitting diodes using small-molecule or polymer hosts

    Chang, Yung-Ting; Liu, Shun-Wei; Yuan, Chih-Hsien; Lee, Chih-Chien; Ho, Yu-Hsuan; Wei, Pei-Kuen; Chen, Kuan-Yu; Lee, Yi-Ting; Wu, Min-Fei; Chen, Chin-Ti; Wu, Chih-I

    2013-01-01

    Single-layer blue phosphorescence organic light emitting diodes (OLEDs) with either small-molecule or polymer hosts are fabricated using solution process and the performances of devices with different hosts are investigated. The small-molecule device exhibits luminous efficiency of 14.7 cd/A and maximum power efficiency of 8.39 lm/W, which is the highest among blue phosphorescence OLEDs with single-layer solution process and small molecular hosts. Using the same solution process for all devices, comparison of light out-coupling enhancement, with brightness enhancement film (BEF), between small-molecule and polymer based OLEDs is realized. Due to different dipole orientation and anisotropic refractive index, polymer-based OLEDs would trap less light than small molecule-based OLEDs internally, about 37% better based simulation results. In spite of better electrical and spectroscopic characteristics, including ambipolar characteristics, higher carrier mobility, higher photoluminescence quantum yield, and larger triplet state energy, the overall light out-coupling efficiency of small molecule-based devices is worse than that of polymer-based devices without BEF. However, with BEF for light out-coupling enhancement, the improved ratio in luminous flux and luminous efficiency for small molecule based device is 1.64 and 1.57, respectively, which are significantly better than those of PVK (poly-9-vinylcarbazole) devices. In addition to the theoretical optical simulation, the experimental data also confirm the origins of differential light-outcoupling enhancement. The maximum luminous efficiency and power efficiency are enhanced from 14.7 cd/A and 8.39 lm/W to 23 cd/A and 13.2 lm/W, respectively, with laminated BEF, which are both the highest so far for single-layer solution-process blue phosphorescence OLEDs with small molecule hosts

  4. Controlling the Morphology of BDTT-DPP-Based Small Molecules via End-Group Functionalization for Highly Efficient Single and Tandem Organic Photovoltaic Cells.

    Kim, Ji-Hoon; Park, Jong Baek; Yang, Hoichang; Jung, In Hwan; Yoon, Sung Cheol; Kim, Dongwook; Hwang, Do-Hoon

    2015-11-04

    A series of narrow-band gap, π-conjugated small molecules based on diketopyrrolopyrrole (DPP) electron acceptor units coupled with alkylthienyl-substituted-benzodithiophene (BDTT) electron donors were designed and synthesized for use as donor materials in solution-processed organic photovoltaic cells. In particular, by end-group functionalization of the small molecules with fluorine derivatives, the nanoscale morphologies of the photoactive layers of the photovoltaic cells were successfully controlled. The influences of different fluorine-based end-groups on the optoelectronic and morphological properties, carrier mobilities, and the photovoltaic performances of these materials were investigated. A high power conversion efficiency (PCE) of 6.00% under simulated solar light (AM 1.5G) illumination has been achieved for organic photovoltaic cells based on a small-molecule bulk heterojunction system consisting of a trifluoromethylbenzene (CF3) end-group-containing oligomer (BDTT-(DPP)2-CF3) as the donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor. As a result, the introduction of CF3 end-groups has been found to enhance both the short circuit current density (JSC) and fill factor (FF). A tandem photovoltaic device comprising an inverted BDTT-(DPP)2-CF3:PC71BM cell and a poly(3-hexylthiophene) (P3HT):indene-C60-bisadduct (IC60BA)-based cell as the top and bottom cell components, respectively, showed a maximum PCE of 8.30%. These results provide valuable guidelines for the rational design of conjugated small molecules for applications in high-performance organic photovoltaic cells. Furthermore, to the best of our knowledge, this is the first report on the design of fluorine-functionalized BDTT-DPP-based small molecules, which have been shown to be a viable candidate for use in inverted tandem cells.

  5. Selectivity of primary events in the radiation chemistry of organic solids and polymers as revealed by model studies of ionized molecules

    Feldman, V.

    2006-01-01

    Selectivity of the primary chemical events induced by ionizing radiation in molecular systems is the key issue of basic radiation chemistry, which is crucially important for controlling the radiation sensitivity of various-type organic and polymeric materials and designing new effective approaches to the radiation modification. In the past decade we have demonstrated that many features of selective localization of the radiation-induced effects in molecular solids can be understood on the basis of model studies of the primary ionized molecules in rigid low-temperature matrices. This talk will outline the key results of these studies and possible implications for radiation chemistry of vatious systems. In particular, the following aspects will be considered: (1) Spectroscopic characteristics of ustable ionized molecules in low-temperature matrices and their correlations with the site-selective reactivity. (2) Experimental modeling of the effect of excess energy on the properties of primary ionized molecules in condensed phases. (3) Intramolecular long-range effects with particular impact on the properties of ionized bifunctional molecules of X-(CH 2 ) n -X and X-(CH 2 ) n -Y types. (4) Modeling of intermolecular long-range positive hole transfer between molecular traps with close ionization energy and manifestations of 'fine tuning' effects resulting from conformation variations and intermolecular interactions. Several illustrative examples of correlation between the properties of primary ionized molecules and selectivity of the radiation-chemical transformations in organic solids and macromolecules will be presented. Finally, the problem of prediction of the radiation-chemical behaviour of complex organic systems on the basis of limited spectroscopic information and quantum-chemical data obtained for model systems will be addressed. This work was supported by the Russian Foundation for Basic Research (Project No. 06-03-33104) and the Russian Academy of Sciences

  6. Solvation study of the non-specific lipid transfer protein from wheat by intermolecular NOEs with water and small organic molecules

    Liepinsh, Edvards; Sodano, Patrick; Tassin, Severine; Marion, Didier; Vovelle, Francoise; Otting, Gottfried

    1999-01-01

    Intermolecular nuclear Overhauser effects (NOEs) were measured between the protons of various small solvent or gas molecules and the non-specific lipid transfer protein (ns-LTP) from wheat. Intermolecular NOEs were observed with the hydrophobic pocket in the interior of wheat ns-LTP, which grew in intensity in the order cyclopropane (saturated solution) < methane (140 bar) < ethane (40 bar) < acetonitrile (5% in water) < cyclohexane (saturated solution) < benzene (saturated solution). No intermolecular NOEs were observed with dioxane (5% in water). The intermolecular NOEs were negative for all of the organic molecules tested. Intermolecular NOEs between wheat ns-LTP and water were weak or could not be distinguished from exchange-relayed NOEs. As illustrated by the NOEs with cyclohexane versus dioxane, the hydrophobic pocket in wheat ns-LTP preferably binds non-polar molecules. Yet, polar molecules like acetonitrile can also be accommodated. The pressure dependence of the NOEs between methane and wheat ns-LTP indicated incomplete occupancy, even at 190 bar methane pressure. In general, NOE intensities increased with the size of the ligand molecule and its vapor pressure. NMR of the vapor phase showed excellent resolution between the signals from the gas phase and those from the liquid phase. The vapor concentration of cyclohexane was fivefold higher than that of the dioxane solution, supporting the binding of cyclohexane versus uptake of dioxane

  7. Gas Chromatographic-Ion Trap Mass Spectrometric Analysis of Volatile Organic Compounds by Ion-Molecule Reactions Using the Electron-Deficient Reagent Ion CCl{3/+}

    Wang, Cheng-Zhong; Su, Yue; Wang, Hao-Yang; Guo, Yin-Long

    2011-10-01

    When using tetrachloromethane as the reagent gas in gas chromatography-ion trap mass spectrometry equipped with hybrid ionization source, the cation CCl{3/+} was generated in high abundance and further gas-phase experiments showed that such an electron-deficient reagent ion CCl{3/+} could undergo interesting ion-molecule reactions with various volatile organic compounds, which not only present some informative gas-phase reactions, but also facilitate qualitative analysis of diverse volatile compounds by providing unique mass spectral data that are characteristic of particular chemical structures. The ion-molecule reactions of the reagent ion CCl{3/+} with different types of compounds were studied, and results showed that such reactions could give rise to structurally diagnostic ions, such as [M + CCl3 - HCl]+ for aromatic hydrocarbons, [M - OH]+ for saturated cyclic ether, ketone, and alcoholic compounds, [M - H]+ ion for monoterpenes, M·+ for sesquiterpenes, [M - CH3CO]+ for esters, as well as the further fragment ions. The mechanisms of ion-molecule reactions of aromatic hydrocarbons, aliphatic ketones and alcoholic compounds with the reagent ion CCl{3/+} were investigated and proposed according to the information provided by MS/MS experiments and theoretical calculations. Then, this method was applied to study volatile organic compounds in Dendranthema indicum var. aromaticum and 20 compounds, including monoterpenes and their oxygen-containing derivatives, aromatic hydrocarbon and sesquiterpenes were identified using such ion-molecule reactions. This study offers a perspective and an alternative tool for the analysis and identification of various volatile compounds.

  8. The Identification of Complex Organic Molecules in the Interstellar Medium: Using Lasers and Matrix Isolation Spectroscopy to Simulate the Interstellar Environment

    Stone, Bradley M.

    1998-01-01

    The Astrochemistry Group at NASA Ames Research Center is interested in the identification of large organic molecules in the interstellar medium Many smaller organic species (e.g. hydrocarbons, alcohols, etc.) have been previously identified by their radiofrequency signature due to molecular rotations. However, this becomes increasingly difficult to observe as the size of the molecule increases. Our group in interested in the identification of the carriers of the Diffuse Interstellar Bands (absorption features observed throughout the visible and near-infrared in the spectra of stars, due to species in the interstellar medium). Polycyclic Aromatic Hydrocarbons (PAHs) and related molecules are thought to be good candidates for these carriers. Laboratory experiments am performed at Ames to simulate the interstellar environment, and to compare spectra obtained from molecules in the laboratory to those derived astronomically. We are also interested in PAHs with respect to their possible connection to the UIR (Unidentified infrared) and ERE (Extended Red Emission) bands - emission features found to emanate from particular regions of our galaxy (e.g. Orion nebula, Red Rectangle, etc.). An old, "tried and proven spectroscopic technique, matrix isolation spectroscopy creates molecular conditions ideal for performing laboratory astrophysics.

  9. Linear and nonlinear relationships between biodegradation potential and molecular descriptors/fragments for organic pollutants and a theoretical interpretation

    He, Jia; Qin, Weichao; Zhang, Xujia; Wen, Yang; Su, Limin; Zhao, Yuanhui

    2013-01-01

    Prediction of the biodegradability of organic pollutants is an ecologically desirable and economically feasible tool for estimating the environmental fate of chemicals. In this paper, linear and nonlinear relationships between biological oxygen demand (BOD) and molecular descriptors/fragments have been investigated for 1130 organic chemicals. Significant relationships have been observed between the simple molecular descriptors and %BOD for some homologous compounds, but not for the whole set of compounds. Electronic parameters, such as E HOMO and E LUMO , are the dominant factors affecting the biodegradability for some homologous chemicals. However, other descriptors, such as molecular weight, acid dissociation constant and polarity still have a significant impact on the biodegradation. The best global model for %BOD prediction is that developed from a chain-based fragmentation scheme. At the same time, the theoretical relationship between %BOD and molecular descriptors/fragments has been investigated, based on a first-order kinetic process. The %BOD is nonlinearly, rather than linearly, related to the descriptors. The coefficients of determination can be significantly improved by using nonlinear models for the homologous compounds and the whole data set. After analysing 1130 ready and not ready biodegradable compounds using 23 simple descriptors and various fragmentation schemes, it was revealed that biodegradation could be well predicted from a chain-based fragmentation scheme, a decision tree and a %BOD model. The models were capable of separating NRB and RB with an overall accuracy of 87.2%, 83.0% and 82.5%, respectively. The best classification model developed was a chain-based model but it used 155 fragments. The simplest model was a decision tree which only used 10 structural fragments. The effect of structures on the biodegradation has been analysed and the biodegradation pathway and mechanisms have been discussed based on activating and inactivating

  10. Structural, Spectroscopic (FT-IR, Raman and NMR, Non-linear Optical (NLO, HOMO-LUMO and Theoretical (DFT/CAM-B3LYP Analyses of N-Benzyloxycarbonyloxy-5-Norbornene-2,3-Dicarboximide Molecule

    Nuri ÖZTÜRK

    2018-02-01

    Full Text Available The experimental spectroscopic investigation of N-benzyloxycarbonyloxy-5-norbornene-2,3-dicarboximide (C17H15NO5 molecule has been done using 1H and 13C NMR chemical shifts, FT-IR and Raman spectroscopies. Conformational forms have been determined depending on orientation of N-benzyloxycarbonyloxy and 5-norbornene-2,3-dicarboximide (NDI groups of the title compound. The structural geometric optimizations, vibrational wavenumbers, NMR chemical shifts (in vacuum and chloroform and HOMO-LUMO analyses for all conformers of the title molecule have been done with DFT/CAM-B3LYP method at the 6-311++G(d,p basis set. Additionally, based on the calculated HOMO and LUMO energy values, some molecular properties such as ionization potential (I, electron affinity (A, electronegativity (χ, chemical hardness (h, chemical softness (z, chemical potential (μ and electrophilicity index (w parameters are determined for all conformers. The non-linear optical (NLO properties have been studied for the title molecule. We can say that the experimental spectral data are in accordance with calculated values.

  11. Association between resting-state brain network topological organization and creative ability: Evidence from a multiple linear regression model.

    Jiao, Bingqing; Zhang, Delong; Liang, Aiying; Liang, Bishan; Wang, Zengjian; Li, Junchao; Cai, Yuxuan; Gao, Mengxia; Gao, Zhenni; Chang, Song; Huang, Ruiwang; Liu, Ming

    2017-10-01

    Previous studies have indicated a tight linkage between resting-state functional connectivity of the human brain and creative ability. This study aimed to further investigate the association between the topological organization of resting-state brain networks and creativity. Therefore, we acquired resting-state fMRI data from 22 high-creativity participants and 22 low-creativity participants (as determined by their Torrance Tests of Creative Thinking scores). We then constructed functional brain networks for each participant and assessed group differences in network topological properties before exploring the relationships between respective network topological properties and creative ability. We identified an optimized organization of intrinsic brain networks in both groups. However, compared with low-creativity participants, high-creativity participants exhibited increased global efficiency and substantially decreased path length, suggesting increased efficiency of information transmission across brain networks in creative individuals. Using a multiple linear regression model, we further demonstrated that regional functional integration properties (i.e., the betweenness centrality and global efficiency) of brain networks, particularly the default mode network (DMN) and sensorimotor network (SMN), significantly predicted the individual differences in creative ability. Furthermore, the associations between network regional properties and creative performance were creativity-level dependent, where the difference in the resource control component may be important in explaining individual difference in creative performance. These findings provide novel insights into the neural substrate of creativity and may facilitate objective identification of creative ability. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Microbial respiration, but not biomass, responded linearly to increasing light fraction organic matter input: Consequences for carbon sequestration.

    Rui, Yichao; Murphy, Daniel V; Wang, Xiaoli; Hoyle, Frances C

    2016-10-18

    Rebuilding 'lost' soil carbon (C) is a priority in mitigating climate change and underpinning key soil functions that support ecosystem services. Microorganisms determine if fresh C input is converted into stable soil organic matter (SOM) or lost as CO 2 . Here we quantified if microbial biomass and respiration responded positively to addition of light fraction organic matter (LFOM, representing recent inputs of plant residue) in an infertile semi-arid agricultural soil. Field trial soil with different historical plant residue inputs [soil C content: control (tilled) = 9.6 t C ha -1 versus tilled + plant residue treatment (tilled + OM) = 18.0 t C ha -1 ] were incubated in the laboratory with a gradient of LFOM equivalent to 0 to 3.8 t C ha -1 (0 to 500% LFOM). Microbial biomass C significantly declined under increased rates of LFOM addition while microbial respiration increased linearly, leading to a decrease in the microbial C use efficiency. We hypothesise this was due to insufficient nutrients to form new microbial biomass as LFOM input increased the ratio of C to nitrogen, phosphorus and sulphur of soil. Increased CO 2 efflux but constrained microbial growth in response to LFOM input demonstrated the difficulty for C storage in this environment.

  13. Remarkable Enhancement of the Hole Mobility in Several Organic Small-Molecules, Polymers, and Small-Molecule:Polymer Blend Transistors by Simple Admixing of the Lewis Acid p-Dopant B(C6F5)3.

    Panidi, Julianna; Paterson, Alexandra F; Khim, Dongyoon; Fei, Zhuping; Han, Yang; Tsetseris, Leonidas; Vourlias, George; Patsalas, Panos A; Heeney, Martin; Anthopoulos, Thomas D

    2018-01-01

    Improving the charge carrier mobility of solution-processable organic semiconductors is critical for the development of advanced organic thin-film transistors and their application in the emerging sector of printed electronics. Here, a simple method is reported for enhancing the hole mobility in a wide range of organic semiconductors, including small-molecules, polymers, and small-molecule:polymer blends, with the latter systems exhibiting the highest mobility. The method is simple and relies on admixing of the molecular Lewis acid B(C 6 F 5 ) 3 in the semiconductor formulation prior to solution deposition. Two prototypical semiconductors where B(C 6 F 5 ) 3 is shown to have a remarkable impact are the blends of 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene:poly(triarylamine) (diF-TESADT:PTAA) and 2,7-dioctyl[1]-benzothieno[3,2-b][1]benzothiophene:poly(indacenodithiophene-co-benzothiadiazole) (C8-BTBT:C16-IDTBT), for which hole mobilities of 8 and 11 cm 2 V -1 s -1 , respectively, are obtained. Doping of the 6,13-bis(triisopropylsilylethynyl)pentacene:PTAA blend with B(C 6 F 5 ) 3 is also shown to increase the maximum hole mobility to 3.7 cm 2 V -1 s -1 . Analysis of the single and multicomponent materials reveals that B(C 6 F 5 ) 3 plays a dual role, first acting as an efficient p-dopant, and secondly as a microstructure modifier. Semiconductors that undergo simultaneous p-doping and dopant-induced long-range crystallization are found to consistently outperform transistors based on the pristine materials. Our work underscores Lewis acid doping as a generic strategy towards high performance printed organic microelectronics.

  14. Remarkable Enhancement of the Hole Mobility in Several Organic Small‐Molecules, Polymers, and Small‐Molecule:Polymer Blend Transistors by Simple Admixing of the Lewis Acid p‐Dopant B(C6F5)3

    Panidi, Julianna; Paterson, Alexandra F.; Khim, Dongyoon; Fei, Zhuping; Han, Yang; Tsetseris, Leonidas; Vourlias, George; Patsalas, Panos A.; Heeney, Martin

    2017-01-01

    Abstract Improving the charge carrier mobility of solution‐processable organic semiconductors is critical for the development of advanced organic thin‐film transistors and their application in the emerging sector of printed electronics. Here, a simple method is reported for enhancing the hole mobility in a wide range of organic semiconductors, including small‐molecules, polymers, and small‐molecule:polymer blends, with the latter systems exhibiting the highest mobility. The method is simple and relies on admixing of the molecular Lewis acid B(C6F5)3 in the semiconductor formulation prior to solution deposition. Two prototypical semiconductors where B(C6F5)3 is shown to have a remarkable impact are the blends of 2,8‐difluoro‐5,11‐bis(triethylsilylethynyl)anthradithiophene:poly(triarylamine) (diF‐TESADT:PTAA) and 2,7‐dioctyl[1]‐benzothieno[3,2‐b][1]benzothiophene:poly(indacenodithiophene‐co‐benzothiadiazole) (C8‐BTBT:C16‐IDTBT), for which hole mobilities of 8 and 11 cm2 V−1 s−1, respectively, are obtained. Doping of the 6,13‐bis(triisopropylsilylethynyl)pentacene:PTAA blend with B(C6F5)3 is also shown to increase the maximum hole mobility to 3.7 cm2 V−1 s−1. Analysis of the single and multicomponent materials reveals that B(C6F5)3 plays a dual role, first acting as an efficient p‐dopant, and secondly as a microstructure modifier. Semiconductors that undergo simultaneous p‐doping and dopant‐induced long‐range crystallization are found to consistently outperform transistors based on the pristine materials. Our work underscores Lewis acid doping as a generic strategy towards high performance printed organic microelectronics. PMID:29375962

  15. Remarkable Enhancement of the Hole Mobility in Several Organic Small-Molecules, Polymers, and Small-Molecule:Polymer Blend Transistors by Simple Admixing of the Lewis Acid p-Dopant B(C6F5)3

    Panidi, Julianna; Paterson, Alexandra F.; Khim, Dongyoon; Fei, Zhuping; Han, Yang; Tsetseris, Leonidas; Vourlias, George; Patsalas, Panos A.; Heeney, Martin; Anthopoulos, Thomas D.

    2017-01-01

    Improving the charge carrier mobility of solution-processable organic semiconductors is critical for the development of advanced organic thin-film transistors and their application in the emerging sector of printed electronics. Here, a simple method is reported for enhancing the hole mobility in a wide range of organic semiconductors, including small-molecules, polymers, and small-molecule:polymer blends, with the latter systems exhibiting the highest mobility. The method is simple and relies on admixing of the molecular Lewis acid B(C6F5)(3) in the semiconductor formulation prior to solution deposition. Two prototypical semiconductors where B(C6F5)(3) is shown to have a remarkable impact are the blends of 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene:poly(triarylamine) (diF-TESADT:PTAA) and 2,7-dioctyl[1]-benzothieno[3,2-b][1]benzothiophene:poly(indacenodithiophene-co-benzothiadiazole) (C8-BTBT:C16-IDTBT), for which hole mobilities of 8 and 11 cm(2) V-1 s(-1), respectively, are obtained. Doping of the 6,13-bis(triisopropylsilylethynyl)pentacene:PTAA blend with B(C6F5)(3) is also shown to increase the maximum hole mobility to 3.7 cm(2) V-1 s(-1). Analysis of the single and multicomponent materials reveals that B(C6F5)(3) plays a dual role, first acting as an efficient p-dopant, and secondly as a microstructure modifier. Semiconductors that undergo simultaneous p-doping and dopant-induced long-range crystallization are found to consistently outperform transistors based on the pristine materials. Our work underscores Lewis acid doping as a generic strategy towards high performance printed organic microelectronics.

  16. Remarkable Enhancement of the Hole Mobility in Several Organic Small-Molecules, Polymers, and Small-Molecule:Polymer Blend Transistors by Simple Admixing of the Lewis Acid p-Dopant B(C6F5)3

    Panidi, Julianna

    2017-10-05

    Improving the charge carrier mobility of solution-processable organic semiconductors is critical for the development of advanced organic thin-film transistors and their application in the emerging sector of printed electronics. Here, a simple method is reported for enhancing the hole mobility in a wide range of organic semiconductors, including small-molecules, polymers, and small-molecule:polymer blends, with the latter systems exhibiting the highest mobility. The method is simple and relies on admixing of the molecular Lewis acid B(C6F5)(3) in the semiconductor formulation prior to solution deposition. Two prototypical semiconductors where B(C6F5)(3) is shown to have a remarkable impact are the blends of 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene:poly(triarylamine) (diF-TESADT:PTAA) and 2,7-dioctyl[1]-benzothieno[3,2-b][1]benzothiophene:poly(indacenodithiophene-co-benzothiadiazole) (C8-BTBT:C16-IDTBT), for which hole mobilities of 8 and 11 cm(2) V-1 s(-1), respectively, are obtained. Doping of the 6,13-bis(triisopropylsilylethynyl)pentacene:PTAA blend with B(C6F5)(3) is also shown to increase the maximum hole mobility to 3.7 cm(2) V-1 s(-1). Analysis of the single and multicomponent materials reveals that B(C6F5)(3) plays a dual role, first acting as an efficient p-dopant, and secondly as a microstructure modifier. Semiconductors that undergo simultaneous p-doping and dopant-induced long-range crystallization are found to consistently outperform transistors based on the pristine materials. Our work underscores Lewis acid doping as a generic strategy towards high performance printed organic microelectronics.

  17. Toward Additive-Free Small-Molecule Organic Solar Cells: Roles of the Donor Crystallization Pathway and Dynamics

    Abdelsamie, Maged

    2015-09-29

    The ease with which small-molecule donors crystallize during solution processing is directly linked to the need for solvent additives. Donor molecules that get trapped in disordered (H1) or liquid crystalline (T1) mesophases require additive processing to promote crystallization, phase separation, and efficient light harvesting. A donor material (X2) that crystallizes directly from solution yields additive-free solar cells with an efficiency of 7.6%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Organic extract of diesel exhaust particles stimulates expression of Ia and costimulatory molecules associated with antigen presentation in rat peripheral blood monocytes but not in alveolar macrophages

    Koike, Eiko; Kobayashi, Takahiro

    2005-01-01

    We hypothesized that diesel exhaust particles (DEP) induce the activation of antigen-presenting cells (APC) in lung. The present study was designed to clarify the following about DEP: (1) whether it affects the expression of Ia and B7 molecules in alveolar macrophages (AM) as a mature cell or in peripheral blood monocytes (PBM) as an immature cell (2) if it affects the antigen-presenting (AP) activity of PBM (3) what component of DEP is responsible for the effects, and (4) whether the effect of DEP is related to oxidative stress. DEP was extracted with methylene chloride. Cells were exposed to whole DEP, organic extract, or residual particles for 24 h. Cell-surface molecules were measured by flow cytometry. AP activity was assessed by antigen-specific T cell proliferation. Whole DEP or organic extract significantly increased the expression of Ia and B7 molecules on PBM but not on AM. No significant effect of residual particles was observed. A low concentration of organic extract also increased the AP activity of PBM. When the induction of an antioxidative enzyme was assessed, heme oxygenase-1 protein was found to be significantly increased by exposure to whole DEP, and the organic extract was more effective than the residual particles. Furthermore, the organic extract-induced expression of Ia antigen on PBM was reduced by the addition of an antioxidative agent. These results suggest that DEP may act on immature APC and enhance their AP activity and that the action contributing to oxidative stress may be mediated by organic compounds of DEP

  19. The tritium labelling of organic molecules by heterogeneous catalytic exchange; El marcado de moleculas organicas con tritio por intercambio catalitico heterogeneo

    Angoso Marina, M; Kaiser Ruiz del Olmo, F.

    1977-07-01

    The influence of the temperature at 65 degree centigree and 120 degree centigree on the labelling of three organic molecules with tritium was studied. The compounds were: benzoic acid, de phenyl glyoxal and 2,3-tetramethylene-4-pantothenyl-7-oxo diacetin.The method employed was the heterogeneous catalytic exchange between tritiated water and the organic compound. The purification was made by thin-layer chromatography and the concentration, purity and specific activity of the products were determined by counting and ultraviolet techniques. The thermal stability and the radiolytic effects on labelled benzoic acid were also considered. (Author) 9 refs.

  20. Solution-processed small molecule-polymer blend organic thin-film transistors with hole mobility greater than 5 cm 2/Vs

    Smith, Jeremy N.

    2012-04-10

    Using phase-separated organic semiconducting blends containing a small molecule, as the hole transporting material, and a conjugated amorphous polymer, as the binder material, we demonstrate solution-processed organic thin-film transistors with superior performance characteristics that include; hole mobility >5 cm 2/Vs, current on/off ratio ≥10 6 and narrow transistor parameter spread. These exceptional characteristics are attributed to the electronic properties of the binder polymer and the advantageous nanomorphology of the blend film. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.