Effect of diblock copolymer properties on the photophysical properties of dendrimer silicon phthalocyanine nanoconjugates

Energy Technology Data Exchange (ETDEWEB)

Chen, Kuizhi [Fujian Normal University, College of Materials Science & Engineering, Fujian Provincial Key Laboratory of Polymer Materials (China); Pan, Sujuan [Fujian Normal University, College of Chemistry & Engineering (China); Zhuang, Xuemei [Fuzhou No.2 Hospital (China); Lv, Hafei; Que, Shoulin [Fujian Normal University, College of Chemistry & Engineering (China); Xie, Shusen; Yang, Hongqin, E-mail: hqyang@fjnu.edu.cn [Fujian Normal University, Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education (China); Peng, Yiru, E-mail: yirupeng@fjnu.edu.cn [Fujian Normal University, College of Chemistry & Engineering (China)

2016-07-15

1–2 generation poly(benzyl aryl ether) dendrimer silicon phthalocyanines with axially disubstituted cyano terminal functionalities (G{sub n}-DSiPc(CN){sub 4n}, (G{sub n} = n-generation dendrimer, n = 1–2)) were synthesized. Their structures were characterized by elemental analysis, IR, {sup 1}H NMR, and ESI-MS. Polymeric nanoparticles (G{sub n}-DSiPc(CN){sub 4n}/m) were formed through encapsulating G{sub n}-DSiPc(CN){sub 4n} into three monomethoxyl poly(ethylene glycol)-poly(ε-caprolactone) diblock copolymers (MPEG–PCL) with different hydrophilic/hydrophobic proportion, respectively. The effect of dendritic generation and the hydrophilic/hydrophobic proportion of diblock copolymers on the UV/Vis and fluorescence spectra of G{sub n}-DSiPc(CN){sub 4n} and G{sub n}-DSiPc(CN){sub 4n}/m were studied. The photophysical properties of polymeric nanoparticles exhibited dendritic generation and hydrophilic/hydrophobic proportion dependence. The fluorescence intensities and lifetimes of G{sub n}-DSiPc(CN){sub 4n}/m were lower than the corresponding free dendrimer phthalocyanines. G{sub n}-DSiPc(CN){sub 4n} encapsulated into MPEG–PCL with hydrophilic/hydrophobic molecular weight ratio 2000:4000 exhibited excellent photophysical property. The mean diameter of MPEG{sub 2000}–PCL{sub 2000} micelles was about 70 nm, which decreased when loaded with G{sub n}-DSiPc(CN){sub 4n}.Graphical abstract .

Enhancing photophysical and photochemical properties of zinc(II) phthalocyanine dyes by substitution of triptycene moieties

Energy Technology Data Exchange (ETDEWEB)

Al-Sohaimi, Bander Roshadan [Department of Chemistry, Faculty of Science, Taibah University, P.O. Box 344, Al-Madinah Al Munawwrah (Saudi Arabia); Pişkin, Mehmet [Çanakkale Onsekiz Mart University, Vocational School of Technical Sciences, Department of Food Technology, Çanakkale 17100 (Turkey); Aljuhani, Ateyatallah; Al-Raqa, Shaya Y. [Department of Chemistry, Faculty of Science, Taibah University, P.O. Box 344, Al-Madinah Al Munawwrah (Saudi Arabia); Durmuş, Mahmut, E-mail: durmus@gtu.edu.tr [Gebze Technical University, Department of Chemistry, P.O. Box 141, Gebze 41400, Kocaeli (Turkey)

2016-05-15

The symmetrical zinc(II) phthalocyanines conjugated with 9,10-dioctyl-6,7-dimethoxy-2,3-dioxytriptycene or 9,10-diundecyl-6,7-dimethoxy-2,3-dioxytriptycene moieties were synthesized in this study. These novel phthalocyanines were characterized by standard characterization techniques such as {sup 1}H-NMR, FT-IR, UV–vis, Mass and Elemental Analysis. All these phthalocyanines showed highly solubility and formed non-aggregated monomeric species in most of the organic solvents. Their photochemical properties such as singlet oxygen, and photodegradation quantum yields, and photophysical properties including fluorescence quantum yields and lifetimes were investigated in toluene. The fluorescence quenching behavior of the studied zinc(II) phthalocyanines by the addition of 1,4-benzoquinone were also described in toluene.

Enhancing photophysical and photochemical properties of zinc(II) phthalocyanine dyes by substitution of triptycene moieties

International Nuclear Information System (INIS)

Al-Sohaimi, Bander Roshadan; Pişkin, Mehmet; Aljuhani, Ateyatallah; Al-Raqa, Shaya Y.; Durmuş, Mahmut

2016-01-01

The symmetrical zinc(II) phthalocyanines conjugated with 9,10-dioctyl-6,7-dimethoxy-2,3-dioxytriptycene or 9,10-diundecyl-6,7-dimethoxy-2,3-dioxytriptycene moieties were synthesized in this study. These novel phthalocyanines were characterized by standard characterization techniques such as 1 H-NMR, FT-IR, UV–vis, Mass and Elemental Analysis. All these phthalocyanines showed highly solubility and formed non-aggregated monomeric species in most of the organic solvents. Their photochemical properties such as singlet oxygen, and photodegradation quantum yields, and photophysical properties including fluorescence quantum yields and lifetimes were investigated in toluene. The fluorescence quenching behavior of the studied zinc(II) phthalocyanines by the addition of 1,4-benzoquinone were also described in toluene.

Photophysical properties of chirality: Experimental and theoretical studies of (R)- and (S)-binaphthol derivatives as a prototype case

International Nuclear Information System (INIS)

Tsuboi, Taiju; An, Zhong-fu; Nakai, Yosuke; Yin, Jun; Chen, Run-feng; Shi, Hui-fang; Huang, Wei

2013-01-01

Highlights: ► The effect of chirality on photophysical properties was investigated. ► The same photophysics of enantiomers was observed in solutions. ► But different photoluminescent efficiency and lifetime were found in neat film. ► The different symmetry and formation probability of dimmers may be the main reason. ► The joint experimental and theoretical study explains these differences well. - Abstract: The key monomers of binaphthol-based chiral materials, (R)- and (S)- 6,6′-dibromo-2,2′-bis(octyloxy)- 1,1′-binaphthyl (R–M and S–M, respectively), were synthesized and characterized by UV–vis absorption spectra, circular dichroism (CD) spectra, photoluminescence (PL) lifetime, PL quantum efficiency at room temperature, together with PL spectra at various temperatures between 12 K and 296 K in both film and solution. The photophysical properties of R–M and S–M were investigated in detail with a joint experimental and theoretical study, in order to reveal the effects of chirality on the π-conjugated chiral systems. Higher photoluminescent quantum efficiency and better PL spectra purity in solid film of R–M were observed and discussed

Spectroscopic and nonlinear photophysical characterization of organic octupolar-compounds supported by anodic-alumina nanotube-arrays

International Nuclear Information System (INIS)

Morales-Saavedra, O.G.; Ontiveros-Barrera, F.G.; Hennrich, G.; Mata-Zamora, M.E.; Rodriguez-Rosales, A.A.; Banuelos, J.G.

2011-01-01

Highlights: → Preparation of organic-inorganic nanostructured hybrid materials. → Insertion of octupolar compounds in alumina nanotube arrays. → Linear and nonlinear photophysical characterization of solid-state hybrid structures. → Fabrication of photonic materials. - Abstract: Amorphous anodic alumina membranes (AAM) comprising highly ordered nanometric porous arrays (porous anodic aluminas: PAA) with 1D-nanotube dimensions of ∼75 nm in diameter and 45 microns in depth were successfully prepared and used as nanostructured host networks for different functionalized octupolar chromophores (named here Oct-(n)). Atomic force microscopy (AFM) studies performed on the developed hybrid systems confirmed a homogeneous insertion of these organic molecules into the PAA nanotube-arrays. Samples with high structural quality were selected for several photophysical characterizations: Comprehensive X-ray diffraction (XRD) and optical spectroscopic characterizations performed according to UV-vis absorption, photoluminescent (PL) and Raman measurements revealed the structural and optical performance of these molecules within the PAA-confinement. Since the implemented optical chromophores were specifically functionalized for nonlinear optical (NLO) applications, the obtained Oct-(n)/PAA-based amorphous hybrids were also characterized according to cubic NLO-techniques such as third harmonic generation (THG) and the Z-Scan method. PAA-confined octupolar chromophores have shown interesting linear and NLO optical properties which have not yet been intensively investigated in bulk hybrid systems; hence, the obtained hybrid nanostructures represent a promising field of investigation in the route to functional octupolar-based materials, where different self-assembled molecular structures may be formed, giving rise to enhanced linear and NLO-properties.

Synthesis of novel styryl derivatives from 4-chloro-2-(morpholin-4-yl)-1,3-thiazole-5-carbaldehyde, study of their photophysical properties and TD-DFT computations

International Nuclear Information System (INIS)

Sekar, Nagaiyan; Umape, Prashant G.; Padalkar, Vikas S.; Tayade, Rajratna P.; Ramasami, Ponnadurai

2014-01-01

Novel fluorescent styryl push–pull compounds having electron donating thiazole unit were synthesized by condensing 4-chloro-2-(morpholin-4-yl)-1,3-thiazole-5-carbaldehyde with active methylene compounds via classical Knoevenagel condensation. The synthesized styryl molecules were characterized by spectral analysis. Photophysical properties of these styryl derivatives were analyzed and the effect of change in solvent polarity and viscosity on their absorptive and emissive properties has been investigated. Density functional theory (DFT) and time dependent-density functional theory (TD-DFT) computations have been used to understand the structural, molecular, electronic and photophysical parameters of push–pull dyes. Bakhshiev and Kawski–Chamma–Viallet correlations were used to calculate the ratio of ground to excited state dipole moment of the synthesized novel styryl compounds. -- Highlights: •Novel styryl derivatives are synthesized from thiazole aldehyde. •Photophysical properties of styryl derivatives were evaluated and supported by TD-DFT computations. •Experimental photophysical results are in good agreement with the theoretical results obtained by TD-DFT computations. •Compounds show fluorescence in solid state as well as in solvents of different polarities

Synthesis and photophysical properties of a series of cyclopenta[b]naphthalene solvatochromic fluorophores.

Science.gov (United States)

Benedetti, Erica; Kocsis, Laura S; Brummond, Kay M

2012-08-01

The synthesis and photophysical properties of a series of naphthalene-containing solvatochromic fluorophores are described within. These novel fluorophores are prepared using a microwave-assisted dehydrogenative Diels-Alder reaction of styrene, followed by a palladium-catalyzed cross coupling reaction to install an electron donating amine group. The new fluorophores are structurally related to Prodan. Photophysical properties of the new fluorophores were studied and intriguing solvatochromic behavior was observed. For most of these fluorophores, high quantum yields (60-99%) were observed in methylene chloride in addition to large Stokes shifts (95-226 nm) in this same solvent. As the solvent polarity increased, so did the observed Stokes shift with one derivative displaying a Stokes shift of ~300 nm in ethanol. All fluorophore emission maxima, and nearly all absorption maxima were significantly red-shifted when compared to Prodan. Shifting the absorption and emission maxima of a fluorophore into the visible region increases its utility in biological applications. Moreover, the cyclopentane portion of the fluorophore structure provides an attachment point for biomolecules that will minimize disruptions of the photophysical properties.

Analysis of the photophysical properties of zearalenone using density functional theory

Science.gov (United States)

The intrinsic photophysical properties of the resorcylic acid moiety of zearalenone offer a convenient label free method to determine zearalenone levels in contaminated agricultural products. Density functional theory and steady-state fluorescence methods were applied to investigate the role of stru...

Rationalizing substituent effects in 1-azathioxanthone photophysics

Science.gov (United States)

Junker, Anne Kathrine R.; Just Sørensen, Thomas

2018-01-01

The influence of an electron donating substituent on the photophysical properties of 1-azathioxanthone dyes has been investigated using optical spectroscopy and theoretical models. The motivation behind the study is based on the fact that thioxanthones are efficient triplet sensitizers, and thus promising sensitizers for lanthanide centered emission. By adding an aza group to one of the phenyl ring systems, direct coordination to a lanthanide center becomes possible, which makes azathoixanthones great candidates as antenna chromophores in lanthanide(III) based dyes. Here, three 1-azathioxanthone derivatives have been synthesized targeting efficient triplet formation following absorption in the visible range of the spectrum. This is achieved by adding methoxy groups to the 1-azathioxanthone core. The derivatives were characterized using absorption, emission, and time-gated emission spectroscopy, where fluorescent quantum yields, singlet and triplet excited states lifetimes were determined. The experimentally determined photophysical properties of the three 1-azathioxanthone compounds are contrasted to those of the parent thioxanthone and is rationalized using the Strickler-Berg equation, Hückel MO theory, and Dewar’s rules in combination with computational chemistry. We find that the transition energies follow predictions, but that the overall photophysical properties are determined by the relative energies as well as the nature of the involved states in both the singlet and the triplet excited state manifolds.

Synthesis, characterization, and photophysical properties of a thiophene-functionalized bis(pyrazolyl) pyridine (BPP) tricarbonyl rhenium(I) complex.

Science.gov (United States)

Lytwak, Lauren A; Stanley, Julie M; Mejía, Michelle L; Holliday, Bradley J

2010-09-07

A bromo tricarbonyl rhenium(I) complex with a thiophene-functionalized bis(pyrazolyl) pyridine ligand (L), ReBr(L)(CO)(3) (1), has been synthesized and characterized by variable temperature and COSY 2-D (1)H NMR spectroscopy, single-crystal X-ray diffraction, and photophysical methods. Complex 1 is highly luminescent in both solution and solid-state, consistent with phosphorescence from an emissive (3)MLCT excited state with an additional contribution from a LC (3)(pi-->pi*) transition. The single-crystal X-ray diffraction structure of the title ligand is also reported.

Physical and photophysical properties of mixed double- and triple-decker sandwiches of porphyrins and phthalocyanines

International Nuclear Information System (INIS)

Salabert, Isabelle

1995-01-01

The study of electron transfer and charge recombination processes in various oligomers of porphyrins and phthalocyanines is reported. Our objective is to determine the nature of processes which compete with electron transfer in such Systems. The first part of this thesis is devoted to the study of mixed double- and triple-decker sandwich compounds of porphyrins and phthalocyanines of cerium and praseodymium. The charge transfer reaction and geminated recombination from excited complexes in solution and in sublimated film are investigated by time-resolved absorption spectroscopy with femtosecond time scale resolution. These results show the influence of the magnetic nature of the metal ion and of the relative position of the chromophores in the complex on the photophysical processes. The physical and photophysical properties of complexes formed by pairing in solution porphyrins and porphyrazines bearing oppositely charged substituent are reported in the second part. The formation of mixed aggregates of high order (2 to 5) is observed and their nature are spectrally characterized. The photoproducts issued from these complexes are extremely stable. (author) [fr

The photophysical and photochemical properties of new unmetallated and metallated phthalocyanines bearing four 5-chloroquinolin-8-yloxy substituents on peripheral sites

Energy Technology Data Exchange (ETDEWEB)

Nas, Asiye; Demirbaş, Ümit [Department of Chemistry, Karadeniz Technical University, 61080 Trabzon (Turkey); Pişkin, Mehmet [Marmara University, Faculty of Art and Science, Department of Chemistry, 34722 Kadıkoy-Istanbul (Turkey); Durmuş, Mahmut [Gebze Institute of Technology, Department of Chemistry, PO Box 141, Gebze, 41400 Kocaeli (Turkey); Kantekin, Halit, E-mail: halit@ktu.edu.tr [Department of Chemistry, Karadeniz Technical University, 61080 Trabzon (Turkey)

2014-01-15

The synthesis and characterization of novel peripherally tetrakis-(5-chloroquinolin-8-yloxy) substituted metal-free (4), zinc(II) (5), lead(II) (6), cobalt(II) (7), copper(II) (8) and nickel(II) (9) phthalocyanines are described for the first time in this study. The spectroscopic, photophysical (fluorescence quantum yields and lifetimes) and photochemical properties (singlet oxygen production and photodegradation under light irradiation) of metal-free (4), zinc(II) (5) and lead(II) (6) phthalocyanines are investigated in N,N-dimetilformamid (DMF). The newly synthesized cobalt(II) (7), copper(II) (8) and nickel(II) (9) phthalocyanine compounds were not evaluated for this purpose due to open shell nature of these central metals in the phthalocyanine cavity. The influence of various the nature of the central metal ion (zinc, lead or without metal) on these properties has also been investigated and compared. -- Highlights: • The synthesis and characterization of novel peripherally tetrakis-(5-chloroquinolin-8-yloxy) substituted metal-free (4), zinc(II) (5), lead(II) (6), cobalt(II) (7), copper(II) (8) and nickel(II) (9) phthalocyanines. • The spectroscopic, photophysical (fluorescence quantum yields and lifetimes) and photochemical properties of metal-free (4), zinc(II) (5) and lead(II) (6)phthalocyanines in N, N-dimetilformamid (DMF). • The influence of various the nature of the central metal ion (zinc, lead or without metal) on these properties.

A novel chlorine derivative of Meso-tris(pentafluorophenyl)-4-pyridyl porphyrin: synthesis, photophysics and photochemical properties

Energy Technology Data Exchange (ETDEWEB)

Maestrin, Ana Paula J.; Ribeiro, Anderson O.; Tedesco, Antonio Claudio; Neri, Claudio R.; Vinhado, Fabio S.; Serra, Osvaldo A.; Martins, Patricia R.; Iamamoto, Yassuko [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Inst. de Quimica]. E-mail: oaserra@ffclrp.usp.br; Silva, Ana Margarida G.; Tome, Augusto C.; Neves, Maria G.P.M.S.; Cavaleiro, Jose A.S. [Universidade de Aveiro (Portugal). Dept. de Quimica]. E-mail: jcavaleiro@dq.ua.pt

2004-12-01

Photodynamic therapy (PDT) is based on the accumulation of a photosensitizer, such as a porphyrin or a chlorine, in a malignant tissue after its administration. Chlorins exhibit photophysical properties similar to those of the porphyrin macrocycles, but with intensified and red-shifted Q bands, making chlorine-containing systems even better candidates for PDT. In this contribution, we report the synthesis of 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin, (2) and its transformation to the novel chlorine derivatives 4, (5,10,20-tris(pentafluorophenyl)-15-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo [3,4-b]porphyrin and 5, (5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo[3,4-b]porphyrin) by 1,3-dipolar cycloaddition with an azomethine ylide. The new products have been characterized by UV-Vis, {sup 1}H NMR and FAB-MS. The photophysics, photochemical and photobleaching properties of chlorine 4 have been evaluated. Its quantum yield of photobleaching ({phi}{sub Pb}, mol Einstein{sup -1}) was 0.047{+-}0.014. In order to demonstrate the production of {sup 1}O{sub 2} when 4 is used as a photosensitizer, uric acid tests have been carried out. The results indicate that chlorine 4 can be considered a promising photosensitizer in PDT. (author)

A novel chlorine derivative of Meso-tris(pentafluorophenyl)-4-pyridyl porphyrin: synthesis, photophysics and photochemical properties

International Nuclear Information System (INIS)

Maestrin, Ana Paula J.; Ribeiro, Anderson O.; Tedesco, Antonio Claudio; Neri, Claudio R.; Vinhado, Fabio S.; Serra, Osvaldo A.; Martins, Patricia R.; Iamamoto, Yassuko; Silva, Ana Margarida G.; Tome, Augusto C.; Neves, Maria G.P.M.S.; Cavaleiro, Jose A.S.

2004-01-01

Photodynamic therapy (PDT) is based on the accumulation of a photosensitizer, such as a porphyrin or a chlorine, in a malignant tissue after its administration. Chlorins exhibit photophysical properties similar to those of the porphyrin macrocycles, but with intensified and red-shifted Q bands, making chlorine-containing systems even better candidates for PDT. In this contribution, we report the synthesis of 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin, (2) and its transformation to the novel chlorine derivatives 4, (5,10,20-tris(pentafluorophenyl)-15-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo [3,4-b]porphyrin and 5, (5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo[3,4-b]porphyrin) by 1,3-dipolar cycloaddition with an azomethine ylide. The new products have been characterized by UV-Vis, 1 H NMR and FAB-MS. The photophysics, photochemical and photobleaching properties of chlorine 4 have been evaluated. Its quantum yield of photobleaching (φ Pb , mol Einstein -1 ) was 0.047±0.014. In order to demonstrate the production of 1 O 2 when 4 is used as a photosensitizer, uric acid tests have been carried out. The results indicate that chlorine 4 can be considered a promising photosensitizer in PDT. (author)

Photophysics of organometallic platinum(II) derivatives of the diketopyrrolopyrrole chromophore

KAUST Repository

Goswami, Subhadip; Winkel, Russell W.; Alarousu, Erkki; Ghiviriga, Ion; Mohammed, Omar F.; Schanze, Kirk S.

2014-01-01

A pair of diketopyrrolopyrrole (DPP) chromophores that are end-functionalized with platinum containing "auxochromes" were subjected to electrochemical and photophysical study. The chromophores contain either platinum acetylide or ortho-metalated 2-thienylpyridinyl(platinum) end-groups (DPP-Pt(CC) and DPP-Pt(acac), respectively). The ground state redox potentials of the chromophores were determined by solution electrochemistry, and the HOMO and LUMO levels were estimated. The chromophores' photophysical properties were characterized by absorption, photoluminescence, and time-resolved absorption spectroscopy on time scales from sub-picoseconds to microseconds. Density functional theory (DFT) computations were performed to understand the molecular orbitals involved in both the singlet and triplet excited state photophysics. The results reveal that in both platinum DPP derivatives the organometallic auxochromes have a significant effect on the chromophores' photophysics. The most profound effect is a reduction in the fluorescence yields accompanied by enhanced triplet yields due to spin-orbit coupling induced by the metal centers. The effects are most pronounced in DPP-Pt(acac), indicating that the orthometalated platinum auxochrome is able to induce spin-orbital coupling to a greater extent compared to the platinum acetylide units. (Figure Presented).

Photophysics of organometallic platinum(II) derivatives of the diketopyrrolopyrrole chromophore

KAUST Repository

Goswami, Subhadip

2014-12-18

A pair of diketopyrrolopyrrole (DPP) chromophores that are end-functionalized with platinum containing "auxochromes" were subjected to electrochemical and photophysical study. The chromophores contain either platinum acetylide or ortho-metalated 2-thienylpyridinyl(platinum) end-groups (DPP-Pt(CC) and DPP-Pt(acac), respectively). The ground state redox potentials of the chromophores were determined by solution electrochemistry, and the HOMO and LUMO levels were estimated. The chromophores\\' photophysical properties were characterized by absorption, photoluminescence, and time-resolved absorption spectroscopy on time scales from sub-picoseconds to microseconds. Density functional theory (DFT) computations were performed to understand the molecular orbitals involved in both the singlet and triplet excited state photophysics. The results reveal that in both platinum DPP derivatives the organometallic auxochromes have a significant effect on the chromophores\\' photophysics. The most profound effect is a reduction in the fluorescence yields accompanied by enhanced triplet yields due to spin-orbit coupling induced by the metal centers. The effects are most pronounced in DPP-Pt(acac), indicating that the orthometalated platinum auxochrome is able to induce spin-orbital coupling to a greater extent compared to the platinum acetylide units. (Figure Presented).

N-2-Aryl-1,2,3-Triazoles: A novel class of blue–green emitting fluorophores-synthesis, photophysical properties study and dft computations

Energy Technology Data Exchange (ETDEWEB)

Padalkar, Vikas S.; Chemate, Santosh B.; Lanke, Sandip K.; Sekar, Nagaiyan, E-mail: n.sekar@ictmumbai.edu.in

2015-12-15

Three novel 2-{2-[4-(N,N-diethylamino)–2–hydroxyphenyl]–1H–benzo[d]imidazol–6–yl} –2H–naphtho [1,2-d] [1,2,3] fluorescent triazole derivatives were synthesized from 2-(5-amino-1H-benzimidazol-2-yl)-5-(N,N-diethylamino)phenol and amino substituted naphthylsulphonic acids. The absorption, emission, quantum yields and dipole moments of these compounds were evaluated in methanol, acetonitrile, N,N-dimethylformamide and dimethylsulfoxide. The compounds 8a and 8c absorb in the near visible region, while compound 8b shows two absorption peaks, short wavelength peak is in the near visible region and long wavelength absorption in the visible region. Compounds are fluorescent in solution and emit in blue and green region. The photophysical properties of the 8a–8c were compared with structural analogs reported till date. The experimental absorption and emission properties were compared with the theoretical data obtained by DFT and TD-DFT computations with TD–B3LYP and CAM–B3LYP functional with 6–31G (d) and 6–311G (d) basis sets. Theoretical results obtained by TD-B3LYP functional are well in line with the experimental results. The compounds are thermally stable up to 300 °C. New compounds were characterized by spectral techniques. - Highlights: • First unique study of blue-emitting ESIPT triazoles. • Improved photophysical properties compared to similar analogues. • Experimental and TDDFT data on photophysical properties. • Dipole moments from solvatochromic data.

The Gas-Phase Photophysics of Eosin Y and its Maleimide Conjugate.

Science.gov (United States)

Daly, Steven; Kulesza, Alexander; Knight, Geoffrey; MacAleese, Luke; Antoine, Rodolphe; Dugourd, Philippe

2016-05-26

The use of the xanthene family of dyes as fluorescent probes in a wide range of applications has provided impetus for the studying of their photophysical properties. In particular, recent advances in gas-phase techniques such as FRET that utilize such chromophores have placed a greater importance on the characterization of these properties in the gas phase. Additionally, the use of synthetic linker chains to graft the chromophores in a site-specific manner to their target system is ubiquitous. There is, however, often limited information on how the addition of such a linker chain may affect the photophysical properties of the chromophores, which is of fundamental importance for interpretation of experimental data reliant on grafted chromophores. Here, we present data on the optical spectroscopy of different protonation states of Eosin Y, a fluorescein derivative. We compare the photophysics of Eosin Y to its maleimide conjugate, and to the thioether product of the reaction of this conjugate with cysteamine. Comparison of the mass spectra following laser irradiation shows that very different relaxation takes place upon addition of the maleimide moiety but that the photophysics of the bare chromophore are restored upon addition of cysteamine. This radical change in the photophysics is interpreted in terms of charge-transfer states, whose energy relative to the S1 ← S0 transition of the chromophore is dependent on the conjugation of the maleimide moiety. We also show that the shape of the absorption band is unchanged in the gas-phase as compared to the solution-phase, showing a maximum with a shoulder toward the blue, and examination of isotope distributions of the isolated ions show that this shoulder cannot be due to the presence of dimers. Consideration of the fluorescence emission spectrum allows a tentative assignment of the shoulder to be due to a vibrational progression with a high Franck-Condon factor.

Photophysical properties of coumarin-120: Unusual behavior in nonpolar solvents

International Nuclear Information System (INIS)

Pal, Haridas; Nad, Sanjukta; Kumbhakar, Manoj

2003-01-01

Photophysical properties of coumarin-120 (C120; 7-amino-4-methyl-1,2-benzopyrone) dye have been investigated in different solvents using steady-state and time-resolved fluorescence and picosecond laser flash photolysis (LFP) and nanosecond pulse radiolysis (PR) techniques. C120 shows unusual photophysical properties in nonpolar solvents compared to those in other solvents of moderate to higher polarities. Where the Stokes shifts (Δν-bar=ν-bar abs -ν-bar fl ), fluorescence quantum yields (Φ f ), and fluorescence lifetimes (τ f ) show more or less linear correlation with the solvent polarity function Δf={(ε-1)/(2ε+1)-(n 2 -1)/(2n 2 +1)}, all these parameters are unusually lower in nonpolar solvents. Unlike in other solvents, both Φ f and τ f in nonpolar solvents are also strongly temperature dependent. It is indicated that the excited singlet (S 1 ) state of C120 undergoes a fast activation-controlled nonradiative deexcitation in nonpolar solvents, which is absent in all other solvents. LFP and PR studies indicate that the intersystem crossing process is negligible for the present dye in all the solvents studied. Photophysical behavior of C120 in nonpolar solvent has been rationalized assuming that in these solvents the dye exists in a nonpolar structure, with its 7-NH 2 group in a pyramidal configuration. In this structure, since the 7-NH 2 group is bonded to the 1,2-benzopyrone moiety by a single bond, the former group can undergo a fast flip-flop motion, which in effect causes the fast nonradiative deexcitation of the dye excited state. In moderate to higher polarity solvents, it is indicated that the dye exists in an intramolecular charge-transfer structure, where the bond between 7-NH 2 group and the 1,2-benzopyrone moiety attains substantial double bond character. In this structure, the flip-flop motion of the 7-NH 2 group is highly restricted and thus there is no fast nonradiative deexcitation process for the excited dye

Unprecedented Hexanuclear Cobalt(II Nonsymmetrical Salamo-Based Coordination Compound: Synthesis, Crystal Structure, and Photophysical Properties

Directory of Open Access Journals (Sweden)

Zong-Li Ren

2018-03-01

Full Text Available A novel hexanuclear Co(II coordination compound with a nonsymmetrical Salamo-type bisoxime ligandH4L, namely [{Co3(HL(MeO(MeOH2(OAc2}2]·2MeOH, was prepared and characterized by elemental analyses, UV–vis, IR and fluorescence spectra, and X-ray single-crystal diffraction analysis. Each Co(II is hexacoordinated, and possesses a distorted CoO6 or CoO4N2 octahedrons. The Co(II coordination compound possesses a self-assembled infinite 2D supramolecular structure with the help of the intermolecular C–H···O interactions. Meanwhile, the photophysical properties of the Co(II coordination compound were studied.

Photophysical properties and energy transfer mechanism of PFO/Fluorol 7GA hybrid thin films

Energy Technology Data Exchange (ETDEWEB)

Al-Asbahi, Bandar Ali, E-mail: alasbahibandar@gmail.com [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Department of Physics, Faculty of Science, Sana' a University (Yemen); Jumali, Mohammad Hafizuddin Haji, E-mail: hafizhj@ukm.my [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Yap, Chi Chin; Flaifel, Moayad Husein [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Salleh, Muhamad Mat [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia)

2013-10-15

Photophysical properties of poly (9,9′-di-n-octylfluorenyl-2.7-diyl) (PFO)/2-butyl-6- (butylamino)benzo [de] isoquinoline-1,3-dione (Fluorol 7GA) and energy transfer between them have been investigated. In this work, both PFO and Fluorol 7GA act as donor and acceptor, respectively. Based on the absorption and luminescence measurements, the photophysical and energy transfer properties such as fluorescence quantum yield (Φ{sub f}), fluorescence lifetime (τ), radiative rate constant (k{sub r}), non-radiative rate constant (k{sub nr}), quenching rate constant (k{sub SV}), energy transfer rate constant (k{sub ET}), energy transfer probability (P{sub DA}), energy transfer efficiency (η), critical concentration of acceptor (C{sub o}), energy transfer time (τ{sub ET}) and critical distance of energy transfer (R{sub o}) were calculated. Large values of k{sub SV}, k{sub ET} and R{sub o} suggested that Förster-type energy transfer was the dominant mechanism for the energy transfer between the excited donor and ground state acceptor molecules. It was observed that the Förster energy transfer together with the trapping process are crucial for performance improvement in ITO/(PFO/Fluorol7GA)/Al device. -- Highlights: • The efficient of energy transfer from PFO to Fluorol 7GA was evidenced. • The resonance energy transfer (Förster type) is the dominant mechanism. • Hsu et al. model was used to calculate Φ{sub f}, τ, k{sub r} and k{sub nr} of PFO thin film. • Several of the photophysical and energy transfer properties were calculated. • Trapping process and Förster energy transfer led to improve the device performance.

Type II photoinitiator substituted zinc phthalocyanine: Synthesis, photophysical and photopolymerization studies

Energy Technology Data Exchange (ETDEWEB)

Korkut, Sibel Eken [Department of Chemistry, Yıldız Technical University, 34210 Davutpaşa, İstanbul (Turkey); Temel, Gokhan [Department of Polymer Engineering, Yalova University, 77100 Yalova (Turkey); Balta, Demet Karaca [Department of Chemistry, Yıldız Technical University, 34210 Davutpaşa, İstanbul (Turkey); Arsu, Nergis, E-mail: narsu@yildiz.edu.tr [Department of Chemistry, Yıldız Technical University, 34210 Davutpaşa, İstanbul (Turkey); Şener, M. Kasım, E-mail: mkasimsener@gmail.com [Department of Chemistry, Yıldız Technical University, 34210 Davutpaşa, İstanbul (Turkey)

2013-04-15

The novel 4-(9-oxo-9 H-thioxanthen-2yloxy) phthalonitrile (TX-Pht) and its peripherally tetra substituted zinc phthalocyanine complex (TX-ZnPc) have been prepared and characterized by spectroscopic and elemental analysis techniques. Photoinitiated polymerization of methyl methacrylate (MMA) with TX-ZnPc has been investigated in the presence and absence of a co-initiator. Fluorescence and phosphorescence measurements have been also performed to determine the photophysical properties. Low fluorescence quantum yield (Φ{sub F}=0.08) compared to the unsubstituted ZnPc has been found. This allows initiator to undergo intersystem crossing into the triplet state and the lowest triplet state possesses π-π{sup ⁎} configuration. Highlights: ► Zinc phthalocyanine (ZnPc), peripherally functionalized with photoactive thioxanthone (TX) groups was synthesized. ► The photophysical and photochemical properties of resulting photoinitiator were studied in DMF. ► Photoinitiated polymerization of MMA with TX-ZnPc was investigated in the presence and absence of co-initiator.

Photochemistry and photophysics concepts, research, applications

CERN Document Server

Balzani , Vincenzo; Juris, Alberto

2014-01-01

This textbook covers the spectrum from basic concepts of photochemistry and photophysics to selected examples of current applications and research.Clearly structured, the first part of the text discusses the formation, properties and reactivity of excited states of inorganic and organic molecules and supramolecular species, as well as experimental techniques. The second part focuses on the photochemical and photophysical processes in nature and artificial systems, using a wealth of examples taken from applications in nature, industry and current research fields, ranging from natural photosynth

Photophysical properties of betaxanthins: Vulgaxanthin I in aqueous and alcoholic solutions

Energy Technology Data Exchange (ETDEWEB)

Wendel, Monika [Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University in Poznan, Umultowska 85, Poznan 61-614 (Poland); Szot, Dominika; Starzak, Karolina; Tuwalska, Dorota [Faculty of Chemical Engineering and Technology, Institute C-1, Section of Analytical Chemistry, Cracow University of Technology, Warszawska 24, Cracow 31-155 (Poland); Gapinski, Jacek [Molecular Biophysics Department, Faculty of Physics, Adam Mickiewicz University in Poznan, Umultowska 85, Poznan 61-614 (Poland); Naskrecki, Ryszard [Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University in Poznan, Umultowska 85, Poznan 61-614 (Poland); Prukala, Dorota; Sikorski, Marek [Faculty of Chemistry, Adam Mickiewicz University in Poznan, Umultowska 89b, Poznan 61-614 (Poland); Wybraniec, Slawomir [Faculty of Chemical Engineering and Technology, Institute C-1, Section of Analytical Chemistry, Cracow University of Technology, Warszawska 24, Cracow 31-155 (Poland); Burdzinski, Gotard, E-mail: gotardb@amu.edu.pl [Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University in Poznan, Umultowska 85, Poznan 61-614 (Poland)

2015-11-15

Betaxanthins are yellow pigments present in Caryophyllales plants and some higher fungi. We characterize photophysical properties of vulgaxanthin I and extracts of Amanita muscaria L. Vulgaxanthin I photoexcitation at λ{sub exc}=476 nm leads to the S{sub 1} excited state with the S{sub 1}→S{sub n} absorption bands at ca. 390 and 920 nm in both aqueous and alcoholic solutions. The S{sub 1} state lifetimes (2.9 and 37 ps in water) imply that vulgaxanthin I exists in two stereoisomeric forms. An increase in the solvent viscosity extends the S{sub 1} lifetimes and fluorescence quantum yields, probably due to hindered internal rotations in the dye. Internal conversion is the major S{sub 1} state deactivation path, with fluorescence being a minor channel, and S{sub 1}→T{sub 1} intersystem crossing not observed. Betaxanthins extracted from A. muscaria L. have similar properties. Efficient dissipation of the absorbed light energy as heat supports the postulate of photoprotective role of betaxanthins in vivo. - Highlights: • Betaxanthin S{sub 1} state deactivation mechanism is mainly radiationless. • S{sub 1} state shows absorption band with maxima at about 390 nm and 920 nm. • Solvent viscosity affects S{sub 1} state lifetime and fluorescence quantum yield. • Addition of potassium iodide to solution enhances ISC in betaxanthin.

Photophysical properties of hexyl diethylaminohydroxybenzoylbenzoate (Uvinul A Plus), a UV-A absorber.

Science.gov (United States)

Shamoto, Yuta; Yagi, Mikio; Oguchi-Fujiyama, Nozomi; Miyazawa, Kazuyuki; Kikuchi, Azusa

2017-09-13

Hexyl diethylaminohydroxybenzoylbenzoate (DHHB, Uvinul A Plus) is a photostable UV-A absorber. The photophysical properties of DHHB have been studied by obtaining the transient absorption, total emission, phosphorescence and electron paramagnetic resonance spectra. DHHB exhibits an intense phosphorescence in a hydrogen-bonding solvent (e.g., ethanol) at 77 K, whereas it is weakly phosphorescent in a non-hydrogen-bonding solvent (e.g., 3-methylpentane). The triplet-triplet absorption and EPR spectra for the lowest excited triplet state of DHHB were observed in ethanol, while they were not observed in 3-methylpentane. These results are explained by the proposal that in the benzophenone derivatives possessing an intramolecular hydrogen bond, intramolecular proton transfer is an efficient mechanism of the very fast radiationless decay from the excited singlet state. The energy level of the lowest excited triplet state of DHHB is higher than those of the most widely used UV-B absorbers, octyl methoxycinnamate (OMC) and octocrylene (OCR). DHHB may act as a triplet energy donor for OMC and OCR in the mixtures of UV-A and UV-B absorbers. The bimolecular rate constant for the quenching of singlet oxygen by DHHB was determined by measuring the near-IR phosphorescence of singlet oxygen. The photophysical properties of diethylaminohydroxybenzoylbenzoic acid (DHBA) have been studied for comparison. It is a closely related building block to assist in interpreting the observed data.

Photophysical and adsorption properties of pyronin B in natural bentonite clay dispersion

Energy Technology Data Exchange (ETDEWEB)

Rostami, Mohammad Reza [Department of Chemistry, Faculty of Sciences, Atatürk University, 25240, Erzurum (Turkey); Kaya, Mehmet [Recep Tayyip Erdoğan University, Faculty of Arts and Sciences, 53100 Rize (Turkey); Gür, Bahri; Onganer, Yavuz [Department of Chemistry, Faculty of Sciences, Atatürk University, 25240, Erzurum (Turkey); Meral, Kadem, E-mail: kademm@atauni.edu.tr [Department of Chemistry, Faculty of Sciences, Atatürk University, 25240, Erzurum (Turkey)

2015-12-30

Graphical abstract: The molecular aggregation of PyB in bentonite aqueous dispersion is observed by using molecular absorption spectrum. - Highlights: • Molecular behavior of PyB adsorbed on bentonite was spectroscopically followed. • H-aggregates of PyB in bentonite aqueous dispersion were formed. • The adsorption characteristics of PyB on bentonite particles were determined. - Abstract: The present study focused on the adsorption and photophysical properties of pyronin B (PyB) in bentonite aqueous dispersion. The photophysical properties of PyB in the aqueous dispersion were studied by using UV–vis absorption, steady-state and time-resolved fluorescence spectroscopy techniques. In this concept, the interaction of the dye with bentonite particles in the aqueous dispersion was spectroscopically followed depending on certain parameters such as interaction time, pH and the dye concentration. Obtained spectral data revealed that the aggregate structures (H-type) of PyB in the aqueous dispersion were formed in the dye concentration range studied. The non-fluorescence nature of H-aggregates and the clay minerals governed the fluorescence property of PyB. The mentioned non-radiative processes caused the fluorescence lifetime of the dye to decrease compared to that in water. The adsorption process of PyB on bentonite was examined depending on contact time and initial adsorbate concentration. An adsorption isotherm was good-fitted by the Freundlich model with a linear regression correlation value of 0.999. The adsorption of PyB on bentonite particles was in agreement with pseudo second-order kinetics.

Aggregation and Photophysical Properties of Water-Soluble Sapphyrins

Czech Academy of Sciences Publication Activity Database

Kubát, Pavel; Lang, Kamil; Zelinger, Zdeněk; Král, V.

2004-01-01

Roč. 395, - (2004), s. 82-86 ISSN 0009-2614 R&D Projects: GA AV ČR KSK4040110 Keywords : water-soluble * sapphyrins * photophysical Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.438, year: 2004

Photophysical characterization of cumarin-doped poly (lactic acid) microparticles and visualization of the biodistribution

International Nuclear Information System (INIS)

Abe, Shigeaki; Kiba, Takayuki; Hosokawa, Kiyotada; Nitobe, Satoru; Hirota, Takashi; Kobayashi, Hirohisa; Akasaka, Tsukasa; Uo, Motohiro; Kuboki, Yoshinori; Sato, Shin-Ichiro; Watari, Fumio; Rosca, Iosif D.

2010-01-01

We prepared fluorescent coumarin dye-doped poly (acrylic acid) microparticles, which are well known as a biodegradable polyester, and the photophysical properties were characterized by scanning electron microscope, atomic force microscope and spectroscopic investigation. Spherical particles with diameters ranging from 0.5 to a few μm were obtained. Based on spectroscopic investigation, the internal environment was close to that of a polar solvent such as methanol, and the dyes were dispersed without aggregation inside the particles. The obtained particles were administered to a mouse through the tail vein, and the biodistribution was then observed after some organs were excited at 1-day and 1-week post-injection. The particles were accumulated in the organs, especially in the lung and spleen. After injection, the particles were trapped temporally in the lung, and then seemed to be transported to other organs by blood circulation. This tendency is similar to the biodistribution of TiO 2 microparticles that we have reported previously.

Protonated serotonin: Geometry, electronic structures and photophysical properties

Science.gov (United States)

Omidyan, Reza; Amanollahi, Zohreh; Azimi, Gholamhassan

2017-07-01

The geometry and electronic structures of protonated serotonin have been investigated by the aim of MP2 and CC2 methods. The relative stabilities, transition energies and geometry of sixteen different protonated isomers of serotonin have been presented. It has been predicted that protonation does not exhibit essential alteration on the S1 ← S0 electronic transition energy of serotonin. Instead, more complicated photophysical nature in respect to its neutral analogue is suggested for protonated system owing to radiative and non-radiative deactivation pathways. In addition to hydrogen detachment (HD), hydrogen/proton transfer (H/PT) processes from ammonium to indole ring along the NH+⋯ π hydrogen bond have been predicted as the most important photophysical consequences of SERH+ at S1 excited state. The PT processes is suggested to be responsible for fluorescence of SERH+ while the HD driving coordinate is proposed for elucidation of its nonradiative deactivation mechanism.

Synthesis, photophysical properties of triazolyl-donor/acceptor chromophores decorated unnatural amino acids: Incorporation of a pair into Leu-enkephalin peptide and application of triazolylperylene amino acid in sensing BSA.

Science.gov (United States)

Bag, Subhendu Sekhar; Jana, Subhashis; Pradhan, Manoj Kumar

2016-08-15

The research in the field of design and synthesis of unnatural amino acids is growing at a fast space for the increasing demand of proteins of potential therapeutics and many other diversified novel functional applications. Thus, we report herein the design and synthesis of microenvironment sensitive fluorescent triazolyl unnatural amino acids (UNAA) decorated with donor and/or acceptor aromatic chromophores via click chemistry. The synthesized fluorescent amino acids show interesting solvatochromic characteristic and/or intramolecular charge transfer (ICT) feature as is revealed from the UV-visible, fluorescence photophysical properties and DFT/TDDFT calculation. HOMO-LUMO distribution shows that the emissive states of some of the amino acids are characterized with more significant electron redistribution between the triazolyl moiety and the aromatic chromophores linked to it leading to modulated emission property. A pair of donor-acceptor amino acid shows interesting photophysical interaction property indicating a FRET quenching event. Furthermore, one of the amino acid, triazolyl-perylene amino acid, has been exploited for studying interaction with BSA and found that it is able to sense BSA with an enhancement of fluorescence intensity. Finally, we incorporated a pair of donor/acceptor amino acids into a Leu-enkephalin analogue pentapeptide which was found to adopt predominantly type II β-turn conformation. We envisage that our investigation is of importance for the development of new fluorescent donor-acceptor unnatural amino acids a pair of which can be exploited for generating fluorescent peptidomimetic probe of interesting photophysical property for applications in studying peptide-protein interaction. Copyright © 2016 Elsevier Ltd. All rights reserved.

Photophysical, Photochemical, and BQ Quenching Properties of Zinc Phthalocyanines with Fused or Interrupted Extended Conjugation

Directory of Open Access Journals (Sweden)

Gülşah Gümrükçü

2014-01-01

Full Text Available The effects of substituents and solvents on the photophysical and photochemical parameters of zinc(II phthalocyanines containing four Schiff’s base substituents attached directly and through phenyleneoxy-bridges on peripheral positions are reported. The group effects on peripheral position and the continual and intermittent conjugation of the phthalocyanine molecules on the photophysical and photochemical properties are also investigated. General trends are described for photodegradation, singlet oxygen, and fluorescence quantum yields of these compounds in dimethylsulfoxide (DMSO, dimethylformamide (DMF, and tetrahydrofurane (THF. Among the different substituents, phthalocyanines with cinnamaldimine moieties (1c and 2c have the highest singlet oxygen quantum yields (ΦΔ and those with nitro groups (1a and 2a have the highest fluorescence quantum yields in all the solvents used. The fluorescence of the substituted zinc(II phthalocyanine complexes is effectively quenched by 1,4-benzoquinone (BQ in these solvents.

Photophysical properties of novel Porphyrin-Flavin Dyads

International Nuclear Information System (INIS)

Stark, S.

2001-10-01

Photosynthesis belongs to the fundamentals of life on earth, therefore it is an important matter in natural sciences. The basic principle of photosynthesis is the transformation of solar light into chemical energy. The starting steps of photosynthesis are light-induced energy- and electron-transfer-steps with singular efficiency. One attempt to enlighten the molecular processes involved is to synthesize simpler model systems with similar properties. Important research goals are the dependencies of light-induced processes on distance and orientation of donor and acceptor. A second aim next to the clarification of the molecular conditions of photosynthesis is to create molecular light-driven machines. The most simple so-called biomimetic model system consists of an electron-donor connected to an electron-acceptor via a spacer-group. This simplest form is also referred to as dyad. Beyond dyads far more complicated compounds have been introduced consisting of several donors and/or acceptors, so-called triads, tetrads, pentads etc. Usually porphyrin serves as electron-donor. Next to chinones several other electron-acceptors are used, e.g. anthracene, pyromellitimide and fullerene. Artificial photosynthetic centers are often more stable and/or the excited states are easier to detect compared to the natural photosynthetic center. The photophysical characteristics of four dyads are reported in this work. The dyads consist of porphyrin (either free-base or zinc-metallated) and flavin, connected by different spacers. These dyads reveal photo-induced electron transfer from porphyrin to flavin and energy-transfer in the reversed direction with different efficiencies. The object of the study is the dependency of these processes on the structural features. The spacer of the dyads 1a-1c is an aromatic bridge which leads to well defined donor-acceptor distances. Because of this structure conjugation through the spacer is increased, whereas the absorption in the visible and near UV

Bibliographic study of photophysical and photochemical properties of laser dyes

International Nuclear Information System (INIS)

Doizi, D.

1986-06-01

Laser isotope separation of uranium requires high power and precise wave length. This report is a bibliographic and experimental study of the photophysical and photochemical properties of seven commercial laser dyes which have an emission wavelength in the range 5500-6500 A: Rhodamine 110 or 560, rhodamine 6G or 590, rhodamine B or 610, rhodamine 101 or 640, sulforhodamine B or kiton red 620, sulforhodamine 101 or 640 and DCM or LC 6500. Absorption and emission cross section values, fluorescence lifetimes and quantum yields in various solvents are indicated. For each dye, a non exhaustive list of laboratory experiments made with two types of pump sources: Nd YAG (532) and copper vapor laser is given. When it is known, the toxicity of the dyes is mentioned [fr

Synthesis, structure, electrochemistry, and photophysics of methyl-substituted phenylpyridine ortho-metalated iridium(III) complexes

International Nuclear Information System (INIS)

Garces, F.O.; King, K.A.; Watts, R.J.

1988-01-01

Synthetic, structural, photophysical, and electrochemical characterizations of ortho-metalated [Ir(NC) 2 Cl] 2 dimeric and [Ir(NC) 2 NN]Cl monomeric complexes, where NC = 2(p-tolyl)pyridine (ptpy) or 3-methyl-2-phenylpyridine (mppy) and NN = 2,2'-bipyridine (bpy) are described. Structural characterizations by 1 H and 13 C nuclear magnetic resonance (NMR) indicate the presence of symmetry elements in these complexes. The ultraviolet-visible absorption properties of these complexes are reported. The results of voltametric measurements of these complexes are included. 55 references, 10 figures, 6 tables

Imaging, photophysical properties and DFT calculations of manganese blue (barium manganate(VI) sulphate)--a modern pigment.

Science.gov (United States)

Accorsi, Gianluca; Verri, Giovanni; Acocella, Angela; Zerbetto, Francesco; Lerario, Giovanni; Gigli, Giuseppe; Saunders, David; Billinge, Rachel

2014-12-18

Manganese blue is a synthetic barium manganate(VI) sulphate compound that was produced from 1935 to the 1990s and was used both as a blue pigment in works of art and by conservators in the restoration of paintings. The photophysical properties of the compound are described as well as the setup needed to record the spatial distribution of the pigment in works of art.

Photophysical properties of some xanthylium salts performances under CVL pumping

International Nuclear Information System (INIS)

Doizi, D.; Lompre, L.A.; Gazeau, M.C.

1995-01-01

We report the photochemical and photophysical performances of some new dyes belonging to the xanthylium salts family. Performances under Copper Vapor Laser (CVL) pumping are described and compared to those of Rhodamine 6G. (author)

Study on photophysical properties of Eu(III) complexes with aromatic β-diketones – Role of charge transfer states in the energy migration

Energy Technology Data Exchange (ETDEWEB)

Räsänen, Markus, E-mail: mpvras@utu.fi [Department of Chemistry, University of Turku, FIN-20014 Turku (Finland); Takalo, Harri [DHR Finland Oy, Innotrac Diagnostics, Biolinja 12, FIN-20750 Turku (Finland); Rosenberg, Jaana; Mäkelä, Joonas [Department of Biochemistry and Food Chemistry, University of Turku, FIN-20014 Turku (Finland); Haapakka, Keijo; Kankare, Jouko [Department of Chemistry, University of Turku, FIN-20014 Turku (Finland)

2014-02-15

We synthesized a set of aromatic β-diketones and measured the photophysical properties of their europium(III) complexes. According to these photophysical properties, the europium complexes can be divided into two groups: the complexes with or without the freely rotating amino-group (FRAG). On the basis of the experimental results, it can be concluded that in the FRAG complexes, the ligand-centered excitation energy is most probably transferred from a ligand to a coordinated europium via the intraligand charge transfer (ILCT) state. The temperature dependency of the lifetimes of the emissive {sup 5}D{sub 0} state revealed that in the FRAG complexes, the energy of the emissive {sup 5}D{sub 0} state is back-transferred to the ligand-to-metal charge transfer (LMCT) state and in the non-FRAG complexes, to the triplet state of the ligand. The most efficient complex synthesized was the europium complex of carbazole derivative L{sup 6} with the quantum yield of 47% and molar absorption coefficient of 70,400 M{sup −1}cm{sup −1}. -- Highlights: • We synthesized a set of substituted aromatic β-diketones and their Eu(III) complexes. • We measured the photophysical properties of these Eu(III) complexes. • Carbazole derivative of β-diketone forms the brightest Eu(III) complex. • The Jablonski diagrams proposed for the luminescence of these complexes.

NLOphoric and solid state emissive BODIPY dyes containing N-phenylcarbazole core at meso position – Synthesis, photophysical properties of and DFT studies

Energy Technology Data Exchange (ETDEWEB)

Telore, Rahul D.; Jadhav, Amol G.; Sekar, Nagaiyan, E-mail: n.sekar@ictmumbai.edu.in

2016-11-15

Two boron-dipyrromethene dyes with N-phenylcarbazole core at meso position were prepared and characterized. They show small Stokes shifts (15–20 nm), high molar extinction coefficient and high quantum yield. Their photophysical properties were compared with the known meso aryl, 4-aminophenyl, N,N-dimethylaniline and N-butylcarbzole boron-dipyrromethene dyes. The bulky nature of N-phenylcarbazole leads to an increase in molar absorptivity and quantum yield. The Catalan solvent parameters are found to be the suitable for defining the solvatochromic absorption and emission properties. Confocal laser scanning microscopy showed solid-state fluorescence. Density Functional Theory is used to determine the static first hyperpolarizability (β{sub ο}) and its components (μ, α{sub 0}, Δα, and γ) using B3LYP/6-31G(d) at ground state and excited state in different polarity solvent. The geometries of the dyes were optimized by using B3LYP/6-31G(d) and their electronic excitation properties were estimated using time dependent density functional theory.

The effect of H- and J-aggregation on the photophysical and photovoltaic properties of small Thiophene–Pyridine–DPP molecules for bulk-heterojunction solar cells

NARCIS (Netherlands)

Más-Montoya, M.; Janssen, R.A.J.

2017-01-01

The performance of organic semiconductors in optoelectronic devices depends on the functional properties of the individual molecules and their mutual orientations when they are in the solid state. The effect of H- and J-aggregation on the photophysical properties and photovoltaic behavior of four

Multifunctional material based on ionic transition metal complexes and gold-silica nanoparticles: synthesis and photophysical characterization for application in imaging and therapy.

Science.gov (United States)

Ricciardi, Loredana; Martini, Matteo; Tillement, Olivier; Sancey, Lucie; Perriat, Pascal; Ghedini, Mauro; Szerb, Elisabeta I; Yadav, Yogesh J; La Deda, Massimo

2014-11-01

A new combination of luminescent ionic transition-metal complexes (M = Ru(II) or Ir(III)) with gold silica-based nanoparticles (GSNPs) gives a promising nanomaterial for application in biomedical fields. Herein we report the synthesis and the photophysical properties of Ru(II) and Ir(III) complexes doped gold core-polysiloxane shell particles prepared by microemulsion method and characterized by Transmission Electron Microscopy, Dynamic Light Scattering and UV-Vis spectroscopy. The cytotoxicity and photodynamic activity of the obtained 50 nm-diameter nanoparticles were evaluated in vitro, providing noteworthy results. Furthermore, their intrinsic phosphorescence allows the localization of the photosensitizing nanoparticles into the cytosol of tumor cells by fluorescence confocal microscope. These valuable features designate them as multifunctional nanoplatforms for theranostic purposes.

Selective synthesis and characterization of chlorins as sensitizers for photodynamic therapy

Science.gov (United States)

Montforts, Franz-Peter; Kusch, Dirk; Hoper, Frank; Braun, Stefan; Gerlach, Benjamin; Brauer, Hans-Dieter; Schermann, Guido; Moser, Joerg G.

1996-04-01

Chlorin type sensitizers have ideal photophysical properties for an application in PDT. The basic chlorin framework of these sensitizers has to be modified by attachment of lipophilic and hydrophilic residues to achieve a good cell uptake and tumor enrichment. In the present study we describe the selective synthesis of amphiphilic chlorins starting from the readily accessible red blood pigment heme. The photophysical properties of the well defined synthetic chlorins are characterized by photophysical investigations. The kinetic of cell uptake, the localization in the cell and the photodynamic behavior of the amphiphilic sensitizers are demonstrated by incubation of A 375 cancer cell lines with structurally different chlorins.

Studies on the photophysical properties of 1,8-naphthalimide derivative and aggregation induced emission recognition for casein

Energy Technology Data Exchange (ETDEWEB)

Sun, Yang, E-mail: 66160692@qq.com [Department of Chemistry and Chemical Engineering, Xi' an University of Arts and Science, No. 168, Taibai South Road, Xi' an, Shaanxi 710065 (China); Liang, Xuhua; Fan, Jun [School of Chemical Engineering, Northwest University, No. 229, Taibai North Road, Xi' an, Shaanxi 710069 (China); Han, Quan, E-mail: xahanq@hotmail.com [Department of Chemistry and Chemical Engineering, Xi' an University of Arts and Science, No. 168, Taibai South Road, Xi' an, Shaanxi 710065 (China)

2013-09-15

A novel water-soluble 1,8-naphthalimide derivative 1, bearing two acetic carboxylic groups, exhibited fluorescent turn-on recognition for casein micelle based on the aggregation induced emission (AIE) character. The photophysical properties of 1 consisting of donor and acceptor units were investigated by the solvation effect. Changing from polar to non-polar solvent increased the solvent interaction; both the excitation and emission spectra were shifted to shorter wavelength and intensity decreased through taking advantage of twisted intramolecular charge transfer (TICT) and self-association fluorescence emission. Moreover, the red-shift and quenching in protic solvent were caused by the excited-state hydrogen bond strengthening effect. The density functional theory (DFT) and time dependent density functional theory (TDDFT) were used to obtain the most stable structure, electronic excitation energy, dipole moments and charge distribution. The AIE mechanism of 1 with casein micelle was due to 1 docked in the hydrophobic cavity between sub-micelles and bound with amino acid residues, resulting in the aggregation of 1 on the casein micelle surface and emission enhancement, based on which, a novel casein assay method was developed. The proposed method exhibited a good linear range from 0.1 to 10.5 μg mL{sup −1}, with the detection limit of 3.0 ng mL{sup −1}. Satisfactory reproducibility, reversibility and a short response time were realized. This method was applied for the determination of casein in milk powder samples, avoiding the interferences from other components and illegal additives in milk. -- Highlights: • A water-soluble 1,8-naphthalimide-based fluorescent probe 1 was synthesized. • Photophysical characterization of 1 was studied. • Aggregation induced emission enhancement of 1 with casein was investigated. • A novel casein quantification method was developed.

Studies on the photophysical properties of 1,8-naphthalimide derivative and aggregation induced emission recognition for casein

International Nuclear Information System (INIS)

Sun, Yang; Liang, Xuhua; Fan, Jun; Han, Quan

2013-01-01

A novel water-soluble 1,8-naphthalimide derivative 1, bearing two acetic carboxylic groups, exhibited fluorescent turn-on recognition for casein micelle based on the aggregation induced emission (AIE) character. The photophysical properties of 1 consisting of donor and acceptor units were investigated by the solvation effect. Changing from polar to non-polar solvent increased the solvent interaction; both the excitation and emission spectra were shifted to shorter wavelength and intensity decreased through taking advantage of twisted intramolecular charge transfer (TICT) and self-association fluorescence emission. Moreover, the red-shift and quenching in protic solvent were caused by the excited-state hydrogen bond strengthening effect. The density functional theory (DFT) and time dependent density functional theory (TDDFT) were used to obtain the most stable structure, electronic excitation energy, dipole moments and charge distribution. The AIE mechanism of 1 with casein micelle was due to 1 docked in the hydrophobic cavity between sub-micelles and bound with amino acid residues, resulting in the aggregation of 1 on the casein micelle surface and emission enhancement, based on which, a novel casein assay method was developed. The proposed method exhibited a good linear range from 0.1 to 10.5 μg mL −1 , with the detection limit of 3.0 ng mL −1 . Satisfactory reproducibility, reversibility and a short response time were realized. This method was applied for the determination of casein in milk powder samples, avoiding the interferences from other components and illegal additives in milk. -- Highlights: • A water-soluble 1,8-naphthalimide-based fluorescent probe 1 was synthesized. • Photophysical characterization of 1 was studied. • Aggregation induced emission enhancement of 1 with casein was investigated. • A novel casein quantification method was developed

Photophysical Properties of Pheophorbide-a Derivatives and Their Photodynamic Therapeutic Effects on a Tumor Cell Line In Vitro

Directory of Open Access Journals (Sweden)

Kang-Kyun Wang

2014-01-01

Full Text Available Pheophorbide-a derivatives have been reported to be potential photosensitizers for photodynamic therapy (PDT. In this study, photophysics of pheophorbide-a derivatives (PaDs were investigated along with their photodynamic tumoricidal effect in vitro. PaDs were modified by changing the coil length and/or making the hydroxyl group (–OH substitutions. Their photophysical properties were studied by steady-state and time-resolved spectroscopic methods. The photodynamic tumoricidal effect was evaluated in the mouse breast cancer cell line (EMT6. Lifetime and quantum yield of fluorescence and quantum yields of triplet state and singlet oxygen were studied to determine the dynamic energy flow. The coil length of the substituted alkyl group did not significantly affect the spectroscopic properties. However, the substitution with the hydroxyl group increased the quantum yields of the triplet state and the singlet oxygen due to the enhanced intersystem crossing. In order to check the application possibility as a photodynamic therapy agent, the PaDs with hydroxyl group were studied for the cellular affinity and the photodynamic tumoricidal effect of EMT6. The results showed that the cellular affinity and the photodynamic tumoricidal effect of PaDs with the hydroxyl group depended on the coil-length of the substituted alkyl group.

Photophysical and photobiological properties of a sulfonated chlorin photosensitiser TPCS(2a) for photochemical internalisation (PCI).

Science.gov (United States)

Wang, Julie T-W; Berg, Kristian; Høgset, Anders; Bown, Stephen G; MacRobert, Alexander J

2013-03-01

This study investigated the photophysical and photobiological properties of a new amphiphilic chlorin photosensitiser, disulfonated tetraphenylchlorin (TPCS(2a)), for photochemical internalisation (PCI). The absorption and fluorescence spectra of TPCS(2a) were examined in a range of solvents together with fluorescence lifetime measurements. The fluorescence lifetime of TPCS(2a) was found to be 8.5 ns in methanol, whereas non-exponential decays were observed in distilled water due to sensitiser dimerisation. The singlet oxygen quantum yield of TPCS(2a) was determined as 0.62 in deuterated methanol by direct observation of singlet oxygen phosphorescence. In a human oral squamous carcinoma (HN5) cell line, intracellular co-localisation of TPCS(2a) and Alexa488-labelled saporin, a macromolecular toxin, was observed corresponding predominantly to a lysosomal distribution. Intracellular fluorescence redistribution of TPCS(2a) and Alexa488-saporin was observed after 405 nm irradiation. Using two-photon confocal microscopy at 840 nm, and fluorescence lifetime imaging (FLIM), the lifetime was measured as 6 ns in HN5 cells. PCI using TPCS(2a) was shown to be very effective, and a synergistic increase in saporin toxicity was achieved in HN5 cells where viability was significantly reduced after light exposure compared to saporin (25 nM) treatment alone. The results demonstrate the favourable photophysical and photobiological properties of TPCS(2a) for PCI, which induces the relocalisation of a macromolecular anti-cancer toxin inside cells and significantly enhances cell death.

Solvent Effect, Photochemical and Photophysical Properties of Phthalocyanines with Different Metallic Nuclei

Directory of Open Access Journals (Sweden)

Charles Biral Silva

2017-12-01

Full Text Available Photophysical and photochemical properties of lithium phthalocyanine (1, gallium(III phthalocyanine chloride (2, titanium(IV phthalocyanine dichloride (3 and iron(II phthalocyanine (4 were investigated in dimethyl sulfoxide (DMSO, tetrahydrofuran (THF and DMSO-THF mixtures. The influence of the central metal on these properties was analyzed according to solvent type, axial ligands and their paramagnetic and diamagnetic effect. Fluorescence lifetimes were recorded using a time correlated single photon counting setup (TCSPC technique. In order to demonstrate the generation of reactive oxygen species under light irradiation, the indirect method (applying 1,3-diphenylisobenzofuran (DPBF as chemical suppressor and the direct method (analyzing the phosphorescence decay curves of singlete oxygen at 1270 nm were employed. Compounds 1, 2 and 3 showed a monomeric behavior in all media while compound 4 presented low aggregation in DMSO, but a very pronounced aggregation behavior in THF. Steady-state fluorescence anisotropy was compared with emission spectra and complex 4 presented values beyond the expected limits. DOI: http://dx.doi.org/10.17807/orbital.v9i5.1047 

Influence of bidentate structure of an aryl phosphine oxide ligand on photophysical properties of its Eu~Ⅲ complex

Institute of Scientific and Technical Information of China (English)

许辉; 魏莹; 赵保敏; 黄维

2010-01-01

The bidentate phosphine oxide ligand 1,8-bis(diphenylphosphino) naphthalene oxide (NAPO) and its EuⅢ complex 1 Eu(TTA)3(NAPO) (TTA=2-thenoyltrifluoroacetonate) were chosen to study the effect of bidentate phosphine oxide ligand on the photophysical properties of the corresponding complex. The intramolecular energy transfer processes of 1 were studied. The investigation showed that with bidentate structure NAPO could suppress solvent-induced quenching by enforcing the ligand-ligand interaction and the rigidi...

Photophysics of Organic-Inorganic Hybrid Lead Iodide Perovskite Single Crystals

NARCIS (Netherlands)

Fang, Honghua; Raissa, Raissa; Abdu-Aguye, Mustapha; Adjokatse, Sampson; Blake, Graeme R.; Even, Jacky; Loi, Maria Antonietta

2015-01-01

Hybrid organometal halide perovskites have been demonstrated to have outstanding performance as semiconductors for solar energy conversion. Further improvement of the efficiency and stability of these devices requires a deeper understanding of their intrinsic photophysical properties. Here, the

Photophysical properties, photodegradation characteristics, and lasing action for coumarin dye C540A in polymeric media

Science.gov (United States)

Jones, Guilford, II; Huang, Zhennian; Pacheco, Dennis P., Jr.; Russell, Jeffrey A.

2004-07-01

Tunable solid-state dye lasers operating in the blue-green spectral region are attractive for a variety of applications. An important consideration in assessing the viability of this technology is the service life of the gain medium, which is presently limited by dye photodegradation. In this study, solid polymeric samples consisting of the coumarin dye C540A in modified PMMA were subjected to controlled photodegradation tests. The excitation laser was a flashlamp-pumped dye laser operating at 440 nm with a pulse duration of 1 μs. A complementary set of data was obtained for dye in solution phase for comparison purposes. Photophysical properties of C540A in water solution of polymethacrylic acid (PMAA) have been investigated with a view to assess the suitability of the sequestering polymer (PMAA) as an effective additive to facilitate use of a water medium for highly efficient blue-green dye lasers. Lasing action of C540A in aqueous PMAA has been realized using flashlamp-pumped laser system, yielding excellent laser efficiencies superior to that achieved in ethanolic solutions with the same dye. Laser characterization of dye in media included measurement of laser threshold, slope efficiency, pulse duration and output wavelength.

The effect of the triblock properties on the morphologies and photophysical properties of nanoparticle loaded with carboxylic dendrimer phthalocyanine

Science.gov (United States)

Lv, Huafei; Chen, Zhe; Yu, Xinxin; Pan, Sujuan; Zhang, Tiantian; Xie, Shusen; Yang, Hongqin; Peng, Yiru

2016-09-01

Photodynamic therapy (PDT) is an emerging alternative treatment for various cancers and age-related macular degeneration. Phthalocyanines (Pcs) and their substituted derivatives are under intensive investigation as the second generation photosensitizers. A big challenge for the application of Pcs is poor solubility and limited accumulation in the tumor tissues, which severely reduced its PDT efficacy. Nano-delivery systems such as polymeric micelles are promising tools for increasing the solubility and improving delivery efficiency of Pcs for PDT application. In this paper, nanoparticles of amphiphilic triblock copolymer poly(L-lysine)-b-poly (ethylene glycol)-b-poly(L-lysine) were developed to encapsulate 1-2 generation carboxylic poly (benzyl aryl ether) dendrimer. The morphologies and photophysical properties of polymeric nanoparticles loaded with 1-2 generation dendritic phthalocyanines (G1-ZnPc(COOH)8/m and G2-ZnPc(COOH)16/m) were studied by AFM, UV/Vis and fluorescent spectroscopic method. The morphologies of self-assembled PLL-PEG-PLL aggregates exhibited concentration dependence. Its morphologies changed from cocoon-like to spheral. The diameters of G1-ZnPc(COOH)8/m and G2-ZnPc(COOH)16/m were in the range of 33-147 nm, increasing with the increase of the concentration of PLL-PEG-PLL. The morphologies of G2-ZnPc(COOH)16/m also changed from cocoon-like to sphere with the increase of the concentration of PLL-PEG-PLL. It was found that, the no obviously Q change was observed between the free phthalocyanines and nanoparticles. The fluorescence intensity of polymer nanoparticles were higher enhanced compared with free dendritic phthalocyanines. The dendrimer phthalocyanine loaded with poly(L-lysine)-b-poly (ethylene glycol)-b-poly(L-lysine) presented suitable physical stability, improved photophysical properties suggesting it may be considered as a promising formulation for PDT.

Novel asymmetrical pyrene derivatives as light emitting materials: Synthesis and photophysics

International Nuclear Information System (INIS)

Li Yang; Wang Dong; Wang Lei; Li Zhengqiang; Cui Qing; Zhang Haiquan; Yang Huai

2012-01-01

A series of novel substituted pyrene derivatives with asymmetrical groups have been successfully synthesized in excellent yield. Structures of the asymmetrical compound were fully characterized by 1 H-NMR, IR spectroscopy and mass spectrometry. By introducing ethynyl functions to pyrene, we obtained highly efficient blue and green light emitting materials. It has been demonstrated that the emission characteristics of pyrene derivatives have been bathochromatically tuned in the visible region by extending the π-conjugation. The photophysical properties of these compounds were carefully examined in different organic solvents and different concentrations. The electrochemical properties and geometrical electronic structures of the new pyrene derivatives have been investigated by cyclic voltammograms and density functional theory (DFT) calculations. - Highlights: ► It is the first research about asymmetrial pyrene derivatives as highly efficient light emitting materials. ► The solvatochromism and concentration effect of the new compounds have been discussed. ► Furthermore, the electrochemical properties and geometrical electronic structures were also investigated in this paper.

Photo-physical properties enhancement of bare and core-shell quantum dots

Energy Technology Data Exchange (ETDEWEB)

Mumin, Md Abdul, E-mail: pcharpentier@eng.uwo.ca; Akhter, Kazi Farida, E-mail: pcharpentier@eng.uwo.ca; Charpentier, Paul A., E-mail: pcharpentier@eng.uwo.ca [Chemical and Biochemical Engineering, Western University, London Ontario (Canada)

2014-03-31

Semiconductor nanocrystals (NCs) (also known as quantum dots, QDs) have attracted immense attention for their size-tunable optical properties that makes them impressive candidates for solar cells, light emitting devices, lasers, as well as biomedical imaging. However monodispersity, high and consistent photoluminescence, photostability, and biocompatibility are still major challenges. This work focuses on optimizing the photophysical properties and biocompatibility of QDs by forming core-shell nanostructures and their encapsulation by a carrier. Highly luminescent CdS and CdS-ZnS core-shell QDs with 5 nm sizes were synthesized using a facile approach based on pyrolysis of the single molecule precursors. After capping the CdS QDs with a thin layer of ZnS to reduce toxicity, the photoluminescence and photostability of the core-shell QDs was significantly enhanced. To make both the bare and core/shell structure QDs more resistant against photochemical reactions, a mesoporous silica layer was grown on the QDs through a reverse microemulsion technique based on hydrophobic interaction. This encapsulation enhanced the quantum yield and photostability compared to the bare QDs by providing much stronger resistance to oxidation and Oswald ripening of QDs. Encapsulation also improved biocompatibility of QDs that was evaluated with human umbilical vein endothelial cell lines (HUVEC)

Theoretical Characterization of Sulfur-to-Selenium Substitution in an Emissive RNA Alphabet: Impact on H-bonding Potential and Photophysical Properties

KAUST Repository

Chawla, Mohit

2018-02-23

We employ density functional theory (DFT) and time-dependent DFT (TDDFT) calculations to investigate the structural, energetic and optical properties of a new computationally designed RNA alphabet, where the nucleobases,tsA, tsG, tsC, and tsU (ts-bases), have been derived by replacing sulfur with selenium in the previously reported tz-bases, based on the isothiazolo[4.3-d]pyrimidine heterocycle core. We find out that the modeled non-natural bases have minimal impact on the geometry and energetics of the classical Watson-Crick base pairs, thus potentially mimicking the natural bases in a RNA duplex in terms of H-bonding. In contrast, our calculations indicate that H-bonded base pairs involving the Hoogsteen edge of purines are destabilized as compared to their natural counterparts. We also focus on the photophysical properties of the non-natural bases and correlate their absorption/emission peaks to the strong impact of the modification on the energy of the lowest unoccupied molecular orbital. It is indeed stabilized by roughly 1.1-1.6 eV as compared to the natural analogues, resulting in a reduction of the gap between the highest occupied and the lowest unoccupied molecular orbital from 5.3-5.5 eV in the natural bases to 3.9-4.2 eV in the modified ones, with a consequent bathochromic shift in the absorption and emission spectra. Overall, our analysis clearly indicates that the newly modelled ts-bases are expected to exhibit better fluorescent properties as compared to the previously reported tz-bases, while retaining similar H-bonding properties. In addition, we show that a new RNA alphabet based on size-extended benzo-homologated ts-bases can also form stable Watson-Crick base pairs with the natural complementary nucleobases.

Copolymers containing meta-pyridylvinylene and para-arylenevinylene fragments: synthesis, quaternization reaction, and photophysical properties

Science.gov (United States)

Barashkov, Nikolay N.; Olivos, Hernando J.; Ferraris, John P.

1997-12-01

We report the Wittig reaction of the diphosphonium salt of 2,6-bis(chloromethyl)pyridine with terephthaldehyde, 2.5- dioctyloxyterephthaldehyde, or 9,10-anthracenedicarbaldehyde to form conjugated copolymers with fragments of 2,6 - pyridylene and para-arylenevinylene. The protonation reaction of poly(para-arylenevinylene)-co-(meta- pyridylvinylene) with hydrochloric acid and the quaternization reaction of poly(2,5-dioctyloxy-1,4- phenylenevinylene)-co-(2,6-pyridylvinylene) with methyl triflate have been investigated by spectrophotometric and fluorescent methods. The absorption, excitation and fluorescence spectra of these copolymers as well as their corresponding model compounds were studied and compared. The photophysical properties of the investigated polymers suggest that these materials could be good candidates for the fabrication of efficient blue and green light-emitting diodes.

Photophysical properties and localization of chlorins substituted with methoxy groups, hydroxyl groups and alkyl chains in liposome-like cellular membrane

Energy Technology Data Exchange (ETDEWEB)

Al-Omari, S [Department of Physics, Hashemite University, Zarqa 13115 (Jordan)

2007-06-01

Some of the photophysical properties (stationary absorbance and fluorescence, fluorescence decay times and singlet oxygen quantum yields) of chlorins substituted with methoxy groups, hydroxyl groups and hydrocarbonic chains were studied in ethanol and dipalmitoyl-phosphatidylcholine (DPPC) liposomes using steady-state and time-resolved fluorescence spectroscopies. The photophysical behaviors of the chlorins in liposomes like cellular membrane were compared with those obtained from chlorin-liposome systems delivered to Jurkat cells in order to select potent photosensitizers for the photodynamic treatment of cancer. The localization of the studied chlorins inside liposomes was found to depend strongly on the substituents of chlorins. Absorption spectra of chlorins embedded in DPPC-liposomes have been recorded in the temperature range of 20-70 deg. C. It is demonstrated that the location of the chlorin molecules depends on the phase state of the phospholipids. These observations are confirmed by the fluorescence lifetimes, singlet oxygen lifetimes and singlet oxygen quantum yields results.

A High Molar Extinction Coefficient Mono-Anthracenyl Bipyridyl Heteroleptic Ruthenium(II Complex: Synthesis, Photophysical and Electrochemical Properties

Directory of Open Access Journals (Sweden)

Peter A. Ajibade

2011-06-01

Full Text Available In our quest to develop good materials as photosensitizers for photovoltaic dye-sensitized solar cells (DSSCs, cis-dithiocyanato-4-(2,3-dimethylacrylic acid-2,2'-bipyridyl-4-(9-anthracenyl-(2,3-dimethylacrylic-2,2'-bipyridyl ruthenium(II complex, a high molar extinction coefficient charge transfer sensitizer, was designed, synthesized and characterized by spectroscopy and electrochemical techniques. Earlier studies on heteroleptic ruthenium(II complex analogues containing functionalized oligo-anthracenyl phenanthroline ligands have been reported and documented. Based on a general linear correlation between increase in the length of π-conjugation bond and the molar extinction coefficients, herein, we report the photophysical and electrochemical properties of a Ru(II bipyridyl complex analogue with a single functionalized anthracenyl unit. Interestingly, the complex shows better broad and intense metal-to ligand charge transfer (MLCT band absorption with higher molar extinction coefficient (λmax = 518 nm, e = 44900 M−1cm−1, and appreciable photoluminescence spanning the visible region than those containing higher anthracenyl units. It was shown that molar absorption coefficient of the complexes may not be solely depended on the extended π-conjugation but are reduced by molecular aggregation in the molecules.

Photophysical and physicochemical studies of rare earths complexes formed with calyx(n)arenes

International Nuclear Information System (INIS)

Ramirez, F.M.; Varbanov, S.; Corine, C.; Muller, G.; Fatin-Rouge, N.; Scopelliti, R.; Bunzli J, C.G.

2001-01-01

In this work, some of the photophysical and physicochemical properties are presented which are observed in the rare earths complexes that are formed with diverse functionalized calyx(n)arenes receptors where n=4-6 designed with predetermined properties and synthesized by own methods. (Author)

Novel nonplanar triphenylamine-centered oligofluorenes: Synthesis, thermal, photophysical and electrochemical properties

International Nuclear Information System (INIS)

Zhang Yujian; Ouyang Mi; Yu Chunhui; Hu Bin; Lou Qianping; Zhang Cheng

2011-01-01

A series of fluorene derivatives containing a triphenylamine (TPA) derivative core and two oligofluorene peripheries was effectively synthesized. These compounds are fluorescent and emission color ranges from blue to red. The spiro-skeleton molecular structure leads to excellent glass transition temperatures and weak intermolecular interactions. Simultaneously, novel nonplanar triphenylamine-centered oligofluorenes solve the spectral stability problem and hole-injection issue for fluorene-based materials. The photophysical properties of 6 and 7 are investigated in solvents with different polarities, which reveal the existence of the Charge Transfer (CT) excited-state in these molecules. - Highlights: → Novel nonplanar oligofluorenes consisting of triphenylamine (TPA) derivatives as the core and oligofluorenes as the peripheries were facilely prepared via CF 3 SO 3 H-promoted Friedel-Crafts and Suzuki cross-coupling reactions. → These as-prepared compounds effectively solve the spectral stability problem and hole-injection issue for fluorene-based materials. → The ability of hole-injection and emission color could be fine tuned by R substituent at the C4 position of TPA.

Synthesis, photophysical and photochemical properties of zinc phthalocyanines bearing fluoro-functionalized substituents

International Nuclear Information System (INIS)

Aktaş, Ayşe; Pişkin, Mehmet; Durmuş, Mahmut; Bıyıklıoğlu, Zekeriya

2014-01-01

In this study, the synthesis of phthalonitrile derivatives bearing fluoro-functionalized groups and their peripherally-tetra substituted zinc phthalocyanine complexes were reported. The phthalonitrile derivatives 2a–5a were prepared by nucleophilic substitution of 4-nitrophthalonitrile with 2-[3-(trifluoromethyl)phenoxy]ethanol, 2-{2-[3-(trifluoromethyl) phenoxy]ethoxy}ethanol, 2-(2,3,5,6-tetrafluorophenoxy)ethanol, 2-[2-(2,3,5,6-tetrafluorophenoxy)ethoxy]ethanol, respectively. Zinc phthalocyanines bearing fluoro-functionalized groups (2b–5b) were obtained from the corresponding phthalonitrile derivatives. The newly synthesized phthalocyanines displayed good solubility in organic solvents such as chloroform (CHCl 3 ), dichloromethane (DCM), tetrahydrofuran (THF), toluene, dimethylformamide (DMF) and dimethylsulfoxide (DMSO). On the other hand, the singlet oxygen, photodegradation, fluorescence quantum yields and fluorescence lifetime of these complexes were determined in DMSO. The effects of the substitution with fluoro-functionalized groups on these parameters were also compared. -- Highlights: • Synthesis of peripherally substituted zinc phthalocyanines. • Photophysical and photochemical properties in DMSO for phthalocyanines. • Photodynamic therapy studies

Synthesis, photophysical and photochemical properties of zinc phthalocyanines bearing fluoro-functionalized substituents

Energy Technology Data Exchange (ETDEWEB)

Aktaş, Ayşe [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Pişkin, Mehmet [Marmara University, Faculty of Art and Science, Department of Chemistry, 34722 Kadikoy-Istanbul (Turkey); Durmuş, Mahmut [Gebze Institute of Technology, Department of Chemistry, PO Box 141, Gebze 41400, Kocaeli (Turkey); Bıyıklıoğlu, Zekeriya, E-mail: zekeriya_61@yahoo.com [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey)

2014-01-15

In this study, the synthesis of phthalonitrile derivatives bearing fluoro-functionalized groups and their peripherally-tetra substituted zinc phthalocyanine complexes were reported. The phthalonitrile derivatives 2a–5a were prepared by nucleophilic substitution of 4-nitrophthalonitrile with 2-[3-(trifluoromethyl)phenoxy]ethanol, 2-{2-[3-(trifluoromethyl) phenoxy]ethoxy}ethanol, 2-(2,3,5,6-tetrafluorophenoxy)ethanol, 2-[2-(2,3,5,6-tetrafluorophenoxy)ethoxy]ethanol, respectively. Zinc phthalocyanines bearing fluoro-functionalized groups (2b–5b) were obtained from the corresponding phthalonitrile derivatives. The newly synthesized phthalocyanines displayed good solubility in organic solvents such as chloroform (CHCl{sub 3}), dichloromethane (DCM), tetrahydrofuran (THF), toluene, dimethylformamide (DMF) and dimethylsulfoxide (DMSO). On the other hand, the singlet oxygen, photodegradation, fluorescence quantum yields and fluorescence lifetime of these complexes were determined in DMSO. The effects of the substitution with fluoro-functionalized groups on these parameters were also compared. -- Highlights: • Synthesis of peripherally substituted zinc phthalocyanines. • Photophysical and photochemical properties in DMSO for phthalocyanines. • Photodynamic therapy studies.

Synthesis, Photophysical and Electrochemical Properties of a Mixed Bipyridyl-Phenanthrolyl Ligand Ru(II Heteroleptic Complex Having trans-2-Methyl-2-butenoic Acid Functionalities

Directory of Open Access Journals (Sweden)

Adewale O. Adeloye

2011-09-01

Full Text Available In this work, two ligands: 4-(trans-2-Methyl-2-butenoic acid-2,2'-bipyridine (L1 and 5-(trans-2-methyl-2-butenoic acid-1,10-phenanthroline (L2, with the corresponding mixed-ligand heteroleptic Ru(II complex were synthesized and characterized by FT-IR, 1H-, 13C-NMR spectroscopy and elemental analysis. The influence of the mixed functionalized polypyridyl ruthenium(II complex on the photophysical and electrochemical properties were investigated and compared to individual single-ligand homoleptic complexes. Interestingly, the mixed-ligand complex formulated as [RuL1L2(NCS2] exhibits broad and intense metal-to-ligand charge transfer (MLCT absorption with a high molar extinction coefficient (λmax = 514 nm, ε = 69,700 M−1 cm−1, better than those of individual single-ligand complexes, [Ru(L12(NCS2] and [Ru(L22(NCS2], and a strong photoluminescence intensity ratio in the red region at λem = 686 nm. The electrochemical properties of the complex indicated that the redox processes are ligand-based.

Photophysical properties of fullerenes prepared in an atmosphere of pyrrole

Energy Technology Data Exchange (ETDEWEB)

Glenis, S.; Cooke, S.; Chen, X.; Labes, M.M. (Temple Univ., Philadelphia, PA (United States))

1994-10-01

Samples of C[sub 60] and C[sub 70] containing a variety of nitrogen-doped species were prepared by arc vaporization of graphite in the presence of pyrrole. Cage-doped fractions were isolated by column chromatography and characterized by mass spectroscopy, optical absorption, and fluorescence measurements. Mass spectra were consistent with the substitution of an even number of carbon atoms of the C[sub 60] and C[sub 70] cages by nitrogen atoms. Carbonaceous clusters including fragmented fullerenes containing hydrogen atoms were also formed. UV-visible spectral analysis indicated that there is an influence of the molecular weight on the fundamental [pi]-[pi]* electronic transition. Fluorescence spectra showed a broad band containing vibrational fine structure that is attributed to photoseparated charges in the fragmented fullerenes and a shoulder on the low-energy side that is related to intrinsic excitation in the nitrogen-doped species. Fluorescence results imply a bandgap of 2.36 eV for the N doped fullerenes and the existence of intermediate excitonic transitions below the optical bandgap. Although it has not yet been possible to isolate a pure cage-doped material, the photophysical studies add credence to their existence and the importance of further attempts at their isolation. 17 refs., 4 figs., 1 tab.

Self-organization, interfacial interaction and photophysical properties of gold nanoparticle complexes derived from resilin-mimetic fluorescent protein rec1-resilin.

Science.gov (United States)

Mayavan, Sundar; Dutta, Naba K; Choudhury, Namita R; Kim, Misook; Elvin, Christopher M; Hill, Anita J

2011-04-01

In this investigation we report the synthesis of optically coupled hybrid architectures based on a new biomimetic fluorescent protein rec1-resilin and nanometer-scale gold nanoparticles (AuNPs) in a one-step method using a non-covalent mode of binding protocol. The presence of uniformly distributed fluorophore sequences, -Ser(Thr)-Tyr-Gly- along the molecular structure of rec1-resilin provides significant opportunity to synthesize fluorophore-modified AuNPs bioconjugates with unique photophysical properties. The detailed analyses of the AuNP-bioconjugates, synthesized under different experimental conditions using spectroscopic, microscopic and scattering techniques demonstrate the organizational pathways and the electronic and photophysical properties of the developed AuNP-rec1-resilin bioconjugates. The calculation of the bimolecular quenching constant using the Stern-Volmer equation confirms that the dominant mechanism involved in quenching of fluorescence of rec1-resilin in the presence of AuNP is static. Photoacoustic infrared spectroscopy was employed to understand the nature of the interfacial interaction between the AuNP and rec1-resilin and its evolution with pH. In such bioconjugates the quenched emission of fluorescence by AuNP on the fluorophore moiety of rec1-resilin in the immediate vicinity of the AuNP has significant potential for fluorescence-based detection schemes, sensors and also can be incorporated into nanoparticle-based devices. Copyright © 2011 Elsevier Ltd. All rights reserved.

Pincer-CNC mononuclear, dinuclear and heterodinuclear Au(III) and Pt(II) complexes supported by mono- and poly-N-heterocyclic carbenes: synthesis and photophysical properties.

Science.gov (United States)

Gonell, S; Poyatos, M; Peris, E

2016-04-07

A family of cyclometallated Au(iii) and Pt(ii) complexes containing a CNC-pincer ligand (CNC = 2,6-diphenylpyridine) supported by pyrene-based mono- or bis-NHC ligands have been synthesized and characterized, together with the preparation of a Pt-Au hetero-dimetallic complex based on a Y-shaped tris-NHC ligand. The photophysical properties of all the new species and of two related Ru(ii)-arene complexes were studied and compared. Whereas the pyrene-based complexes only exhibit emission in solution, those containing the Y-shaped tris-NHC ligand are only luminescent when dispersed in poly(methyl methacrylate) (PMMA). In particular, the pyrene-based complexes were found to be emissive in the range of 373-440 nm, with quantum yields ranging from 3.1 to 6.3%, and their emission spectra were found to be almost superimposable, pointing to the fluorescent pyrene-centered nature of the emission. This observation suggests that the emission properties of the pyrene fragment may be combined with some of the numerous applications of NHCs as supporting ligands allowing, for instance, the design of biological luminescent agents.

6-Aminocoumarin-naphthoquinone conjugates: design, synthesis, photophysical and electrochemical properties and DFT calculations

Energy Technology Data Exchange (ETDEWEB)

Miranda, Fabio S.; Ronconi, Celia M.; Sousa, Mikaelly O.B.; Silveira, Gleiciani Q.; Vargas, Maria D., E-mail: miranda@vm.uff.br, E-mail: mdvargascp@gmail.com [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Quimica

2014-01-15

Four novel 6-aminocoumarin-naphthoquinone conjugates were synthesized and their photophysical and electrochemical properties, investigated. 2-Chloro-3-(2-oxo-2H-chromen-6- ylamino)-1,4-naphthoquinone 1 did not present appreciable fluorescence in solution in comparison with 6-aminocoumarin, 6-AC. In order to understand the reasons for the fluorescence quenching in this compound, two strategies were attempted. Firstly, compound 1 was N-methylated to remove the intramolecular N-H...O=C electrostatic interaction that maintained the two units fixed, but the emission properties of the product 2 were not significantly different from those of 1. Time-dependent density functional theory (TD-DFT) calculations of compounds 1 and 2 indicate that the fluorescence quenching is related to the electron acceptor character of the naphthoquinone ring. The second strategy, therefore, involved the substitution of the chlorine atom in position 2 of the naphthoquinone nucleus for different electron donor groups (compounds 3-5), but again the emission properties did not change significantly. To explain these experimental findings, TD-DFT calculations of the ground (S{sub 0}) and excited (S{sub 1}) states of all molecules in solution were carried out. The results suggest that the energy states in these conjugates are such that the fluorescent group (6-AC) donates electrons to the naphthoquinone LUMO resulting in an oxidative photoinduced electron transfer (oxidative-PET). (author)

Synthesis of fluorinated ReCl(4,4'-R2-2,2'-bipyridine)(CO)3 complexes and their photophysical characterization in CH3CN and supercritical CO2.

Science.gov (United States)

Doherty, Mark D; Grills, David C; Fujita, Etsuko

2009-03-02

Two new CO(2)-soluble rhenium(I) bipyridine complexes bearing the fluorinated alkyl ligands 4,4'-(C(6)F(13)CH(2)CH(2)CH(2))(2)-2,2'-bipyridine (1a), and 4,4'-(C(8)F(17)CH(2)CH(2)CH(2))(2)-2,2'-bipyridine (1b) have been prepared and their photophysical properties investigated in CH(3)CN and supercritical CO(2). Electrochemical and spectroscopic characterization of these complexes in CH(3)CN suggests that the three methylene units effectively insulate the bipyridyl rings and the rhenium center from the electron-withdrawing effect of the fluorinated alkyl chains. Reductive quenching of the metal-to-ligand charge-transfer excited states with triethylamine reveals quenching rate constants in supercritical CO(2) that are only 6 times slower than those in CH(3)CN.

Computational Investigation of the Influence of Halogen Atoms on the Photophysical Properties of Tetraphenylporphyrin and Its Zinc(II) Complexes.

Science.gov (United States)

De Simone, Bruna C; Mazzone, Gloria; Russo, Nino; Sicilia, Emilia; Toscano, Marirosa

2018-03-15

How the tetraphenylporphyrin (TPP) and its zinc(II) complexes (ZnTPP) photophysical properties (absorption energies, singlet-triplet energy gap and spin-orbit coupling contributions) can change due to the presence of an increasing number of heavy atoms in their molecular structures has been investigated by means of density functional theory and its time-dependent formulation. Results show that the increase of the atomic mass of the substituted halogen strongly enhances the spin-orbit coupling values, allowing a more efficient singlet-triplet intersystem crossing. Different deactivation channels have been considered and rationalized on the basis of El-Sayed and Kasha rules. Most of the studied compounds possess the appropriate properties to generate cytotoxic singlet molecular oxygen ( 1 Δ g ) and, consequently, they can be proposed as photosensitizers in photodynamic therapy.

Photo-physics study of an hydroxy-quinoline derivative as inhibitor of Pim-1 kinase

DEFF Research Database (Denmark)

Lamhasni, T.; Aitlyazidi, S.; Hnach, M.

2013-01-01

The photophysical properties of the antiviral 7-nicotinoyl-styrylquinoline (MB96) were investigated by means of UV-Vis linear dichroism (LD) spectroscopy on molecular samples aligned in stretched polyvinylalcohol (PVA), supported by Time Dependent Density Functional Theory (TD-DFT) calculations...

Synthesis and photo-physical properties of fluorescent 1,3,5-triazine styryl derivatives

Directory of Open Access Journals (Sweden)

Padalkar Vikas S

2011-12-01

Full Text Available Abstract Background Organic fluorophore contains well-defined D-π-A (Donor-π system-Acceptor push-pull system have wide application in the field of NLO, OLED and high tech application. Electron donor diphenyl, triphenyl and carbazole conjugated with electron acceptor terminal through π-system were reported recently for high-tech applications. N,N-Dialkyl substituted 1,3,5-triazine also acts as donor keeping this idea in mind we developed D-π-A styryl dyes. Results Novel "Y"-shaped acceptor-π-donor-π-acceptor type of compounds were synthesized from 4,4'-((6-(4-(diethylaminophenyl-1,3,5-triazine-2,4diylbis(oxy dibenzaldehyde (DIPOD as electron donors and different active methylene compounds as electron acceptors by conventional Knoevenagel condensation reaction. Their photophysical and thermal properties were investigated. Conclusion It was found that the strong electron acceptor-donor chromophoric system of these compounds showed high Stoke's shift and excellent thermal stability. Compounds showed positive solvatofluorism behavior from nonpolar to polar solvent. All compounds have good thermal stability.

Environmental Effects on the Photophysics of Organic-Inorganic Halide Perovskites.

Science.gov (United States)

Galisteo-López, Juan F; Anaya, M; Calvo, M E; Míguez, H

2015-06-18

The photophysical properties of films of organic-inorganic lead halide perovskites under different ambient conditions are herein reported. We demonstrate that their luminescent properties are determined by the interplay between photoinduced activation and darkening processes, which strongly depend on the atmosphere surrounding the samples. We have isolated oxygen and moisture as the key elements in each process, activation and darkening, both of which involve the interaction with photogenerated carriers. These findings show that environmental factors play a key role in the performance of lead halide perovskites as efficient luminescent materials.

Photophysics of Carbon Nanotubes Interfaced with Organic and Inorganic Materials

CERN Document Server

Levitsky, Igor A; Karachevtsev, Victor A

2012-01-01

Photophysics of Carbon Nanotubes Interfaced with Organic and Inorganic Materials describes physical, optical and spectroscopic properties of the emerging class of nanocomposites formed from carbon nanotubes (CNTs)  interfacing with organic and inorganic materials. The three main chapters detail novel trends in  photophysics related to the interaction of  light with various carbon nanotube composites from relatively simple CNT/small molecule assemblies to complex hybrids such as CNT/Si and CNT/DNA nanostructures.   The latest experimental results are followed up with detailed discussions and scientific and technological perspectives to provide a through coverage of major topics including: ·   Light harvesting, energy conversion, photoinduced charge separation  and transport  in CNT based nanohybrids · CNT/polymer composites exhibiting photoactuation; and ·         Optical  spectroscopy  and structure of CNT/DNA complexes. Including original data and a short review of recent research, Phot...

Photophysics of ionic biochromophores

CERN Document Server

Brøndsted Nielsen, Steen

2014-01-01

This concise guide to studying ionic biochromophores features the first integrated overview of the photophysics of differing classes of biomolecules, from single amino acids to DNA. It includes an appraisal of the latest theories and experimental techniques.

Photophysics of GaN single-photon emitters in the visible spectral range

Science.gov (United States)

Berhane, Amanuel M.; Jeong, Kwang-Yong; Bradac, Carlo; Walsh, Michael; Englund, Dirk; Toth, Milos; Aharonovich, Igor

2018-04-01

In this work, we present a detailed photophysical analysis of recently discovered, optically stable single-photon emitters (SPEs) in gallium nitride (GaN). Temperature-resolved photoluminescence measurements reveal that the emission lines at 4 K are three orders of magnitude broader than the transform-limited width expected from excited-state lifetime measurements. The broadening is ascribed to ultrafast spectral diffusion. The photophysical study on several emitters at room temperature (RT) reveals an average brightness of (427 ±215 )kCounts /s . Finally, polarization measurements from 14 emitters are used to determine visibility as well as dipole orientation of defect systems within the GaN crystal. Our results underpin some of the fundamental properties of SPEs in GaN both at cryogenic and RT, and define the benchmark for future work in GaN-based single-photon technologies.

Study of the photophysical properties of composite film assembled of porphyrin and TiO{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Feng, X -S; Kang, S -Z; Liu, H -G; Mu, J [Shandong Univ., Jinan (China). Key Lab. for Colloid and Interface Chem. of Education Ministry

1999-09-08

In this paper, the formation, structure, and photophysical properties of functional mixed film of 5,10,15,20-tetra-4-(2-decanoic acid)phenyl porphyrin (TDPP) with TiO{sub 2} nanoparticles formed from the 2D sol-gel process of tetrabutoxyltitanium (TBT) at the air/water interface is reported. The composite multilayer films were assembled by transferring the mixed monolayer onto quartz plates. The diameter distribution and crystallinity of TiO{sub 2} particles were estimated by TEM observation and electron diffraction. The sensitization of TDPP upon TiO{sub 2} nanoparticles was confirmed by the spectral changes of UV-visible absorption and fluorescence of TDPP in the composite films. Furthermore the photosensitization greatly affected the photocatalytic activity of TiO{sub 2} particles with respect to the degradation of methylene blue (MO). (orig.)

The steady-state and time-resolved photophysical properties of a dimeric indium phthalocyanine complex

International Nuclear Information System (INIS)

Chen Yu; Araki, Yasuyuki; Dini, Danilo; Liu Ying; Ito, Osamu; Fujitsuka, Mamoru

2006-01-01

The steady-state and time-resolved photophysical properties and some molecular orbital calculation results of a dimeric indium phthalocyanine complex with an indium-indium bond, i.e., [tBu 4 PcIn] 2 .2tmed, have been described. The results regarding triplet excited state lifetimes can be ascribed to strong intramolecular interactions existing only in the excited state of this dimer because no significant difference in the absorption spectra of the tBu 4 PcInCl monomer and the [tBu 4 PcIn] 2 .2tmed dimer is observed, suggesting that no ground-state interaction can be assessed. The deactivation processes of the excited singlet state of [tBu 4 PcIn] 2 .2tmed are apparently faster than that of μ-oxo-bridged PcIn dimer [tBu 4 PcIn] 2 O. Molecular orbital calculation on the PcIn dimer shows no node between two indium atoms was found in the HOMO - 2 of the PcIn-InPc dimer, suggesting that bonding electrons distribute between two indium atoms

Synthesis, characterization and photophysical properties

Indian Academy of Sciences (India)

and medicinal application such as photodynamic thera- py.9–11 Intramolecular ... resident metallo/metalloid ion of porphyrin.15–18 In con- trast, energy or electron ... or flash chromatography was used for compound purifi- cation. Where as a ...

Specific solvent effect on lumazine photophysics: A combined fluorescence and intrinsic reaction coordinate analysis

Energy Technology Data Exchange (ETDEWEB)

Moyon, N. Shaemningwar; Gashnga, Pynsakhiat Miki; Phukan, Smritakshi; Mitra, Sivaprasad, E-mail: smitra@nehu.ac.in

2013-06-27

Highlights: • Correlation of lumazine photophysics with multiparametric Kamlet–Taft equation. • Solvent basicity (β) contributes maximum towards the hydrogen bonding (HB) effect. • HB interaction occurs at N1 and N3 proton in S{sub 0} and S{sub 1} state, respectively. • IRC calculation for different tautomerization processes both in S{sub 0} and S{sub 1} states. • Process related to riboflavin biosynthesis is thermodynamically feasible. - Abstract: The photophysical properties and tautomerization behavior of neutral lumazine were studied by fluorescence spectroscopy and density functional theory calculation. A quantitative estimation of the contributions from different solvatochromic parameters, like solvent polarizibility (π{sup ∗}), hydrogen bond donation (α) and hydrogen bond accepting (β) ability of the solvent, was made using linear free energy relationships based on the Kamlet–Taft equation. The analysis reveals that the hydrogen bond acceptance ability of the solvent is the most important parameter characterizing the excited state behavior of lumazine. Theoretical calculations result predict an extensive charge redistribution of lumazine upon excitation corresponding to the N3 and N1 proton dissociation sites by solvents in the ground and excited states, respectively. Comparison of S{sub 0} and S{sub 1} state potential energy curves constructed for several water mediated tautomerization processes by intrinsic reaction coordinate analysis of lumazine-H{sub 2}O cluster shows that (3,2) and (1,8) hydrogen migrations are the most favorable processes upon excitation.

Fabrication of Ag/ZnO heterostructure and the role of surface coverage of ZnO microrods by Ag nanoparticles on the photophysical and photocatalytic properties of the metal-semiconductor system

Energy Technology Data Exchange (ETDEWEB)

Sarma, Bikash; Sarma, Bimal K., E-mail: sarmabimal@gmail.com

2017-07-15

Highlights: • Fabrication of Ag/ZnO heterostructure by facile chemical processes. • Decoration of plasmonic Ag nanoparticles on ZnO microrods through direct attachment. • Quenching of photoluminescence is observed in Ag/ZnO heterostructure. • Extent of surface coverage governs photophysical and photochemical properties. - Abstract: This report presents findings on microstructural, photophysical, and photocatalytic properties of Ag/ZnO heterostructure grown on flexible and silicon substrates. ZnO microrods are prepared by thermal decomposition method for different solute concentrations and Ag/ZnO heterostructure are fabricated by photo-deposition of Ag nanoparticles on ZnO microrods. X-ray diffraction and electron microscopy studies confirm that ZnO microrods belong to the hexagonal wurtzite structure and grown along [001] direction with random alignment showing that majority microrods are aligned with (100) face parallel to the sample surface. Plasmonic Ag nanoparticles are attached to different faces of ZnO. In the optical reflection spectra of Ag/ZnO heterostructure, the surface plasmon resonance peak due to Ag nanoparticles appears at 445 nm. Due to the oxygen vacancies the band gaps of ZnO microrods turn out to be narrower compared to that of bulk ZnO. The presence of Ag nanoparticles decreases the photoluminescence intensity which might be attributed to the non-radiative energy and direct electron transfer in the plasmon–exciton system. The quenching of photoluminescence in Ag/ZnO heterostructure at different growth conditions depend on the extent of surface coverage of ZnO by plasmonic Ag nanoparticles. Photocatalytic degradation efficiency of Ag/ZnO heterostructure is higher than that of ZnO microrods. The extent of surface coverage of ZnO microrods by Ag nanoparticles is crucial for the observed changes in photophysical and photochemical properties.

Synthesis and photophysical properties of fluorescence sensing diester-terminated 1,8-naphthalimide

International Nuclear Information System (INIS)

Bojinov, N. I. Georgiev. V. B.

2011-01-01

Full text: The immediate detection and determination of environmental pollutants have been gaining particular importance. In recent years, extensive research has been carried out on fluorescent organic compounds whose photophysical properties are sensitive to environmental changes. Such interest is due to the possibility of tailoring the design of molecular devices for environmental pollution caused by heavy and transition metal ions. Photoinduced electron transfer (PET) using the 'fluorophore-spacer-receptor' format, developed by de Silva, is one of the most popular approaches to the design of fluorescent sensors.; This work reports the synthesis and sensor activity of a 1,8-naphthalimide sensor based on the 'fluorophore-spacer-receptor' format. The diester-terminated 1,8-naphthalimide was found to display sensitive fluorescence signal amplification over a wide pH scale, which has been ascribed to a photoinduced electron transfer from the tertiary amine receptor to the fluorophore. From the changes in the fluorescence intensity, a pKa value of 4.42 was determined, making the synthesized compound of potential use as pH chemosensing material.; In addition, the ability to detect ions has been evaluated in DMF by monitoring the quenching of the fluorescence intensity. Different ions have been tested: Zn 2+ , Ni 2+ , Pb 2+ , Co 2+ , Cu 2+ , and Fe 3+ for this purpose. The results have clearly shown that only Fe 3+ could be efficiently detected

Synthesis, photophysical and electrochemical properties, and protein-binding studies of luminescent cyclometalated iridium(III) bipyridine estradiol conjugates.

Science.gov (United States)

Lo, Kenneth Kam-Wing; Zhang, Kenneth Yin; Chung, Chi-Keung; Kwok, Karen Ying

2007-01-01

A new series of luminescent cyclometalated iridium(III) bipyridine estradiol conjugates [Ir(N-C)2(N-N)](PF6) (N-N = 5-(4-(17alpha-ethynylestradiolyl)phenyl)-2,2'-bipyridine, bpy-est, HN-C = 2-phenylpyridine, Hppy (1 a), 1-phenylpyrazole, Hppz (2 a), 7,8-benzoquinoline, Hbzq (3 a), 2-phenylquinoline, Hpq (4 a), 2-((1,1'-biphenyl)-4-yl)benzothiazole, Hbsb (5 a); N-N = 4-(N-(6-(4-(17alpha-ethynylestradiolyl)benzoylamino)hexyl)aminocarbonyl)-4'-methyl-2,2'-bipyridine, bpy-C6-est, HN-C = Hppy (1 b), Hppz (2 b), Hbzq (3 b), Hpq (4 b), Hbsb (5 b)) was synthesized, characterized, and their photophysical and electrochemical properties studied. Upon photoexcitation, all the complexes displayed intense and long-lived emission in fluid solutions at 298 K and in low-temperature glass. The emission of complexes 1 a-3 a and 1 b-3 b was assigned to a triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi(Ir)-->pi*(bpy-est and N-C-)) state mixed with some triplet intraligand ((3)IL) (pi-->pi*) (N-C- and N-N) character. However, the emissive states of the pq- and bsb- complexes 4 a, 4 b, 5 a, and 5 b showed substantial (3)IL (pi-->pi*) (pq-/bsb-) character. The lipophilicity of all the complexes was determined by reversed-phase HPLC. Upon binding to estrogen receptor alpha, all of these iridium(III) estradiol conjugates exhibited emission enhancement and lifetime extension, rendering them a novel series of luminescent probes for this receptor.

Photophysical properties of novel small acceptor molecules and their application in hybrid small-molecular/polymeric organic solar cells

Energy Technology Data Exchange (ETDEWEB)

Inal, Sahika; Castellani, Mauro; Neher, Dieter [Universitaet Potsdam, Institut fuer Physik und Astronomie, Potsdam-Golm (Germany); Sellinger, Alan [Institute of Materials Research and Engineering, Singapore (Singapore)

2009-07-01

Recent experimental investigations revealed that the photovoltaic properties of our devices are related to the balance between recombination and field-induced dissociation of interfacial excited states such as exciplexes or geminate polaron pairs. This balance was shown to be affected by the nanomorphology at the heterojunction. We have analyzed the photophysical properties of a new materials couple comprising an electron-donating PPV copolymer and a vinazene-based small molecule acceptor. Steady state and time-resolved photoluminescence (PL) spectroscopy in solution and in the solid state showed the formation of excimers within the acceptor. The associated long-range diffusion promise efficient energy harvesting at the heterojunction. On the other hand, blends of the PPV-derivative and the small molecule revealed strong exciplex formation. Therefore, bilayered hybrid small-molecular/polymeric solar cells have been fabricated by consequently spin-coating the macromolecular donor and the small molecule acceptor from two different solvents. The bilayer architecture limits recombination processes enabling high FFs of around 44% and a technologically important open circuit voltage of 1Volt.

Photophysics of aggregated 9-methylthiacarbocyanine bound to polyanions

Science.gov (United States)

Chibisov, Alexander K.; Görner, Helmut

2002-05-01

The photophysical properties of 3,3 '-diethyl-9-methylthiacarbocyanine (DTC) were studied in the presence of polystyrene sulfonate (PSS), polyacrylic acid (PAA) and polymethacrylic acid (PMA). The absorption spectra reflect a monomer/dimer equilibrium in neat aqueous solution and a shift towards bound H-aggregates, bound dimers and bound monomers on increasing the ratio of polyanion residue to dye concentrations ( r). These equilibria also determine the photodeactivation modes of DTC. The fluorescence intensity is reduced, when dimers and aggregates are present and strongly enhanced for low dye loading ( r=10 4). In contrast, the quantum yield of intersystem crossing is enhanced for bound dimers ( r=10 3).

Protein-based nanostructures as carriers for photo-physically active molecules in biosystems

OpenAIRE

Delcanale, Pietro

2017-01-01

In nature, many proteins function as carriers, being able to bind, transport and possibly release a ligand within a biological system. Protein-based carriers are interesting systems for drug delivery, with the remarkable advantage of being water-soluble and, as inherent components of biosystems, highly bio-compatible. This work focuses on the use of protein-based carriers for the delivery of hydrophobic photo-physically active molecules, whose structure and chemical properties lead to spontan...

Photophysical properties of open-framework germanates templated by nickel complexes

KAUST Repository

Peskov, Maxim; Schwingenschlö gl, Udo

2014-01-01

Open-framework germanates are a group of germanium oxides with a well-defined porous structure, suitable for ion-exchange and gas adsorption applications. Recently, Ni incorporation into the porous structure by establishing Ge-O-Ni bonds with the molecular complexes [Ni(H 2N(CH2)2NH2)2] was realized. We investigate the optical and electronic features of these systems (SUT-1 and SUT-2) from first principles. To describe the photophysical behavior, we analyze the bonding between the Ni and nearest-neighboring atoms and simulate the absorption spectra. Because of their optical characteristics, germania-based nanomaterials are expected to be essential components of future optical and electronic devices. We discuss to what extent molecular transition-metal complexes embedded into porous germanium oxide can modify the optical response to potentially expand the area of applications. This journal is © the Partner Organisations 2014.

Photophysics of three delocalized lipophilic cations in reverse micelles: A fluorescence spectroscopy study

Energy Technology Data Exchange (ETDEWEB)

Li, Dong-Wei [State Key Laboratory of Virology and College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Qi, Zu-De [State Key Laboratory of Virology and College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong (China); Ding, Xin-Liang; Li, Jia-Han; Jiang, Feng-Lei [State Key Laboratory of Virology and College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Liu, Yi, E-mail: prof.liuyi@263.net [State Key Laboratory of Virology and College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Kwong, Daniel W.J. [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong (China); Wong, Wai-Kwok, E-mail: wkwong@hkbu.edu.hk [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong (China)

2013-02-15

In this paper, aiming at the trans-membrane transport properties of the different DLCs related with the cytotoxicities, we have studied photophysics of DLCs in RMs. MTT assays indicated that DLC 1 were more cytotoxic than DLC 2 and 3. Steady-state absorption and fluorescence method have been used to characterize the binding model of three DLCs (1, 2, and 3) in RMs and bovine serum albumin (BSA). The progressive red-shift of compound 1 indicated that it can experience the hydrophilic and hydrophobic environment owing to the rigid structure, thus it can more easily cross the double membrane of cell than compounds 2 and 3. In conclusion, we simulated a model of compound 1 in RMs. The present study of F16 derivatives in microenvironment would provide some useful information to the cell membrane simulation and design of DLCs. - Graphical abstract: Aiming at the trans-membrane transport properties of the different DLCs related with the antitumor properties, MTT assay, steady-state absorption and fluorescence method have been used to characterize the binding model of three DLCs (1, 2, and 3) in reverse micelles (RMs) and bovine serum albumin (BSA). Highlights: Black-Right-Pointing-Pointer The drugs penetrating into the reverse micelles core were used to mimic the feature of drug trans-membrane transport. Black-Right-Pointing-Pointer Compound 1 was incorporated into the Stern Layer of reverse micelles, while compound 3 was not. Black-Right-Pointing-Pointer Reverse micelles would be used as a biomimic for drug designing and screening.

New naphthalene polyimide with unusual molar absorption coefficient and excited state properties: Synthesis, photophysics and electrochemistry

Energy Technology Data Exchange (ETDEWEB)

Ozser, Mustafa E. [Girne American University, Faculty of Engineering and Architecture, Department of Industrial Engineering, Girne, North Cyprus (Cyprus); Yucekan, Ilke; Bodapati, Jagadeesh B. [Eastern Mediterranean University, Faculty of Arts and Sciences, Department of Chemistry, Famagusta, North Cyprus (Cyprus); Icil, Huriye, E-mail: huriye.icil@emu.edu.tr [Eastern Mediterranean University, Faculty of Arts and Sciences, Department of Chemistry, Famagusta, North Cyprus (Cyprus)

2013-11-15

A high molecular weight 1,4,5,8-naphthalene polyimide (ENPI) by one-step polycondensation mechanism and for comparison its monomeric diimide (ENDI) were synthesized; the photophysical and electrochemical properties were studied in detail for ENPI. Monomer has shown unusual insolubility so that the characterization proven to be difficult, whereas ENPI has shown better solubility. The molecular weight data obtained by GPC for the polymer were M{sub n}=8240 and M{sub w}=34,000 g mol{sup −1} respectively with a polydispersity of 4.13. The polyimide exhibited outstandingly high molar absorption coefficients as 599,000, 1,021,000, and 972,700 M{sup −1} cm{sup −1}, which is first time reported in literature for the characteristic 0–2, 0–1, and 0–0 electronic transitions, respectively. ENPI showed concentration dependent and red shifted excimer emission in 1,1,2,2-tetrachloroethane (TCE). The polymer has undergone multielectron reductions in CHCl{sub 3} solution below 100 mV s{sup −1} scan rates which merged into two reversible one-electron reduction peaks at higher scan rates. In solid-state, similar scan rate dependent reduction peaks were noticed. The LUMO, HOMO and optical band gap values obtained for ENPI were −3.73, −6.91, and 3.18 eV respectively. ENDI polymer with striking features has great potential as new sensitizer for efficient dye sensitized organic cells. Highlights: • A high molecular weight naphthalene polyimide was synthesized (M{sub w}=34,000 g mol{sup −1}). • The oligoether polyimide exhibited outstanding molar absorptivity (972,700 M{sup −1} cm{sup −1}). • A red shifted excimer emission has been observed. • The polymer has undergone multielectron reductions.

Photophysical properties of a surfactive long-chain styryl merocyanine dye as fluorescent probe

Energy Technology Data Exchange (ETDEWEB)

Ismail, L.F.M., E-mail: Lailafmi@yahoo.com [Al-Azhar University, Faculty of Science, Chemistry Department, Nasr City, 12 Ibrahim El-Nagar, El-Hegaz Sq. Heliopolis, Cairo 11315 (Egypt)

2012-09-15

This work deals with detailed investigations of the photophysical properties of a styryl merocyanine dye, namely 1-cetyl-4-[4 Prime -(methoxy) styryl]-pyridinium bromide (CMSPB) of molecular rotor type. The solvatochromic analyses of the data in different solvents using the Kamlet-Taft parameters ({alpha}, {beta}, {pi}{sup Low-Asterisk }) were discussed. Optical excitation of the studied merocyanine dye populates a CT S{sub 1} state with about 22.64 folds higher dipole moment value relative to that in the S{sub 0} state. Moreover, the effect of solvent viscosity (glycerol at various temperatures (299.0-351.0 K)) on CMSPB fluorescent properties is analyzed to understand the molecular mechanisms of the characteristic increase in CMSPB fluorescence intensity. The results indicate that CMSPB exhibits fluorescent properties typical for molecular rotors. The results show that torsional relaxation dynamics of molecular rotors in high-viscosity solvents cannot be described by the simple stick boundary hydrodynamics defined by the Debye-Stokes-Einstein (DSE) equation. The fluorescence depolarization behavior in glycerol at various temperatures (299.0-351.0 K) shows that the molecular rotational diffusion is controlled by the free volume of the medium. Furthermore, excited state studies in ethanol/chloroform mixture revealed the formation of weak complex with chloroform of stoichiometry 1:1 with formation constant of 0.004l mol{sup -1}. Moreover, the increase of the quantum yield values in micellar solutions of CTAB and SDS relative to that of water indicates that the guest dye molecules are microencapsulated into the hydrophobic interior of host micelle. The obtained non-zero values of fluorescence polarization in micellar solution imply reduced rotational depolarization of dye molecules via association with the surfactant. Upon comparing the spectral data in micelles with those in homogeneous solvent systems, more can be learned of the structural details of the micellar

Fluorescent water-Soluble Probes Based on Ammonium Cation Peg Substituted Perylenepisimides: Synthesis, Photophysical Properties, and Live Cell Images

Science.gov (United States)

Yang, Wei; Cai, Jiaxuan; Zhang, Shuchen; Yi, Xuegang; Gao, Baoxiang

2018-01-01

To synthesize perylenbisimides (PBI) fluorescent probes that will improve the water-soluble ability and the cytocompatibility, the synthesis and properties of fluorescent water-soluble probes based on dendritic ammonium cation polyethylene glycol (PEG) substituted perylenebisimides(GPDIs) are presented. As we expected, with increased ammonium cation PEG, the aggregation of the PBI in an aqueous solution is completely suppressed by the hydrophilic ammonium cation PEG groups. And the fluorescence quantum yield increases from 25% for GPDI-1 to 62% for GPDI-2. When incubated with Hela cells for 48 h, the viabilities are 71% (for GPDI-1) and 76% (for GPDI-2). Live cell imaging shows that these probes are efficiently internalized by HeLa cells. The study of the photophysical properties indicated increasing the ammonium cation PEG generation can increase the fluorescence quantum yield. Live cell imaging shows that with the ammonium cation PEG chains of perylenebisimides has high biocompatibility. The exceptionally low cytotoxicity is ascribed to the ammonium cation PEG chains, which protect the dyes from nonspecifically interacting with the extracellular proteins. Live cell imaging shows that ammonium cations PEG chains can promote the internalization of these probes.

Photo-physical and interactional behavior of two members of group B vitamins in different solvent media

Science.gov (United States)

Zakerhamidi, M. S.; Zare Haghighi, L.; Seyed Ahmadian, S. M.

2017-09-01

In this paper, absorption and fluorescence spectra of vitamin B12 (cyanocobalamin) and vitamin B6 (pyridoxine) were recorded in solvents with different polarity, at room temperature. These vitamins' photo-physical behavior depends strongly on the solvent's nature along with different attached groups in their structures. In order to investigate the solvent-solute interactions and environmental effect on spectral variations, linear solvation energy relationships concept, suggested by Kamlet and Taft was used. Solvatochromic method was also used for measuring the ground and excited state dipole moments of these vitamins. According to our experimental results, dipole moment of these groups of vitamins in excited state is larger than ground state. Furthermore, obtained photo-physical and interactional properties of used vitamins can give important information on how this group of vitamins behaves in biological systems.

Photophysical properties of 1-acetoxy-8-hydroxy-1,4,4a,9a-tetrahydroanthraquinone: Evidence for excited state proton transfer reaction

International Nuclear Information System (INIS)

Singh, Rupashree Balia; Mahanta, Subrata; Guchhait, Nikhil

2007-01-01

The photophysical properties of 1-acetoxy-8-hydroxy-1,4,4a,9a-tetrahydroanthraquinone (HTHQ) have been investigated by steady state and time resolved spectroscopy in combination with quantum chemical calculations. The effects of various parameters such as the nature of solvent and pH of the medium on the spectral properties confirm the existence of different neutral and ionic species in the ground and excited states. In the ground state, HTHQ exists as intramolecularly hydrogen bonded closed conformer in non-polar and polar aprotic solvents. Apart from the closed conformer, the intermolecular hydrogen bonded solvated species and the anion of HTHQ are present in hydroxylic solvents. The closed conformer shows excited state intramolecular proton transfer in all solvents and the solvent polarity independent red shifted emission indicates only keto-enol tautomerism. Evaluation of the potential energy surfaces by quantum chemical calculation using density functional theory point towards the possibility of proton transfer reaction in the first excited state but not in the ground state

Photophysical investigation of cyano-substituted terrylenediimide derivatives.

Science.gov (United States)

Kennes, Koen; Baeten, Yannick; Vosch, Tom; Sempels, Wouter; Yordanov, Stoyan; Stappert, Sebastian; Chen, Long; Müllen, Klaus; Hofkens, Johan; Van der Auweraer, Mark; Fron, Eduard

2014-12-18

Two new terrylenediimide (TDI) chromophores with cyano substituents in the bay and core area (BCN-TDI and OCN-TDI, respectively) have been characterized by a wide range of techniques, and their applicability for stimulated emission depletion (STED) microscopy has been tested. By cyano substitution an increase of the fluorescence quantum yield and a decrease of the nonradiative rate constant is achieved and attributed to a reduced charge-transfer character of the excited state due to a lower electron density of the TDI core. For BCN-TDI, the substitution in the bay area induces a strong torsional twist in the molecule which, similar to phenoxy bay-perylenediimide (PDI), has a strong effect on the fluorescence lifetime but appears to prevent the aggregation that is observed for OCN-TDI. The single-molecule photobleaching stability of BCN- and OCN-TDI is lower than that of a reference TDI without cyano substitution (C7-TDI), although less so for OCN-TDI. The photophysical properties of the excited singlet state are only slightly influenced by the cyano groups. The observed intense stimulated emission, the pump-dump-probe experiments, and STED single-molecule imaging indicate that STED experiments with the cyano-substituted TDIs are possible. However, because of aggregation and more efficient photobleaching, the performance of BCN- and OCN-TDI is worse than that of the reference compound without cyano groups (C7-TDI). Bay-substituted TDIs are less suitable for STED microscopy.

Synthesis, characterization and photophysical study of ethynyl pyrene derivatives as promising materials for organic optoelectronics

Energy Technology Data Exchange (ETDEWEB)

Gama, Paola E.; Corrêa, Rodrigo J.; Garden, Simon J., E-mail: garden@iq.ufrj.br

2015-05-15

Two series of pyrene derivatives, phenylethynyl (4–6) and the previously unknown ethynylcyclohexanol (7–9), were prepared by Sonogashira cross-coupling reactions. The introduction of an increasing number of ethynyl substituents resulted in a progressive bathochromic shift in the absorption and emission spectra which culminated in an inversion of the nature of the first two excited states ({sup 1}L{sub a} and {sup 1}L{sub b}) of the tetra-substituted derivatives (6 and 9) relative to pyrene. In solution, only for the mono-cyclohexanolethynyl pyrene (7) a sufficiently concentrated solution could be obtained so as to observe the excimer. Additionally, the emission band ratio I{sub 1}/I{sub 3} for 7 was found to be moderately sensitive to the nature of the solvent and the ratio directly correlated with the Py scale. TDDFT calculations were used to explore the variation of the properties of the low lying excited states. Fluorescence emission in the solid state, with the appropriate choice of materials, covers the entire visible region of the electromagnetic spectrum due to static excimer emission. A massive red-shift for solid state photoluminescence from 9 resulted in emission at longer wavelength than the more highly conjugated 6. - Highlights: • Phenyl and cyclohexanol ethynylpyrene derivatives: photophysically compared. • Excimer formation and solvent dependent emission from cyclohexanolethynylpyrene. • Systematic red shifting of solid state photoluminescence from static excimers. • Massive red-shift in the solid state photoluminescence of 9. • TDDFT calculations: properties of the lowest singlet states, systematic comparison.

Photophysics Applied to Cavitands and Capsules.

Science.gov (United States)

Berryman, Orion B; Dube, Henry; Rebek, Julius

2011-07-01

The use of light as a stimulus to control functional materials or nano-devices is appealing as it provides convenient control of triggering events where and when they are desired without introducing extra components to the system. Many photophysical and photochemical processes are extremely fast, giving rise to nearly instantaneous onset of events. However, these fast processes can be challenging to engineer into chemical systems. Supramolecular chemistry offers a convenient way to study and control photoprocesses. Given the reversible and self-programmed nature of modern host-guest systems, a modular approach can be considered in which different photoprocesses are coupled to obtain complex functions that emerge and are controlled solely by light inputs. In this review, we highlight recent examples of photoswitching and photophysics applied in the context of supramolecular host-guest systems, with a particular emphasis on resorcinarene based cavitands and hydrogen bonded capsules.

Fatigue Property of Oxidized Photochromic Dithienylethene Derivative for Permanent Optical Recording

International Nuclear Information System (INIS)

Jeong, Yong Chul; Ahn, Kwang Hyun; Yang, Sung Ik; Kim, Eun Kyoung

2005-01-01

We have synthesized and characterized the photophysical and fatigue properties of DMTFO4. The results have shown that the photo-stability of DMTFO4 was significantly decreased compared with the unoxidized DMTF6. The possible application of DMTFO4 would be the development of permanent recording material based on a non-reversible photochromic conversion. Photochromic diarylethenes, such as 1,2-bis(2-methyl-1-benzothiophene-3-yl)perfluorocyclopentene (BTF6) and 1,2-bis(2,5-dimethylthien-3-yl)perfluorocyclopentene (DMTF6), have been extensively investigated in recent years in order to develop materials for molecular photonic devices such as optical memory and switch. In the design of photochromic materials, thermal stability and fatigue resistant are important features to be considered. The thiophene analogues undergo photochromic ring closure efficiently but the fatigue property is generally low, resulting irreversible photochromism. If the photochromism is in an irreversible manner it could be applied in the permanent optical recording such as write once read many (WORM) memory. This motivates us to examine the effect of oxidation in the photophysical properties of diarylethenes with thiophene unit. As the thiophene analogues, we chose DMTF6 and its oxidized analogue, 1,2-bis(2,5-dimethylthien-1,1-dioxide-3-yl)perfluorocyclopentene (DMTFO4). Herein we report the synthesis and characterization of the photochromic properties including the fatigue property of DMTFO4

Spectroscopy and photophysics of self-organized zinc porphyrin nanolayers. 1. Optical spectroscopy of excitonic interactions involving the soret band

NARCIS (Netherlands)

Donker, H.; Koehorst, R.B.M.; Schaafsma, T.J.

2005-01-01

The photophysical properties of excited singlet states of zinc tetra-(p-octylphenyl)-porphyrin in 5-25-nm-thick films spin-coated onto quartz slides have been investigated by optical spectroscopy. Analysis of the polarized absorption spectra using a dipole-dipole exciton model with two mutually

Spectral characterizations and photophysical properties of one-step synthesized blue fluorescent 4′-aryl substituted 2,2′:6′,2′′-terpyridine for OLEDs application

Energy Technology Data Exchange (ETDEWEB)

Lakshmanan, Raja [Department of Physics, Birla Institute of Technology and Science, Pilani, Rajasthan 333031 (India); Shivaprakash, Narayanapura Chennegowda [Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012 (India); Nair, Sindhu Sukumaran, E-mail: sindhunair@pilani.bits-pilani.ac.in [Department of Physics, Birla Institute of Technology and Science, Pilani, Rajasthan 333031 (India)

2015-12-15

We have synthesized a series of 4′-aryl substituted 2,2′:6′,2′′-terpyridine (terpy) derivatives, namely 4′-(4-methylphenyl)-2,2′:6′,2′′-terpyridine (C-1), 4′-(2-furyl)-2,2′:6′2′′-terpyridine (C-2), and 4′-(3,4,5-trimethoxyphenyl)-2,2′:6′,2′′-terpyridine (C-3). The synthesized terpy compounds were characterized by elemental analyses, FTIR, NMR ({sup 1}H and {sup 13}C), and ESI-Mass spectrometry. Photophysical, electrochemical and thermal properties of terpy compounds were systematically studied. Maximum excitation band was observed between 240 and 330 nm using UV–visible spectra, and maximum emission peaks from PL spectra were observed at 385, 405 and 440 nm for C-1, C-2 and C-3 respectively. Fluorescence lifetime (τ) of the fluorophores was found to be 0.35 and 1.55 ns at the excitation wavelength of 406 nm for C-1 and C-2 respectively, and τ value for C-3 was found to be 0.29 ns at the excitation wavelength of 468 nm. We noticed that the calculated values of HOMO energy levels were increased from 5.96 (C-1) to 6.08 (C-3) eV, which confirms that C-3 derivative is more electrons donating in nature. The calculated electrochemical band gaps were 2.95, 2.82 and 3.02 eV for C-1, C-2 and C-3 respectively. These blue fluorescent emitter derivatives can be used as an electron transport and electroluminescent material to design the blue fluorescent organic light emitting diode (OLED) applications. - Highlights: • Facile one-step synthesized blue fluorescent emitter, 2,2′:6′,2′′-terpyridine derivatives. • The exceptionally broad emission band (365–525 nm) was achieved in the blue region. • Fast fluorescence life time and good thermal stability.

Synthesis, Photophysics, Electrochemistry and Electrogenerated Chemiluminescence of a Homologous Set of BODIPY-Appended Bipyridine Derivatives.

Science.gov (United States)

Rosenthal, Joel; Nepomnyashchii, Alexander B; Kozhukh, Julia; Bard, Allen J; Lippard, Stephen J

2011-09-15

Two new 2,2'-bipyridine (bpy) based ligands with ancillary BODIPY chromophores attached at the 4 and 4'-positions were prepared and characterized, which vary in the substitution pattern about the BODIPY periphery by either excluding (BB1) or including (BB2) a β-alkyl substituent. Both absorb strongly throughout the visible region and are strongly emissive. The basic photophysics and electrochemical properties of BB1 and BB2 are comparable to those of the BODIPY monomers on which they are based. The solid-state structures and electronic structure calculations both indicate that there is negligible electronic communication between the BODIPY moieties and the intervening bpy spacers. Electrogenerated chemiluminescence spectra of the two Bpy-BODIPY derivatives are similar to their recorded fluorescence profiles and are strongly influenced by substituents on the BODIPY chromophores. These 2,2'-bipyridine derivatives represent a new set of ligands that should find utility in applications including light-harvesting, photocatalysis, and molecular electronics.

Photophysical properties of columnar phases formed by triphenylene derivatives

International Nuclear Information System (INIS)

Sigal, Herve

1997-01-01

This research thesis reports the study of the spectroscopic properties and of the migration of excitation energy in the singlet state in columnar phases formed by alkyloxy and alkylthio derivatives of triphenylene. First, the author studied the spectroscopic properties of chromophores in solutions, and characterized excited states by using computation codes (CS-INDO-CIPSI). Then, by using the excitonic theory in the case of the considered triphenylene derivatives, the author studied the influence of molecular movements and of the intra-columnar order on the spectroscopic properties. In some circumstances, the non-radiative transfer of excitation energy is governed by a mechanism displaying a random evolution. This stochastic movement is studied by using Monte Carlo simulations. The author shows that the energy migration is one-dimensional on short times, and then becomes three-dimensional. The evolution of excitation energy in space and in time is determined [fr

Photophysics and lasing correlation of pyrromethene 567 dye in crosslinked polymeric networks

International Nuclear Information System (INIS)

Banuelos Prieto, J.; Lopez Arbeloa, F.; Garcia, O.; Arbeloa, I. Lopez

2007-01-01

The photophysical properties of the pyrromethene 567 dye incorporated in copolymers of methylmethacrylate with different acrylic and methacrylic crosslinking monomers are reported. In general, the solid matrices improve the fluorescence capacity of the dye, due to both an increase and a decrease in the radiative and non-radiative deactivation rate constants, respectively, as consequence of a more rigid environment. It is observed that there is an optimal crosslinking degree for the highest fluorescence efficiency, which depends on the nature of the crosslinking monomer. Taking into account the lasing properties for these systems, it is established a good correlation between the lasing and the fluorescence characteristics of the dye in agreement with previous conclusions obtained in liquid solutions

Acetone photophysics at 282 nm excitation at elevated pressure and temperature. II: Fluorescence modeling

Science.gov (United States)

Hartwig, Jason; Raju, Mandhapati; Sung, Chih-Jen

2017-07-01

This is the second in a series of two papers that presents an updated fluorescence model and compares with the new experimental data reported in the first paper, as well as the available literature data, to extend the range of acetone photophysics to elevated pressure and temperature conditions. This work elucidates the complete acetone photophysical model in terms of each and every competing radiative and non-radiative rate. The acetone fluorescence model is then thoroughly examined and optimized based on disparity with recently conducted elevated pressure and temperature photophysical calibration experiments. The current work offers insight into the competition between non-radiative and vibrational energy decay rates at elevated temperature and pressure and proposes a global optimization of model parameters from the photophysical model developed by Thurber (Acetone Laser-Induced Fluorescence for Temperature and Multiparameter Imaging in Gaseous Flows. PhD thesis, Stanford University Mechanical Engineering Department, 1999). The collisional constants of proportionality, which govern vibrational relaxation, are shown to be temperature dependent at elevated pressures. A new oxygen quenching rate is proposed which takes into account collisions with oxygen as well as the oxygen-assisted intersystem crossing component. Additionally, global trends in ketone photophysics are presented and discussed.

Photophysical processes and light extraction in organic light emitting devices; Photophysikalische Prozesse und Lichtextraktion in organischen Leuchtdioden

Energy Technology Data Exchange (ETDEWEB)

Reinke, Nils Andre

2008-11-10

Alq{sub 3} is the most commonly used material for electron transport and as an emission layer in organic LEDs. However many of its photophysical properties are still unknown. The phosphorescence - known as a low temperature effect - was measured at room temperature for the first time. A new experimental method is presented to identify and characterize a new molecular conversion process into an unknown dark state. This conversion process represents an additional fundamental energy loss channel which is especially important for the development of organic lasers. A physically intuitive model was developed, which allows the calculation of light emission from OLEDs. In addition, a new method for the quantification of optical losses in OLEDs based on an dipole approach has been implemented and verified experimentally. The use of OLEDs was demonstrated for the first time in a chemical sensor, which is based on the detection of the surface plasmon resonance. (orig.)

Advanced optical measurements for characterizing photophysical properties of single nanoparticles.

Energy Technology Data Exchange (ETDEWEB)

Polsky, Ronen; Davis, Ryan W.; Arango, Dulce C.; Brozik, Susan Marie; Wheeler, David Roger

2009-09-01

Formation of complex nanomaterials would ideally involve single-pot reaction conditions with one reactive site per nanoparticle, resulting in a high yield of incrementally modified or oriented structures. Many studies in nanoparticle functionalization have sought to generate highly uniform nanoparticles with tailorable surface chemistry necessary to produce such conjugates, with limited success. In order to overcome these limitations, we have modified commercially available nanoparticles with multiple potential reaction sites for conjugation with single ssDNAs, proteins, and small unilamellar vesicles. These approaches combined heterobifunctional and biochemical template chemistries with single molecule optical methods for improved control of nanomaterial functionalization. Several interesting analytical results have been achieved by leveraging techniques unique to SNL, and provide multiple paths for future improvements for multiplex nanoparticle synthesis and characterization. Hyperspectral imaging has proven especially useful for assaying substrate immobilized fluorescent particles. In dynamic environments, temporal correlation spectroscopies have been employed for tracking changes in diffusion/hydrodynamic radii, particle size distributions, and identifying mobile versus immobile sample fractions at unbounded dilution. Finally, Raman fingerprinting of biological conjugates has been enabled by resonant signal enhancement provided by intimate interactions with nanoparticles and composite nanoshells.

Photophysical and photochemical properties of Bauhinia megalandra (Caesalpinaceae) extracts as new PDT photosensitizer

Science.gov (United States)

Vargas Tovar, Franklin R.; Rivas, C.; Estrada, O.; Marcano O., Aristides A.; Echevarria, Lorenzo; Diaz, Yrene; Alexander, I.; Rodriguez, L.; Padron, L.; Rivera, I. R.

2004-10-01

Recently new photosensitizers, chlorophyll "a and b" derivatives, for photodynamic therapy (PDT) have been presented. It already passed complete pre-clinical investigations. This prompted us to carry out an extensive study of photophysical properties of chlorine derivatives, important both for optimization of their clinic applications and for study of mechanisms of chlorine PDT&. The fresh leaves of Bauhinia megalandra (Caesalpinaceae) were extracted with methanol by percolation, and re-extract with a mixture of methanol-water (1:1), the insoluble fraction was then separated by column chromatography [RP18/hexane-ethylacetate (9:1)] to obtain four fractions named 1 to 4. These compounds were identified by NMR data. We found that 3 and 4 efficiently generates singlet oxygen when irradiated with visible light. Detection of the singlet oxygen was fulfilled by its reaction with histidine and detected by bleaching p-nitrosodimethylaniline under 440 nm irradiation. The quantum yields of singlet oxygen determined by us were 0.088 (1), 0.151 (2), 0.219 (3) and 0.301 (4). We measured absorption and fluorescence spectra of compounds 1 to 4 (Mg-chlorophyll-a, Pheophytin, Mg-chlorophyll-b and chlorophyll-b respectively) in different media and in aqueous solutions of human serum albumin. The association constant of the compounds 1, 2, 3 and 4 in the presence of HSA were estimated. The binding and quenching studies suggest that only 1 and 3 may serve as a useful fluorescence probe for structure/function studies of different chlorophyll binding proteins. No photoinduced binding was observed after irradiation by all the studied compounds in presence of human serum albumin.

Photophysical Properties of Novel Organic, Inorganic, and Hybrid Semiconductor Materials

Science.gov (United States)

Chang, Angela Yenchi

For the past 200 years, novel materials have driven technological progress, and going forward these advanced materials will continue to deeply impact virtually all major industrial sectors. Therefore, it is vital to perform basic and applied research on novel materials in order to develop new technologies for the future. This dissertation describes the results of photophysical studies on three novel materials with electronic and optoelectronic applications, namely organic small molecules DTDCTB with C60 and C70, colloidal indium antimonide (InSb) nanocrystals, and an organic-inorganic hybrid perovskite with the composition CH3NH3PbI 3-xClx, using transient absorption (TA) and photoluminescence (PL) spectroscopy. In chapter 2, we characterize the timescale and efficiency of charge separation and recombination in thin film blends comprising DTDCTB, a narrow-band gap electron donor, and either C60 or C70 as an electron acceptor. TA and time-resolved PL studies show correlated, sub-picosecond charge separation times and multiple timescales of charge recombination. Our results indicate that some donors fail to charge separate in donor-acceptor mixed films, which suggests material manipulations may improve device efficiency. Chapter 3 describes electron-hole pair dynamics in strongly quantum-confined, colloidal InSb nanocrystal quantum dots. For all samples, TA shows a bleach feature that, for several picoseconds, dramatically red-shifts prior to reaching a time-independent position. We suggest this unusual red-shift relates transient population flow through two energetically comparable conduction band states. From pump-power-dependent measurements, we also determine biexciton lifetimes. In chapter 4, we examine carrier dynamics in polycrystalline methylammonium lead mixed halide perovskite (CH3NH3PbI3-xCl x) thin films as functions of temperature and photoexcitation wavelength. At room temperature, the long-lived TA signals stand in contrast to PL dynamics, where the

Photophysics and electrochemistry relevant to photocatalytic water splitting involved at solid–electrolyte interfaces

KAUST Repository

Shinagawa, Tatsuya

2016-08-04

Direct photon to chemical energy conversion using semiconductor-electrocatalyst-electrolyte interfaces has been extensively investigated for more than a half century. Many studies have focused on screening materials for efficient photocatalysis. Photocatalytic efficiency has been improved during this period but is not sufficient for industrial commercialization. Detailed elucidation on the photocatalytic water splitting process leads to consecutive six reaction steps with the fundamental parameters involved: The photocatalysis is initiated involving photophysics derived from various semiconductor properties (1: photon absorption, 2: exciton separation). The generated charge carriers need to be transferred to surfaces effectively utilizing the interfaces (3: carrier diffusion, 4: carrier transport). Consequently, electrocatalysis finishes the process by producing products on the surface (5: catalytic efficiency, 6: mass transfer of reactants and products). Successful photocatalytic water splitting requires the enhancement of efficiency at each stage. Most critically, a fundamental understanding of the interfacial phenomena is highly desired for establishing "photocatalysis by design" concepts, where the kinetic bottleneck within a process is identified by further improving the specific properties of photocatalytic materials as opposed to blind material screening. Theoretical modeling using the identified quantitative parameters can effectively predict the theoretically attainable photon-conversion yields. This article provides an overview of the state-of-the-art theoretical understanding of interfacial problems mainly developed in our laboratory. Photocatalytic water splitting (especially hydrogen evolution on metal surfaces) was selected as a topic, and the photophysical and electrochemical processes that occur at semiconductor-metal, semiconductor-electrolyte and metal-electrolyte interfaces are discussed.

Photo-physics of third-order nonlinear optical processes in organic dyes

International Nuclear Information System (INIS)

Delysse, Stephane

1997-01-01

We study some aspects of the nonlinear picosecond photo-physics in organic dyes using Kerr ellipsometry. The aim is to establish link between the photo-physics and nonlinear optics in these compounds. First, we study coherent processes directly linked to the third-order susceptibility. Thus, we measure two-photon absorption spectra of large internal charge transfer dyes. We take into account all coupling between three electronic states which can interfere to explain the particular response of some stilbene dyes. On the second hand, we expose a more photophysical approach to determine the S 1 → S n transition energies and moments using the measurement of excited state absorption cross sections. These results allow the prediction of the susceptibilities relevant to alternative nonlinear optical methods. Nevertheless, the stationary approach hides the complex relaxation processes which can take place in organic dyes. As an illustration, we study the formation and disappearance of a TICT (Twisted intramolecular charge transfer) in a pyrylium salt in solvents of increasing viscosity. (author) [fr

Synthesis, photophysical and preliminary investigation of the dye

Indian Academy of Sciences (India)

Synthesis, photophysical and preliminary investigation of the dye-sensitized solar ... with most reduction potential which might be due to increase in the conjugation of ... CSIR Materials Science and Manufacturing, PO Box 395, Pretoria 0001, ...

Synthesis, structural characterization, luminescent properties and theoretical study of three novel lanthanide metal-organic frameworks of Ho(III), Gd(III) and Eu(III) with 2,5-thiophenedicarboxylate anion

Energy Technology Data Exchange (ETDEWEB)

Marques, Lippy F. [Instituto de Química, Universidade do Estado do Rio de Janeiro, Rio de Janeiro 20550-013 (Brazil); Correa, Charlane C. [Departamento de Química-ICE, Universidade Federal de Juiz de Fora, Juiz de Fora-MG, 36036-330 (Brazil); Ribeiro, Sidney J.L.; Santos, Molíria V. dos [Institute of Chemistry, São Paulo State University − UNESP, CP 355 Araraquara-SP 14801-970 Brazil (Brazil); Dutra, José Diogo L.; Freire, Ricardo O. [Pople Computational Chemistry Laboratory, Departamento de Química, Universidade Federal de Sergipe, São Cristóvão-SE 49100-000 (Brazil); Machado, Flávia C., E-mail: flavia.machado@ufjf.edu.br [Departamento de Química-ICE, Universidade Federal de Juiz de Fora, Juiz de Fora-MG, 36036-330 (Brazil)

2015-07-15

In this paper, the synthesis of three new metal-organic frameworks of lanthanides (LnMOFs) ([Ln{sub 2}(2,5-tdc){sub 3}(dmso){sub 2}]·H{sub 2}O){sub n} (Ln=Ho (1); Gd (2); Eu (3); 2,5-tdc=2,5-thiophenedicarboxylate anion; dmso=dimethylsulfoxide), and their complete characterization, including single crystal X-ray diffraction, FTIR spectroscopy and thermogravimetric analysis are reported. In especial, photophysical properties of Eu(III) complex have been studied in detail via both theoretical and experimental approaches. Crystal structure of (1) reveals that each lanthanide ion is seven-coordinated by oxygen atoms in an overall distorted capped trigonal – prismatic geometry. The 2,5-tdc{sup 2−} ligands connect four Ln(III) centers, adopting (κ{sup 1}–κ{sup 1})–(κ{sup 1}–κ{sup 1})–μ{sub 4} coordination mode, generating an 8-connected uninodal 3D network. In addition, theoretical studies for Eu(III) complex were performed using the Sparkle model for lanthanide complexes. - Graphical abstract: Three new metal-organic frameworks of lanthanides (LnMOFs) ([Ln{sub 2}(2,5-tdc){sub 3}(dmso){sub 2}]·H{sub 2}O){sub n} (Ln=Ho (1); Gd (2); Eu (3); 2,5-tdc=2,5-thiophenedicarboxylate anion; dmso=dimethylsulfoxide), were synthesized and their complete characterization, including single crystal X-ray diffraction, FTIR spectroscopy and thermogravimetric analysis are reported. In especial, photophysical properties of Eu(III) complex have been studied in detail via both theoretical and experimental approaches. - Highlights: • Three new LnMOFs were synthesized and fully characterized. • Ho{sup 3+}, Gd{sup 3+} and Eu{sup 3+} complexes photoluminescence properties were investigated. • Theoretical approaches for Eu{sup 3+} complex luminescence has been performed. • An energy level diagram is used to establish the ligand-to-metal energy transfer. • These metal−organic frameworks can act as light conversion molecular devices.

Tetra- and octa-[4-(2-hydroxyethyl)phenoxy bearing novel metal-free and zinc(II) phthalocyanines: Synthesis, characterization and investigation of photophysicochemical properties

Energy Technology Data Exchange (ETDEWEB)

Köksoy, Baybars [Marmara University, Department of Chemistry, 34722 Kadıköy, Istanbul (Turkey); Durmuş, Mahmut [Gebze Technical University, Department of Chemistry, 41400 Gebze, Kocaeli (Turkey); Bulut, Mustafa, E-mail: mbulut@marmara.edu.tr [Marmara University, Department of Chemistry, 34722 Kadıköy, Istanbul (Turkey)

2015-05-15

In this study, four novel phthalonitriles (1–4) and their corresponding metal-free (5–8) and zinc(II) phthalocyanine derivatives (9–12) bearing 4-(hydroxyethyl)phenoxy groups were synthesized. These novel compounds were characterized by IR, elemental analyses, {sup 1}H-NMR, UV–vis, and MALDI-TOF spectral data. Furthermore, photophysical (fluorescence quantum yields and lifetimes) and photochemical properties (singlet oxygen generation and photodegradation quantum yields) of these phthalocyanines were investigated in dimethylsulfoxide. The studied zinc(II) phthalocyanines generated highly singlet oxygen which is very important for the photodynamic therapy (PDT) of cancer. The fluorescence quenching behaviour of the newly synthesized phthalocyanine compounds were also investigated using 1,4-benzoquinone. - Highlights: • Octa and tetra 4-(hydroxyethyl)phenoxy substituted metal-free and zinc(II) phthalocyanines. • Study of photophysicochemical properties of eight new phthalocyanines. • Highly singlet oxygen generation for novel zinc(II) phthalocyanine photosensitizers.

Photophysics and Photochemistry of Canonical Nucleobases’ Thioanalogs: From Quantum Mechanical Studies to Time Resolved Experiments

Directory of Open Access Journals (Sweden)

Serra Arslancan

2017-06-01

Full Text Available Interest in understanding the photophysics and photochemistry of thiated nucleobases has been awakened because of their possible involvement in primordial RNA or their potential use as photosensitizers in medicinal chemistry. The interpretation of the photodynamics of these systems, conditioned by their intricate potential energy surfaces, requires the powerful interplay between experimental measurements and state of the art molecular simulations. In this review, we provide an overview on the photophysics of natural nucleobases’ thioanalogs, which covers the last 30 years and both experimental and computational contributions. For all the canonical nucleobase’s thioanalogs, we have compiled the main steady state absorption and emission features and their interpretation in terms of theoretical calculations. Then, we revise the main topographical features, including stationary points and interstate crossings, of their potential energy surfaces based on quantum mechanical calculations and we conclude, by combining the outcome of different spectroscopic techniques and molecular dynamics simulations, with the mechanism by which these nucleobase analogs populate their triplet excited states, which are at the origin of their photosensitizing properties.

Photophysics of charge transfer in a polyfluorene/violanthrone blend

Science.gov (United States)

Cabanillas-Gonzalez, J.; Virgili, T.; Lanzani, G.; Yeates, S.; Ariu, M.; Nelson, J.; Bradley, D. D. C.

2005-01-01

We present a study of the photophysical and photovoltaic properties of blends of violanthrone in poly[9, 9-bis (2-ethylhexyl)-fluorene-2, 7-diyl ] (PF2/6) . Photoluminescence quenching and photocurrent measurements show moderate efficiencies for charge generation, characteristic of such polymer/dye blends. Pump-probe measurements on blend films suggest that while ˜47% of the total exciton population dissociates within 4ps of photoexcitation, only ˜32% subsequently results in the formation of dye anions. We attribute the discrepancy to the likely formation of complex species with long lifetimes, such as stabilized interface charge pairs or exciplexes. This conclusion is supported by the appearance of a long lifetime component of 2.4ns in the dynamics of the photoinduced absorption signal associated to polarons in photoinduced absorption bands centered at 560nm .

Photophysical studies of oxicam group of NSAIDs: piroxicam, meloxicam and tenoxicam

Science.gov (United States)

Banerjee, Rona; Chakraborty, Hirak; Sarkar, Munna

2003-04-01

Oxicam group of non steroidal anti-inflammatory drugs has been chosen as a prototype molecular group that shows diverse biological functions and dynamic structural features. Photophysical studies of three drugs from this group viz., piroxicam, meloxicam and tenoxicam have been carried out in different solvents with varying polarity, H-bond character and viscosity. The spectral responses of different prototropic forms of these drugs towards varying solvent parameters have been studied, with the aim to characterize their interaction in biomimetic environment non-invasively. The nature of the lowest transition has been identified. The extinction coefficient, quantum yield and viscosity dependence on the nature of the solvents, all indicate the extreme sensitivity of these drugs to their microenvironment.

Structural, thermal and photo-physical data of azo-aromatic TEMPO derivatives before and after their grafting to polyolefins

Directory of Open Access Journals (Sweden)

Francesca Cicogna

2016-03-01

Full Text Available The data reported in this paper are complementary to the characterization of 4-(phenylazo-benzoyl-2,2,6,6-tetramethylpiperidine-1-oxyl radical (AzO-TEMPO and of the 4-(2-thienylazo-benzoyl-2,2,6,6-tetramethylpiperidine-1-oxyl radical (ThiO-TEMPO before and after their grafting to two polyethylene matrices (a copolymer ethylene/α-olefin (co-EO and a high density polyethylene (HDPE. Particularly the data reported in this paper confirm the structure (FT-IR analysis, the thermal (TGA and EPR and the photo-physical (UV–vis properties of the RO-TEMPO derivatives before and after their grafting. Herein, the FT-IR spectrum and TGA thermogram of ThiO-TEMPO were compared with those of AzO-TEMPO. Moreover, the superimposition of UV–vis spectra collected during the irradiation under 366 or 254 nm emitting lamp of AzO-TEMPO and ThiO-TEMPO in acetonitrile solution are reported. Finally, a complete DSC characterization of the functionalized POs is shown.DOI of original article: 〈http://dx.doi.org/10.1016/j.polymer.2015.11.018〉 [1

Single-crystal structure, photophysical characteristics and electroluminescent properties of bis(2-(4-trifluoromethyl-2-hydroxyphenyl)benzothiazolate)zinc

International Nuclear Information System (INIS)

Xu Huixia; Yue, Yan; Wang Hua; Chen Liuqing; Hao Yuying; Xu Bingshe

2012-01-01

In this paper, a zinc (II) complex of Zn 2 (4-tfmBTZ) 4 (4-tfmBTZ=2-(4-trifluoromethyl-2-hydroxyphenyl)benzothiazolate) was reported. Via combination of experimental and theoretical approaches, its molecular structure, photophysical characteristics, electronic structure and electroluminescent properties were investigated. The results indicate that Zn 2 (4-tfmBTZ) 4 exists as five-coordinate geometric structure and two zinc atoms are bridged by oxygen atoms. The intense absorption band was located at 404 nm, which mainly originate from the transition HOMO−1 to LUMO+2. The blue-light emission was observed in tetrahydrofuran solution and thin film. White-light emission with four emission peaks was observed with CIE coordinate of (0.29, 0.33) and a higher CRI of 85.1 by fabricating bilayer device using Zn 2 (4-tfmBTZ) 4 as electron-transport and NPB as hole-transport material. - Highlights: ► The single-crystal and electronic structures of Zn 2 (4-tfmBTZ) 4 . ► The multicolor emission of Zn 2 (4-tfmBTZ) 4 were realized by the simple devices. ► White OLED is achieved with particularly high color rending index (CRI) by the emission of Zn 2 (4-tfmBTZ) 4 .

Synthesis and photophysical properties of indium(III) phthalocyanine derivatives

Energy Technology Data Exchange (ETDEWEB)

Özceşmeci, İbrahim, E-mail: ozcesmecii@itu.edu.tr [Department of Chemistry, Technical University of Istanbul, Maslak 34469, Istanbul (Turkey); Gelir, Ali [Department of Physics, Technical University of Istanbul, Maslak 34469, Istanbul (Turkey); Gül, Ahmet [Department of Chemistry, Technical University of Istanbul, Maslak 34469, Istanbul (Turkey)

2014-03-15

Three chloroindium(III) phthalocyanine derivatives bearing four aromatic (naphthalene or pyrene) or aliphatic (hexylthio) groups were prepared from corresponding phthalonitrile compounds. The indium(III) phthalocyanine derivatives were characterized with elemental analyses, mass, proton nuclear magnetic resonance ({sup 1}H NMR), Fourier transform infrared spectroscopy (FT-IR) and ultraviolet–visible spectroscopy (UV–vis) techniques. Quantum yields and the energy transfer from the substituents to phthalocyanine core were examined. No energy transfer was observed for 5. The energy transfer efficiency from pyrene units to indium phthalocyanine core was calculated as 0.27 for 6. Quantum yields of all samples were very small due to heavy atom effect of indium atom in the core. It was also observed that upon binding of pyrene and naphthalene units to indium phthalocyanine as substituents, the quantum yields of indium phthalocyanine parts of 5 and 6 decreased. -- Highlights: • Three chloroindium(III) phthalocyanines were prepared and characterized. • Aggregation properties of these compounds were investigated. • The energy transfer efficiency was examined. • Quantum yield of these systems were calculated.

Thermostability and photophysical properties of mixed-ligand carboxylate/benzimidazole Zn(II)-coordination polymers

International Nuclear Information System (INIS)

Barros, Bráulio Silva; Chojnacki, Jaroslaw; Macêdo Soares, Antonia Alice; Kulesza, Joanna; Lourenço da Luz, Leonis; Júnior, Severino Alves

2015-01-01

The reaction between Zn(NO 3 ) 2 ·6H 2 O or Zn(CH 3 COO) 2 ·2H 2 O and isophthalic acid (1,3-H 2 bdc) in the presence of benzimidazole (Hbzim) in dimethylformamide (DMF)/ethanol (EtOH)/H 2 O solvent mixture at room temperature yielded two structurally different coordination polymers: [Zn 2 (1,3-bdc) 2 (Hbzim) 2 ] (1) and [Zn 2 (1,3-bdc)(bzim) 2 ] (2). (1) is a 2D-layered framework with a molecule of benzimidazole coordinated to the Zn center, whereas (2) is a 3D framework with benzimidazolate species acting as a co-ligand and bridging two Zn(II) ions. Reactions performed at 90 °C led to the formation of coordination polymers structurally similar to (2), independently of the Zn(II) source used. In the absence of benzimidazole, the reaction between ZnAc 2 .2H 2 O and 1,3-H 2 bdc at 90 °C resulted in the formation of (3), a 3D coordination polymer Zn(HCOO) 3 (Me 2 NH 2 + ). It was observed that the thermostability and the photophysical properties of (1) and (2) are strongly dependent on the coordination modes and packing of benzimidazole in the solid state. These materials present photoluminescence in the wide range of the spectrum, from UV to IR. A full understanding of a physical process occurring in these intriguing systems, including complete energy level diagrams with possible transitions were provided. - Graphical abstract: Display Omitted - Highlights: • Structurally different Zn(II)-coordination polymers were prepared. • The formation of frameworks was counter anion and temperature dependent. • Photoluminescence in the wide range of the spectrum, from UV to IR was observed. • Thermostability and luminescence depended on bzim packing in the structure

Effective photosensitized energy transfer of nonanuclear terbium clusters using methyl salicylate derivatives.

Science.gov (United States)

Omagari, Shun; Nakanishi, Takayuki; Seki, Tomohiro; Kitagawa, Yuichi; Takahata, Yumie; Fushimi, Koji; Ito, Hajime; Hasegawa, Yasuchika

2015-03-12

The photophysical properties of the novel nonanuclear Tb(III) clusters Tb-L1 and Tb-L2 involving the ligands methyl 4-methylsalicylate (L1) and methyl 5-methylsalicylate (L2) are reported. The position of the methyl group has an effect on their photophysical properties. The prepared nonanuclear Tb(III) clusters were identified by fast atom bombardment mass spectrometry and powder X-ray diffraction. Characteristic photophysical properties, including photoluminescence spectra, emission lifetimes, and emission quantum yields, were determined. The emission quantum yield of Tb-L1 (Φ(ππ*) = 31%) was found to be 13 times larger than that of Tb-L2 (Φ(ππ*) = 2.4%). The photophysical characterization and DFT calculations reveal the effect of the methyl group on the electronic structure of methylsalicylate ligand. In this study, the photophysical properties of the nonanuclear Tb(III) clusters are discussed in relation to the methyl group on the aromatic ring of the methylsalicylate ligand.

DFT/TDDFT investigation on the electronic structures and photophysical properties of phosphorescent iridium(III) complexes with 2-(pyridin-2-yl)-benzo[d]imidazole ligand

Energy Technology Data Exchange (ETDEWEB)

Shang, Xiaohong, E-mail: shangxiaohong58@aliyun.com [College of Chemistry and Life Science, Changchun University of Technology, Changchun 130012 (China); Han, Deming [School of Life Science and Technology, Changchun University of Science and Technology, Changchun 130022 (China); Li, Dongfeng [College of Chemistry and Life Science, Changchun University of Technology, Changchun 130012 (China); Zhang, Gang [State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China)

2014-03-15

We have reported a theoretical analysis of a series of heteroleptic iridium(III) complexes (mpmi){sub 2}Ir(pybi) [mpmi=1-(4-tolyl)-3-methyl-imidazole, pybi=2-(pyridin-2-yl)-benzo[d]imidazole] (1a), (fpmi){sub 2}Ir(pybi) [fpmi=1-(4-fluoro-phenyl)-3-methyl-imidazole] (1b), (tfpmi){sub 2}Ir(pybi) [tfpmi=1-methyl-3-(4-trifluoromethyl-phenyl)-imidazole] (1c), (pypmi){sub 2}Ir(pybi) [pypmi=3-(3-methyl-imidazol)-pyrazole] (2a), (phpymi){sub 2}Ir(pybi) [phpymi=3-(3-methyl-imidazol)-5-phenyl-pyrazole] (2b), and (inpymi){sub 2}Ir(pybi) [inpymi=3-(3-methyl-imidazol)-indeno[1,2-c]pyrazole] (2c) by using the density functional theory (DFT) method to investigate their electronic structures and photophysical properties and obtain further insights into the phosphorescent efficiency mechanism. By changing cyclometalated ligands, the conjugation length, and substituents of the cyclometalated ligands, one can tune the emission color from green (λ{sub em}=520 nm) to orange (λ{sub em}=592 nm). Complexes 1a, 1b, 2a, and 2b have the almost identical emission wavelength about 550 nm, while 592 nm for 1c and 520 nm for 2c are red shifted and blue shifted, respectively, relative to 1a. The calculated results indicate that, for 1b and 1c, the substituents of −F and −CF{sub 3} at the phenyl moiety cause a poor hole-injection ability compared with that of 1a. For all these complexes studied, the hole-transporting performances are better than the electron-transporting ones. The difference between reorganization energies for hole transport (λ{sub ih}) and reorganization energies for electron transport (λ{sub ie}) for complex 1c are relatively smaller, indicating that the hole and electron transfer balance could be achieved more easily in the emitting layer. The alteration of cyclometalated ligands with different conjugation lengths and substituents has an impact on the optoelectronic properties of these complexes. It is believed that the larger metal to ligand charge transfer (MLCT

Probing photoinduced electron-transfer in graphene-dye hybrid materials for DSSC

NARCIS (Netherlands)

Guarracino, Paola; Gatti, Teresa; Canever, Nicolo; Abdu-Aguye, Mustapha; Loi, Maria Antonietta; Menna, Enzo; Franco, Lorenzo

2017-01-01

We investigated the photophysical properties of a newly synthesized hybrid material composed of a triphenylamine dye covalently bound to reduced graphene oxide, potentially relevant as a stable photosensitizer in dye-sensitized solar cells. The photophysical characterization has been carried out by

Single-crystal structure, photophysical characteristics and electroluminescent properties of bis(2-(4-trifluoromethyl-2-hydroxyphenyl)benzothiazolate)zinc

Energy Technology Data Exchange (ETDEWEB)

Xu Huixia, E-mail: xuhuixia0824@163.com [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Taiyuan 030024 (China); Yue, Yan [Department of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); Wang Hua [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Taiyuan 030024 (China); Chen Liuqing [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Taiyuan 030024 (China); College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Hao Yuying [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); Xu Bingshe [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Taiyuan 030024 (China); College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

2012-04-15

In this paper, a zinc (II) complex of Zn{sub 2}(4-tfmBTZ){sub 4} (4-tfmBTZ=2-(4-trifluoromethyl-2-hydroxyphenyl)benzothiazolate) was reported. Via combination of experimental and theoretical approaches, its molecular structure, photophysical characteristics, electronic structure and electroluminescent properties were investigated. The results indicate that Zn{sub 2}(4-tfmBTZ){sub 4} exists as five-coordinate geometric structure and two zinc atoms are bridged by oxygen atoms. The intense absorption band was located at 404 nm, which mainly originate from the transition HOMO-1 to LUMO+2. The blue-light emission was observed in tetrahydrofuran solution and thin film. White-light emission with four emission peaks was observed with CIE coordinate of (0.29, 0.33) and a higher CRI of 85.1 by fabricating bilayer device using Zn{sub 2}(4-tfmBTZ){sub 4} as electron-transport and NPB as hole-transport material. - Highlights: Black-Right-Pointing-Pointer The single-crystal and electronic structures of Zn{sub 2}(4-tfmBTZ){sub 4}. Black-Right-Pointing-Pointer The multicolor emission of Zn{sub 2}(4-tfmBTZ){sub 4} were realized by the simple devices. Black-Right-Pointing-Pointer White OLED is achieved with particularly high color rending index (CRI) by the emission of Zn{sub 2}(4-tfmBTZ){sub 4}.

Photophysical properties of neutral and dissociated forms of rosmarinic acid

Energy Technology Data Exchange (ETDEWEB)

Danaf, Nader Al [Department of Chemistry, American University of Beirut, Beirut (Lebanon); Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen (Germany); Melhem, Racha Abi [Department of Chemistry, American University of Beirut, Beirut (Lebanon); Assaf, Khaleel I.; Nau, Werner M. [Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen (Germany); Patra, Digambara, E-mail: dp03@aub.edu.lb [Department of Chemistry, American University of Beirut, Beirut (Lebanon)

2016-07-15

Polyphenols are bioactive components that have attracted attention by chemists over many years. Rosmarinic acid (RA) is a polyphenol that is widely investigated for its broad range of potential applications as an anti-carcinogenic agent, an anti-inflammatory drug, and antioxidant. The spectroscopic properties of this molecule are addressed in details in this study. The absorption and fluorescence of RA are investigated at different pH values, characterizing the dissociated forms of RA. In a similar manner, RA was characterized in a set of different solvents. The spectral shifts of RA in the different solvents were addressed by using the Lippert–Mataga and the Stokes' shift vs. E{sub T}30 plots, which revealed two sets of linearity for the behavior of RA in polar protic and aprotic solvents. The lifetime decay profile of the dissociated forms of RA and those of RA in different solvents are characterized by bi-exponential lifetime decay functions. A theoretical study on the molecular structure of the different dissociated forms of RA is also reported. The simulated UV–vis spectra of the dissociated forms of RA were studied and compared to the experimental spectra by performing TDDFT calculations. Besides the UV-simulated spectra, the frontier molecular orbitals (FMO) of the different RA dissociated forms were also calculated.

Photophysical properties of neutral and dissociated forms of rosmarinic acid

International Nuclear Information System (INIS)

Danaf, Nader Al; Melhem, Racha Abi; Assaf, Khaleel I.; Nau, Werner M.; Patra, Digambara

2016-01-01

Polyphenols are bioactive components that have attracted attention by chemists over many years. Rosmarinic acid (RA) is a polyphenol that is widely investigated for its broad range of potential applications as an anti-carcinogenic agent, an anti-inflammatory drug, and antioxidant. The spectroscopic properties of this molecule are addressed in details in this study. The absorption and fluorescence of RA are investigated at different pH values, characterizing the dissociated forms of RA. In a similar manner, RA was characterized in a set of different solvents. The spectral shifts of RA in the different solvents were addressed by using the Lippert–Mataga and the Stokes' shift vs. E T 30 plots, which revealed two sets of linearity for the behavior of RA in polar protic and aprotic solvents. The lifetime decay profile of the dissociated forms of RA and those of RA in different solvents are characterized by bi-exponential lifetime decay functions. A theoretical study on the molecular structure of the different dissociated forms of RA is also reported. The simulated UV–vis spectra of the dissociated forms of RA were studied and compared to the experimental spectra by performing TDDFT calculations. Besides the UV-simulated spectra, the frontier molecular orbitals (FMO) of the different RA dissociated forms were also calculated.

Photophysical study of a charge transfer oxazole dye in micelles: Role of surfactant headgroups

Energy Technology Data Exchange (ETDEWEB)

Maiti, Jyotirmay [Department of Chemistry, West Bengal State University, Barasat, Kolkata 700126 (India); Sarkar, Yeasmin; Parui, Partha Pratim [Department of Chemistry, Jadavpur University, Kolkata 700032 (India); Chakraborty, Sandipan [Department of Microbiology, University of Calcutta, Kolkata 700019 (India); Biswas, Suman [Department of Chemistry, West Bengal State University, Barasat, Kolkata 700126 (India); Das, Ranjan, E-mail: ranjan.das68@gmail.com [Department of Chemistry, West Bengal State University, Barasat, Kolkata 700126 (India)

2015-07-15

Photophysics of 5-(4′′-dimethylaminophenyl)-2-(4′-sulfophenyl)oxazole, sodium salt (DMO) which undergoes intramolecular charge transfer in the excited state was studied in micelles. In the cationic and the nonionic micelles, significantly higher fluorescence quantum yield is observed in comparison to the anionic micelles, due to much lower accessibility of DMO to the water molecules in the former micelles than the latter. Time-resolved fluorescence decays were characterized by a fast (τ{sub 1}) and a slow (τ{sub 2}) component of decay in all the micelles. The fast decay component (τ{sub 1}) increases significantly in going from the anionic micelles to the cationic micelles, because of the poorly hydrated headgroup region of the latter micelles compared to the former. Furthermore, much higher value of the slow component of decay (τ{sub 2}) is observed for the cationic and the neutral micelles than the anionic micelles. This is attributed to the increased penetration of water molecules into the micellar core of the anionic micelles compared to the cationic and the neutral micelles. - Highlights: • Photophysics of the fluorophore are remarkably different in the cationic and the anionic micelles. • Differential hydration of the surfactant headgroups gives rise to significantly different fluorescence quantum yield and lifetime in oppositely charged micelles. • Electrostatic interactions fine tune location of the fluorophore in the micelle–water interface of ionic micelles.

Influence of Bridgehead Substitution and Ring Annelation on the Photophysical Properties of Polycyclic DBO-Type Azoalkanes.

Science.gov (United States)

Adam, Waldemar; Nikolaus, Achim; Sauer, Jürgen

1999-05-14

The photophysical data for the polycyclic, bridgehead-substituted derivatives 1-10 of the photoreluctant diazabicyclo[2.2.2]oct-2-ene (DBO) are presented. Substitution on the bridgehead positions with radical-stabilizing substituents enhances the photoreactivity (Phi(r)) and decreases the fluorescence quantum yields (Phi(f)) and lifetimes (tau) compared to the parent DBO. The annelated rings have no influence on the photoreactivity, except when steric interactions with an alpha substituent hinder the optimal radical-stabilizing conformation. The fused rings and some of the bridgehead substituents reduce the solvent-induced quenching of the singlet-excited azo chromophore by steric shielding of the azo group and, thus, increase the fluorescence quantum yields and lifetimes.

A New Star-shaped Carbazole Derivative with Polyhedral Oligomeric Silsesquioxane Core: Crystal Structure and Unique Photoluminescence Property.

Science.gov (United States)

Xu, Zixuan; Yu, Tianzhi; Zhao, Yuling; Zhang, Hui; Zhao, Guoyun; Li, Jianfeng; Chai, Lanqin

2016-01-01

A new inorganic–organic hybrid material based on polyhedral oligomeric silsesquioxane (POSS) capped with carbazolyl substituents, octakis[3-(carbazol-9-yl)propyldimethylsiloxy]-silsesquioxane (POSS-8Cz), was successfully synthesized and characterized. The X-ray crystal structure of POSS-8Cz were described. The photophysical properties of POSS-8Cz were investigated by using UV–vis,photoluminescence spectroscopic analysis. The hybrid material exhibits blue emission in the solution and the solid film.The morphology and thermal stablity properties were measured by X-ray diffraction (XRD) and TG-DTA analysis.

Photophysics and photochemistry of Riboflavin-induced corneal Cross-Linking

DEFF Research Database (Denmark)

Breitenbach, Thomas

In this talk, we will describe general pathways involved in the photophysics of a photosensitized process, which can lead to crosslinking due to light excitation of Riboflavin in the cornea. Furthermore, we will show the contribution of singlet molecular oxygen O2(a1Δg) to this phenomena and show...

Preparation and fluorescent recognition properties for fluoride of a nanostructured covalently bonded europium hybrid material

Institute of Scientific and Technical Information of China (English)

余旭东; 李景印; 李亚娟; 耿丽君; 甄小丽; 于涛

2015-01-01

A novel covalently bonded Eu3+-based silica hybrid material was designed and its spectrophotometric anion sensing prop-erty was studied. The fluorescent receptor (europium complex) was covalently grafted to the silica matrix via a sol-gel approach. FTIR, UV-vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescent spectra were characterized, and the results revealed that the hybrid material with nanosphere structure displayed excellent photophysical property. In addition, the selective anion sensing property of the hybrid material was studied by UV-vis and fluorescence spectra. The results showed that the hybrid material exhibited a smart response with fluoride anions.

Synthesis, crystal structure and photophysical properties of (E)-4-(4-(2-hydroxybenzylideneamino)benzyl)oxazolidin-2-one

International Nuclear Information System (INIS)

Kumari, Rekha; Varghese, Anitha; George, Louis

2016-01-01

A new Schiff base, (4-(benzylideneamino)benzyl)oxazolidin-2-one has been synthesised from 4-(4-aminobenzyl)oxazolidin-2-one and salicylaldehyde by a simple condensation reaction. Single-crystal X-ray analysis of (E)-4-(4-(2-hydroxybenzylideneamino) benzyl)oxazolidin-2-one (HBOA) revealed that there is a 1-D, slipped, face-to-face motif with off-set, head-to-tail stacked columns. Detailed studies on photophysical properties of the synthesised compound in solutions indicate their potential applications in the field of organic light emitting devices and nonlinear optical materials. Absorption and fluorescence study of HBOA has been conducted in a series of solvents with increasing polarity at room temperature. Ground and excited state dipole moments have been determined experimentally by using Lippert–Mataga polarity function, Bakhshiev solvent polarity parameter, Kawskii–Chamma–Viallet solvent polarity parameter and RichardtГ—Віs microscopic solvent polarity parameter. Due to the considerable π-electron density redistribution, the excited state dipole moment was found to be larger than that of the ground state. The ground state dipole moment value was determined by quantum chemical method which was used to estimate excited state dipole moment through solvatochromic correlations. Kamlet–Taft and Catalan methods were used to get the information of both non-specific solute–solvent interactions and hydrogen bonding interactions. TD-DFT (B3LYP/6-311G(d,p)) has been used for the determination of HOMO–LUMO energies. Mulliken charges and Molecular electrostatic potential were also evaluated from DFT calculations.

η6-Cycloparaphenylene transition metal complexes: synthesis, structure, photophysical properties, and application to the selective monofunctionalization of cycloparaphenylenes.

Science.gov (United States)

Kubota, Natsumi; Segawa, Yasutomo; Itami, Kenichiro

2015-01-28

The synthesis, structure, photophysical properties, and reactivity of cycloparaphenylenes (CPPs) coordinated to group 6 transition metal fragments are described. The η(6)-coordination of [9]CPP or [12]CPP with M(CO)6 (M = Cr, Mo, W) afforded the corresponding [n]CPP-M(CO)3 complexes (n = 9, 12; M = Cr, Mo, W). In the (1)H NMR spectra of these complexes, characteristic upfield-shifted singlet signals corresponding to the four hydrogen atoms attached to the coordinated C6H4 ring of the CPPs were observed at 5.4-5.9 ppm. The complex [9]CPP-Cr(CO)3 could be successfully isolated in spite of its instability. X-ray crystallographic analysis and computational studies of [9]CPP-Cr(CO)3 revealed that chromium-CPP coordination occurs at the convex surface of [9]CPP both in the solid state and in solution. TD-DFT calculations suggested that the emerging high-wavenumber absorption peak upon coordination of [9]CPP to Cr(CO)3 should be assigned to a weak HOMO-LUMO transition. Moreover, by using the complex [9]CPP-Cr(CO)3, a rapid and highly monoselective CPP functionalization has been achieved. The established one-pot method, consisting of complexation, deprotonation, nucleophilic substitution, and decomplexation steps, yielded silyl-, boryl-, and methoxycarbonyl-substituted CPPs in up to 93% yield relative to reacted starting material.

Photochemical and Photophysical Properties of Phthalocyanines Modified with Optically Active Alcohols

Directory of Open Access Journals (Sweden)

Aline A. Ramos

2015-07-01

Full Text Available Three phthalocyanine derivatives were synthesized and characterized: one modified with a racemic mixture of 1-(4-bromophenylethanol and two other macrocycles modified with each one of the enantioenriched isomers (R-1-(4-bromophenylethanol and (S-1-(4-bromophenylethanol. The compounds were characterized by 1H-NMR spectroscopy, mass spectrometry, UV-Vis absorption, and excitation and emission spectra. Additionally, partition coefficient values and the quantum yield of the generation of oxygen reactive species were determined. Interestingly, the phthalocyanine containing a (R-1-(4-bromophenylethoxy moiety showed higher quantum yield of reactive oxygen species generation than other compounds under the same conditions. In addition, the obtained fluorescence microscopy and cell viability results have shown that these phthalocyanines have different interactions with mammary MCF-7 cells. Therefore, our results indicate that the photochemical and biological properties of phthalocyanines with chiral ligands should be evaluated separately for each enantiomeric species.

Synthesis and Preliminary Characterization of a PPE-Type Polymer Containing Substituted Fullerenes and Transition Metal Ligation Sites

Directory of Open Access Journals (Sweden)

Corinne A. Basinger

2015-01-01

Full Text Available A substituted fullerene was incorporated into a PPE-conjugated polymer repeat unit. This subunit was then polymerized via Sonogashira coupling with other repeat units to create polymeric systems approaching 50 repeat units (based on GPC characterization. Bipyridine ligands were incorporated into some of these repeat units to provide sites for transition metal coordination. Photophysical characterization of the absorption and emission properties of these systems shows excited states located on both the fullerene and aromatic backbone of the polymers that exist in a thermally controlled equilibrium. Future work will explore other substituted polyaromatic systems using similar methodologies.

Electronic structures and photophysics of d8-d8 complexes

Czech Academy of Sciences Publication Activity Database

Gray, H. B.; Záliš, Stanislav; Vlček, Antonín

2017-01-01

Roč. 345, AUG 2017 (2017), s. 297-317 ISSN 0010-8545 R&D Projects: GA MŠk LH13015 Grant - others:COST(XE) CM1405 Institutional support: RVO:61388955 Keywords : excitation * electronic structures * photophysics Subject RIV: CG - Electrochemistry OBOR OECD: Physical chemistry Impact factor: 13.324, year: 2016

Effects of π-conjugation attenuation on the photophysics and exciton dynamics of poly(p-phenylenevinylene) polymers incorporating 2,2'-bipyridines

International Nuclear Information System (INIS)

Chen, L. X.; Jager, W. J.; Niemczyk, M. P.; Wasielewski, M. R.

1999-01-01

The effect of π-conjugation attenuation on the photophysics and exciton dynamics of two conjugated polymers 1 and 2 are examined in solution. The structures of polymers 1 and 2 have 2,2'-bipyridyl-5-vinylene units that alternate with one and three 2,5-bis(n-decyloxy)-1,4-phenylenevinylene monomer units, respectively. The photophysics and exciton dynamics of polymers 1 and 2 were compared to those of the homopolymer, poly(2,5-bis(2'-ethylhexyloxy)-1,4-phenylenevinylene) (BEH-PPV). A series of changes in the photophysics of polymers 1 and 2 were found as a result of π-conjugation attenuation. These changes include blue shifts in absorption and emission spectra, spectral diffusion in stimulated emission, enhancement in photoluminescence quantum yields and lifetimes, and increases in photoinduced absorption intensities and lifetimes. These changes are systematically more pronounced in polymer 1 than in polymer 2 and are correlated with π-conjugation attenuation in the polymers due to twisting of the 2,2'-bipyridine groups about the 2,2' single bond. An exciton dynamics model involving an ensemble of initial exciton states localized on oligomeric segments within the polymer with different conjugation lengths is proposed to describe the observed differences between polymers 1 and 2 and BEH-PPV. When the electronic coupling between these segments is strong, the polymer displays characteristics that are close to those of a one-dimensional semiconductor. However, when these couplings are weakened by groups, such as the 2,2'-bipyridine that attenuate π-conjugation, the polymer displays properties of an ensemble of oligomers

A study on the redox, spectroscopic, and photophysical characteristics of a series of octahedral hexamolybdenum(ii) clusters: [{Mo6X8}Y6]2- (X, Y = Cl, Br, or I).

Science.gov (United States)

Akagi, Soichiro; Fujii, Sho; Kitamura, Noboru

2018-01-23

We report a systematic study on the redox, spectroscopic, and photophysical properties of a series of [{Mo 6 X 8 }Y 6 ] 2- (X, Y = Cl, Br, or I. 1-9). All of the [{Mo 6 X 8 }Y 6 ] 2- clusters show intense and long-lived phosphorescence in both CH 3 CN and crystalline phases at 298 K. We found that the emission quantum yields (Φ em ) of 1-9 increase in the sequences X = Cl Br Br Br < Cl for given {Mo 6 X 8 } 4+ -core clusters. The present data demonstrate that arbitrary combinations of X and Y in [{Mo 6 X 8 }Y 6 ] 2- could tune τ em and Φ em in the ranges of 85-300 μs and 0.09-0.47, respectively. Both capping (X) and terminal ligand (Y) effects on the photophysical properties of the clusters are discussed on the basis of the energy gap (i.e., emission energy) dependence of the nonradiative decay rate constant.

Pyrene based D-π-A architectures: synthesis, density functional theory, photophysics and electron transfer dynamics.

Science.gov (United States)

Kathiravan, Arunkumar; Srinivasan, Venkatesan; Khamrang, Themmila; Velusamy, Marappan; Jaccob, Madhavan; Pavithra, Nagaraj; Anandan, Sambandam; Velappan, Kandavelu

2017-01-25

Pyrene derivatives show immense potential as sensitizers for dye-sensitized solar cells (DSCs). Therefore, this work focuses on the impact of π-spacers on the photophysical, electrochemical and photovoltaic properties of pyrene based D-π-A dyes, since the insertion of π-spacers is one of the doable strategies to improve the light harvesting properties of the dye. In this respect, three new pyrene based D-π-A dyes have been synthesized and characterized by 1 H, 13 C NMR, and elemental analyses and EI-MS spectrometry. The selected π-spacers are benzene, thiophene and furan. Compared with a benzene spacer, the introduction of a heterocyclic ring spacer reduces the band gap of the dye and brings about the broadening of the absorption spectra to the longer wavelength region through intramolecular charge-transfer (ICT). Combined experimental and theoretical studies were performed to investigate the ICT process involved in the pyrene derivatives. The profound solvatochromism with increased nonradiative rate constants (k nr ) has been construed in terms of ICT from the pyrene core to rhodanine-3-acetic acid via conjugated π-spacers. Electrochemical data also reveal that the HOMO and LUMO energy levels are fine-tuned by incorporating different π-spacers between pyrene and rhodanine-3-acetic acid. On the basis of the optimized DSC test conditions, the best performance was found for PBRA, in which a benzene group is the conjugated π-spacer. The divergence in the photovoltaic behaviors of these dyes was further explicated by femtosecond fluorescence and electrochemical impedance spectroscopy.

Optical, photo-physical properties and photostability of pyrromethene (PM-597) in ionic liquids as benign green-solvents

International Nuclear Information System (INIS)

AL-Aqmar, Dalal M.; Abdelkader, H.I.; Abou Kana, Maram T.H.

2015-01-01

Laser dye pyrromethene-597 was dissolved with different concentrations in three types of ionic liquids (ILs): 1-Butyl-3-methylimidazolium chloride (BMIM Cl), 1-butyl-3-methylimidazolium tetrachloroaluminate (BMIM AlCl 4 ) and 1-butyl-3-methylimidazolium tetrafluoro-borate (BMIM BF 4 ) in addition to ethanol as reference solvent. This paper investigates optical spectra and some photo-physical parameters of PM-597 in BMIM Cl, BMIM AlCl 4 , BMIM BF 4 and ethanol. These parameters are absorption and emission cross sections, fluorescence lifetime and quantum yield. The amplified spontaneous emission (ASE) was studied using the second harmonic Nd-YAG laser of 532 nm. Also, the gain and energy conversion efficiencies were investigated. Relatively high efficiency was obtained with good photostability in case of PM-597 in BMIM BF 4 that was a decrease to ~90% of the initial amplified spontaneous emission. This output energy was observed after pumping by 75,000 shots at a relatively high repetition rate of 10 Hz and pumping energy of 37 mJ. The composition and properties of the matrix of ILs were found to lead to optimize the laser performance and photostability of the investigated laser dye. In this study, we considered ionic liquids as the environmentally benign green solvents in place of volatile toxic organic solvents. - Highlights: • Pyrromethen-597 as laser dye was dissolved in three types of ionic liquids (ILs): BMIM Cl, BMIM AlCl 4 and BMIM BF 4 as benign green-solvent in addition to ethanol as reference solvent. • Important spectroscopic properties of PM-597 dye such as quantum yield, fluorescence lifetime, radiative and nonradiative rate, transition dipole moment, attenuation length and oscillator strength were affected by changing the host material. • The dye laser gain, quantum yield, peak intensity of ASE and photostability were found to be better in BMIM BF 4 than in BMIM Cl and in ethanol. • ILs may be used as ideal hosts for dye laser systems to

Polar red-emitting rhodamine dyes with reactive groups: synthesis, photophysical properties, and two-color STED nanoscopy applications.

Science.gov (United States)

Kolmakov, Kirill; Wurm, Christian A; Meineke, Dirk N H; Göttfert, Fabian; Boyarskiy, Vadim P; Belov, Vladimir N; Hell, Stefan W

2014-01-03

The synthesis, reactivity, and photophysical properties of new rhodamines with intense red fluorescence, two polar residues (hydroxyls, primary phosphates, or sulfonic acid groups), and improved hydrolytic stability of the amino-reactive sites (NHS esters or mixed N-succinimidyl carbonates) are reported. All fluorophores contain an N-alkyl-1,2-dihydro-2,2,4-trimethylquinoline fragment, and most of them bear a fully substituted tetrafluoro phenyl ring with a secondary carboxamide group. The absorption and emission maxima in water are in the range of 635-639 and 655-659 nm, respectively. A vastly simplified approach to red-emitting rhodamines with two phosphate groups that are compatible with diverse functional linkers was developed. As an example, a phosphorylated dye with an azide residue was prepared and was used in a click reaction with a strained alkyne bearing an N-hydroxysuccinimid (NHS) ester group. This method bypasses the undesired activation of phosphate groups, and gives an amphiphilic amino-reactive dye, the solubility and distribution of which between aqueous and organic phases can be controlled by varying the pH. The presence of two hydroxyl groups and a phenyl ring with two carboxyl residues in the dyes with another substitution pattern is sufficient for providing the hydrophilic properties. Selective formation of a mono-N-hydroxysuccinimidyl ester from 5-carboxy isomer of this rhodamine is reported. The fluorescence quantum yields varied from 58 to 92% for free fluorophores, and amounted to 18-64% for antibody conjugates in aqueous buffers. The brightness and photostability of these fluorophores facilitated two-color stimulated emission depletion (STED) fluorescence nanoscopy of biological samples with high contrast and minimal background. Selecting a pair of fluorophores with absorption/emission bands at 579/609 and 635/655 nm enabled two-color channels with low cross-talk and negligible background at approximately 40 nm resolution. Copyright �

Characterization of a sol-gel-entrapped artificial receptor

Science.gov (United States)

Dunbar, Richard A.; Narang, Upvan; Prasad, Paras N.; Bright, Frank V.

1993-04-01

We report on the development, characterization, and photophysics of a new fiber-optic-based sensor which uses a sol-gel entrapped recognition element. The recognition element is modified (beta) -cyclodextrin to which we have added a short tether (glycine) and a fluorophore (dansyl). This recognition element forms an intramolecular complex, and the dansyl group can include within the cyclodextrin cavity. Non-fluorescent analytes, that bind to the cyclodextrin cavity, can effectively displace the included dansyl group and result in a measurable change in signal. We report on the detection limits, dynamic range, and photophysics (i.e., transduction mechanism) of this new sensor.

Synthesis and Characterization of Polyfunctional Polyhedral Silsesquioxane Cages

Science.gov (United States)

Sulaiman, Santy

Recent studies on octameric polyhedral silsesquioxanes, (RSiO1.5 )8, indicate that the silsesquioxane cage is not just a passive component but appears to be involved in electron delocalization with conjugated organic tethers in the excited state. This dissertation presents the synthesis and characterization of (RSiO1.5)8 molecules with unique photophysical properties that provide support for the existence of conjugation that involves the (RSiO1.5)8 cage. The dissertation first discusses the elaboration of octavinylsilsesquioxane via cross-metathesis to form styrenyl-functionalized octasilsesquioxane molecules. Subsequent Heck coupling reactions of p-bromostyrenyl derivative provides vinylstilbene-functionalized octasilsesquioxane. The amino derivative, NH2VinylStilbeneOS, show highly red-shifted emission spectrum (100 nm from the simple organic analog p-vinylstilbene) and high two-photon absorption (TPA) cross-section value (100 GM/moiety), indicating charge-transfer processes involving the silsesquioxane cage as the electron acceptor. The unique photophysical properties of polyfunctional luminescent cubic silsesquioxanes synthesized from ortho-8-, (2,5)-16-, and 24-brominated octaphenylsilsesquioxane (OPS) via Heck coupling show how the steric interactions of the organic tethers at the silsesquioxane cage corner affect conjugation with the silsesquioxane cage. Furthermore, the high TPA cross-section (10 GM/moiety) and photoluminescence quantum yield (20%) of OPS functionalized with 24 acetoxystyrenyl groups suggest that the existence excited states in these molecules with similar energies and decay rates: normal radiative pi- pi* transition and charge transfer involving the silsesquioxane cage. The fluoride ion-catalyzed rearrangement reactions of cage and polymeric silsesquioxanes provide a convenient route to a mixture of deca- and dodecameric silsesquioxane molecules in high yields, giving us the opportunity to investigate the effect of silsesquioxane cage

New electroluminescent carbazole-containing conjugated polymer: synthesis, photophysics, and electroluminescence

Czech Academy of Sciences Publication Activity Database

Cimrová, Věra; Ulbricht, C.; Dzhabarov, Vagif; Výprachtický, Drahomír; Egbe, D. A. M.

2014-01-01

Roč. 55, č. 24 (2014), s. 6220-6226 ISSN 0032-3861 R&D Projects: GA ČR GAP106/12/0827; GA ČR(CZ) GA13-26542S Institutional support: RVO:61389013 Keywords : carbazole-containing conjugated polymer * synthesis * photophysics and electroluminescence Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.562, year: 2014

Chromophore photophysics and dynamics in fluorescent proteins of the GFP family

International Nuclear Information System (INIS)

Nienhaus, Karin; Nienhaus, G Ulrich

2016-01-01

Proteins of the green fluorescent protein (GFP) family are indispensable for fluorescence imaging experiments in the life sciences, particularly of living specimens. Their essential role as genetically encoded fluorescence markers has motivated many researchers over the last 20 years to further advance and optimize these proteins by using protein engineering. Amino acids can be exchanged by site-specific mutagenesis, starting with naturally occurring proteins as templates. Optical properties of the fluorescent chromophore are strongly tuned by the surrounding protein environment, and a targeted modification of chromophore-protein interactions requires a profound knowledge of the underlying photophysics and photochemistry, which has by now been well established from a large number of structural and spectroscopic experiments and molecular-mechanical and quantum-mechanical computations on many variants of fluorescent proteins. Nevertheless, such rational engineering often does not meet with success and thus is complemented by random mutagenesis and selection based on the optical properties. In this topical review, we present an overview of the key structural and spectroscopic properties of fluorescent proteins. We address protein-chromophore interactions that govern ground state optical properties as well as processes occurring in the electronically excited state. Special emphasis is placed on photoactivation of fluorescent proteins. These light-induced reactions result in large structural changes that drastically alter the fluorescence properties of the protein, which enables some of the most exciting applications, including single particle tracking, pulse chase imaging and super-resolution imaging. We also present a few examples of fluorescent protein application in live-cell imaging experiments. (topical review)

Chromophore photophysics and dynamics in fluorescent proteins of the GFP family

Science.gov (United States)

Nienhaus, Karin; Nienhaus, G. Ulrich

2016-11-01

Proteins of the green fluorescent protein (GFP) family are indispensable for fluorescence imaging experiments in the life sciences, particularly of living specimens. Their essential role as genetically encoded fluorescence markers has motivated many researchers over the last 20 years to further advance and optimize these proteins by using protein engineering. Amino acids can be exchanged by site-specific mutagenesis, starting with naturally occurring proteins as templates. Optical properties of the fluorescent chromophore are strongly tuned by the surrounding protein environment, and a targeted modification of chromophore-protein interactions requires a profound knowledge of the underlying photophysics and photochemistry, which has by now been well established from a large number of structural and spectroscopic experiments and molecular-mechanical and quantum-mechanical computations on many variants of fluorescent proteins. Nevertheless, such rational engineering often does not meet with success and thus is complemented by random mutagenesis and selection based on the optical properties. In this topical review, we present an overview of the key structural and spectroscopic properties of fluorescent proteins. We address protein-chromophore interactions that govern ground state optical properties as well as processes occurring in the electronically excited state. Special emphasis is placed on photoactivation of fluorescent proteins. These light-induced reactions result in large structural changes that drastically alter the fluorescence properties of the protein, which enables some of the most exciting applications, including single particle tracking, pulse chase imaging and super-resolution imaging. We also present a few examples of fluorescent protein application in live-cell imaging experiments.

Heterodiazocines: Synthesis and Photochromic Properties, Trans to Cis Switching within the Bio-optical Window.

Science.gov (United States)

Hammerich, Melanie; Schütt, Christian; Stähler, Cosima; Lentes, Pascal; Röhricht, Fynn; Höppner, Ronja; Herges, Rainer

2016-10-04

Diazocines, bridged azobenzenes, exhibit superior photophysical properties compared to parent azobenzenes such as high switching efficiencies, quantum yields, and particularly switching wavelengths in the visible range. Synthesis, however, proceeds with low yields, and derivatives are difficult to prepare. We now present two heterodiazocines which are easier to synthesize, and the general procedures should also provide facile access to derivatives. Moreover, both compounds can be switched with light in the far-red (650 nm). Accessibility and photophysical properties make them ideal candidates for applications such as photoswitchable drugs and functional materials.

Effect of quencher, denaturants, temperature and pH on the fluorescent properties of BSA protected gold nanoclusters

Energy Technology Data Exchange (ETDEWEB)

Chib, Rahul, E-mail: Rahul.chib@live.unthsc.edu [Department of Cell Biology and Immunology, Center for Fluorescence Technologies and Nanomedicine, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States); Butler, Susan [Department of Cell Biology and Immunology, Center for Fluorescence Technologies and Nanomedicine, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States); Raut, Sangram [Department of Cell Biology and Immunology, Center for Fluorescence Technologies and Nanomedicine, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States); Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129 (United States); Shah, Sunil; Borejdo, Julian [Department of Cell Biology and Immunology, Center for Fluorescence Technologies and Nanomedicine, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States); Gryczynski, Zygmunt [Department of Cell Biology and Immunology, Center for Fluorescence Technologies and Nanomedicine, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States); Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129 (United States); Gryczynski, Ignacy, E-mail: ignacy.gryczynski@unthsc.edu [Department of Cell Biology and Immunology, Center for Fluorescence Technologies and Nanomedicine, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States)

2015-12-15

In this paper, we have synthesized BSA protected gold nanoclusters (BSA Au nanocluster) and studied the effect of quencher, protein denaturant, pH and temperature on the fluorescence properties of the tryptophan molecule of the BSA Au nanocluster and native BSA. We have also studied their effect on the peak emission of BSA Au nanoclusters (650 nm). The photophysical characterization of a newly developed fluorophore in different environments is absolutely necessary to futher develop their biomedical and analytical applications. It was observed from our experiments that the tryptophan in BSA Au nanoclusters is better shielded from the polar environment. Tryptophan in native BSA showed a red shift in its peak emission wavelength position. Tryptophan is a highly polarity sensitive dye and a minimal change in its microenvironment can be easily observed in its photophysical properties. - Highlights: • Tryptophan is easily accessible in native BSA compared to BSA Au nanoclusters. • Guanidine HCL denatures native BSA more compared to BSA Au nanoclusters. • High temperature decreases the quantum yield of tryptophan and BSA Au nanocluster. • Emission wavelength of BSA Au nanoclusters remains constant with increasing pH. • BSA Au nanoclusters are robust to the changes in their environments.

Effect of quencher, denaturants, temperature and pH on the fluorescent properties of BSA protected gold nanoclusters

International Nuclear Information System (INIS)

Chib, Rahul; Butler, Susan; Raut, Sangram; Shah, Sunil; Borejdo, Julian; Gryczynski, Zygmunt; Gryczynski, Ignacy

2015-01-01

In this paper, we have synthesized BSA protected gold nanoclusters (BSA Au nanocluster) and studied the effect of quencher, protein denaturant, pH and temperature on the fluorescence properties of the tryptophan molecule of the BSA Au nanocluster and native BSA. We have also studied their effect on the peak emission of BSA Au nanoclusters (650 nm). The photophysical characterization of a newly developed fluorophore in different environments is absolutely necessary to futher develop their biomedical and analytical applications. It was observed from our experiments that the tryptophan in BSA Au nanoclusters is better shielded from the polar environment. Tryptophan in native BSA showed a red shift in its peak emission wavelength position. Tryptophan is a highly polarity sensitive dye and a minimal change in its microenvironment can be easily observed in its photophysical properties. - Highlights: • Tryptophan is easily accessible in native BSA compared to BSA Au nanoclusters. • Guanidine HCL denatures native BSA more compared to BSA Au nanoclusters. • High temperature decreases the quantum yield of tryptophan and BSA Au nanocluster. • Emission wavelength of BSA Au nanoclusters remains constant with increasing pH. • BSA Au nanoclusters are robust to the changes in their environments.

Photo-physical and structural interactions between viologen phosphorus-based dendrimers and human serum albumin

International Nuclear Information System (INIS)

Ciepluch, Karol; Katir, Nadia; El Kadib, Abdelkrim; Weber, Monika; Caminade, Anne-Marie; Bousmina, Mostapha; Pierre Majoral, Jean; Bryszewska, Maria

2012-01-01

This work deals with photo-physical and structural interactions between viologen phosphorus dendrimers and human serum albumin (HSA). Viologens are derivatives of 4,4′-bipyridinium salts. Aiming to rationalize the parameters governing such interactions eight types of these polycationic dendrimers in which the generation, the number of charges, the nature of the core and of the terminal groups vary from one to another, were designed and used. The influence of viologen-based dendrimers' on human serum albumin has been investigated. The photo-physical interactions of the two systems have been monitored by fluorescence quenching of free L-tryptophan and of HSA tryptophan residue. Additionally, using circular dichroism (CD) the effect of dendrimers on the secondary structure of albumin was measured. The obtained results show that viologen dendrimers interact with human serum albumin quenching its fluorescence either by collisional (dynamic) way or by forming complexes in a ground state (static quenching). In some cases the quenching is accompanied by changes of the secondary structure of HSA. - Highlights: ► Photo-physical interactions between viologen phosphorus dendrimers and human serum albumin (HSA) were investigated. ► The viologen dendrimers can quench the fluorescence of tryptophan in HSA. ► CD spectra to explain the changes in secondary structure of albumin after exposition of dendrimers.

Luminescent cyclometalated iridium(III) polypyridine indole complexes--synthesis, photophysics, electrochemistry, protein-binding properties, cytotoxicity, and cellular uptake.

Science.gov (United States)

Lau, Jason Shing-Yip; Lee, Pui-Kei; Tsang, Keith Hing-Kit; Ng, Cyrus Ho-Cheong; Lam, Yun-Wah; Cheng, Shuk-Han; Lo, Kenneth Kam-Wing

2009-01-19

A series of luminescent cyclometalated iridium(III) polypyridine indole complexes, [Ir(N--C)(2)(N--N)](PF(6)) (HN--C = 2-phenylpyridine (Hppy), N--N = 4-((2-(indol-3-yl)ethyl)aminocarbonyl)-4'-methyl-2,2'-bipyridine (bpy-ind) (1a), N--N = 4-((5-((2-(indol-3-yl)ethyl)aminocarbonyl)pentyl)aminocarbonyl)-4'-methyl-2,2'-bipyridine (bpy-C6-ind) (1b); HN--C = 7,8-benzoquinoline (Hbzq), N--N = bpy-ind (2a), N--N = bpy-C6-ind (2b); and HN--C = 2-phenylquinoline (Hpq), N--N = bpy-ind (3a), N--N = bpy-C6-ind (3b)), have been synthesized, characterized, and their photophysical and electrochemical properties and lipophilicity investigated. Photoexcitation of the complexes in fluid solutions at 298 K and in alcohol glass at 77 K resulted in intense and long-lived luminescence (lambda(em) = 540-616 nm, tau(o) = 0.13-5.15 mus). The emission of the complexes has been assigned to a triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi(Ir) --> pi*(N--N)) excited state, probably with some mixing of triplet intraligand ((3)IL) (pi --> pi*) (pq) character for complexes 3a,b. Electrochemical measurements revealed that all the complexes showed an irreversible indole oxidation wave at ca. +1.1 V versus SCE, a quasi-reversible iridium(IV/III) couple at ca. +1.3 V, and a reversible diimine reduction couple at ca. -1.3 V. The interactions of these complexes with an indole-binding protein, bovine serum albumin (BSA), have been studied by emission titrations, and the K(a) values are on the order of 10(4) M(-1). Additionally, the cytotoxicity of the complexes toward human cervix epithelioid carcinoma (HeLa) cells has been examined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. The IC(50) values of the complexes ranged from 1.1 to 6.3 microM, which are significantly smaller than that of cisplatin (30.7 microM) under the same experimental conditions. Furthermore, the cellular uptake of the complexes has been investigated by flow cytometry and laser

Photoluminescent Copper(I) Complex Based on 3-(2-(Cyclohexylthio) ethoxy)pyridine: Synthesis, Structure, and Physical Properties

Energy Technology Data Exchange (ETDEWEB)

Park, Hyunjin; Kwon, Eunjin; Kang, Gihaeng; Kim, Jieun; Kim, Tae Ho [Gyeongsang National University, Jinju (Korea, Republic of)

2016-07-15

In recent years, the Cu(I) complexes, with d 10 electronic configuration, have been attracting interest due to their diverse structures and photophysical properties. A copper(I) coordination polymer 1 based on a sulfur-containing pyridyl ligand L was synthesized and identified by X-ray crystallography. Photophysical and thermal properties of 1 have been investigated. More Cu(I) coordination polymers based on mixed donor ligands are under investigation in order to discover factors governing luminescence wavelength, such as Cu[BOND]Cu distances, intermolecular interactions, structures of ligands, and so on.

Synthesis and Characterization of a Heteroleptic Ru(II Complex of Phenanthroline Containing Oligo-Anthracenyl Carboxylic Acid Moieties

Directory of Open Access Journals (Sweden)

Peter A. Ajibade

2010-09-01

Full Text Available In an effort to develop new ruthenium(II complexes, this work describes the design, synthesis and characterization of a ruthenium(II functionalized phenanthroline complex with extended π-conjugation. The ligand were L1 (4,7-bis(2,3-dimethylacrylic acid-1,10-phenanthroline, synthesized by a direct aromatic substitution reaction, and L2 (4,7-bis(trianthracenyl-2,3-dimethylacrylic acid-1,10-phenanthroline, which was synthesized by the dehalogenation of halogenated aromatic compounds using a zero-valent palladium cross-catalyzed reaction in the absence of magnesium-diene complexes and/or cyclooctadienyl nickel (0 catalysts to generate a new carbon-carbon bond (C-C bond polymerized hydrocarbon units. The ruthenium complex [RuL1L2(NCS2] showed improved photophysical properties (red-shifted metal-to-ligand charge-transfer transition absorptions and enhanced molar extinction coefficients, luminescence and interesting electrochemical properties. Cyclic and square wave voltammetry revealed five major redox processes. The number of electron(s transferred by the ruthenium complex was determined by chronocoulometry in each case. The results show that processes I, II and III are multi-electron transfer reactions while processes IV and V involved one-electron transfer reaction. The photophysical property of the complex makes it a promising candidate in the design of chemosensors and photosensitizers, while its redox-active nature makes the complex a potential mediator of electron transfer in photochemical processes.

Spectroscopy and photophysics of flavin related compounds: Riboflavin and iso-(6,7)-riboflavin

International Nuclear Information System (INIS)

Sikorska, Ewa; Khmelinskii, Igor; Komasa, Anna; Koput, Jacek; Ferreira, Luis F.V.; Herance, Jose R.; Bourdelande, Jose L.; Williams, Sian L.; Worrall, David R.; Insinska-Rak, MaIgorzata; Sikorski, Marek

2005-01-01

The photochemistry and photophysics of isoalloxazines (10-substituted 2,3,4,10-tetrahydro-benzo[g]pteridine-2,4-diones), and especially flavins (7,8-dimethyl substituted isoalloxazines), are of considerable interest due to the biological relevance of these compounds. In this paper we report data concerning the photophysics of riboflavin and iso-(6,7)-riboflavin (10-(2,3,4,5-tetrahydroxypentyl)-6,7-dimethylbenzo[g]pteridine-2,4(3H,10H) -dione), and correlate the spectroscopic observations with theoretical calculations performed using time-dependent density functional theory. On the basis of these calculations the lowest excited singlet and triplet states are both assigned (π,π*) symmetry, and this result is used to explain the relatively low singlet oxygen quantum yields in comparison with alloxazines. Time-resolved emission studies have indicated 6,7-dimethylalloxazine a photodegradation product of iso-(6,7)-riboflavin

Synthesis and optoelectronic characterization of some triphenylamine-based compounds containing strong acceptor substituents

Energy Technology Data Exchange (ETDEWEB)

Grigoras, Mircea, E-mail: grim@icmpp.ro; Ivan, Teofilia; Vacareanu, Loredana; Catargiu, Ana Maria; Tigoianu, Radu

2014-09-15

Three novel triphenylamine-based compounds containing strong electron acceptor groups have been synthesized and their comparative photophysical properties are presented. These compounds were obtained by a two-step method: (i) triphenylamine compounds with one, two and three phenylacetylene arms were synthesized by Sonogashira reaction between iodine-substituted triphenylamines and phenylacetylene, followed by (ii) post-modification of these electron-rich alkynes by addition of the strong electron acceptor, tetracyanoethylene. Characterization of all oligomers was made by FTIR, {sup 1}H-NMR, UV–vis and fluorescence spectroscopy. A batochromic shifting of the UV and photoluminescence maxima was observed with the increase of the acceptor group number. The electrochemical behavior was studied by cyclic voltammetry. The cyclic voltammograms have evidenced that triphenylamine-phenylacetylene compounds undergo only oxidation processes while compounds modified with tetracyanoethylene show both oxidation and reduction peaks associated with donor and acceptor groups, respectively. The donor–acceptor compounds coordinate metal ions (i.e., Hg{sup 2+} and Sn{sup 2+}) by cyano groups resulting in the decreasing of charge transfer band intensity, and they can be used as chemosensors. - Highlights: • Three triphenylamine-based ethynylene compounds were prepared by Sonogashira reaction. • Post-modification of ethynylene linkages by tetracyanethylene cycloaddition and retroconversion led to donor–acceptor compounds. • Photophysical properties of donor–acceptor oligomers were studied in different solvents.

Photo-physical and structural interactions between viologen phosphorus-based dendrimers and human serum albumin

Energy Technology Data Exchange (ETDEWEB)

Ciepluch, Karol, E-mail: ciepluch@biol.uni.lodz.pl [Department of General Biophysics, University of Lodz, 141/143 Pomorska St., 90-236 Lodz (Poland); Katir, Nadia [Laboratoire de Chimie de Coordination du CNRS (LCC), 205 route de Narbonne, F-31077 Toulouse cedex 4 (France); Institute of Nanomaterials and Nanotechnology (INANOTECH)-MAScIR (Moroccan Foundation for Advanced Science, Innovation and Research), ENSET, Avenue de l' Armee Royale, Madinat El Irfane, 10100 Rabat (Morocco); El Kadib, Abdelkrim [Institute of Nanomaterials and Nanotechnology (INANOTECH)-MAScIR (Moroccan Foundation for Advanced Science, Innovation and Research), ENSET, Avenue de l' Armee Royale, Madinat El Irfane, 10100 Rabat (Morocco); Weber, Monika [Department of General Biophysics, University of Lodz, 141/143 Pomorska St., 90-236 Lodz (Poland); Caminade, Anne-Marie [Laboratoire de Chimie de Coordination du CNRS (LCC), 205 route de Narbonne, F-31077 Toulouse cedex 4 (France); Bousmina, Mostapha [Hassan II Academy of Sciences and Technology, Avenue MVI, Km4, 10220 Rabat (Morocco); Pierre Majoral, Jean [Laboratoire de Chimie de Coordination du CNRS (LCC), 205 route de Narbonne, F-31077 Toulouse cedex 4 (France); Hassan II Academy of Sciences and Technology, Avenue MVI, Km4, 10220 Rabat (Morocco); Bryszewska, Maria [Department of General Biophysics, University of Lodz, 141/143 Pomorska St., 90-236 Lodz (Poland)

2012-06-15

This work deals with photo-physical and structural interactions between viologen phosphorus dendrimers and human serum albumin (HSA). Viologens are derivatives of 4,4 Prime -bipyridinium salts. Aiming to rationalize the parameters governing such interactions eight types of these polycationic dendrimers in which the generation, the number of charges, the nature of the core and of the terminal groups vary from one to another, were designed and used. The influence of viologen-based dendrimers' on human serum albumin has been investigated. The photo-physical interactions of the two systems have been monitored by fluorescence quenching of free L-tryptophan and of HSA tryptophan residue. Additionally, using circular dichroism (CD) the effect of dendrimers on the secondary structure of albumin was measured. The obtained results show that viologen dendrimers interact with human serum albumin quenching its fluorescence either by collisional (dynamic) way or by forming complexes in a ground state (static quenching). In some cases the quenching is accompanied by changes of the secondary structure of HSA. - Highlights: Black-Right-Pointing-Pointer Photo-physical interactions between viologen phosphorus dendrimers and human serum albumin (HSA) were investigated. Black-Right-Pointing-Pointer The viologen dendrimers can quench the fluorescence of tryptophan in HSA. Black-Right-Pointing-Pointer CD spectra to explain the changes in secondary structure of albumin after exposition of dendrimers.

Optical, photo-physical properties and photostability of pyrromethene (PM-597) in ionic liquids as benign green-solvents

Energy Technology Data Exchange (ETDEWEB)

AL-Aqmar, Dalal M. [Physics Department, Ibb University, Ibb (Yemen); Physics Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Abdelkader, H.I. [Physics Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Abou Kana, Maram T.H., E-mail: mabou202@niles.edu.eg [National Institute of Laser Enhanced Sciences, Cairo University, Giza (Egypt)

2015-05-15

Laser dye pyrromethene-597 was dissolved with different concentrations in three types of ionic liquids (ILs): 1-Butyl-3-methylimidazolium chloride (BMIM Cl), 1-butyl-3-methylimidazolium tetrachloroaluminate (BMIM AlCl{sub 4}) and 1-butyl-3-methylimidazolium tetrafluoro-borate (BMIM BF{sub 4}) in addition to ethanol as reference solvent. This paper investigates optical spectra and some photo-physical parameters of PM-597 in BMIM Cl, BMIM AlCl{sub 4}, BMIM BF{sub 4} and ethanol. These parameters are absorption and emission cross sections, fluorescence lifetime and quantum yield. The amplified spontaneous emission (ASE) was studied using the second harmonic Nd-YAG laser of 532 nm. Also, the gain and energy conversion efficiencies were investigated. Relatively high efficiency was obtained with good photostability in case of PM-597 in BMIM BF{sub 4} that was a decrease to ~90% of the initial amplified spontaneous emission. This output energy was observed after pumping by 75,000 shots at a relatively high repetition rate of 10 Hz and pumping energy of 37 mJ. The composition and properties of the matrix of ILs were found to lead to optimize the laser performance and photostability of the investigated laser dye. In this study, we considered ionic liquids as the environmentally benign green solvents in place of volatile toxic organic solvents. - Highlights: • Pyrromethen-597 as laser dye was dissolved in three types of ionic liquids (ILs): BMIM Cl, BMIM AlCl{sub 4} and BMIM BF{sub 4} as benign green-solvent in addition to ethanol as reference solvent. • Important spectroscopic properties of PM-597 dye such as quantum yield, fluorescence lifetime, radiative and nonradiative rate, transition dipole moment, attenuation length and oscillator strength were affected by changing the host material. • The dye laser gain, quantum yield, peak intensity of ASE and photostability were found to be better in BMIM BF{sub 4} than in BMIM Cl and in ethanol. • ILs may be used as ideal

The synthesis, characterization and optical properties of novel 1,3,4-oxadiazole-containing imidazo[1,5-a]pyridine derivatives

International Nuclear Information System (INIS)

Ge Yanqing; Hao Benqian; Duan Guiyun; Wang Jianwu

2011-01-01

A series of novel substituted 1,3,4-oxadiazole derivatives were synthesized by the reaction of 3-butyl-1-chloroimidazo[1,5-a]pyridine-7-carbohydrazide with propionyl chloride and substituted benzoic chloride in the presence of phosphorus oxychloride. The compounds were characterized using IR, 1 H NMR, 13 C NMR and HRMS. Absorption and fluorescence spectra were measured in dichloromethane; an intense absorption maxima was noted at ca. 290 nm and emission maxima was noted at ca. 470 nm. The absorption spectra of the 1,3,4-oxadiazole derivatives reveal that a phenyl and an ethyl group attached to the 1,3,4-oxadiazole ring markedly influenced the maximum absorption. The structures based on density function theory (DFT) calculation show planar configurations for the compounds. The calculated molecular orbital correlates well with their absorption. - Research highlights: → Novel imidazo[1,5-a]pyridine derivatives were synthesized. → The structures were determined by IR, 1 H NMR, 13 C NMR and HRMS spectra. → We investigated the absorption and fluorescence spectral characteristics of the compounds. → The side group in 1,3,4-oxadiazole ring can affect its photophysical properties markedly. → Quantum calculation correlates well with their absorption.

A class of fluorescent heterocyclic dyes revisited: photophysics, structure, and solvent effects

DEFF Research Database (Denmark)

Zhu, Lianjie; Jensen, Hans-Christian Becker; Henriksen, Lars

2009-01-01

The photophysical behavior of a series of 2-methylthio-5-(Z-carbonyl)thieno-[3,4-e]-3,4-dihydro-1,2,3-triazine-4-ones was investigated by absorption and emission spectroscopy in a range of solvents representing a systematic variation in polarity, polarizability, as well as hydrogen bond donating ...

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

Science.gov (United States)

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

Pathways and Mechanisms Underlying the Photophysics and Photochemistry of Riboflavin induced cornea crosslinking

DEFF Research Database (Denmark)

Breitenbach, Thomas; Ogilby, Peter Remsen

In this talk, we will describe general pathways involved in the photophysics of a photosensitized process, which can lead to crosslinking due to light excitation of Riboflavin in the cornea. Furthermore, we will elucidate different aspects of reactions that can produce crosslinks, with respect...

Synthesis and luminescent properties of star-burst D-π-A compounds based on 1,3,5-triazine core and carbazole end-capped phenylene ethynylene arms

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zheng [Department of Applied Chemistry, Nanjing Tech University, Nanjing 210009 (China); Liu, Rui, E-mail: rui.liu@njtech.edu.cn [Department of Applied Chemistry, Nanjing Tech University, Nanjing 210009 (China); Zhu, Xiaolin [Department of Applied Chemistry, Nanjing Tech University, Nanjing 210009 (China); Li, Yuhao [Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433 (China); Chang, Jin [Queensland University of Technology, 2 George St., Brisbane 4000 (Australia); Zhu, Hongjun, E-mail: zhuhjnjut@hotmail.com [Department of Applied Chemistry, Nanjing Tech University, Nanjing 210009 (China); Ma, Liangwei; Lv, Wangjie; Guo, Jun [Department of Applied Chemistry, Nanjing Tech University, Nanjing 210009 (China)

2014-12-15

Two new star-burst compounds based on 1,3,5-triazine core and carbazole end-capped phenylene ethynylene arms (1a and 1b) were synthesized and characterized. Their photophysical properties were investigated systematically via spectroscopic and theoretical methods. Both compounds exhibit strong {sup 1}π–π{sup ⁎} transitions in the UV region and intense {sup 1}π–π{sup ⁎}/intramolecular charge transfer ({sup 1}ICT) absorption bands in the UV–vis region. Introducing the carbazole end-capped phenylene ethynylene arm on the 1,3,5-triazine core causes a slight bathochromic shift and enhanced molar extinction coefficient of the {sup 1}π–π{sup ⁎}/{sup 1}ICT transition band. Both compounds are emissive in solution at room temperature and 77 K, which exhibit pronounced positive solvatochromic effect. The emitting state could be ascribed to {sup 1}ICT state in more polar solvent, and {sup 1}π–π{sup ⁎} state in low-polarity solvent. The high emission quantum yields (Φ{sub em}=0.90∼1.0) of 1a and 1b (in hexane and toluene) make them potential candidates as efficient light-emitting materials. The spectroscopic studies and theoretical calculations indicate that the photophysical properties of these compounds can be tuned by the carbazole end-capped phenylene ethynylene arm, which would also be useful for rational design of photofunctional materials. - Highlights: • Star-burst compounds based on 1,3,5-triazine core and carbazole end-capped phenylene ethynylene arms. • Photophysical properties of target compounds were investigated systematically via spectroscopic and theoretical methods. • The relatively high fluorescence quantum yields make them potential candidates as light-emitting materials.

A new photoactive Ru(II)tris(2,2'-bipyridine) templated Zn(II) benzene-1,4-dicarboxylate metal organic framework: structure and photophysical properties.

Science.gov (United States)

Whittington, Christi L; Wojtas, Lukasz; Gao, Wen-Yang; Ma, Shengqian; Larsen, Randy W

2015-03-28

It has now been demonstrated that Ru(ii)tris(2,2'-bipyridine) (RuBpy) can be utilized to template the formation of new metal organic framework (MOF) materials containing crystallographically resolved RuBpy clusters with unique photophysical properties. Two such materials, RWLC-1 and RWLC-2, have now been reported from our laboratory and are composed of RuBpy encapsulated in MOFs composed of Zn(ii) ions and 1,3,5-tris(4-carboxyphenyl)benzene ligands (C. L. Whittington, L. Wojtas and R. W. Larsen, Inorg. Chem., 2014, 53, 160-166). Here, a third RuBpy templated photoactive MOF is described (RWLC-3) that is derived from the reaction between Zn(ii) ions and 1,4-dicarboxybenzene in the presence of RuBpy. Single Crystal X-ray diffraction studies determined the position of RuBpy cations within the crystal lattice. The RWLC-3 structure is described as a 2-fold interpenetrated pillared honeycomb network (bnb) containing crystallographically resolved RuBpy clusters. The two bnb networks are weakly interconnected. The encapsulated RuBpy exhibits two emission decay lifetimes (τ-fast = 120 ns, τ-slow = 453 ns) and a bathochromic shift in the steady state emission spectrum relative to RuBpy in ethanol.

Synthesis and characterization of poly(phenylacetylene)s with Ru(II) bis-terpyridine complexes in the side-chain.

Science.gov (United States)

Breul, Alexander M; Kübel, Joachim; Häupler, Bernhard; Friebe, Christian; Hager, Martin D; Winter, Andreas; Dietzek, Benjamin; Schubert, Ulrich S

2014-04-01

An alkyne-functionalized ruthenium(II) bis-terpyridine complex is directly copolymerized with phenylacetylene by alkyne polymerization. The polymer is characterized by size-exclusion chromatography (SEC), (1) H NMR spectroscopy, cyclic voltammetry (CV) measurements, and thermal analysis. The photophysical properties of the polymer are studied by UV-vis absorption spectroscopy. In addition, spectro-electrochemical measurements are carried out. Time-resolved luminescence lifetime decay curves show an enhanced lifetime of the metal complex attached to the conjugated polymer backbone compared with the Ru(tpy)2 (2+) model complex. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Linear and nonlinear photophysics and bioimaging of an integrin-targeting water-soluble fluorenyl probe.

Science.gov (United States)

Morales, Alma R; Luchita, Gheorghe; Yanez, Ciceron O; Bondar, Mykhailo V; Przhonska, Olga V; Belfield, Kevin D

2010-06-07

Linear photophysical characterization and two-photon absorption (2PA) properties of a new water-soluble fluorene derivative, 3-(9-(2-(2-methoxyethoxy)ethyl)-2,7-bis{3-[2-(polyethyleneglycol-550-monomethylether-1-yl)]-4-(benzo[d]thiazol-2-yl)styryl}-9H-fluoren-9-yl)propanoic acid (1), were investigated in several organic solvents and water at room temperature. A comprehensive analysis of the steady-state absorption, emission and excitation anisotropy spectra revealed electronic structures of 1, including mutual orientation of the transition dipoles, relatively weak solvatochromic effects, high fluorescence quantum yield (approximately 0.5-1.0), and strong aggregation in water. The 2PA spectra of 1 were obtained in the 600-900 nm spectral range by two-photon induced fluorescence (2PF) and open aperture Z-scan methods using femtosecond laser sources. No discrete 2PA bands were apparent and values of the corresponding 2PA cross sections monotonically increased in the short wavelength range up to 3000 GM in organic solvents and approximately 6000 GM in aqueous solution, reflecting relatively high two-photon absorptivity. The 2PA efficiency of in water increased 2-3 times relative to aprotic solvents and can be explained by cooperative electronic effects of molecular aggregates of 1 produced in aqueous media. The carboxylic acid fluorenyl probe 1 was conjugated with the cyclic peptide RGDfK. Two-photon fluorescence microscopy (2PFM) imaging of U87MG cells (and MCF-7 as control), incubated with fluorene-RGD peptide conjugate 2, demonstrated high alpha(v)beta(3) integrin selectivity, making this probe particularly attractive for integrin imaging.

Synthesis, dynamics and photophysics of nanoscale systems

Science.gov (United States)

Mirkovic, Tihana

The emerging field of nanotechnology, which spans diverse areas such as nanoelectronics, medicine, chemical and pharmaceutical industries, biotechnology and computation, focuses on the development of devices whose improved performance is based on the utilization of self-assembled nanoscale components exhibiting unique properties owing to their miniaturized dimensions. The first phase in the conception of such multifunctional devices based on integrated technologies requires the study of basic principles behind the functional mechanism of nanoscale components, which could originate from individual nanoobjects or result as a collective behaviour of miniaturized unit structures. The comprehensive studies presented in this thesis encompass the mechanical, dynamical and photophysical aspects of three nanoscale systems. A newly developed europium sulfide nanocrystalline material is introduced. Advances in synthetic methods allowed for shape control of surface-functionalized EuS nanocrystals and the fabrication of multifunctional EuS-CdSe hybrid particles, whose unique structural and optical properties hold promise as useful attributes of integrated materials in developing technologies. A comprehensive study based on a new class of multifunctional nanomaterials, derived from the basic unit of barcoded metal nanorods is presented. Their chemical composition affords them the ability to undergo autonomous motion in the presence of a suitable fuel. The nature of their chemically powered self-propulsion locomotion was investigated, and plausible mechanisms for various motility modes were presented. Furthermore functionalization of striped metallic nanorods has been realized through the incorporation of chemically controlled flexible hinges displaying bendable properties. The structural aspect of the light harvesting machinery of a photosynthetic cryptophyte alga, Rhodomonas CS24, and the mobility of the antenna protein, PE545, in vivo were investigated. Information obtained

Tetraaryl-, Pentaaryl-, and Hexaaryl-1,4-dihydropyrrolo 3,2-b pyrroles: Synthesis and Optical Properties

DEFF Research Database (Denmark)

Krzeszewski, M.; Thorsted, B.; Brewer, J.

2014-01-01

. Strategic placement of electron-withdrawing substituents at the 2-, 3-, 5-, and 6-positions produced an acceptor donor acceptor type fluorophore. The resulting multiply substituted heteropentalenes displayed intriguing optical properties. The relationship between the structure and photophysical properties...

One pot synthesis, X-ray crystal structure of 2-(2‧-hydroxyphenyl)oxazolo[4,5-b]pyridine derivatives and studies of their optical properties

Science.gov (United States)

Briseño-Ortega, Horacio; Juárez-Guerra, Lizbeth; Rojas-Lima, Susana; Mendoza-Huizar, Luis Humberto; Vázquez-García, Rosa A.; Farfán, Norberto; Arcos-Ramos, Rafael; Santillan, Rosa; López-Ruiz, Heralio

2018-04-01

A series of five 2-(2-hydroxyphenyl)oxazolo [4,5-b]pyridines (HPOP) (3a-e), where four are novel, were synthesized by a mild, one pot, phenylboronic acid-NaCN catalyzed reaction. Spectroscopic characterization and photophysical properties of these compounds are reported. Absorption and excitation spectra of the compounds were dependent on the substituents in the phenyl ring. Fluorescence quantum yields (0.009-0.538) were associated with the donor strength and the position of the substituents. Also, DFT analysis allowed us to determine the contribution of diethylamino and methoxy moieties to the π-system, which is in agreement with the experimental data analyzed in solution and by cyclic voltammetry. The results obtained in the solid state by single-crystal X-ray diffraction experiments indicate that, the quasi-planarity envisioned for the explored compounds is present, supporting the hypothesis that both the H-bonding of a hydroxyl group to the Cdbnd N moiety and a donor groups such as diethylamino and methoxy moieties favor an electronic communication. Due to the facile synthesis and their photophysical properties, the novel HPOP 3a-e have potential application as organic semiconductors.

Properties and characterization of modern materials

CERN Document Server

Altenbach, Holm

2017-01-01

This book focuses on robust characterization and prediction methods for materials in technical applications as well as the materials’ safety features during operation. In particular, it presents methods for reliably predicting material properties, an aspect that is becoming increasingly important as engineering materials are pushed closer and closer to their limits to boost the performance of machines and structures. To increase their engineering value, components are now designed under the consideration of their multiphysical properties and functions, which requires much more intensive investigation and characterization of these materials. The materials covered in this monograph range from metal-based groups such as lightweight alloys, to advanced high-strength steels and modern titanium alloys. Furthermore, a wide range of polymers and composite materials (e.g. with micro- and nanoparticles or fibres) is covered. The book explores methods for property prediction from classical mechanical characterization-...

Lanthanide(III) complexes of bis-semicarbazone and bis-imine-substituted phenanthroline ligands: solid-state structures, photophysical properties, and anion sensing.

Science.gov (United States)

Nadella, Sandeep; Selvakumar, Paulraj M; Suresh, Eringathodi; Subramanian, Palani S; Albrecht, Markus; Giese, Michael; Fröhlich, Roland

2012-12-21

Phenanthroline-based hexadentate ligands L(1) and L(2) bearing two achiral semicarbazone or two chiral imine moieties as well as the respective mononuclear complexes incorporating various lanthanide ions, such as La(III), Eu(III), Tb(III), Lu(III), and Y(III) metal ions, were synthesized, and the crystal structures of [ML(1)Cl(3)] (M=La(III), Eu(III), Tb(III), Lu(III), or Y(III)) complexes were determined. Solvent or water molecules act as coligands for the rare-earth metals in addition to halide anions. The big Ln(III) ion exhibits a coordination number (CN) of 10, whereas the corresponding Eu(III), Tb(III), Lu(III), and Y(III) centers with smaller ionic radii show CN=9. Complexes of L(2), namely [ML(2)Cl(3)] (M=Eu(III), Tb(III), Lu(III), or Y(III)) ions could also be prepared. Only the complex of Eu(III) showed red luminescence, whereas all the others were nonluminescent. The emission properties of the Eu derivative can be applied as a photophysical signal for sensing various anions. The addition of phosphate anions leads to a unique change in the luminescence behavior. As a case study, the quenching behavior of adenosine-5'-triphosphate (ATP) was investigated at physiological pH value in an aqueous solvent. A specificity of the sensor for ATP relative to adenosine-5'-diphosphate (ADP) and adenosine-5'-monophosphate (AMP) was found. (31)P NMR spectroscopic studies revealed the formation of a [EuL(2)(ATP)] coordination species. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Impact of charge carrier injection on single-chain photophysics of conjugated polymers

Energy Technology Data Exchange (ETDEWEB)

Hofmann, Felix J.; Vogelsang, Jan, E-mail: jan.vogelsang@physik.uni-regensburg.de; Lupton, John M. [Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg (Germany)

2016-06-27

Charges in conjugated polymer materials have a strong impact on the photophysics and their interaction with the primary excited state species has to be taken into account in understanding device properties. Here, we employ single-molecule spectroscopy to unravel the influence of charges on several photoluminescence (PL) observables. The charges are injected either stochastically by a photochemical process or deterministically in a hole-injection sandwich device configuration. We find that upon charge injection, besides a blue-shift of the PL emission and a shortening of the PL lifetime due to quenching and blocking of the lowest-energy chromophores, the non-classical photon arrival time distribution of the multichromophoric chain is modified towards a more classical distribution. Surprisingly, the fidelity of photon antibunching deteriorates upon charging, whereas one would actually expect the opposite: the number of chromophores to be reduced. A qualitative model is presented to explain the observed PL changes. The results are of interest to developing a microscopic understanding of the intrinsic charge-exciton quenching interaction in devices.

Photophysical Properties of II-VI Semiconductor Nanocrystals

Science.gov (United States)

Gong, Ke

As it is well known, semiconductor nanocrystals (also called quantum dots, QDs) are being actively pursued for use in many different types of luminescent optical materials. These materials include the active media for luminescence downconversion in artificial lighting, lasers, luminescent solar concentrators and many other applications. Chapter 1 gives general introduction of QDs, which describe the basic physical properties and optical properties. Based on the experimental spectroscopic study, a semiquantitative method-effective mass model is employed to give theoretical prediction and guide. The following chapters will talks about several topics respectively. A predictive understanding of the radiative lifetimes is therefore a starting point for the understanding of the use of QDs for these applications. Absorption intensities and radiative lifetimes are fundamental properties of any luminescent material. Meantime, achievement of high efficiency with high working temperature and heterostructure fabrication with manipulation of lattice strain are not easy and need systematic investigation. To make accurate connections between extinction coefficients and radiative recombination rates, chapter 2 will consider three closely related aspects of the size dependent spectroscopy of II-VI QDs. First, it will consider the existing literature on cadmium selenide (CdSe) QD absorption spectra and extinction coefficients. From these results and fine structure considerations Boltzmann weighted radiative lifetimes are calculated. These lifetimes are compared to values measured on very high quality CdSe and CdSe coated with zinc selenide (ZnSe) shells. Second, analogous literature data are analyzed for cadmium telluride (CdTe) nanocrystals and compared to lifetimes measured for very high quality QDs. Furthermore, studies of the absorption and excitation spectra and measured radiative lifetimes for CdTe/CdSe Type-II core/shell QDs are reported. These results are also analyzed in

Effect of the substituents on the photophysical, electrochemical and electroluminescence properties of OLED dopant Iridium bis(2-phenylbenzothiozolato- N,C2')(acetylacetonate)

Science.gov (United States)

Ivanov, P.; Tomova, R.; Petrova, P.

2014-12-01

The effect of two substituents: clorine and 1,3-diphenylpropane-1,3-dionate, placed on different position in the molecule of Iridium (III) bis(2-phenylbenzothiozolato-N,C2')- (acetylacetonate) (bt)2Ir(acac), on its electrochemical behaviour, photophysical and electroluminescence properties were investigated. Three complexes (bt)2Ir(acac), Iridium (III) bis[2-(4-chlorophenyl)benzothiazolato-N,C2']-acetylacetonate (Clbt)2Ir(acac), in which the Cl atom was introduced on the 4-position in the benzothiazole ring, and the new Iridium (Ill) bis[2 -phenylbenzothiazolato -N,C2'] -(1,3 -diphenylpropane-1,3 -dionate) (bt)2Ir(dbm), where ancillary acetylacetonate ligand was replaced by 1,3-diphenylpropane-1,3-dionate, were synthesized and characterised by 1H-NMR and elemental analysis. The HOMO/LUMO energy levels of the complexes were determined by cyclic voltammetry (CV) and their properties were established by UV-Visible and fluorescence spectroscopy. The application of (Clbt)2Ir(acac), (bt)2Ir(bsm) and (bt)2Ir(acac) as dopants in hole transporting layer (HTL) of Organic light- emitting diodes(OLEDs). It was found that with respect to the reference (bt)2Ir(acac): both LUMO and HOMO of the substituted complexes were shifted to more positive values accordingly with 0.23 and 0.19 eV for (Clbt)2Ir(acac) and 0.14 and 0.12 eV for (bt)2Ir(dbm). OLEDs doped with 1 w% of the complexes irradiated the warm white light with Commission internationale de l'eclairage (CIE) coordinates: 0.24;0.38 for (Clbt)2Ir(acac), 0.30;0.44 for (bt)2Ir(acac) and 0.28;0.46 for (bt)2Ir(dbm). Devices doped with 10 w% of all complexes irradiated in the yellow orange region of the spectrum.

Photophysical and photochemical study of styrene dyes related to their laser efficiency

International Nuclear Information System (INIS)

Meyer, Martine

1989-01-01

The photophysical and photochemical properties of two styrene dyes: 4-dicyanomethylene-2-methyl-6-p-dimethylamino-styryl-4H-pyran (DCM) and 7-dimethylamino-3-(-p-formyl-styryl)-1,4-benzoxazine-2-one (DFSBO) have been studied. These molecules have electron donor and electron acceptor groups which give to their fluorescent excited state a charge transfer state character. The red shifts of the absorption and fluorescence spectra in polar solvents and the large Stokes shift related to the increase of the dipole moment from the ground state to the singlet excited state have been fully characterised. The absorption spectra of the first excited singlet and triplet states and the quantum yields of the intersystem crossing to the triplet state have been determined. The existence of conformers of the two dyes has been evidenced. The synthesis of DCM leads to the trans isomer which, under light exposure undergoes photo-isomerization to the cis-compound. Their fluorescence lifetimes and the photo-isomerization efficiency are solvent dependent. The DFSBO emission spectra depend greatly on the excitation wavelength. This effect can be explained by the occurrence of two rotational conformers one being stabilised by an intramolecular hydrogen bond. The spectral properties of these two molecules enable us to explain why DCM is a very good laser dye whereas DFSBO has a poor laser efficiency. (author) [fr

Photophysical study of a cyclophane displaying intramolecular exciplex emission

International Nuclear Information System (INIS)

Galindo, Francisco; Isabel Burguete, M.; Luis, Santiago V.

2004-01-01

The photophysical behavior of cyclophane 1, comprised by two L-valine units and one naphthalene ring, has been studied. It displays exciplex (EX) emission with a maximum in the range 390-460 nm, depending on solvent polarity. From this dependence a dipole moment of 19.4 D for the excited charge-transfer state has been calculated. Fluorescence quantum yields in organic media ranging from 0.012 to 0.038 have been measured. This phenomenon has been interpreted taking into account the rigidity imposed by the cyclophane framework which could pre-orient the donor and the acceptor subunits for a favorable interaction

Photophysical study of a cyclophane displaying intramolecular exciplex emission

Energy Technology Data Exchange (ETDEWEB)

Galindo, Francisco; Isabel Burguete, M.; Luis, Santiago V

2004-07-12

The photophysical behavior of cyclophane 1, comprised by two L-valine units and one naphthalene ring, has been studied. It displays exciplex (EX) emission with a maximum in the range 390-460 nm, depending on solvent polarity. From this dependence a dipole moment of 19.4 D for the excited charge-transfer state has been calculated. Fluorescence quantum yields in organic media ranging from 0.012 to 0.038 have been measured. This phenomenon has been interpreted taking into account the rigidity imposed by the cyclophane framework which could pre-orient the donor and the acceptor subunits for a favorable interaction.

Emergent properties resulting from type-II band alignment in semiconductor nanoheterostructures.

Science.gov (United States)

Lo, Shun S; Mirkovic, Tihana; Chuang, Chi-Hung; Burda, Clemens; Scholes, Gregory D

2011-01-11

The development of elegant synthetic methodologies for the preparation of monocomponent nanocrystalline particles has opened many possibilities for the preparation of heterostructured semiconductor nanostructures. Each of the integrated nanodomains is characterized by its individual physical properties, surface chemistry, and morphology, yet, these multicomponent hybrid particles present ideal systems for the investigation of the synergetic properties that arise from the material combination in a non-additive fashion. Of particular interest are type-II heterostructures, where the relative band alignment of their constituent semiconductor materials promotes a spatial separation of the electron and hole following photoexcitation, a highly desirable property for photovoltaic applications. This article highlights recent progress in both synthetic strategies, which allow for material and architectural modulation of novel nanoheterostructures, as well as the experimental work that provides insight into the photophysical properties of type-II heterostructures. The effects of external factors, such as electric fields, temperature, and solvent are explored in conjunction with exciton and multiexciton dynamics and charge transfer processes typical for type-II semiconductor heterostructures.

Photophysical characterization and time-resolved spectroscopy of a anthradithiophene dimer: exploring the role of conformation in singlet fission

KAUST Repository

Dean, Jacob C.

2017-08-18

Quantitative singlet fission has been observed for a variety of acene derivatives such as tetracene and pentacene, and efforts to extend the library of singlet fission compounds is of current interest. Preliminary calculations suggest anthradithiophenes exhibit significant exothermicity between the first optically-allowed singlet state, S1, and 2 × T1 with an energy difference of >5000 cm−1. Given the fulfillment of this ingredient for singlet fission, here we investigate the singlet fission capability of a difluorinated anthradithiophene dimer (2ADT) covalently linked by a (dimethylsilyl)ethane bridge and derivatized by triisobutylsilylethynyl (TIBS) groups. Photophysical characterization of 2ADT and the single functionalized ADT monomer were carried out in toluene and acetone solution via absorption and fluorescence spectroscopy, and their photo-initiated dynamics were investigated with time-resolved fluorescence (TRF) and transient absorption (TA) spectroscopy. In accordance with computational predictions, two conformers of 2ADT were observed via fluorescence spectroscopy and were assigned to structures with the ADT cores trans or cis to one another about the covalent bridge. The two conformers exhibited markedly different excited state deactivation mechanisms, with the minor trans population being representative of the ADT monomer showing primarily radiative decay, while the dominant cis population underwent relaxation into an excimer geometry before internally converting to the ground state. The excimer formation kinetics were found to be solvent dependent, yielding time constants of ∼1.75 ns in toluene, and ∼600 ps in acetone. While the difference in rates elicits a role for the solvent in stabilizing the excimer structure, the rate is still decidedly long compared to most singlet fission rates of analogous dimers, suggesting that the excimer is neither a kinetic nor a thermodynamic trap, yet singlet fission was still not observed. The result

An ultrahigh vacuum monochromator for photophysics beamline

International Nuclear Information System (INIS)

Meenakshi Raja Rao, P.; Padmanabhan, Saraswathy; Raja Sekhar, B.N.; Shastri, Aparna; Khan, H.A.; Sinha, A.K.

2000-08-01

The photophysics beamline designed for carrying out photoabsorption and fluorescence studies using the 450 MeV Synchrotron Radiation Source (SRS), INDUS-1, uses a 1 metre monochromator as premonochromator for monochromatising the continuum. An ultra high vacuum compatible monochromator in Seya-Namioka mount has been designed and fabricated indigenously. The monochromator was assembled and tested for its performance. Wavelength scanning mechanism was tested for its reproducibility and the monochromator was tested for its resolution using UV and VUV sources. An average spectral resolution of 2.5 A was achieved using a 1200 gr/mm grating. A wavelength repeatability of ± 1A was obtained. An ultra high vacuum of 2 X 10 -8 mbar was also achieved in the monochromator. Details of fabrication, assembly and testing are presented in this report. (author)

Optically Detected Magnetic Resonance and Thermal Activation Spectroscopy Study of Organic Semiconductors

International Nuclear Information System (INIS)

Chang-Hwan Kim

2003-01-01

Organic electronic materials are a new class of emerging materials. Organic light emitting devices (OLEDs) are the most promising candidates for future flat panel display technologies. The photophysical characterization is the basic research step one must follow to understand this new class of materials and devices. The light emission properties are closely related to the transport properties of these materials. The objective of this dissertation is to probe the relation between transport and photophysical properties of organic semiconductors. The transport characteristics were evaluated by using thermally stimulated current and thermally stimulated luminescence techniques. The photoluminescence detected magnetic resonance and photoluminescence quantum yield studies provide valuable photophysical information on this class of materials. OLEDs are already in the market. However, detailed studies on the degradation mechanisms are still lacking. Since both optically detected magnetic resonance and thermal activation spectroscopy probe long-lived defect-related states in organic semiconductors, the combined study generates new insight on the OLED operation and degradation mechanisms

Optically Detected Magnetic Resonance and Thermal Activation Spectroscopy Study of Organic Semiconductors

Energy Technology Data Exchange (ETDEWEB)

Kim, Chang-Hwan [Iowa State Univ., Ames, IA (United States)

2003-01-01

Organic electronic materials are a new class of emerging materials. Organic light emitting devices (OLEDs) are the most promising candidates for future flat panel display technologies. The photophysical characterization is the basic research step one must follow to understand this new class of materials and devices. The light emission properties are closely related to the transport properties of these materials. The objective of this dissertation is to probe the relation between transport and photophysical properties of organic semiconductors. The transport characteristics were evaluated by using thermally stimulated current and thermally stimulated luminescence techniques. The photoluminescence detected magnetic resonance and photoluminescence quantum yield studies provide valuable photophysical information on this class of materials. OLEDs are already in the market. However, detailed studies on the degradation mechanisms are still lacking. Since both optically detected magnetic resonance and thermal activation spectroscopy probe long-lived defect-related states in organic semiconductors, the combined study generates new insight on the OLED operation and degradation mechanisms.

Exciplex dynamics in a blend of π-conjugated polymers with electron donating and accepting properties: MDMO-PPV and PCNEPV

NARCIS (Netherlands)

Offermans, T.; Hal, van P.A.; Meskers, S.C.J.; Koetse, M.M.; Janssen, R.A.J.

2005-01-01

The photophysical properties of a solution processed blend of two semiconducting polymers with electron donating and electron accepting properties, respectively, as used in polymer photovoltaic devices have been investigated. We show that in the binary mixture of

Alternative Thieno[3,2-b][1]benzothiophene Isoindigo Polymers for Solar Cell Applications

KAUST Repository

Neophytou, Marios; Bryant, Daniel; Lopatin, Sergei; Chen, Hu; Hallani, Rawad K.; Cater, Lewis; McCulloch, Iain; Yue, Wan

2018-01-01

This work reports the synthesis, characterization, photophysical, and photovoltaic properties of five new thieno[3,2-b][1]benzothiophene isoindigo (TBTI)-containing low bandgap donor-acceptor conjugated polymers with a series of comonomers

Synthesis, photophysical and electrochemical properties of 2,8 ...

Indian Academy of Sciences (India)

dibenzothiophene derivatives for organic electronics. Pabitra K Nayak ... These molecules have electron withdrawing or electron donating groups at the para phenyl position, which alters the electronic properties of these derivatives. The quantum yield ...

Synthesis and characterization of near-IR absorbing metal-free and zinc(II phthalocyanines modified with aromatic azo groups

Directory of Open Access Journals (Sweden)

Mukaddes Özçeşmeci

2015-05-01

Full Text Available Metal-free and zinc(II phthalocyanine complexes bearing peripheral (E-4-((2-hydroxynaphthalen-1-yldiazenyl units have been synthesized. Novel phthalonitrile derivative required for the preparation of phthalocyanine complexes was prepared by coupling 4-aminophthalonitrile and 2-naphthol. The structures of these new compounds were characterized by using elemental analyses, proton nuclear magnetic resonance, fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, fluorescence spectroscopy and mass spectrometry. In the UV-Vis spectra a broad absorption band appears for phthalocyanine complexes at around 450–500 nm resulting from azo-group introduced onto the phthalocyanine ring. The photophysical properties of metal-free and zinc(II phthalocyanines were studied in tetrahydrofuran.

Nonlinear absorbing cationic iridium(III) complexes bearing benzothiazolylfluorene motif on the bipyridine (N∧N) ligand: synthesis, photophysics and reverse saturable absorption.

Science.gov (United States)

Li, Yuhao; Dandu, Naveen; Liu, Rui; Hu, Lei; Kilina, Svetlana; Sun, Wenfang

2013-07-24

Four new heteroleptic cationic Ir(III) complexes bearing benzothiazolylfluorene motif on the bipyridine (N∧N) (1 and 2) and phenylpyridine (C∧N) (3 and 4) ligands are synthesized and characterized. The influence of the position of the substituent and the extent of π-conjugation on the photophysics of these complexes is systematically investigated by spectroscopic methods and simulated by time-dependent density functional theory (TDDFT). The complexes exhibit ligand-centered (1)π,π* transitions with admixtures of (1)ILCT (π(benzothiazolylfluorene) → π*(bpy)) and (1)MLCT (metal-to-ligand charge transfer) characters below 475 nm, and very weak (1,3)MLCT and (1,3)LLCT (ligand-to-ligand charge transfer) transitions above 475 nm. The emission of these complexes at room temperature in CH2Cl2 solutions is ascribed to be predominantly from the (3)MLCT/(3)LLCT states for 1 and from the (3)π,π* state for 2, while the emitting state of 3 and 4 are assigned to be an admixture of (3)MLCT, (3)LLCT, and (3)π,π* characters. The variations of the photophysical properties of 1-4 are attributed to different degrees of π-conjugation in the bipyridine and phenylpyridine ligands induced by different positions of the benzothiazolylfluorenyl substituents on the bipyridine ligand and different extents of π-conjugation in the phenylpyridine ligands, which alters the energy and lifetime of the lowest singlet and triplet excited states. 1-4 all possess broadband transient absorption (TA) upon nanosecond laser excitation, which extends from the visible to the NIR region. Therefore, 1-4 all exhibit strong reverse saturable absorption (RSA) at 532 nm for ns laser pulses. However, the TA of complexes 1, 2, and 3 are much stronger than that of 4. This feature, combined with the difference in ground-state absorption and triplet excited-state quantum yield, result in the difference in RSA strength, which follows this trend: 1 ≈ 2 ≈ 3 > 4. Therefore, complexes 1-3 are strong

Synthesis and photophysical properties of a novel corrole–anthraquinone–corrole molecular system

International Nuclear Information System (INIS)

Sudhakar, Kolanu; Kanaparthi, Ravi Kumar; Kumar, Challa Kiran; Giribabu, Lingamallu

2014-01-01

A novel molecular triad (AQ-(H 3 ) 2 ) based on tritolylcorrole and anthraquinone having azomethine-bridge at the pyrrole-β position has been designed and synthesized by following a facile one step reaction. The molecular system, AQ-(H 3 ) 2 is characterized by elemental analysis, MALDI-MS, 1 H-NMR, UV–Visible and fluorescence spectroscopy (steady-state and time-resolved) as well as electrochemical methods. In absorption spectra, prominent changes such as red-shift (∼7 nm) and broadening of the both Soret and Q-bands with respect to their monomer units were observed. The present study supported by density functional theory calculations manifest that there exists a negligible electronic communication in the ground state between the donor tritolylcorrole and acceptor anthraquinone of the triad. However, interestingly, in the triad AQ-(H 3 ) 2 , fluorescence emission of the tritolylcorrole quenched significantly (17–80%) compared to their monomeric units. The emission quenching is attributed to the excited state intramolecular photoinduced electron transfer from donor tritolylcorrole to acceptor anthraquinone and the electron transfer rates (k ET ) are found in the range 4.1×10 8 to 2.4×10 9 s −1 and are found to be solvent dependent. - Highlights: • Molecular triad based on corrole and anthraquinone having azomethine-bridge at pyrrole-β position. • Ground state properties showed that there exist minimum π–π interactions. • Excited state properties showed intramolecular photoinduced electron transfer from corrole to anthraquinone

Molecular Polygons Probe the Role of Intramolecular Strain in the Photophysics of π-Conjugated Chromophores.

Science.gov (United States)

Wilhelm, Philipp; Vogelsang, Jan; Poluektov, Georgiy; Schönfelder, Nina; Keller, Tristan J; Jester, Stefan-Sven; Höger, Sigurd; Lupton, John M

2017-01-24

π-Conjugated segments, chromophores, are the electronically active units of polymer materials used in organic electronics. To elucidate the effect of the bending of these linear moieties on elementary electronic properties, such as luminescence color and radiative rate, we introduce a series of molecular polygons. The π-system in these molecules becomes so distorted in bichromophores (digons) that these absorb and emit light of arbitrary polarization: any part of the chain absorbs and emits radiation with equal probability. Bending leads to a cancellation of transition dipole moment (TDM), increasing excited-state lifetime. Simultaneously, fluorescence shifts to the red as radiative transitions require mixing of the excited state with vibrational modes. However, strain can become so large that excited-state localization on shorter units of the chain occurs, compensating TDM cancellation. The underlying correlations between shape and photophysics can only be resolved in single molecules. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Theory of interfacial charge-transfer complex photophysics in π-conjugated polymer-fullerene blends

Science.gov (United States)

Aryanpour, K.; Psiachos, D.; Mazumdar, S.

2010-03-01

We present a theory of the electronic structure and photophysics of 1:1 blends of derivatives of polyparaphenylenevinylene and fullerenes [1]. Within the same Coulomb-correlated Hamiltonian applied previously to interacting chains of single-component π-conjugated polymers [2], we find an exciplex state that occurs below the polymer's optical exciton. Weak absorption from the ground state occurs to the exciplex. We explain transient photoinduced absorptions in the blend [3], observed for both above-gap and below-gap photoexcitations, within our theory. Photoinduced absorptions for above-gap photoexcitation are from the optical exciton as well as the exciplex, while for below-gap photoexcitation induced absorptions are from the exciplex alone. In neither case are free polarons generated in the time scale of the experiment. Importantly, the photophysics of films of single-component π-conjugated polymers and blends can both be understood by extending Mulliken's theory of ground state charge-transfer to the case of excited state charge-transfer. [1] K. Aryanpour, D. Psiachos, and S. Mazumdar, arXiv:0908.0366 [2] D. Psiachos and S. Mazumdar, Phys. Rev. B. 79 155106 (2009) [3] T. Drori et al., Phys. Rev. Lett. 101, 037402 (2008)

Synthesis, Characterization and Photophysical Properties of Pyridine-Carbazole Acrylonitrile Derivatives

Science.gov (United States)

Pérez-Gutiérrez, Enrique; Percino, M. Judith; Chapela, Víctor M.; Cerón, Margarita; Maldonado, José Luis; Ramos-Ortiz, Gabriel

2011-01-01

We synthesized three novel highly fluorescent compounds, 2-(2’-pyridyl)-3-(N-ethyl-(3’-carbazolyl))acrylonitrile, 2-(3”-pyridyl)-3-(N-ethyl-(3’-carbazolyl))acrylonitrile, and 2-(4-pyridyl)-3-(N-ethyl-(3’-carbazolyl))acrylonitrile by Knoevenagel condensation. The first two were synthesized without solvent in the presence of piperidine as a catalyst; the third was synthesized without a catalyst and with N,N-dimethylformamide as a solvent. In solution, the molar absorption coefficients showed absorptions at 380, 378, and 396 nm, respectively; in solid state, absorptions were at 398, 390, and 442 nm, respectively. The fluorescence emission was at 540, 540 and 604 nm, respectively, the 2-(4-pyridyl)-3-(N-ethyl-(3’-carbazolyl))acrylonitrile showed a red shift in the emission of 64 nm compared to the other two compounds. The fluorescence quantum yield for the compounds in powder form showed values of 0.05, 0.14, and 0.006, respectively; compared with the value measured for the Alq3 reference, 2-(3”-pyridyl)-3-(N-ethyl-(3’-carbazolyl))acrylonitrile had a lightly higher value. The third harmonic generation measurement for 2-(2’-pyridyl)-3-(N-ethyl-(3’-carbazolyl))acrylonitrile yielded a χ(3) value of 5.5 × 10−12 esu, similar to that reported for commercial polymers. PMID:28880006

Synthesis, Characterization and Photophysical Properties of Pyridine-Carbazole Acrylonitrile Derivatives

Directory of Open Access Journals (Sweden)

Gabriel Ramos-Ortiz

2011-03-01

Full Text Available We synthesized three novel highly fluorescent compounds, 2-(2’-pyridyl-3-(N-ethyl-(3’-carbazolylacrylonitrile, 2-(3”-pyridyl-3-(N-ethyl-(3’-carbazolylacrylonitrile, and 2-(4-pyridyl-3-(N-ethyl-(3’-carbazolylacrylonitrile by Knoevenagel condensation. The first two were synthesized without solvent in the presence of piperidine as a catalyst; the third was synthesized without a catalyst and with N,N-dimethylformamide as a solvent. In solution, the molar absorption coefficients showed absorptions at 380, 378, and 396 nm, respectively; in solid state, absorptions were at 398, 390, and 442 nm, respectively. The fluorescence emission was at 540, 540 and 604 nm, respectively, the 2-(4-pyridyl-3-(N-ethyl-(3’-carbazolylacrylonitrile showed a red shift in the emission of 64 nm compared to the other two compounds. The fluorescence quantum yield for the compounds in powder form showed values of 0.05, 0.14, and 0.006, respectively; compared with the value measured for the Alq3 reference, 2-(3”-pyridyl-3-(N-ethyl-(3’-carbazolylacrylonitrile had a lightly higher value. The third harmonic generation measurement for 2-(2’-pyridyl-3-(N-ethyl-(3’-carbazolylacrylonitrile yielded a χ(3 value of 5.5 × 10−12 esu, similar to that reported for commercial polymers.

Photophysical properties and excited state intramolecular proton transfer in 2-hydroxy-5-[(E)-(4-methoxyphenyl)diazenyl]benzoic acid in homogeneous solvents and micro-heterogeneous environments

Energy Technology Data Exchange (ETDEWEB)

Gashnga, Pynsakhiat Miki [Centre for Advanced Studies, Department of Chemistry, North-Eastern Hill University, Shillong 793022, Meghalaya (India); Singh, T. Sanjoy [Department of Chemistry, Assam University, Silchar 788011, Assam (India); Baul, Tushar S. Basu [Centre for Advanced Studies, Department of Chemistry, North-Eastern Hill University, Shillong 793022, Meghalaya (India); Mitra, Sivaprasad, E-mail: smitra@nehu.ac.in [Centre for Advanced Studies, Department of Chemistry, North-Eastern Hill University, Shillong 793022, Meghalaya (India)

2014-04-15

A systematic study on the photophysical properties and excited state intramolecular proton transfer (ESIPT) behavior of 2-hydroxy-5-[(E)-(4-methoxyphenyl)diazenyl]benzoic acid, is reported using steady-state and time-resolved fluorescence spectroscopy in homogeneous solvents as well as in different micro-heterogeneous environments. Depending on the nature of intramolecular hydrogen bond (IHB), the salicylic acid derivative may exist in two different ground state conformers (I and II). Structure I having IHB between the carbonyl oxygen and phenolic hydrogen can undergo ESIPT upon excitation as evidenced by largely Stokes-shifted fluorescence at ∼455 nm; whereas, normal fluorescence in the blue side of the spectrum (∼410 nm) is due to the spontaneous emission from conformer II. The results in homogeneous solvents were compared with those in bio-mimicking environments of β-cyclodextrin (CD) and surfactants. The intensity of the ESIPT fluorescence increases substantially upon encapsulation of the probe into the cyclodextrin as well as micellar nano-cavities. Detailed analysis of the spectroscopic data indicates that the probe forms 1:1 complex with CD in aqueous medium. Binding constant of the probe with the micelles as well as critical micelle concentration was obtained from the variation of fluorescence intensity on increasing concentration of different surfactants in aqueous medium. -- Highlights: • Steady state and time resolved fluorescence study on ESIPT in HMBA. • Dual fluorescence corresponding to the pro- and non-ESIPT structures. • Modulation of ESIPT fluorescence in micro-heterogeneous environments. • 1:1 stoichiometry for interaction with cyclodextrin. • Calculation of binding constant and other physico-chemical properties from fluorescence titration data in surfactants.

Photophysical properties and excited state intramolecular proton transfer in 2-hydroxy-5-[(E)-(4-methoxyphenyl)diazenyl]benzoic acid in homogeneous solvents and micro-heterogeneous environments

International Nuclear Information System (INIS)

Gashnga, Pynsakhiat Miki; Singh, T. Sanjoy; Baul, Tushar S. Basu; Mitra, Sivaprasad

2014-01-01

A systematic study on the photophysical properties and excited state intramolecular proton transfer (ESIPT) behavior of 2-hydroxy-5-[(E)-(4-methoxyphenyl)diazenyl]benzoic acid, is reported using steady-state and time-resolved fluorescence spectroscopy in homogeneous solvents as well as in different micro-heterogeneous environments. Depending on the nature of intramolecular hydrogen bond (IHB), the salicylic acid derivative may exist in two different ground state conformers (I and II). Structure I having IHB between the carbonyl oxygen and phenolic hydrogen can undergo ESIPT upon excitation as evidenced by largely Stokes-shifted fluorescence at ∼455 nm; whereas, normal fluorescence in the blue side of the spectrum (∼410 nm) is due to the spontaneous emission from conformer II. The results in homogeneous solvents were compared with those in bio-mimicking environments of β-cyclodextrin (CD) and surfactants. The intensity of the ESIPT fluorescence increases substantially upon encapsulation of the probe into the cyclodextrin as well as micellar nano-cavities. Detailed analysis of the spectroscopic data indicates that the probe forms 1:1 complex with CD in aqueous medium. Binding constant of the probe with the micelles as well as critical micelle concentration was obtained from the variation of fluorescence intensity on increasing concentration of different surfactants in aqueous medium. -- Highlights: • Steady state and time resolved fluorescence study on ESIPT in HMBA. • Dual fluorescence corresponding to the pro- and non-ESIPT structures. • Modulation of ESIPT fluorescence in micro-heterogeneous environments. • 1:1 stoichiometry for interaction with cyclodextrin. • Calculation of binding constant and other physico-chemical properties from fluorescence titration data in surfactants

Reverse saturable absorption (RSA) in fluorinated iridium derivatives

Science.gov (United States)

Ferry, Michael J.; O'Donnell, Ryan M.; Bambha, Neal; Ensley, Trenton R.; Shensky, William M.; Shi, Jianmin

2017-08-01

The photophysical properties of cyclometallated iridium compounds are beneficial for nonlinear optical (NLO) applications, such as the design of reverse saturable absorption (RSA) materials. We report on the NLO characterization of a family of compounds of the form [Ir(pbt)2(LX)], where pbt is 2-phenylbenzothiazole and LX is a beta-diketonate ligand. In particular, we investigate the effects of trifluoromethylation on compound solubility and photophysics compared to the parent acetylacetonate (acac) version. The NLO properties, such as the singlet and triplet excited-state cross sections, of these compounds were measured using the Z-scan technique. The excited-state lifetimes were determined from visible transient absorption spectroscopy.

The Chameleonic Nature of Platinum(II) Imidazopyridine Complexes.

Science.gov (United States)

Pinter, Piermaria; Pittkowski, Rebecca; Soellner, Johannes; Strassner, Thomas

2017-10-12

The synthesis and characterization of cyclometalated C^C* platinum(II) complexes with unique photophysical properties, aggregation induced enhancement of the quantum yields with a simultaneous decrease of phosphorescence lifetimes, is reported. Additionally, a change of emission color is induced by variation of the excitation wavelength. The aggregation behavior of these complexes is controlled by the steric demand of the substituents. The photophysical properties of these complexes are investigated through emission-excitation matrix analysis (EEM). The monomeric complexes are excellent room temperature phosphorescent blue emitters with emission maxima below 470 nm and quantum yields of up to 93 %. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and photophysical properties of a novel corrole–anthraquinone–corrole molecular system

Energy Technology Data Exchange (ETDEWEB)

Sudhakar, Kolanu [Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500007, Andhra Pradesh (India); Kanaparthi, Ravi Kumar [Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500007, Andhra Pradesh (India); Department of Chemistry, Central University of Kerala, Reverside Transit Campus, Padanakkad, Nileshwar Kasaragod District - 671 314 Kerala (India); Kumar, Challa Kiran [Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500007, Andhra Pradesh (India); Giribabu, Lingamallu, E-mail: giribabu@iict.res.in [Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500007, Andhra Pradesh (India)

2014-09-15

A novel molecular triad (AQ-(H{sub 3}){sub 2}) based on tritolylcorrole and anthraquinone having azomethine-bridge at the pyrrole-β position has been designed and synthesized by following a facile one step reaction. The molecular system, AQ-(H{sub 3}){sub 2} is characterized by elemental analysis, MALDI-MS, {sup 1}H-NMR, UV–Visible and fluorescence spectroscopy (steady-state and time-resolved) as well as electrochemical methods. In absorption spectra, prominent changes such as red-shift (∼7 nm) and broadening of the both Soret and Q-bands with respect to their monomer units were observed. The present study supported by density functional theory calculations manifest that there exists a negligible electronic communication in the ground state between the donor tritolylcorrole and acceptor anthraquinone of the triad. However, interestingly, in the triad AQ-(H{sub 3}){sub 2}, fluorescence emission of the tritolylcorrole quenched significantly (17–80%) compared to their monomeric units. The emission quenching is attributed to the excited state intramolecular photoinduced electron transfer from donor tritolylcorrole to acceptor anthraquinone and the electron transfer rates (k{sub ET}) are found in the range 4.1×10{sup 8} to 2.4×10{sup 9} s{sup −1} and are found to be solvent dependent. - Highlights: • Molecular triad based on corrole and anthraquinone having azomethine-bridge at pyrrole-β position. • Ground state properties showed that there exist minimum π–π interactions. • Excited state properties showed intramolecular photoinduced electron transfer from corrole to anthraquinone.

Biosorption of arsenic from groundwater using Vallisneria gigantea plants. Kinetics, equilibrium and photophysical considerations.

Science.gov (United States)

Iriel, Analia; Lagorio, M Gabriela; Fernández Cirelli, Alicia

2015-11-01

Arsenic (V) uptake from groundwater by using Vallisneria gigantea plants was studied using batch experiments. Reflectance and fluorescence of intact plants were investigated and changes in photophysical properties following arsenic absorption were reported. Good correlations have been found between arsenic concentration in groundwater and parameters derived from reflectance and fluorescence measurements. This system reached its equilibrium after seven days when the removal quantities were strongly dependent on the initial arsenic concentration. Interestingly, Vallisneria plants were able to accumulate from 100 to 600 mg As kg(-1) in roots and fronds although the translocation factors were low (0.6-1.6). Kinetic data for biosorption process followed a first-order law. At low arsenic concentrations the uptake in plants was governed by diffusion aspects. Langmuir, Freundlich and Dubinin-Radushkevich models were applied and results demonstrated that arsenic uptake was better described by the Langmuir model. As a final remark we concluded that a plant of this species should be able to remove 1mg As per week. Copyright © 2015 Elsevier Ltd. All rights reserved.

A diamine ligand with long 'arms' and its corresponding dinuclear rhenium(I) complex: Synthesis, characterization, photophysical property, and sensing activity towards molecular oxygen

Energy Technology Data Exchange (ETDEWEB)

Xu Xiaoyong, E-mail: dreamxxy01@163.com [Center for Functional Materials of Pingxiang, Pingxiang 337055 (China) and College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Xiao Hanning [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China)

2012-09-15

In this paper, we synthesize a novel diamine ligand of 4,7-dinonadecyl-1,10-phenanthroline (DN-Phen) with two long alkyl chain arms serving as a shield and its corresponding dinuclear Re(I) complex of Re{sub 2}(CO){sub 6}(bpy)(DN-Phen){sub 2} (bpy=4,4 Prime -bipyridine), aiming at an optical sensor immune to the surrounding interferences. Its geometric and electronic structures are investigated, which suggest that the introduced long alkyl chains act as a shield for the excited state of emissive center. The promising photophysical parameters of Re{sub 2}(CO){sub 6}(bpy)(DN-Phen){sub 2}, including the immunity of emission towards the surrounding interferences and long excited state lifetime, make itself a potential probe for oxygen detection. By doping Re{sub 2}(CO){sub 6}(bpy)(DN-Phen){sub 2} into two silica matrixes of MCM-41 and SBA-15, oxygen sensing performances of the resulted composite materials are investigated. Finally, a high sensitivity of 20.1 is realized, with short response/recovery time of 8 s/42 s. Here, sensitivity is defined as the ratio of emission maximum under pure nitrogen to emission minimum under pure oxygen, response and recovery times are the times for a sample to lose (response time) or recover (recovery time) 95% of its emission maximum upon periodically changed atmosphere. - Highlights: Black-Right-Pointing-Pointer A ligand with two long alkyl chain arms serving as a shield is synthesized. Black-Right-Pointing-Pointer The shield protects the excited state emissive center. Black-Right-Pointing-Pointer The emission of Re(I) complex is immune towards surrounding interference. Black-Right-Pointing-Pointer A high sensitivity of 20.1 is realized.

Simulation of some dynamical aspects of the photophysics of dye molecules encapsulated in a dendrimer

Energy Technology Data Exchange (ETDEWEB)

Teobaldi, Gilberto [Dipartimento di Chimica ' G. Ciamician' , Universita di Bologna, Via F. Selmi 2, Bologna I-40126 (Italy); Zerbetto, Francesco [Dipartimento di Chimica ' G. Ciamician' , Universita di Bologna, Via F. Selmi 2, Bologna I-40126 (Italy)]. E-mail: francesco.zerbetto@unibo.it

2005-03-15

We use a combination of molecular dynamics and quantum chemical calculations to investigate the photophysics of Eosin Y encapsulated in a fourth generation of poly-propylene amine dendrimer functionalized in the periphery with dansyl units. Once in contact with the macromolecule, the guests display a double exponential decay of the excited states that is reproduced by the present model.

Simulation of some dynamical aspects of the photophysics of dye molecules encapsulated in a dendrimer

International Nuclear Information System (INIS)

Teobaldi, Gilberto; Zerbetto, Francesco

2005-01-01

We use a combination of molecular dynamics and quantum chemical calculations to investigate the photophysics of Eosin Y encapsulated in a fourth generation of poly-propylene amine dendrimer functionalized in the periphery with dansyl units. Once in contact with the macromolecule, the guests display a double exponential decay of the excited states that is reproduced by the present model

Synthesis and optical properties of water-soluble biperylene-based dendrimers.

Science.gov (United States)

Shao, Pin; Jia, Ningyang; Zhang, Shaojuan; Bai, Mingfeng

2014-05-30

We report the synthesis and photophysical properties of three biperylene-based dendrimers, which show red fluorescence in water. A fluorescence microscopy study demonstrated uptake of biperylene-based dendrimers in living cells. Our results indicate that these biperylene-based dendrimers are promising candidates in fluorescence imaging applications with the potential as therapeutic carriers.

Synthesis, spectral and third-order nonlinear optical properties of terpyridine Zn(II) complexes based on carbazole derivative with polyether group

Science.gov (United States)

Kong, Ming; Liu, Yanqiu; Wang, Hui; Luo, Junshan; Li, Dandan; Zhang, Shengyi; Li, Shengli; Wu, Jieying; Tian, Yupeng

2015-01-01

Four novel Zn(II) terpyridine complexes (ZnLCl2, ZnLBr2, ZnLI2, ZnL(SCN)2) based on carbazole derivative group were designed, synthesized and fully characterized. Their photophysical properties including absorption and one-photon excited fluorescence, two-photon absorption (TPA) and optical power limiting (OPL) were further investigated systematically and interpreted on the basis of theoretical calculations (TD-DFT). The influences of different solvents on the absorption and One-Photon Excited Fluorescence (OPEF) spectral behavior, quantum yields and the lifetime of the chromophores have been investigated in detail. The third-order nonlinear optical (NLO) properties were investigated by open/closed aperture Z-scan measurements using femtosecond pulse laser in the range from 680 to 1080 nm. These results revealed that ZnLCl2 and ZnLBr2 exhibited strong two-photon absorption and ZnLCl2 showed superior optical power limiting property.

Synthesis, characterization, and photo-physical properties of nano-crystallites of CdyZn1-yS semiconductors

International Nuclear Information System (INIS)

Cizeron, Joel

1996-01-01

This research thesis reports the study of the synthesis of particles of semiconductor with a hybrid composition (Cd y Zn 1-y S) in an inverse micellar system. This system is made of nano-scopic water droplets suspended in oil by Brownian movement. Inverse micelles of AOT/water/alkane have been successfully used in laboratory to synthesize semiconductor particles (CdS, Ag 2 S, AgI, PbS) and metallic particles (Ag, Cu, Co) with a diameter of few nanometers. The objective has been to demonstrate the feasibility of synthesises of solid solution with a composition controlled by colloidal techniques. It was then possible to identify new information on the mechanism which governs the size of semiconductor particles. Optical properties of these particles were then studied. These nano-particles exhibit a displacement of their exciton towards high energies; it is the so-called size quantum effect. This effect has been analysed for the particles and their fluorescence [fr

Fluorescence properties of 6-aryl-2‧-deoxy-furanouridine and -pyrrolocytidine and their derivatives

Science.gov (United States)

Ro, Jong Jin; Go, Gui Han; Wilhelmsson, L. Marcus; Hyean Kim, Byeang

2018-01-01

2‧-deoxyfuranouridine derivatives presenting various aryl groups have been synthesized through Cu(I)-catalyzed intramolecular cyclizations. Moreover, corresponding pyrrolo-dC derivatives have been synthesized and both families of compounds thoroughly characterized using UV/vis and fluorescence spectroscopy as well as time-dependent density functional theory calculations. The photophysical characterization, show that our newly synthesized derivatives of the important pyrrolo-dC family have high fluorescence quantum yields (QYs) and brightness values. Pyrrolo-dC derivative, 3a, shows an environment sensitive QY of up to >60% and brightness of almost 3000, in low polarity solvents and excitation and emission maxima between 365-381 nm and 479-510 nm, respectively, in solvents of different polarities. Two other derivatives, 3b and 3c, show high QYs and brightness values of up to 3300 that are fairly insensitive to their microenvironment. These promising photophysical features suggest future applicability as fluorescent nucleobase analogs.

Symmetrical N-acylsubstituted dihydrazones containing bithiophene core - Photophysical, electrochemical and thermal characterization

Science.gov (United States)

Jarczyk-Jedryka, Anna; Filapek, Michal; Malecki, Grzegorz; Kula, Slawomir; Janeczek, Henryk; Boharewicz, Bartosz; Iwan, Agnieszka; Schab-Balcerzak, Ewa

2016-04-01

Four symmetrical N-acylsubstituted dihydrazones containing bithiophene core were synthesized from condensation of 2,2‧-bithiophene-5,5‧-dicarboxyaldehyde with benzoic, isonicotinoyl, 2-thiophenic and 2-furoic hydrazide. The obtained compounds were characterized through the data from 1H nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), elemental analysis, UV-vis absorption spectroscopy, photoluminescence (PL), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements. Additionally, the electronic properties including orbital energies and resulting energy gaps were calculated by density functional theory (DFT). Their thermal behavior was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). They were thermal sable up to 320 °C. The prepared N-acylsubstituted dihydrazones emitted light with λem in the range of 499-530 nm in solution, whereas, in solid state as blend with PMMA blue emission was observed. They undergo quasi-reversible and irreversible electrochemical reduction and oxidation processes, respectively. Additionally, the selected compounds were tested preliminary as component of active layer in organic photovoltaic cells. The highest value of power conversion efficiency, equal to 1.68% under simulated 100 mW/cm2 AM 1.5G irradiation was found for device with the architecture ITO/PEDOT:PSS/P3HT:PCBM:FBTH (1:2:2)/Al.

Antibacterial, kinetics and bacteriolytic properties of silver(I) pyridinedicarboxylate compounds

Energy Technology Data Exchange (ETDEWEB)

Azócar, M. Ignacio, E-mail: manuel.azocar@usach.cl [Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Bernardo O' Higgins 3363, Santiago (Chile); Gómez, Grace; Velásquez, Carla; Abarca, Romina [Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Bernardo O' Higgins 3363, Santiago (Chile); Kogan, Marcelo J. [Departamento de Quimica Farmacologica y Toxicologica, Facultad de Ciencias Quimicas y Farmaceuticas, Universidad de Chile. Advanced Center for Chronic Diseases (ACCDiS) (Chile); Páez, Maritza [Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Bernardo O' Higgins 3363, Santiago (Chile)

2014-04-01

Antibacterial properties of silver(I)-pyridinedicarboxylate compounds (with Pyridine-2,3-dicarboxylic(Lutidinic acid), pyridine-2,4-dicarboxylic (Quinolinic acid) and pyridine-2,5-dicarboxylic (Isocinchomeronic acid)) were studied against Escherichia coli, Listeria monocytogenes (ISP-65-08), Salmonella typhi and Staphylococcus aureus (ATCC 25923) using kinetics of grown inhibition, viability assays, minimum inhibitory concentration and optical microscopy. The 3 silver compounds were tested toward UV-radiation in order to characterize their light insensitivity for potential medical devices: UV-radiation curable polymers. Photophysical measurements show remarkable differences toward UV-radiation, which were explained based on their polymeric structures with multiple nature bonds between pyridinedicarboxylic ligands and Ag(I) centers. We found a bacteriolytic effect and differences in the antibacterial efficiency depending on the structure of the complexes and the nature of Ag-X (X = oxygen and nitrogen) bonds: AgQuinol > AgLutidin > AgIsocinchom. - Highlights: • Antibacterial efficiency of silver(I) complexes • Improving antimicrobial properties of silver(I) complexes • Insensitivity to air and UV light for medical devices • Broad-spectrum antibiotic ointment • Bacteriolytic mechanism of silver compounds.

Synthesis and characterization of Na(Y,Gd)F{sub 4} upconversion nanoparticles and an investigation of their effects on the photophysical properties of an unsubstituted tetrathiophenoxy phthalocyanine

Energy Technology Data Exchange (ETDEWEB)

Taylor, Jessica M.; Litwinski, Christian; Nyokong, Tebello; Antunes, Edith M., E-mail: ebeukes@uwc.ac.za [Rhodes University, Department of Chemistry (South Africa)

2015-02-15

Sphere- and star-shaped Na(Y,Gd)F{sub 4}:Yb/Er(Tm)upconversion nanoparticles (UCNP) were successfully synthesized utilizing a methanol-assisted thermal decomposition approach and their spectroscopic (absorption, emission and luminescence lifetime) properties fully characterized. The factors affecting the size and shape of the UCNPs were studied and discussed in detail. The size of the nanoparticles was determined using TEM primarily and found to be approximately 19 and 30 nm for the Er and Tm spheres, respectively, while the Er and Tm “stars” were found to be much larger with sizes ranging from 110 to 240 nm, respectively (as determined along the width of the nanoparticle). In addition, their influence on the spectroscopic properties of an unsubstituted tetrathiophenoxy phthalocyanine (H{sub 2}Pc) was investigated. The UCNP were found to produce characteristic upconversion luminescence emissions in the blue, green, red and NIR regions. Simple mixing with an H{sub 2}Pc in toluene was found to exert no obvious changes in the spectroscopic properties of the Pc, although a considerable increase in the radiative lifetimes is observed for the Pc in the presence of the UCNPs. The singlet oxygen generation mediated by the red light excitation of the H{sub 2}Pc mixed with UCNP was found to decrease in the presence of the NPs.

Synthesis, structural characterization and photoluminescence properties of rhenium(I) complexes based on bipyridine derivatives with carbazole moieties.

Science.gov (United States)

Li, Hong-Yan; Wu, Jing; Zhou, Xin-Hui; Kang, Ling-Chen; Li, Dong-Ping; Sui, Yan; Zhou, Yong-Hui; Zheng, You-Xuan; Zuo, Jing-Lin; You, Xiao-Zeng

2009-12-21

Three N,N-bidentate ligands, 5,5'-dibromo-2,2-bipyridine (L1) and two carbazole containing ligands of 5-bromo-5'-carbazolyl-2,2-bipyridine (L2), 5,5'-dicarbazolyl-2,2'-bipyridine (L3), and their corresponding rhenium Re(CO)3Cl(L) complexes (ReL1-ReL3) have been successfully synthesized and characterized by elemental analysis, 1H NMR and IR spectra. Their photophysical properties and thermal analysis, along with the X-ray crystal structure analysis of L3 and complexes ReL1 and ReL3 are also described. In CH2Cl2 solution at room temperature, all complexes display intense absorption bands at ca. 220-350 nm, which can be assigned to spin-allowed intraligand (pi-->pi*) transitions, and the low energy broad bands in the 360-480 nm region are attributed to the metal to ligand charge-transfer d(Re)-->pi* (diimine) (MLCT). The introduction of carbazole moieties improves the MLCT absorption and molar extinction coefficient of these complexes. Upon excitation at the peak maxima, all complexes show strong emissions around 620 nm, which are assigned to d(Re)-->pi* (diimine) MLCT phosphorescence. The photoluminescence lifetime decay of Re(I) complexes were measured and the quantum efficiencies of the rhenium(I) complexes were calculated by using air-equilibrated [Ru(bpy)3]2+ x 2 Cl- aqueous solution as standard (phi(std) = 0.028). The complexes with appended carbazole moieties exhibit enhanced luminescence performances relative to ReL1.

Short-time synthesis of poly[4,6-bis(3′-(2-ethylhexyl)thien-2′-yl)thieno[3,4-c][1,2,5]thiadiazole-alt-9,9-dioctylfluorene], its photophysical, electrochemical and photovoltaic properties

Czech Academy of Sciences Publication Activity Database

Cimrová, Věra; Kmínek, Ivan; Výprachtický, Drahomír; Pokorná, Veronika

2015-01-01

Roč. 59, 24 February (2015), s. 298-304 ISSN 0032-3861 R&D Projects: GA ČR(CZ) GA13-26542S; GA ČR GAP106/12/0827 Institutional support: RVO:61389013 Keywords : low-bandgap thienothiadiazole copolymer * Suzuki coupling * photophysics and photovoltaics Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.586, year: 2015

Thermophysical property characterization of tris(hydroxymethyl)aminomethane

International Nuclear Information System (INIS)

Soriano, Allan N.; Cabahug, Denise Irene V.; Li Menghui

2011-01-01

In this present work, a thermophysical property characterization of aqueous solution of tris(hydroxymethyl)aminomethane (TRIS), a biological buffer, was done. The investigated properties were refractive index (n), density (ρ), and electrolytic conductivity (κ). These properties were measured for temperatures up to 353.15 K (at normal atmospheric condition) and for the entire composition range where TRIS is still soluble in water. The measured properties were reported as functions of temperature and composition. A modified form of the Vogel-Tamman-Fulcher equation which leads to an Arrhenius-type asymptotic exponential function was used to generally correlate the temperature and compositional dependence of the considered properties and satisfactory results were obtained.

Photophysical studies of the interactions of poly(amidoamine) generation zero (PAMAM G0) with copper and zinc ions

Energy Technology Data Exchange (ETDEWEB)

López-Cabaña, Z.E. [Laboratory of Asymmetric Synthesis, Chemistry Institute of Natural Resources, University of Talca (Chile); Valdés, O. [Nanobiotechnology Division at University of Talca, Fraunhofer Chile Research Foundation – Center for Systems Biotechnology, FCR-CSB, P.O. Box 747 Talca (Chile); Vergara, C.E. [Laboratory of Asymmetric Synthesis, Chemistry Institute of Natural Resources, University of Talca (Chile); Camarada, M.B. [Universidad Andrés Bello, Facultad de Biología, Center for Bioinformatics and Integrative Biology (CBIB), República 239, Santiago (Chile); Fundación Fraunhofer Chile Research, M. Sánchez Fontecilla 310 piso 14, Las Condes (Chile); Nachtigall, F.M. [Nanobiotechnology Division at University of Talca, Fraunhofer Chile Research Foundation – Center for Systems Biotechnology, FCR-CSB, P.O. Box 747 Talca (Chile); González-Nilo, F.D. [Universidad Andrés Bello, Facultad de Biología, Center for Bioinformatics and Integrative Biology (CBIB), República 239, Santiago (Chile); Fundación Fraunhofer Chile Research, M. Sánchez Fontecilla 310 piso 14, Las Condes (Chile); Santos, Leonardo S., E-mail: lssantos@utalca.cl [Laboratory of Asymmetric Synthesis, Chemistry Institute of Natural Resources, University of Talca (Chile); Nanobiotechnology Division at University of Talca, Fraunhofer Chile Research Foundation – Center for Systems Biotechnology, FCR-CSB, P.O. Box 747 Talca (Chile)

2015-08-15

This study reports the photophysical behavior of poly(amidoamine) generation zero (PAMAM G0) in the presence of Cu(II) and Zn(II) ions in aqueous solutions using absorption and fluorescence spectroscopy. Theoretical and experimental results confirmed the presence of a strong covalent metal–ligand interaction between PAMAM G0 and copper ion that favored the formation of a ligand–metal charge transfer band coordination complex. In the case of Zn(II), no complex formation with PAMAM G0 was registered. Structure analysis identified the presence of aggregate like PAMAM G0–Zn moieties that generated an enhancement in the fluorescence emission of PAMAM G0. - Highlights: • Photophysical behavior of PAMAM G0 dendrimer with Cu and Zn ions was studied. • Strong covalent metal–ligand interaction was confirmed between PAMAM G0–Cu(II). • No complex formation with PAMAM G0 was registered in the case of Zn(II). • Dendrimer aggregate generated an enhancement in fluorescence emission.

Photophysical studies of the interactions of poly(amidoamine) generation zero (PAMAM G0) with copper and zinc ions

International Nuclear Information System (INIS)

López-Cabaña, Z.E.; Valdés, O.; Vergara, C.E.; Camarada, M.B.; Nachtigall, F.M.; González-Nilo, F.D.; Santos, Leonardo S.

2015-01-01

This study reports the photophysical behavior of poly(amidoamine) generation zero (PAMAM G0) in the presence of Cu(II) and Zn(II) ions in aqueous solutions using absorption and fluorescence spectroscopy. Theoretical and experimental results confirmed the presence of a strong covalent metal–ligand interaction between PAMAM G0 and copper ion that favored the formation of a ligand–metal charge transfer band coordination complex. In the case of Zn(II), no complex formation with PAMAM G0 was registered. Structure analysis identified the presence of aggregate like PAMAM G0–Zn moieties that generated an enhancement in the fluorescence emission of PAMAM G0. - Highlights: • Photophysical behavior of PAMAM G0 dendrimer with Cu and Zn ions was studied. • Strong covalent metal–ligand interaction was confirmed between PAMAM G0–Cu(II). • No complex formation with PAMAM G0 was registered in the case of Zn(II). • Dendrimer aggregate generated an enhancement in fluorescence emission

Synthesis, photophysical analysis, and in vitro cytotoxicity assessment of the multifunctional (magnetic and luminescent) core@shell nanomaterial based on lanthanide-doped orthovanadates

International Nuclear Information System (INIS)

Szczeszak, Agata; Ekner-Grzyb, Anna; Runowski, Marcin; Mrówczyńska, Lucyna; Grzyb, Tomasz; Lis, Stefan

2015-01-01

Rare earths orthovanadates (REVO 4 ) doped with luminescent lanthanide ions (Ln 3+ ) play an important role as promising light-emitting materials. Gadolinium orthovanadate exhibits strong absorption of ultraviolet radiation and as a matrix doped with Eu 3+ ions is well known for its efficient and intense red emission, induced by energy transfer from the VO 4 3− groups to Eu 3+ ions. In the presented study, Fe 3 O 4 @SiO 2 @GdVO 4 :Eu 3+ 5 % nanomaterial was investigated. The core@shell structures demonstrate attractive properties, such as higher thermal stability, enhanced water solubility, increased optical response, higher luminescence, longer decay times, and magnetic properties. Silica coating may protect nanocrystals from the surrounding environment. Therefore, such silica-covered nanoparticles (NPs) are successfully utilized in biomedical research. Multifunctional magnetic nanophosphors are very interesting due to their potential biomedical applications such as magnetic resonance imaging, hyperthermic treatment, and drug delivery. Therefore, the aim of our study was to investigate photophysical, chemical, and biological properties of multifunctional REVO 4 doped with Ln 3+ . Moreover, the studied NPs did not affect erythrocyte sedimentation rate, cell membrane permeability, and morphology of human red blood cells

Synthesis, photophysical analysis, and in vitro cytotoxicity assessment of the multifunctional (magnetic and luminescent) core@shell nanomaterial based on lanthanide-doped orthovanadates

Science.gov (United States)

Szczeszak, Agata; Ekner-Grzyb, Anna; Runowski, Marcin; Mrówczyńska, Lucyna; Grzyb, Tomasz; Lis, Stefan

2015-03-01

Rare earths orthovanadates (REVO4) doped with luminescent lanthanide ions (Ln3+) play an important role as promising light-emitting materials. Gadolinium orthovanadate exhibits strong absorption of ultraviolet radiation and as a matrix doped with Eu3+ ions is well known for its efficient and intense red emission, induced by energy transfer from the VO4 3- groups to Eu3+ ions. In the presented study, Fe3O4@SiO2@GdVO4:Eu3+ 5 % nanomaterial was investigated. The core@shell structures demonstrate attractive properties, such as higher thermal stability, enhanced water solubility, increased optical response, higher luminescence, longer decay times, and magnetic properties. Silica coating may protect nanocrystals from the surrounding environment. Therefore, such silica-covered nanoparticles (NPs) are successfully utilized in biomedical research. Multifunctional magnetic nanophosphors are very interesting due to their potential biomedical applications such as magnetic resonance imaging, hyperthermic treatment, and drug delivery. Therefore, the aim of our study was to investigate photophysical, chemical, and biological properties of multifunctional REVO4 doped with Ln3+. Moreover, the studied NPs did not affect erythrocyte sedimentation rate, cell membrane permeability, and morphology of human red blood cells.

Comparing the photophysics of the two forms of the Orange Carotenoid Protein using 2D electronic spectroscopy

Directory of Open Access Journals (Sweden)

Mathies R.A.

2013-03-01

Full Text Available Broadband two-dimensional electronic spectroscopy is applied to investigate the photophysics of the photoactive orange carotenoid protein, which is involved in nonphotochemical quenching in cyanobacteria. Differences in dynamics between the light and dark forms arise from the different structure of the carotenoid in the protein pocket, with consequences for the biological role of the two forms.

Preparation and fluorescence properties of 6-carboxyfluorescein/hydrotalcite nanocomposites

International Nuclear Information System (INIS)

Li, Chunfang; Qi, Yanhai; Li, Qianru; Li, Dongxiang; Hou, Wanguo

2014-01-01

The nanocomposites of fluorescent dye/hydrotalcite-like compounds (HTlc) synthesized by intercalation and/or surface adsorption methods have exhibited specific photophysical and photochemical property. In this work, 6-carboxyfluorescein (6CF)/HTlc nanocomposites were synthesized by ammonia coprecipitation and reconstruction-induced surface adsorption methods, and they were characterized by powder X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Thermogravimetric differential thermal measurements (TG-DTA) and fluorescence spectra. The results demonstrate that the dye molecules are primarily adsorbed on HTlc surface. The fluorescence emission of 6CF/Mg–Al HTlc composites is related with 6CF dosage due to the self-quenching mechanism. The 6CF/Zn–Al HTlc nanocomposite reconstructed at high temperature have much strong luminescence than that reconstructed at room temperature and the 6CF/Mg–Al HTlc nanocomposites. -- Highlights: • Fluorescent 6-carboxyfluorescein/HTlc nanocomposites were synthesized. • Fluorescent dye molecules are primarily adsorbed on HTlc surface. • Nanocomposite luminescence is related with the cluster structure of fluorescent dyes

Application of spectroscopy and super-resolution microscopy: Excited state

Energy Technology Data Exchange (ETDEWEB)

Bhattacharjee, Ujjal [Iowa State Univ., Ames, IA (United States)

2016-02-19

Photophysics of inorganic materials and organic molecules in complex systems have been extensively studied with absorption and emission spectroscopy.1-4 Steady-state and time-resolved fluorescence studies are commonly carried out to characterize excited-state properties of fluorophores. Although steady-state fluorescence measurements are widely used for analytical applications, time-resolved fluorescence measurements provide more detailed information about excited-state properties and the environment in the vicinity of the fluorophore. Many photophysical processes, such as photoinduced electron transfer (PET), rotational reorientation, solvent relaxation, and energy transfer, occur on a nanosecond (10^-9 s) timescale, thus affecting the lifetime of the fluorophores. Moreover, time-resolved microscopy methods, such as lifetimeimaging, combine the benefits of the microscopic measurement and information-rich, timeresolved data. Thus, time-resolved fluorescence spectroscopy combined with microscopy can be used to quantify these processes and to obtain a deeper understanding of the chemical surroundings of the fluorophore in a small area under investigation. This thesis discusses various photophysical and super-resolution microscopic studies of organic and inorganic materials, which have been outlined below.

Triphenylamine Derived 3-Acetyl and 3-Benzothiazolyl Bis and Tris Coumarins: Synthesis, Photophysical and DFT Assisted Hyperpolarizability Study

Science.gov (United States)

Erande, Yogesh; Kothavale, Shantaram; Sreenath, Mavila C.; Chitrambalam, Subramaniyan; Joe, Isaac H.; Sekar, Nagaiyan

2018-02-01

Triphenylamine derived bis- and tris-branched donor-pi-acceptor coumarins with acetyl and benzothiazolyl acceptors are studied for their linear and nonlinear optical properties that originate from their photophysical and molecular structure. Plots of solvent polarities versus the Stokes shift, frontier molecular orbital analysis and Generalised Mulliken Hush analysis have established their strong charge transfer character supported by the strong emission solvatochromism of these chromophores. On the basis of excited state intramolecular charge transfer, the first-, second- and third-order polarizability of these dyes are determined by a solvatochromic method and supported by density functional theory calculations using CAM-B3LYP/6-31g(d). Compared to the acetyl group, the benzothiazolyl group is a strong acceptor, and its corresponding derivatives show enhanced absorption, emission maxima and non-linear optical response. Bond length alternation and bond order alternation analysis reveals that these chromophores approach the cyanine-like framework which is responsible for maximum perturbation to produce high nonlinear optical response. Third order nonlinear susceptibility for dyes 1 and 2 is determined by Z-scan measurement. All of these methods are used to determine the nonlinear optical properties, and thermogravimetric analysis suggests that these chromophores are thermally robust and efficient nonlinear optical materials.

Hydrothermal syntheses, crystal structures, and photophysical properties of two coordination polymers with mixed ligands

Science.gov (United States)

Yan, Li; Liu, Chun-Ling

2017-10-01

Two novel metal-organic coordination polymers [Cd(ipdt)(m-BDC)·3H2O]n (1) and [Pb(mip)2(NTC) ·2H2O]n (2) [ipdt = 2,6-Dimethoxy-4-(1H-1,3,7,8-tetraaza-cyclopenta[l]phenanthren-2-yl)-phenol, mip = 2-(3-methoxyphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, m-BDC = isophthalic acid, NTC = nicotinic acid] have been synthesized by hydrothermal reactions and characterized by elemental analysis, thermogravimetric (TG) analysis, infrared spectrum (IR) and single-crystal X-ray diffraction. Single-crystal X-ray diffraction reveals that 1 exhibits two-dimensional (2D) layer architecture, and 2 shows 1D chain architecture. TG analysis shows clear courses of weight loss, which corresponds to the decomposition of different ligands. The luminescent properties for the ligand ipdt, mip and complexes 1-2 are also discussed in detail, which should be acted as potential luminescent material.

Investigation on the electronic structures and photophysical properties of a series of cyclometalated iridium(III) complexes based on DFT/TDDFT calculations

Energy Technology Data Exchange (ETDEWEB)

Shang, Chunyu, E-mail: shang.chun.yu@163.com; Xu, Jie; Du, Yanqiu; Zhao, Jie

2016-07-15

The electronic structures and photophysical properties of a series of cyclometalated iridium (III) complexes Ir(C{sup ∧}N){sub 2}(H{sub 2}NNHCOO), including 1 [C{sup ∧}N=2-phenyl-pyridine], 2 [C{sup ∧}N=5-fluoro-2-phenylpyridine], 3 [C{sup ∧}N=2-phenyl-5-trifluoromethylpyridine], 4 [C{sup ∧}N=6-phenyl-[2, 3] bipyridinyl], 5 [C{sup ∧}N=7-phenyl-cyclopenta [4] dipyridine] and 6 [C{sup ∧}N=8-phenyl-[1, 9] phenanthroline], have been theoretically investigated based on density functional theory (DFT) and time-dependent DFT. The characteristics in phosphorescent performances have been outlined for each of the complexes in the applications in OLED. On the basis of the two simplifications presented in this paper and the available experimental data, the magnitudes of phosphorescent radiative rates for complexes 1–6 were approximately calculated to be: 5.56×10{sup 5} s{sup −1}, 2.68×10{sup 5} s{sup −1}, 1.17×10{sup 6} s{sup −1}, 9.78×10{sup 4} s{sup −1}, 5.30×10{sup 6} s{sup −1} and 6.71×10{sup 6} s{sup −1}, respectively. Meanwhile, the sequence of phosphorescent quantum efficiencies was obtained to be: Φ{sub PL}(4)<Φ{sub PL}(2)<Φ{sub PL}(1)<Φ{sub PL}(3)<Φ{sub PL}(5)<Φ{sub PL}(6), in which Φ{sub PL}(4) is by far the lowest, Φ{sub PL}(5) is much larger and Φ{sub PL}(6) is by far the largest. In contrast to complex 1, the emission wavelengths are slightly red-shifted for 2 and 3 and significantly red-shifted for 4 and 5, while the emission wavelength of 6 is slightly blue-shifted. In comparison, complexes 6 and 5 may be singled out to be the most efficient phosphorescence emitters for the applications in OLED.

Hydrogen-bonding effects on film structure and photoelectrochemical properties of porphyrin and fullerene composites on nanostructured TiO 2 electrodes

NARCIS (Netherlands)

Kira, Aiko; Tanaka, Masanobu; Umeyama, Tomokazu; Matano, Yoshihiro; Yoshimoto, Naoki; Zhang, Yi; Ye, Shen; Lehtivuori, Heli; Tkachenko, Nikolai V.; Lemmetyinen, Helge; Imahori, Hiroshi

2007-01-01

Hydrogen-bonding effects on film structures and photophysical, photoelectrochemical, and photovoltaic properties have been examined in mixed films of porphyrin and fullerene composites with and without hydrogen bonding on nanostructured TiO2 electrodes. The nanostructured TiO2 electrodes modified

The Effect of a Fluorophore Photo-Physics on the Lipid Vesicle Diffusion Coefficient Studied by Fluorescence Correlation Spectroscopy.

Science.gov (United States)

Drabik, Dominik; Przybyło, Magda; Sikorski, Aleksander; Langner, Marek

2016-03-01

Fluorescence Correlation Spectroscopy (FCS) is a technique, which allows determination of the diffusion coefficient and concentration of fluorescent objects suspended in the solution. The measured parameter is the fluctuation of the fluorescence signal emitted by diffusing molecules. When 100 nm DOPC vesicles labeled with various fluorescent dyes (Fluorescein-PE, NBD-PE, Atto488 DOPE or βBodipy FL) were measured, different values of diffusion coefficients have been obtained. These diffusion coefficients were different from the expected values measured using the dynamic light scattering method (DLS). The FCS was initially developed for solutions containing small fluorescent molecules therefore the observed inconsistency may result from the nature of vesicle suspension itself. The duration of the fluorescence signal may depend on the following factors: the exposure time of the labeled object to the excitation beam, the photo-physical properties (e.g., stability) of a fluorophore, the theoretical model used for the calculations of the diffusion coefficient and optical properties of the vesicle suspension. The diffusion coefficients determined for differently labeled liposomes show that its dependence on vesicle size and quantity of fluorescent probed used for labeling was significant demonstrating that the fluorescence properties of the fluorophore itself (bleaching and/or blinking) were critical factors for a correct outcome of FCS experiment. The new, based on combined FCS and DLS measurements, method for the determination of the focal volume prove itself to be useful for the evaluation of a fluorescence dye with respect to its applicability for FCS experiment.

The importance of charge-transfer interactions in determining chromophoric dissolved organic matter (CDOM) optical and photochemical properties.

Science.gov (United States)

Sharpless, Charles M; Blough, Neil V

2014-04-01

Absorption of sunlight by chromophoric dissolved natural organic matter (CDOM) is environmentally significant because it controls photic zone depth and causes photochemistry that affects elemental cycling and contaminant fate. Both the optics (absorbance and fluorescence) and photochemistry of CDOM display unusual properties that cannot easily be ascribed to a superposition of individual chromophores. These include (i) broad, unstructured absorbance that decreases monotonically well into the visible and near IR, (ii) fluorescence emission spectra that all fall into a single envelope regardless of the excitation wavelength, and (iii) photobleaching and photochemical quantum yields that decrease monotonically with increasing wavelength. In contrast to a simple superposition model, these phenomena and others can be reasonably well explained by a physical model in which charge-transfer interactions between electron donating and accepting chromophores within the CDOM control the optical and photophysical properties. This review summarizes current understanding of the processes underlying CDOM photophysics and photochemistry as well as their physical basis.

Influence of push-pull group substitution patterns on excited state properties of donor-acceptor co-monomers and their trimers

NARCIS (Netherlands)

de Gier, Hilde D.; Rietberg, Bernd J.; Broer, Ria; Havenith, Remco W. A.

2014-01-01

Organic electronics form a very promising new generation of cheap, lightweight and flexible devices. Of special interest is the ability to engineer photo-physical properties of organic molecules by chemical modification. In this regard, the purpose of this research is to understand the influence of

Characterization and morphological properties of glass fiber ...

African Journals Online (AJOL)

Characterization and morphological properties of glass fiber reinforced epoxy composites fabricated under varying degrees of hand lay-up techniques. ... Hence, these composites are projected to possess better dimensional stability adaptable for high performance structural applications. Keywords: composite, interfacial ...

Computational Photophysics in the Presence of an Environment

Science.gov (United States)

Nogueira, Juan J.; González, Leticia

2018-04-01

Most processes triggered by ultraviolet (UV) or visible (vis) light in nature take place in complex biological environments. The first step in these photophysical events is the excitation of the absorbing system or chromophore to an electronically excited state. Such an excitation can be monitored by the UV-vis absorption spectrum. A precise calculation of the UV-vis spectrum of a chromophore embedded in an environment is a challenging task that requires the consideration of several ingredients, besides an accurate electronic-structure method for the excited states. Two of the most important are an appropriate description of the interactions between the chromophore and the environment and accounting for the vibrational motion of the whole system. In this contribution, we review the most common theoretical methodologies to describe the environment (including quantum mechanics/continuum and quantum mechanics/molecular mechanics models) and to account for vibrational sampling (including Wigner sampling and molecular dynamics). Further, we illustrate in a series of examples how the lack of these ingredients can lead to a wrong interpretation of the electronic features behind the UV-vis absorption spectrum.

Synthesis, photophysical analysis, and in vitro cytotoxicity assessment of the multifunctional (magnetic and luminescent) core@shell nanomaterial based on lanthanide-doped orthovanadates

Energy Technology Data Exchange (ETDEWEB)

Szczeszak, Agata [Adam Mickiewicz University, Department of Rare Earths, Faculty of Chemistry (Poland); Ekner-Grzyb, Anna [Adam Mickiewicz University, Department of Behavioural Ecology, Faculty of Biology (Poland); Runowski, Marcin [Adam Mickiewicz University, Department of Rare Earths, Faculty of Chemistry (Poland); Mrówczyńska, Lucyna [Adam Mickiewicz University, Department of Cell Biology, Faculty of Biology (Poland); Grzyb, Tomasz; Lis, Stefan, E-mail: blis@amu.edu.pl [Adam Mickiewicz University, Department of Rare Earths, Faculty of Chemistry (Poland)

2015-03-15

Rare earths orthovanadates (REVO{sub 4}) doped with luminescent lanthanide ions (Ln{sup 3+}) play an important role as promising light-emitting materials. Gadolinium orthovanadate exhibits strong absorption of ultraviolet radiation and as a matrix doped with Eu{sup 3+} ions is well known for its efficient and intense red emission, induced by energy transfer from the VO{sub 4}{sup 3−} groups to Eu{sup 3+} ions. In the presented study, Fe{sub 3}O{sub 4}@SiO{sub 2}@GdVO{sub 4}:Eu{sup 3+} 5 % nanomaterial was investigated. The core@shell structures demonstrate attractive properties, such as higher thermal stability, enhanced water solubility, increased optical response, higher luminescence, longer decay times, and magnetic properties. Silica coating may protect nanocrystals from the surrounding environment. Therefore, such silica-covered nanoparticles (NPs) are successfully utilized in biomedical research. Multifunctional magnetic nanophosphors are very interesting due to their potential biomedical applications such as magnetic resonance imaging, hyperthermic treatment, and drug delivery. Therefore, the aim of our study was to investigate photophysical, chemical, and biological properties of multifunctional REVO{sub 4} doped with Ln{sup 3+}. Moreover, the studied NPs did not affect erythrocyte sedimentation rate, cell membrane permeability, and morphology of human red blood cells.

A series of luminescent Re(I) complexes with electron-donor/acceptor moieties: Synthesis, characterization, and photoluminescence

International Nuclear Information System (INIS)

Ge Hu; Qing She; Lei Guo

2012-01-01

In this paper, we synthesize three Re(I) complexes of Re(CO) 3 (PPO)Br, Re(CO) 3 (PTO)Br, and Re(CO) 3 (PBI)Br, where PPO=2-phenyl-5-(pyridin-2-yl)-1,3,4-oxadiazole, PTO=2-(pyridin-2-yl)-5-p-tolyl-1,3,4-oxadiazole, PBI=2-(pyridin-2-yl)-1H-benzo[d]imidazole. Their single crystals and photophysical properties are measured and discussed in detail. The correlation between ligand structure and corresponding PL characteristics of Re(I) complex has been investigated. It is found that a ligand with strong electron-donor can efficiently increase both absorption and emissive energy of Re(I) complex. In addition, electron-rich ligand can increase the electron density of the complex and thus enhance the oscillator strength of electronic transition, improving the photoluminescence performance. - Highlights: ► Three novel phosphorescent Re(I) complexes are synthesized. ► Molecular structures, photophysical, and electronic properties are studied. ► Strong electron-donor can increase emissive energy. ► Electron-rich ligand can enhance the oscillator strength of electronic transition.

Photophysical characterization of pyrromethene 597 laser dye in cross-linked silicon-containing organic copolymers

Energy Technology Data Exchange (ETDEWEB)

Tyagi, A.; Agua, D. del [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, 93053 Regensburg (Germany); Penzkofer, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, 93053 Regensburg (Germany)], E-mail: alfons.penzkofer@physik.uni-regensburg.de; Garcia, O.; Sastre, R. [Instituto de Ciencia y Tecnologia de Polimeros, CSIC, Juan de la Cierva 3, 28006 Madrid (Spain); Costela, A.; Garcia-Moreno, I. [Instituto de Quimica Fisica ' Rocasolano' , CSIC, Serrano 119, 28006 Madrid (Spain)

2007-12-06

Samples of the dipyrromethene-BF{sub 2} dye PM597 incorporated in copolymers of 3-trimethoxysilylpropyl 2-methylprop-2-enoate (TMSPMA, number of polymerizable CC double bonds: {kappa} = 1) with 2-(2-methylprop-2-enoyloxy)ethyl 2-methylprop-2-enoate (EGDMA, {kappa} = 2), [2-(hydroxymethyl)-3-prop-2-(prop-2-enoyloxymethyl)propyl] prop-2-enoate (PETA, {kappa} = 3), and [3-prop-2-enoyloxy-2,2-bis(prop-2-2-enoyloxymethyl)propyl]prop-2-enoate (PETRA, {kappa} = 4) are characterized. The fluorescence quantum distributions, fluorescence quantum yields, degrees of fluorescence polarization, and fluorescence lifetimes are measured. The radiative lifetimes are calculated from fluorescence lifetime and quantum yield. Absorption coefficient spectra are determined from transmission measurements. Absolute absorption cross-section spectra and dye concentrations are obtained by calibration to the radiative lifetimes and to saturable absorptions. Excited-state absorption cross-sections at 527 nm are determined by saturable absorption measurements. The photo-degradation is studied under cw laser excitation conditions and quantum yields of photo-degradation are extracted. The excited-state absorption cross-sections were found to be rather small, and the photo-stability turned out to be high (up to 3 million excitation cycles before degradation) making this class of dipyrromethene dye-doped polymers attractive active laser media. Structural and thermo-mechanical properties of the materials have been determined by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry, densitometry, and refractometry. They improve with increasing inter-crossing (copolymerization of TMSPMA with PETA and PETRA). The laser properties of the PM597 doped copolymers were evaluated by transverse pumping with 6 ns laser pulses at 532 nm. The best laser materials resulted to be the 7:3 and 9:1 TMSPMA-monomer copolymers.

The Photo-Physics of Polythiophene Nanoparticles for Biological Applications.

Science.gov (United States)

Bargigia, Ilaria; Zucchetti, Elena; Srimath Kandada, Ajay Ram; Moreira, Miguel; Bossio, Caterina; Wong, Walter; Miranda, Paulo; Decuzzi, Paolo; Soci, Cesare; D'Andrea, Cosimo; Lanzani, Guglielmo

2018-05-01

In this work the photo-physics of poly(3-hexyltiophene) nanoparticles (NPs) is investigated in the context of their biological applications. The NPs made as colloidal suspensions in aqueous buffers present a distinct absorption band in the low energy region. Based on systematic analysis of absorption and transient absorption spectra taken under different pH conditions, this band is associated to charge transfer states generated by the polarization of loosely bound polymer chains and originated from complexes formed with electron withdrawing species. Importantly, the ground state depletion of these states upon photo-excitation is active even in the microsecond timescales, suggesting that they act as precursor states for long-living polarons which could be beneficial for cellular stimulation. Preliminary results of transient absorption microscopy of NPs internalized within the cells reveal the presence of long-living species, further substantiating their relevance in bio-interfaces. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photophysics of conjugated polymers: interplay between Förster energy migration and defect concentration in shaping a photochemical funnel in PPV.

Science.gov (United States)

Saini, Sangeeta; Bagchi, Biman

2010-07-21

Recent single molecule experiments have suggested the existence of a photochemical funnel in the photophysics of conjugated polymers, like poly[2-methoxy-5-(2'-ethylhexyl)oxy-1,4-phenylenevinylene] (MEH-PPV). The funnel is believed to be a consequence of the presence of conformational or chemical defects along the polymer chain and efficient non-radiative energy transfer among different chromophore segments. Here we address the effect of the excitation energy dynamics on the photophysics of PPV. The PPV chain is modeled as a polymer with the length distribution of chromophores given either by a Gaussian or by a Poisson distribution. We observe that the Poisson distribution of the segment lengths explains the photophysics of PPV better than the Gaussian distribution. A recently proposed version of an extended 'particle-in-a-box' model is used to calculate the exciton energies and the transition dipole moments of the chromophores, and a master equation to describe the excitation energy transfer among different chromophores. The rate of energy transfer is assumed to be given here, as a first approximation, by the well-known Förster expression. The observed excitation population dynamics confirms the photochemical funneling of excitation energy from shorter to longer chromophores of the polymer chain. The time scale of spectral shift and energy transfer for our model polymer, with realistic values of optical parameters, is in the range of 200-300 ps. We find that the excitation energy may not always migrate towards the longest chromophore segments in the polymer chain as the efficiency of energy transfer between chromophores depends on the separation distance between the two and their relative orientation.

Photophysical properties of [Ru(2,2′-bipyridine){sub 3}]{sup 2+} encapsulated within the Uio-66 zirconium based metal organic framework

Energy Technology Data Exchange (ETDEWEB)

Larsen, Randy W., E-mail: rwlarsen@usf.edu; Wojtas, Lukasz

2017-03-15

The ability to encapsulate photo-active guest molecules within the pores of metal organic frameworks (MOFs) affords the opportunity to develop robust photocatalysts as well as solar energy conversion systems. An important criteria for such systems is stability of the new materials towards moisture, high temperatures, etc which preclude the use of many MOF frameworks. Here, the ability to encapsulate [Ru(II)(2,2′-bipyridine){sub 3}]{sup 2+}([Ru(bpy){sub 3}]{sup 2+}) into the cavities of the zirconium based MOF Uio-66 as well as the photophysical properties of the complex are reported. The X-ray powder diffraction data of the orange Uio-66 powder are consistent with the formation of Uio-66 in the presence of [Ru(bpy){sub 3}]{sup 2+}. The steady state emission exhibits a significant bathochromic shift from 603 nm in ethanol to 610 nm in Uio-66. The corresponding emission decay of the encapsulated [Ru(bpy){sub 3}]{sup 2+} complex is biexponential with a fast component of 128 ns and a slower component of 1176 ns (20 deg C). The slow component is consistent with encapsulation of [Ru(bpy){sub 3}]{sup 2+} into cavities with restricted volume that prevents the population of a triplet ligand field transition that is anti-bonding with respect to the Ru-N bonds. The origin of the fast component is unclear but may involve interactions of the [Ru(bpy){sub 3}]{sup 2+} encapsulated within large cavities formed through missing ligand defect sites within the Uio-66 materials. Co-encapsulated quenchers contained within these larger cavities gives rise to the reduced lifetimes of the [Ru(bpy){sub 3}]{sup 2+} complexes. - Graphical abstract: One-pot synthesis of Ru(II)tris(2,2-bipyridine)@Uio-66 (left) and the effects of encapsulation on the excited state energy levels and decay pathways of the Ru(II)tris(2,2-bipyridine) complex (right).

Towards PSII analogs driven by ruthenium photophysics

International Nuclear Information System (INIS)

Olsson, Jerry

2002-01-01

A number of model complexes have been prepared in an attempt to develop models for photosystem II (PSII) in green plants. As replacement for the chlorophyll photosensitizer, we have used Ru(ll) tris-2,2-bipyridyl or Ru(ll) bis-2,2';6',2 - terpyridyl complexes linked to a pendant 2,2'-bipyridyl or 2,2';6',2''-terpyridyl moieties via spacers of varying lengths. Manganese (ll) has been covalently linked to the pendant 2,2'-bipyridyl /2,2';6',2''-terpyridyl moieties. The use of different ruthenium centres and spacers has made it possible to make assumptions about the way and how easily manganese is coordinated through self-assembly to the pendant 2,2'-bipyridyl or 2,2';6',2''-terpyridyl groups. Several polynuclear complexes containing a photoactive centre (Ru(ll) tris-2,2'-bipyridine or Ru(ll) bis-2,2';6',2''-terpyridine) or other metal ions (Co 2+ , Fe 2+ , Mn 2= ) have been prepared and characterised. The main work has been focused on organic synthesis and characterisation of polypyridine ligands and coordinated to different metal centres. The complexes have been investigated electrochemically and photophysically. Several new phenol-based ligands have been prepared by organic synthetic methods and characterised by various different methods. (author)

Three coordination polymers based on a star-like geometry 4, 4', 4'' -nitrilotribenzoic acid ligand and their framework dependent luminescent properties

Science.gov (United States)

Hu, Zhiyong; Zhao, Meng; Su, Jian; Xu, Shasha; Hu, Lei; Liu, Hui; Zhang, Qiong; Zhang, Jun; Wu, Jieying; Tian, Yupeng

2018-02-01

Three novel coordination polymers, [Zn(μ2-HTCA)(Phen)]n (1), {[Cd(μ3-HTCA)(Phen)]·2H2O}n (2), [Mn(μ2-HTCA)(Phen)(H2O)]n (3) were prepared by hydrothermal synthesis from the 4, 4', 4''-nitrilotribenzoicacid (H3TCA) and 1, 10-phenanthroline monohydrate (Phen) with different transition metal salts, which were characterized by elemental analysis, IR spectra, powder and single-crystal X-ray diffraction and thermogravimetric analysis. The photophysical properties of the complexes were investigated by solid-state diffuse reflectance spectra, photoluminescent properties, lifetime and quantum yield. For these complexes, it was found that the band gaps follow the order: 3 ＜ 2 ＜ 1 ＜ 2.80 eV, fluorescence intensity order: 1 ＞ H3TCA ＞ 2 ＞ 3; quantum yield order: H3TCA ＞ 1 ＞ 2 ＞ 3; while the lifetime order: 1 ＞ 2 ＞ H3TCA ＞ 3.

D-π-A-A-π-D prototype 2,2'-bipyridine dyads exhibiting large structure and environment-sensitive fluorescence: synthesis, photophysics, and computation.

Science.gov (United States)

Sarma, Monima; Chatterjee, Tanmay; Ghanta, Susanta; Das, Samar K

2012-01-06

A series of 4,4'-π-conjugated-2,2'-bipyridine chromophores (MS 1-8) were synthesized, and their photophysical and thermal properties were investigated. The title "push-pull' chromophores", except MS 1, were integrated with both alkoxy and alkylamino donor functionalities that differ in their donation capabilities. The oligophenylenevinylene (OPV) chromophores MS 4-8 are associated with a π-extended backbone in which the position and the number of alkoxy donors were systematically varied. All of the studied systems possess a D-π-A-A-π-D dyad archetype in which the A-A is the central 2,2'-bipyridine acceptor core that is electronically attached with the donor termini through π-linkers. The fluorescence quantum yields of the synthesized chromophores are found to be sensitive to the molecular archetype and the solvent medium. Out of the eight fluorescent compounds reported in this article, the compound MS 5 exhibits fluorescence in the solid state also. The modulating effect of the nature, position, and number of donor functionalities on the optical properties of these classes of compounds has further been comprehended on the basis of DFT and TD-DFT computation in a solvent reaction field.

Electrochemical, spectroscopic, and photophysical properties of structurally diverse polyazine-bridged Ru(II),Pt(II) and Os(II),Ru(II),Pt(II) supramolecular motifs.

Science.gov (United States)

Knoll, Jessica D; Arachchige, Shamindri M; Wang, Guangbin; Rangan, Krishnan; Miao, Ran; Higgins, Samantha L H; Okyere, Benjamin; Zhao, Meihua; Croasdale, Paul; Magruder, Katherine; Sinclair, Brian; Wall, Candace; Brewer, Karen J

2011-09-19

Five new tetrametallic supramolecules of the motif [{(TL)(2)M(dpp)}(2)Ru(BL)PtCl(2)](6+) and three new trimetallic light absorbers [{(TL)(2)M(dpp)}(2)Ru(BL)](6+) (TL = bpy = 2,2'-bipyridine or phen = 1,10-phenanthroline; M = Ru(II) or Os(II); BL = dpp = 2,3-bis(2-pyridyl)pyrazine, dpq = 2,3-bis(2-pyridyl)quinoxaline, or bpm = 2,2'-bipyrimidine) were synthesized and their redox, spectroscopic, and photophysical properties investigated. The tetrametallic complexes couple a Pt(II)-based reactive metal center to Ru and/or Os light absorbers through two different polyazine BL to provide structural diversity and interesting resultant properties. The redox potential of the M(II/III) couple is modulated by M variation, with the terminal Ru(II/III) occurring at 1.58-1.61 V and terminal Os(II/III) couples at 1.07-1.18 V versus Ag/AgCl. [{(TL)(2)M(dpp)}(2)Ru(BL)](PF(6))(6) display terminal M(dπ)-based highest occupied molecular orbitals (HOMOs) with the dpp(π*)-based lowest unoccupied molecular orbital (LUMO) energy relatively unaffected by the nature of BL. The coupling of Pt to the BL results in orbital inversion with localization of the LUMO on the remote BL in the tetrametallic complexes, providing a lowest energy charge separated (CS) state with an oxidized terminal Ru or Os and spatially separated reduced BL. The complexes [{(TL)(2)M(dpp)}(2)Ru(BL)](6+) and [{(TL)(2)M(dpp)}(2)Ru(BL)PtCl(2)](6+) efficiently absorb light throughout the UV and visible regions with intense metal-to-ligand charge transfer (MLCT) transitions in the visible at about 540 nm (M = Ru) and 560 nm (M = Os) (ε ≈ 33,000-42,000 M(-1) cm(-1)) and direct excitation to the spin-forbidden (3)MLCT excited state in the Os complexes about 720 nm. All the trimetallic and tetrametallic Ru-based supramolecular systems emit from the terminal Ru(dπ)→dpp(π*) (3)MLCT state, λ(max)(em) ≈ 750 nm. The tetrametallic systems display complex excited state dynamics with quenching of the (3)MLCT emission at

Method to characterize dielectric properties of powdery substances

Science.gov (United States)

Tuhkala, M.; Juuti, J.; Jantunen, H.

2013-07-01

An open ended coaxial cavity method for dielectric characterization of powdery substance operating at 4.5 GHz in TEM mode is presented. Classical mixing rules and electromagnetic modeling were utilized with measured effective permittivities and Q factors to determine the relative permittivity and dielectric loss tangent of different powders with ɛr up to 30. The modeling enabled determination of the correction factor for the simplified equation for the relative permittivity of an open ended coaxial resonator and mixing rules having the best correlation with experiments. SiO2, Al2O3, LTCC CT 2000, ZrO2, and La2O3 powders were used in the experiments. Based on the measured properties and Bruggeman symmetric and Looyenga mixing rules, the determined dielectric characteristics of the powders exhibited good correlation with values in the literature. The presented characterization method enabled the determination of dielectric properties of powdery substances within the presented range, and therefore could be applied to various research fields and applications where dielectric properties of powders need to be known and controlled.

Non-empirical Prediction of the Photophysical and Magnetic Properties of Systems with Open d- and f-Shells Based on Combined Ligand Field and Density Functional Theory (LFDFT).

Science.gov (United States)

Daul, Claude

2014-09-01

Despite the important growth of ab initio and computational techniques, ligand field theory in molecular science or crystal field theory in condensed matter offers the most intuitive way to calculate multiplet energy levels arising from systems with open shells d and/or f electrons. Over the past decade we have developed a ligand field treatment of inorganic molecular modelling taking advantage of the dominant localization of the frontier orbitals within the metal-sphere. This feature, which is observed in any inorganic coordination compound, especially if treated by Density Functional Theory calculation, allows the determination of the electronic structure and properties with a surprising good accuracy. In ligand field theory, the theoretical concepts consider only a single atom center; and treat its interaction with the chemical environment essentially as a perturbation. Therefore success in the simple ligand field theory is no longer questionable, while the more accurate molecular orbital theory does in general over-estimate the metal-ligand covalence, thus yields wave functions that are too delocalized. Although LF theory has always been popular as a semi-empirical method when dealing with molecules of high symmetry e.g. cubic symmetry where the number of parameters needed is reasonably small (3 or 5), this is no more the case for molecules without symmetry and involving both an open d- and f-shell (# parameters ∼90). However, the combination of LF theory and Density Functional (DF) theory that we introduced twenty years ago can easily deal with complex molecules of any symmetry with two and more open shells. The accuracy of these predictions from 1(st) principles achieves quite a high accuracy (<5%) in terms of states energies. Hence, this approach is well suited to predict the magnetic and photo-physical properties arbitrary molecules and materials prior to their synthesis, which is the ultimate goal of each computational chemist. We will illustrate the

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

Science.gov (United States)

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.

Thin film properties of triphenylamine-cored dendrimers: A molecular approach to control aggregation

International Nuclear Information System (INIS)

Vamvounis, George; Pivrikas, Almantas; Shaw, Paul E.; Burn, Paul L.

2013-01-01

The solid-state photophysical and charge transport properties of two first-generation dendrimers are presented. The dendrimers are comprised of a triphenylamine core, dendrons containing a phenyl branching unit with thiophene (Dendrimer 1) or bithiophene (Dendrimer 2) moieties, and dodecyl surface groups. For Dendrimer 1, the excited state is located within the center of the dendrimer giving rise to a moderate solid-state photoluminescence quantum yield (Φ pl ) (0.13) and significant charge trapping, with both observations due to the degree of overlap of the main electroactive chromophores on adjacent dendrimers. For Dendrimer 2, the excited state is located within the dendron and in the solid-state this leads to a strongly red-shifted and weakened emission (Φ pl ∼ 0.02) due to strong intermolecular chromophore interactions. For films of Dendrimer 2 the charge mobility was higher than Dendrimer 1 but was still limited by a low density of strongly interacting electroactive chromophores. The pronounced difference between the solid-state properties of the two dendrimers is simply engineered by the addition of an extra thiophene in each of the dendrons. - Highlights: • Photophysical and charge-transport properties of two dendrimers are investigated. • Excited-state is on the center for Dendrimer 1 and on the dendron for Dendrimer 2. • Film quantum yield of luminescence is higher for Dendrimer 1. • Dendrimer 1 displays greater charge trapping at high fields

Development and Characterization of Reactive Triangulenium Chromophores for Bioconjugation Applications

DEFF Research Database (Denmark)

Bora, Ilkay

and a novel, highly absorptive homotrimeric rotor. Non-rotating reference compounds were as well prepared and used in comparison. These probes can serve as molecular viscometers, whose lifetimes and emission intensity show a linear dependence on the viscosity of their surrounding medium. Thus, they are able...... to detect fluid viscosity on the microscopic scale and can potentially find application in mapping viscosity differences in cells and tissue. In collaboration with my partners, the photophysical properties and their performance as viscosity sensors were investigated....

Porphyrins intercalated in Zn/Al and Mg/Al layered double hydroxides: properties and structural arrangement

Czech Academy of Sciences Publication Activity Database

Káfuňková, Eva; Taviot-Guého, Ch.; Bezdička, Petr; Klementová, Mariana; Kovář, P.; Kubát, Pavel; Mosinger, Jiří; Pospíšil, M.; Lang, Kamil

2010-01-01

Roč. 22, č. 8 (2010), s. 2481-2490 ISSN 0897-4756 R&D Projects: GA ČR GA203/07/1424; GA ČR GAP207/10/1447 Institutional research plan: CEZ:AV0Z40320502; CEZ:AV0Z40400503 Keywords : hydrotalcite-like compounds * molecular-dynamic simulations * photophysical properties Subject RIV: CA - Inorganic Chemistry Impact factor: 6.400, year: 2010

A Statistics-Based Material Property Analysis to Support TPS Characterization

Science.gov (United States)

Copeland, Sean R.; Cozmuta, Ioana; Alonso, Juan J.

2012-01-01

Accurate characterization of entry capsule heat shield material properties is a critical component in modeling and simulating Thermal Protection System (TPS) response in a prescribed aerothermal environment. The thermal decomposition of the TPS material during the pyrolysis and charring processes is poorly characterized and typically results in large uncertainties in material properties as inputs for ablation models. These material property uncertainties contribute to large design margins on flight systems and cloud re- construction efforts for data collected during flight and ground testing, making revision to existing models for entry systems more challenging. The analysis presented in this work quantifies how material property uncertainties propagate through an ablation model and guides an experimental test regimen aimed at reducing these uncertainties and characterizing the dependencies between properties in the virgin and charred states for a Phenolic Impregnated Carbon Ablator (PICA) based TPS. A sensitivity analysis identifies how the high-fidelity model behaves in the expected flight environment, while a Monte Carlo based uncertainty propagation strategy is used to quantify the expected spread in the in-depth temperature response of the TPS. An examination of how perturbations to the input probability density functions affect output temperature statistics is accomplished using a Kriging response surface of the high-fidelity model. Simulations are based on capsule configuration and aerothermal environments expected during the Mars Science Laboratory (MSL) entry sequence. We identify and rank primary sources of uncertainty from material properties in a flight-relevant environment, show the dependence on spatial orientation and in-depth location on those uncertainty contributors, and quantify how sensitive the expected results are.

Wall Turbulence with Designer Properties: Identification, Characterization and Manipulation of Energy Pathways

Science.gov (United States)

2016-02-26

AFRL-AFOSR-VA-TR-2016-0108 Wall turbulence with designer properties Beverley Mckeon CALIFORNIA INSTITUTE OF TECHNOLOGY Final Report 02/26/2016... Wall turbulence with designer properties: Identification, characterization & manipulation of energy pathways 5a. CONTRACT NUMBER 5b. GRANT NUMBER...identification, characterization and manipulation of energy pathways in wall turbulence . The objectives were pursued separately and collaboratively by the

Poly(anthranilic acid) Microspheres: Synthesis, Characterization and their Electrocatalytic Properties

Energy Technology Data Exchange (ETDEWEB)

Ranganathan, Suresh; Raju, Prabu; Arunachalam, Vijayaraj; Krishnamoorty, Giribabu; Ramadoss, Manigandan; Arumainathan, Stephen; Vengidusamy, Narayanan [University of Madras, Guindy Maraimalai Campus, Chennai (India)

2012-06-15

Poly(anthranilic acid) was synthesized by rapid mixing method using 5-sulphosalicylic acid as a dopant. The synthesized polymer was characterized by various techniques like FT-IR, UV-Visible, and X-ray diffraction etc., The FT-IR studies reveal that the 5-sulphosalicylic acid is well doped within the polymer. The morphological property was characterized by field emission scanning electron microscopic technique. The electrochemical properties of the polymer were studied by cyclic voltammetric method. The synthesized polymer was used to modify glassy carbon electrode (GCE) and the modified electrode was found to exhibit electrocatalytic activity for the oxidation of uric acid (UA)

Poly(anthranilic acid) Microspheres: Synthesis, Characterization and their Electrocatalytic Properties

International Nuclear Information System (INIS)

Ranganathan, Suresh; Raju, Prabu; Arunachalam, Vijayaraj; Krishnamoorty, Giribabu; Ramadoss, Manigandan; Arumainathan, Stephen; Vengidusamy, Narayanan

2012-01-01

Poly(anthranilic acid) was synthesized by rapid mixing method using 5-sulphosalicylic acid as a dopant. The synthesized polymer was characterized by various techniques like FT-IR, UV-Visible, and X-ray diffraction etc., The FT-IR studies reveal that the 5-sulphosalicylic acid is well doped within the polymer. The morphological property was characterized by field emission scanning electron microscopic technique. The electrochemical properties of the polymer were studied by cyclic voltammetric method. The synthesized polymer was used to modify glassy carbon electrode (GCE) and the modified electrode was found to exhibit electrocatalytic activity for the oxidation of uric acid (UA)

Crystal Structures and Physical Properties of Ag(I) Coordination Polymers with Unsymmetrical Dipyridyl Ligand

International Nuclear Information System (INIS)

Lee, Eunji; Ryu, Hyunsoo; Park, Kimin

2013-01-01

Three Ag(I) coordination polymers with the formula [Ag(L)]·(X)·(DMSO) n (X = ClO 4 (1), BF 4 (2), and PF 6 (3), and L = dipyridyl ligand) were prepared and characterized fully their structures. All three compounds are isostructures and stable 2-D honeycomb type coordination polymers, in which 1-D zigzag chains with -(Ag-L)- motif are linked by the argentophilic interactions and the π···π stacking interactions between pyridine rings. The investigation on photophysical properties of all compounds shows that the nature of emission can be attributed to the metal-to-ligand charge transfer as well as the formation of the polymeric structures with restriction of the flexibility of the free ligand. Based on the present solid state results, further investigation on the development and characterization of new coordination polymers using flexible unsymmetrical ligand is in progress. During last two decades, silver coordination polymers based on dipyridyl type ligands have attracted particular interest because of the various intriguing architectures caused by a variety of coordination geometry of Ag(I) ion as well as their potential applications as functional materials

Photophysical study of blue-light excitable ternary Eu(III) complexes and their encapsulation into polystyrene nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Räsänen, Markus, E-mail: mpvras@utu.fi [Department of Chemistry, University of Turku, FIN-20014 Turku (Finland); Takalo, Harri [DHR Finland Oy, Innotrac Diagnostics, Biolinja 12, FIN-20750 Turku (Finland); Soukka, Tero [Department of Biochemistry/Biotechnology, University of Turku, FIN-20014 Turku (Finland); Haapakka, Keijo; Kankare, Jouko [Department of Chemistry, University of Turku, FIN-20014 Turku (Finland)

2015-04-15

In this work, 14 ternary Eu(III) complexes were studied by means of spectroscopy. The studied Eu(III) complexes consisted of Lewis bases (4′-(4-diethylaminophenyl)-2,2′:6′,2″-terpyridine (L{sup 8}) or 1,10-phenanthroline (L{sup 9})) and differently substituted β-diketones. The ternary complexes with L{sup 8} show the excitation peak at 405 nm and the quantum yield even 76%. The brightest ternary complex at the 405 nm excitation was Eu(L{sup 3}){sub 3}L{sup 8} while Eu(L{sup 7}){sub 3}L{sup 8} (HL{sup 3}=4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, HL{sup 7}=1-(9-ethyl-9H-carbazol-3-yl)-4,4,5,5,5-pentafluoro-1,3-pentanedione) was found to be the brightest at the ligand-centred excitation maximum. The ternary complexes were studied mainly in toluene as the model environment for the polystyrene nanoparticle cavities. The complexes were successfully loaded into the polystyrene nanoparticles enabling their bioanalytical application in aqueous environment. The encapsulation of the complexes preserved, or even enhanced, their good photophysical features. - Highlights: • Ternary Eu{sup 3+} complexes with some β-diketone and substituted terpyridine were studied. • Ternary complexes with substituted terpyridine showed blue-light excitability. • Ternary complexes were successfully loaded into the polystyrene nanoparticles. • Encapsulation of the complexes preserved their good photophysical features.

Synthesis and property characterization of two novel side-chain isoindigo copolymers for polymer solar cells

Directory of Open Access Journals (Sweden)

X. Liu

2015-11-01

Full Text Available Two novel side-chain conjugated polymers, PTBT-TID and PTBT-TTID, based on the new synthetic thiophene-benzne-thiophene (TBT unit, side-chain isoindigo (ID unit, and the introduced thiophene π-bridge, have been designed and synthesized. The photophysical, electrochemical and photovoltaic properties of the two polymers have been systematically investigated. The two polymers possess relatively good solubility as well as excellent thermal stability up to 380°C, and all of the polymer solar cell (PSC devices based on the two polymers obtain high open circuit voltage (Voc of about 0.8 V. The polymer solar cells based on the polymer PTBT-TID show relatively higher efficiencies than the PTBT-TTID-based ones, due to the broader absorption spectrum, a relatively higher hole mobility, a lower HOMO (the highest occupied molecular orbital energy level, a stronger IPCE (the incident photon to current conversion efficiency response and a better microphase separation, Consequently, the device based on PTBT-TID:PC61BM (1:2, by weight gives the best power conversion efficiency (PCE of 2.04%, with a short-circuit current density (Jsc of 5.39 mA·cm–2, an open-circuit voltage (Voc of 0.83 V, and a fill factor (FF of 0.45.

PFE: ZnO hybrid nanocomposites for OLED applications: Fabrication and photophysical properties

Energy Technology Data Exchange (ETDEWEB)

Belhaj, M. [Université de Monastir, Faculté des sciences de Monastir, Département de physique, Laboratoire des Interfaces et des Matériaux Avancés, 5019 Monastir (Tunisia); Dridi, C., E-mail: cherif.Dridi@issatso.rnu.tn [Université de Monastir, Faculté des sciences de Monastir, Département de physique, Laboratoire des Interfaces et des Matériaux Avancés, 5019 Monastir (Tunisia); Université de Sousse, Institut Supérieur des Sciences Appliquées et de Technologie de Sousse, Cité Ettafala, 4003 Ibn Khaldoun Sousse (Tunisia); Elhouichet, H. [Centre National de Recherches en Sciences des Matériaux, Laboratoire de physico-Chimie des Matériaux Minéreaux et leurs applications, B.P. 95 Hammam-Lif 2050 (Tunisia)

2015-01-15

In this work, ZnO nanoparticles (n-ZnO) and poly (9, 9-dioctyl-fluorenyl-2, 7-yleneethynylene) (PFE): n-ZnO based thin films were spin-coated onto glass substrates. Structural, morphological and optical properties of ZnO, PFE and the PFE: n-ZnO hybrid films with different n-ZnO mass ratios were investigated. n-ZnO films obtained by sol–gel technique are polycrystalline with a hexagonal wurtzite structure. They are also homogenous with an average grain size of about 35 nm. For polymer nanocomposite, the optical properties are closely related to the ZnO content in the mixture. Among the tested active layers, the best performance is observed for that containing 2 wt% of ZnO nanoparticles. - Highlights: • We have analyzed the optical properties of PFE: ZnO nanocomposites . • We have optimized the best PFE: ZnO nanocomposite for the OLED application. • We have demonstrated the feasibility of white OLED devices.

PFE: ZnO hybrid nanocomposites for OLED applications: Fabrication and photophysical properties

International Nuclear Information System (INIS)

Belhaj, M.; Dridi, C.; Elhouichet, H.

2015-01-01

In this work, ZnO nanoparticles (n-ZnO) and poly (9, 9-dioctyl-fluorenyl-2, 7-yleneethynylene) (PFE): n-ZnO based thin films were spin-coated onto glass substrates. Structural, morphological and optical properties of ZnO, PFE and the PFE: n-ZnO hybrid films with different n-ZnO mass ratios were investigated. n-ZnO films obtained by sol–gel technique are polycrystalline with a hexagonal wurtzite structure. They are also homogenous with an average grain size of about 35 nm. For polymer nanocomposite, the optical properties are closely related to the ZnO content in the mixture. Among the tested active layers, the best performance is observed for that containing 2 wt% of ZnO nanoparticles. - Highlights: • We have analyzed the optical properties of PFE: ZnO nanocomposites . • We have optimized the best PFE: ZnO nanocomposite for the OLED application. • We have demonstrated the feasibility of white OLED devices

NIR dual luminescence from an extended porphyrin. Spectroscopy, photophysics and theory.

Science.gov (United States)

Gourlaouen, Christophe; Daniel, Chantal; Durola, Fabien; Frey, Julien; Heitz, Valérie; Sauvage, Jean-Pierre; Ventura, Barbara; Flamigni, Lucia

2014-05-22

Spectroscopic and photophysical properties of an extended Zn porphyrin with fused bis(tetraazaanthracene) arms including a 2,9-diphenyl-1,10-phenanthroline incorporated in a polyether macrocycle are investigated in solvents of different polarity pointing to the presence of two emitting singlet excited states. The absorption and emission features are identified and ascribed, on the basis of solvent polarity dependence, to a π-π* and to a charge transfer (CT) state, respectively. Whereas the intraligand π-π* transition is assigned to the intense absorption observed at 442-455 nm, the CT states contribute to the bands at 521-525 nm and 472-481 nm. The theoretical analysis of the absorption spectrum confirms the presence of two strong bands centered at 536 and 437 nm corresponding to CT and π-π* states, respectively. Weak CT transitions are calculated at 657 and 486 nm. Two emission maxima are observed in toluene at 724 nm from a (1)π-π* state and at 800 nm from a (1)CT state, respectively. (1)CT bands shift bathochromically by increasing the solvent polarity whereas the energy of the (1)π-π band is less affected. Likewise, the emission yield and lifetime associated with the low energy (1)CT band are strongly affected by solvent polarity. This is rationalized by a (1)π-π* → (1)CT internal conversion driven by solvent polarity, this process being competitive with the (1)π-π* to ground state deactivation channel. Time resolved absorption spectra indicate the presence of two triplet states, a short-lived one (nanoseconds range) and a longer lived one (hundreds of microsecond range) ascribed to a (3)π-π* and a (3)CT, respectively. For them, a conversion mechanism similar to that of the singlet excited states is suggested.

A photophysical study of two fluorogen-activating proteins bound to their cognate fluorogens

Energy Technology Data Exchange (ETDEWEB)

Gaiotto, Tiziano [Los Alamos National Laboratory; Nguyen, Hau B [Los Alamos National Laboratory; Jung, Jaemyeong [Los Alamos National Laboratory; Bradbury, Andrew M [Los Alamos National Laboratory; Gnanakaran, S. [Los Alamos National Laboratory; Schmidt, Jurgen G [Los Alamos National Laboratory; Waldo, Geoffrey S [Los Alamos National Laboratory; Goodwin, Peter M [Los Alamos National Laboratory

2010-12-14

We are exploring the feasibility of using recently developed flu orogen-activating proteins (FAPs) as reporters for single-molecule imaging. FAPs are single-chain antibodies choosen to specifically bind small chromophoric molecules termed f1uorogens. Upon binding to its cognate FAP the fluorescence quantum yield of the fluorogen can increase substantially giving rise to a fluorescent complex. Based on the seminal work of Szent-Gyorgyi et al. (Nature Biotechnology, Volume 26, Number 2, pp 235-240, 2008) we have chosen to study two fluorogen-activating single-chain antibodies, HL 1.0.1-TOI and H6-MG bound to their cognate fluorogens, thiazole orange and malachite green derivatives, respectively. Here we use fluorescence correlation spectroscopy study the photophysics of these fluorescent complexes.

Photophysical properties of a novel axially substituted tetra-α-(pentyloxy) Titanium(IV) Phthalocyanine - Hematoxylin

Science.gov (United States)

Jiang, Yufeng; Lv, Huafei; Yu, Xinxin; Pan, Sujuan; Zhang, Tiantian; Huang, Yide; Wang, Yuhua; Xie, Shusen; Yang, Hongqin; Peng, Yiru

2017-06-01

Metal phthalocyanines (MPcs) are a very important class of widespread application compounds. They are not only used as dyes but also used as catalysts, data storage, electron charge carriers in photocopiers, photoconductors in chemical sensors, and photo-antenna devices in photosysthesis, photovoltaic cells. A particular application of Pcs is that it was used as a photosensitizers (PS) for treatment of certain cancer by photodynamic therapy of cancer and non-cancer diseases. However, the molecular aggregation of phthalocyanines, which is an intrinsic property of these large π-π conjugated systems, provides an efficient non-radioactive energy relaxation pathway, thereby shortening the excited state lifetimes, and reducing the photosensitizing and target efficiency. To overcome these problems, the introduction of axial ligands to phthalocyanine can prevent the formation of aggregation to some extend. In this paper, hematoxylin axially substituted tetra-α-(pentoxy) titanium (IV) phthalocyanine (TiPc(OC5H11)4-Hematoxylin) were characterized by elemental analysis, IR, 1H NMR, UV-Vis, fluorescence spectra. No obviously Q band change was observed after the hematoxylin was substituted at the peripheral position of substituted phthalocyanine ring. Because of the rigidity structure of the hematoxylin, the fluorescence intensity of hematoxylin peripheral substituted phthalocyanine decreased compared with free substituted phthalocyanines. The fluorescence lifetimes of axially substituted phthalocyanine was fitted to be 3.613 ns. This compound may be considered as a promising photosensitizer for PDT.

Thin film properties of triphenylamine-cored dendrimers: A molecular approach to control aggregation

Energy Technology Data Exchange (ETDEWEB)

Vamvounis, George, E-mail: g.vamvounis@uq.edu.au; Pivrikas, Almantas; Shaw, Paul E.; Burn, Paul L.

2013-12-02

The solid-state photophysical and charge transport properties of two first-generation dendrimers are presented. The dendrimers are comprised of a triphenylamine core, dendrons containing a phenyl branching unit with thiophene (Dendrimer 1) or bithiophene (Dendrimer 2) moieties, and dodecyl surface groups. For Dendrimer 1, the excited state is located within the center of the dendrimer giving rise to a moderate solid-state photoluminescence quantum yield (Φ{sub pl}) (0.13) and significant charge trapping, with both observations due to the degree of overlap of the main electroactive chromophores on adjacent dendrimers. For Dendrimer 2, the excited state is located within the dendron and in the solid-state this leads to a strongly red-shifted and weakened emission (Φ{sub pl} ∼ 0.02) due to strong intermolecular chromophore interactions. For films of Dendrimer 2 the charge mobility was higher than Dendrimer 1 but was still limited by a low density of strongly interacting electroactive chromophores. The pronounced difference between the solid-state properties of the two dendrimers is simply engineered by the addition of an extra thiophene in each of the dendrons. - Highlights: • Photophysical and charge-transport properties of two dendrimers are investigated. • Excited-state is on the center for Dendrimer 1 and on the dendron for Dendrimer 2. • Film quantum yield of luminescence is higher for Dendrimer 1. • Dendrimer 1 displays greater charge trapping at high fields.

Thioxanthone based 9-[2-(methyl-phenyl-amino)-acetyl]-thia-naphthacene-12-one as a visible photoinitiator

International Nuclear Information System (INIS)

Doğruyol, Sevnur Keskin; Doğruyol, Zekeriya; Arsu, Nergis

2013-01-01

Photoinitiators that operate in the visible range of the electromagnetic spectrum have widespread applications. Thioxanthone based 9-[2-(methyl-phenyl-amino)-acetyl]-thia-naphthacene-12-one (TX-MPA) was synthesized and the characterization of this initiator was confirmed by spectral analysis methods. TX-MPA has excellent absorption properties in the visible range (ε 480 nm =3576 L/mol.cm). Photophysical studies; fluorescence quantum yield (φ f =0.22, DPA), phosphorescence lifetime (τ p =115 ms) and triplet lifetime (τ=190 ns) were explored. To explore the initiation mechanism of TX-MPA, besides the photophysical and photochemical studies, the polymer (PMMA) obtained from the photopolymerization studies was subjected to a phosphorescence study and τ p was found to be 105 ms compared to 115 ms for the initiator TX-MPA which proved attachment of the initiator to the polymer. Possibly both intermolecular and intramolecular hydrogen abstraction, occur during the initiation stage depending on the concentration of the initiator. Highlights: ► Synthesis and photophysical properties of a visible photoinitiator (TX-MPA) are proposed. ► TX-MPA has high molar absorption values in the visible region. ► TX-MPA can initiate photopolymerization of methylmethacrylate monomer under UV and sunlight. ► Inter or intramolecular hydrogen abstraction mechanisms occur depending on initiator concentration

Synthesis and photophysical properties of aluminium tris-(4-morpholine-8-hydroxyquinoline).

Science.gov (United States)

Omar, Walaa A E

2013-11-01

Aluminium tris(4-morpholinyl-8-hydroxyquinoline) has been synthesized and characterized. The photoluminescence measurements showed that the new derivative is blue shifted and has relative photoluminescence quantum yield two times higher compared to the pristine Al tris(8-hydroxyquinoline). Deferential scanning colorimetric studies revealed that the newly synthesized Alq3 derivative in this work is amorphous material with the highest transition glass temperature value among the reported amorphous Alq3 derivatives.

Microfluidic Impedance Flow Cytometry Enabling High-Throughput Single-Cell Electrical Property Characterization

Science.gov (United States)

Chen, Jian; Xue, Chengcheng; Zhao, Yang; Chen, Deyong; Wu, Min-Hsien; Wang, Junbo

2015-01-01

This article reviews recent developments in microfluidic impedance flow cytometry for high-throughput electrical property characterization of single cells. Four major perspectives of microfluidic impedance flow cytometry for single-cell characterization are included in this review: (1) early developments of microfluidic impedance flow cytometry for single-cell electrical property characterization; (2) microfluidic impedance flow cytometry with enhanced sensitivity; (3) microfluidic impedance and optical flow cytometry for single-cell analysis and (4) integrated point of care system based on microfluidic impedance flow cytometry. We examine the advantages and limitations of each technique and discuss future research opportunities from the perspectives of both technical innovation and clinical applications. PMID:25938973

Synthesis and photophysical properties of aluminium tris-(4-morpholine-8-hydroxyquinoline

Directory of Open Access Journals (Sweden)

Walaa A.E. Omar

2013-11-01

Full Text Available Aluminium tris(4-morpholinyl-8-hydroxyquinoline has been synthesized and characterized. The photoluminescence measurements showed that the new derivative is blue shifted and has relative photoluminescence quantum yield two times higher compared to the pristine Al tris(8-hydroxyquinoline. Deferential scanning colorimetric studies revealed that the newly synthesized Alq3 derivative in this work is amorphous material with the highest transition glass temperature value among the reported amorphous Alq3 derivatives.

Electromagnetic NDT to characterize usage properties of flat steel products

Energy Technology Data Exchange (ETDEWEB)

Altpeter, I.; Dobmann, G.; Szielasko, K., E-mail: iab.altlau@t-online.de, E-mail: gerd.dobmann@t-online.de, E-mail: klaus.szielasko@izfp.fraunhofer.de [Fraunhofer Inst. - IZFP, Saarbruecken (Germany)

2015-07-15

The Fraunhofer Institute for Non-destructive Testing (IZFP) in Saarbruecken, Germany, started its activities in materials characterization of flat steel products in the eighties of the last century in the basic program of the European Community of Coal and Steel (ECCS). Throughout the years, continuous research and development were performed. The objective of the work, presented within this three-part series of reports, is to discuss the history of an innovation which began in 1988 with R&D in the area of texture characterization in steel sheets produced for car-body manufacturing (Part 1). In the following years the activities were to automate online property determination in terms of yield strength, tensile strength, planar, and vertical-anisotropy-factors. Again, steel sheets were the focus of the developments and the first NDT systems that came into industrial application for this project. Parallel research was performed to characterize the mechanical properties and hardness of heavy steel plates, mainly produced for pipeline manufacturing and off-shore applications (Part 2) The final report in the series (Part 3) will discuss steel sheet characterization and presents the successful development of a combination-transducer which combines ultrasonics with electromagnetic NDT. (author)

Electromagnetic NDT to characterize usage properties of flat steel products

International Nuclear Information System (INIS)

Altpeter, I.; Dobmann, G.; Szielasko, K.

2015-01-01

The Fraunhofer Institute for Non-destructive Testing (IZFP) in Saarbruecken, Germany, started its activities in materials characterization of flat steel products in the eighties of the last century in the basic program of the European Community of Coal and Steel (ECCS). Throughout the years, continuous research and development were performed. The objective of the work, presented within this three-part series of reports, is to discuss the history of an innovation which began in 1988 with R&D in the area of texture characterization in steel sheets produced for car-body manufacturing (Part 1). In the following years the activities were to automate online property determination in terms of yield strength, tensile strength, planar, and vertical-anisotropy-factors. Again, steel sheets were the focus of the developments and the first NDT systems that came into industrial application for this project. Parallel research was performed to characterize the mechanical properties and hardness of heavy steel plates, mainly produced for pipeline manufacturing and off-shore applications (Part 2) The final report in the series (Part 3) will discuss steel sheet characterization and presents the successful development of a combination-transducer which combines ultrasonics with electromagnetic NDT. (author)

Characterization of the electromechanical properties of EAP materials

Science.gov (United States)

Bar-Cohen, Yoseph; Sherrita, Stewart; Bhattachary, Kaushik; Lih, Shyh-Shiuh

2001-01-01

Electroactive polymers (EAP) are an emerging class of actuation materials. Their large electrically induced strains (longitudinal or bending), low density, mechanical flexibility, and ease of processing offer advantages over traditional electroactive materials. However, before the capability of these materials can be exploited, their electrical and mechanical behavior must be properly quantified. Two general types of EAP can be identified. The first type is ionic EAP, which requires relatively low voltages (EAP and it involves electrostrictive and/or Maxwell stresses. This type of materials requires large electric fields (>100MV/m) to achieve longitudinal deformations at the range from 4 - 360%. Some of the difficulties in characterizing EAP include: nonlinear properties, large compliance (large mismatch with metal electrodes), nonhomogeneity resulting from processing, etc. To support the need for reliable data, the authors are developing characterization techniques to quantify the electroactive responses and material properties of EAP materials. The emphasis of the current study is on addressing electromechanical issues related to the ion-exchange type EAP also known as IPMC. The analysis, experiments and test results are discussed in this paper.

Characterization of porosity in support of mechanical property analysis

International Nuclear Information System (INIS)

Price, R.H.; Martin, R.J. III; Boyd, P.J.

1992-01-01

Previous laboratory investigations of tuff have shown that porosity has a dominant, general effect on mechanical properties. As a result, it is very important for the interpretation of mechanical property data that porosity is measured on each sample tested. Porosity alone, however, does not address all of the issues important to mechanical behavior. Variability in size and distribution of pore space produces significantly different mechanical properties. A nondestructive technique for characterizing the internal structure of the sample prior to testing is being developed and the results are being analyzed. The information obtained from this technique can help in both qualitative and quantitative interpretation of test results

Physical property characterization of 183-H Basin sludge

International Nuclear Information System (INIS)

Biyani, R.K.; Delegard, C.H.

1995-01-01

This document describes the characterization of 183-H Basin sludge physical properties, e.g. bulk density of sludge and absorbent, and determination of free liquids. Calcination of crucible-size samples of sludge was also done and the resulting 'loss-on-ignition' was compared to the theoretical weight loss based on sludge analysis obtained from Weston Labs

Mirror boxes and mirror mounts for photophysics beamline

International Nuclear Information System (INIS)

Raja Rao, P.M.; Raja Sekhar, B.N.; Das, N.C.; Khan, H.A.; Bhattacharya, S.S.; Roy, A.P.

1996-01-01

Photophysics beamline makes use of one metre Seya-Namioka monochromator and two toroidal mirrors in its fore optics. The first toroidal mirror (pre mirror) focuses light originating from the tangent point of the storage ring onto the entrance slit of the monochromator and second toroidal mirror (post mirror) collects light from the exit slit of the monochromator and focuses light onto the sample placed at a distance of about one metre away from the 2nd mirror. To steer light through monochromator and to focus it on the sample of 1mm x 1mm size require precision rotational and translational motion of the mirrors and this has been achieved with the help of precision mirror mounts. Since Indus-1 operates at pressures less than 10 -9 m.bar, the mirror mounts should be manipulated under similar ultra high vacuum conditions. Considering these requirements, two mirror boxes and two mirror mounts have been designed and fabricated. The coarse movements to the mirrors are imparted from outside the mirror chamber with the help of x-y tables and precision movements to the mirrors are achieved with the help of mirror mounts. The UHV compatibility and performance of the mirror mounts connected to mirror boxes under ultra high vacuum condition is evaluated. The details of the design, fabrication and performance evaluation are discussed in this report. 5 refs., 9 figs., 1 tab

Study on photophysical and aggregation induced emission recognition of 1,8-naphthalimide probe for casein by spectroscopic method

Science.gov (United States)

Sun, Yang; Liu, Zhen; Liang, Xuhua; Fan, Jun; Han, Quan

2013-05-01

A novel water-soluble 1,8-naphthalimide derivative 1, bearing two acetic carboxylic groups, exhibited fluorescent turn-on recognition for casein based on the aggregation induced emission (AIE) character. The photophysical properties of 1 consisting of donor and acceptor units were investigated in different solutions. The fluorescence intensity decreased through taking advantage of twisted intramolecular charge transfer (TICT) and self-association emission with increasing solvent polarity. Moreover, the spectral red-shift and intensity quench in protic solvents were caused by the excited-state hydrogen bond strengthening effect. Density Functional Theory (DFT) calculations revealed that 1 exhibited a strong TICT character. The AIE mechanism of 1 with casein was due to 1 docked in the hydrophobic cavity between sub-micelles and bound with Tyr and Trp residues, resulting in the aggregation of 1 on the casein surface and emission enhancement. Based on this, a novel casein assay method was developed. The proposed exhibited a good linear range from 0.1 to 22 μg mL-1, with the detection limit of 2.8 ng mL-1. Satisfactory reproducibility, reversibility and a short response time were realized. This method was applied to the determination of casein in milk powder samples and the results were in good agreement with the result of Biuret method.

Dependence of Exciton Diffusion Length and Diffusion Coefficient on Photophysical Parameters in Bulk Heterojunction Organic Solar Cells

Science.gov (United States)

Yeboah, Douglas; Singh, Jai

2017-11-01

Recently, the dependence of exciton diffusion length (LD ) on some photophysical parameters of organic solids has been experimentally demonstrated, however no systematic theoretical analysis of this phenomenon has been carried out. We have conducted a theoretical study by using the Förster resonance energy transfer and Dexter carrier transfer mechanisms together with the Einstein-Smoluchowski diffusion equation to derive analytical models for the diffusion lengths (LD ) and diffusion coefficients (D) of singlet (S) and triplet (T) excitons in organic solids as functions of spectral overlap integral (J) , photoluminescence (PL) quantum yield (φD ) , dipole moment (μT ) and refractive index (n) of the photoactive material. The exciton diffusion lengths and diffusion coefficients in some selected organic solids were calculated, and we found that the singlet exciton diffusion length (LDS ) increases with φD and J, and decreases with n. Also, the triplet exciton diffusion length (LDT ) increases with φD and decreases with μT . These may be achieved through doping the organic solids into broad optical energy gap host materials as observed in previous experiments. The calculated exciton diffusion lengths are compared with experimental values and a reasonably good agreement is found between them. The results presented are expected to provide insight relevant to the synthesis of new organic solids for fabrication of bulk heterojunction organic solar cells characterized by better power conversion efficiency.

Controllable synthesis of Eu{sup 3+}/Tb{sup 3+} activated lutetium fluorides nanocrystals and their photophysical properties

Energy Technology Data Exchange (ETDEWEB)

Lin, Jintai; Huo, Jiansheng [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Cai, Yuepeng [Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Wang, Qianming, E-mail: qmwang@scnu.edu.cn [Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China)

2013-12-15

In this paper, phosphors of LuF{sub 3}:Eu{sup 3+}/Tb{sup 3+} have been successfully synthesized with small chelator ethylenediaminetetra acetic acid (EDTA) or amphiphilic polymer (polyethylene glycol, PEG-1000) as templates via a hydrothermal method. X-ray powder diffraction (XRD), scanning electronic microscope (SEM), and photo-luminescent spectra techniques (PL) were used to characterize the as-prepared samples. XRD patterns showed that well crystallized lanthanide fluorides with hexagonal phase were achieved. SEM images revealed that different regular microstructures were achieved. The photo-luminescent properties of LuF{sub 3}:Eu{sup 3+} demonstrated that there are significant energy transfers from fluorides to Eu{sup 3+}. The results presented that EDTA as the template will lead to the highest emission intensities. -- Highlights: • Various templates were used to synthesize LuF{sub 3}:Eu{sup 3+}/Tb{sup 3+}. • All the phosphors were red or green emissive. • Different morphologies were acquired and controllable.

Rational design of tetraphenylethylene-based luminescent down-shifting molecules: photophysical studies and photovoltaic applications in a CdTe solar cell from small to large units.

Science.gov (United States)

Li, Yilin; Li, Zhipeng; Ablekim, Tursunjan; Ren, Tianhui; Dong, Wen-Ji

2014-12-21

A rational design strategy of novel fluorophores for luminescent down-shifting (LDS) application was proposed and tested in this paper. Three new fluorophores (1a-c) with specific intramolecular charge transfer (ICT) and aggregation-induced emission (AIE) characteristics were synthesized as LDS molecules for increasing the output short circuit current density (Jsc) of a CdTe solar cell. Photophysical studies of their solution and solid states, and photovoltaic measurements of their PMMA solid films applied on a CdTe solar cell suggested that the specific spectroscopic properties and Jsc enhancement effects of these molecules were highly related to their chemical structures. The Jsc enhancement effects of these fluorophores were measured on both a CdTe small cell and a large panel. An increase in the output Jsc by as high as 5.69% for a small cell and 8.88% for a large panel was observed. Compared to a traditional LDS molecule, Y083, these fluorophores exhibited more superior capabilities of LDS.

Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

Directory of Open Access Journals (Sweden)

Mathieu L. Lepage

2015-05-01

Full Text Available The synthesis and photophysical properties of the first examples of iminosugar clusters based on a BODIPY or a pyrene core are reported. The tri- and tetravalent systems designed as molecular probes and synthesized by way of Cu(I-catalysed azide–alkyne cycloadditions are fluorescent analogues of potent pharmacological chaperones/correctors recently reported in the field of Gaucher disease and cystic fibrosis, two rare genetic diseases caused by protein misfolding.

Characterization and modelling of the mechanical properties of mineral wool

DEFF Research Database (Denmark)

Chapelle, Lucie

2016-01-01

and as a consequence focus on the mechanical properties of mineral wool has intensified. Also understanding the deformation mechanisms during compression of low density mineral wool is crucial since better thickness recovery after compression will result in significant savings on transport costs. The mechanical...... properties of mineral wool relate closely to the arrangement and characteristics of the fibres inside the material. Because of the complex architecture of mineral wool, the characterization and the understanding of the mechanism of deformations require a new methodology. In this PhD thesis, a methodology...... of the structure on mechanical properties can be explored. The size of the representative volume elements for the prediction of the elastic properties is determined for two types of applied boundary conditions. For sufficiently large volumes, the predicted elastic properties are consistent with results from...

Photo-physics study of an hydroxy-quinoline derivative as inhibitor of Pim-1 kinase: ultraviolet-visible linear dichroism spectroscopy and quantum chemical calculations.

Science.gov (United States)

Lamhasni, T; Ait Lyazidi, S; Hnach, M; Haddad, M; Desmaële, D; Spanget-Larsen, J; Nguyen, D D; Ducasse, L

2013-09-01

The photophysical properties of the antiviral 7-nicotinoyl-styrylquinoline (MB96) were investigated by means of UV-Vis linear dichroism (LD) spectroscopy on molecular samples aligned in stretched polyvinylalcohol (PVA), supported by time dependent density functional theory (TD-DFT) calculations. Experimentally, the directions of the transitions moments with respect to the long axis of the molecule were deduced from the orientation K factors, determined by means of "trial-and-error" procedure. The absorption spectrum presents two parts. The main transition in the lowest energy part, observed around 365 nm and showing the highest K value 0.8, is longitudinally in-plane polarized. The highest energy part which is extended between 230 and 320 nm, large, diffuse, and of weak intensity, shows estimated K values between 0.2 and 0.5. This complex structure is transversally polarized with some contamination by the longitudinal character of the first strong band. The TD-DFT results agree fairly well with the LD measurements. Copyright © 2013 Elsevier B.V. All rights reserved.

Nanocomposite Coatings: Preparation, Characterization, Properties, and Applications

Directory of Open Access Journals (Sweden)

Phuong Nguyen-Tri

2018-01-01

Full Text Available Incorporation of nanofillers into the organic coatings might enhance their barrier performance, by decreasing the porosity and zigzagging the diffusion path for deleterious species. Thus, the coatings containing nanofillers are expected to have significant barrier properties for corrosion protection and reduce the trend for the coating to blister or delaminate. On the other hand, high hardness could be obtained for metallic coatings by producing the hard nanocrystalline phases within a metallic matrix. This article presents a review on recent development of nanocomposite coatings, providing an overview of nanocomposite coatings in various aspects dealing with the classification, preparative method, the nanocomposite coating properties, and characterization methods. It covers potential applications in areas such as the anticorrosion, antiwear, superhydrophobic area, self-cleaning, antifouling/antibacterial area, and electronics. Finally, conclusion and future trends will be also reported.

Photophysics of size-selected InP nanocrystals: Exciton recombination kinetics

International Nuclear Information System (INIS)

Kim, S.; Wolters, R.H.; Heath, J.R.

1996-01-01

We report here on the size-dependent kinetics of exciton recombination in a III endash V quantum dot system, InP. The measurements reported include various frequency dependent quantum yields as a function of temperature, frequency dependent luminescence decay curves, and time-gated emission spectra. This data is fit to a three-state quantum model which has been previously utilized to explain photophysical phenomena in II endash VI quantum dots. The initial photoexcitation is assumed to place an electron in a (delocalized) bulk conduction band state. Activation barriers for trapping and detrapping of the electron to surface states, as well as activation barriers for surface-state radiationless relaxation processes are measured as a function of particle size. The energy barrier to detrapping is found to be the major factor limiting room temperature band-edge luminescence. This barrier increases with decreasing particle size. For 30 A particles, this barrier is found to be greater than 6 kJ/mol emdash a barrier which is more than an order of magnitude larger than that previously found for 32 A CdS nanocrystals. copyright 1996 American Institute of Physics

Characterization of cell mechanical properties by computational modeling of parallel plate compression.

Science.gov (United States)

McGarry, J P

2009-11-01

A substantial body of work has been reported in which the mechanical properties of adherent cells were characterized using compression testing in tandem with computational modeling. However, a number of important issues remain to be addressed. In the current study, using computational analyses, the effect of cell compressibility on the force required to deform spread cells is investigated and the possibility that stiffening of the cell cytoplasm occurs during spreading is examined based on published experimental compression test data. The effect of viscoelasticity on cell compression is considered and difficulties in performing a complete characterization of the viscoelastic properties of a cell nucleus and cytoplasm by this method are highlighted. Finally, a non-linear force-deformation response is simulated using differing linear viscoelastic properties for the cell nucleus and the cell cytoplasm.

Thioxanthone based 9-[2-(methyl-phenyl-amino)-acetyl]-thia-naphthacene-12-one as a visible photoinitiator

Energy Technology Data Exchange (ETDEWEB)

Doğruyol, Sevnur Keskin [Department of Chemistry, Yıldız Technical University, Davutpasa Campus, Esenler, 34220 Istanbul (Turkey); Doğruyol, Zekeriya [Department of Engineering Science, Istanbul University, 34850, Avcılar, Istanbul (Turkey); Arsu, Nergis, E-mail: narsu@yildiz.edu.tr [Department of Chemistry, Yıldız Technical University, Davutpasa Campus, Esenler, 34220 Istanbul (Turkey)

2013-06-15

Photoinitiators that operate in the visible range of the electromagnetic spectrum have widespread applications. Thioxanthone based 9-[2-(methyl-phenyl-amino)-acetyl]-thia-naphthacene-12-one (TX-MPA) was synthesized and the characterization of this initiator was confirmed by spectral analysis methods. TX-MPA has excellent absorption properties in the visible range (ε{sub 480} {sub nm}=3576 L/mol.cm). Photophysical studies; fluorescence quantum yield (φ{sub f}=0.22, DPA), phosphorescence lifetime (τ{sub p}=115 ms) and triplet lifetime (τ=190 ns) were explored. To explore the initiation mechanism of TX-MPA, besides the photophysical and photochemical studies, the polymer (PMMA) obtained from the photopolymerization studies was subjected to a phosphorescence study and τ{sub p} was found to be 105 ms compared to 115 ms for the initiator TX-MPA which proved attachment of the initiator to the polymer. Possibly both intermolecular and intramolecular hydrogen abstraction, occur during the initiation stage depending on the concentration of the initiator. Highlights: ► Synthesis and photophysical properties of a visible photoinitiator (TX-MPA) are proposed. ► TX-MPA has high molar absorption values in the visible region. ► TX-MPA can initiate photopolymerization of methylmethacrylate monomer under UV and sunlight. ► Inter or intramolecular hydrogen abstraction mechanisms occur depending on initiator concentration.

Graphene optoelectronics synthesis, characterization, properties, and applications

CERN Document Server

bin M Yusoff, Abdul Rashid

2014-01-01

This first book on emerging applications for this innovative material gives an up-to-date account of the many opportunities graphene offers high-end optoelectronics.The text focuses on potential as well as already realized applications, discussing metallic and passive components, such as transparent conductors and smart windows, as well as high-frequency devices, spintronics, photonics, and terahertz devices. Also included are sections on the fundamental properties, synthesis, and characterization of graphene. With its unique coverage, this book will be welcomed by materials scientists, solid-

Photoprotection and the photophysics of acylated anthocyanins.

Science.gov (United States)

da Silva, Palmira Ferreira; Paulo, Luísa; Barbafina, Adrianna; Eisei, Fausto; Quina, Frank H; Maçanita, António L

2012-03-19

The proposed role of anthocyanins in protecting plants against excess solar radiation is consistent with the occurrence of ultrafast (5-25 ps) excited-state proton transfer as the major de-excitation pathway of these molecules. However, because natural anthocyanins absorb mainly in the visible region of the spectra, with only a narrow absorption band in the UV-B region, this highly efficient deactivation mechanism would essentially only protect the plant from visible light. On the other hand, ground-state charge-transfer complexes of anthocyanins with naturally occurring electron-donor co-pigments, such as hydroxylated flavones, flavonoids, and hydroxycinnamic or benzoic acids, do exhibit high UV-B absorptivities that complement that of the anthocyanins. In this work, we report a comparative study of the photophysics of the naturally occurring anthocyanin cyanin, intermolecular cyanin-coumaric acid complexes, and an acylated anthocyanin, that is, cyanin with a pendant coumaric ester co-pigment. Both inter- and intramolecular anthocyanin-co-pigment complexes are shown to have ultrafast energy dissipation pathways comparable to those of model flavylium cation-co-pigment complexes. However, from the standpoint of photoprotection, the results indicate that the covalent attachment of co-pigment molecules to the anthocyanin represents a much more efficient strategy by providing the plant with significant UV-B absorption capacity and at the same time coupling this absorption to efficient energy dissipation pathways (ultrafast internal conversion of the complexed form and fast energy transfer from the excited co-pigment to the anthocyanin followed by adiabatic proton transfer) that avoid net photochemical damage. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation on the photophysical properties of tungsten trioxide and tungstate based nanocomposites

Science.gov (United States)

Palanisamy, G.; Pazhanivel, T.

2018-04-01

Tungsten trioxide (WO3), Metal tungstates (SrWO4, Cr2WO6), WO3/SrWO4 and WO3/Cr2WO6 nanocomposites were successfully prepared by microwave irradiation method at relatively low temperature (500 °C). The synthesized samples were subjected to different investigation techniques, to know the materials physical and chemical properties. The structural and phase change formation of nanoparticles were investigated through XRD analysis. It shows that, the nanoparticles have highly crystalline nature. The shape and composition of the prepared nanoparticles were investigated through SEM and EDAX analysis. The optical properties of the synthesized samples were verified by Ultraviolet-diffuse reflectance spectroscopy and photoluminescence spectrometer. The emission intensity maximum of WO3 nanoparticle was red shifted when compared to composites. It may be due to the effect of delocalized electrons in the parent material. Simultaneously, the emission intensity was decreased because of trap states occurred on the surface of the composite nanoparticles. The photoluminescence spectra of the synthesized samples exhibit different emission (violet and blue) behavior. Hence, it may be useful for light emitting diode (LED) applications.

C-shaped diastereomers containing cofacial thiophene-substituted quinoxaline rings: synthesis, photophysical properties, and X-ray crystallography.

Science.gov (United States)

DeBlase, Catherine R; Finke, Ryan T; Porras, Jonathan A; Tanski, Joseph M; Nadeau, Jocelyn M

2014-05-16

Synthesis and characterization of two diastereomeric C-shaped molecules containing cofacial thiophene-substituted quinoxaline rings are described. A previously known bis-α-diketone was condensed with an excess of 4-bromo-1,2-diaminobenzene in the presence of zinc acetate to give a mixture of two C-shaped diastereomers with cofacial bromine-substituted quinoxaline rings. After chromatographic separation, thiophene rings were installed by a microwave-assisted Suzuki coupling reaction, resulting in highly emissive diastereomeric compounds that were studied by UV-vis, fluorescence, and NMR spectroscopy, as well as X-ray crystallography. The unique symmetry of each diastereomer was confirmed by NMR spectroscopy. NMR data indicated that the syn isomer has restricted rotation about the bond connecting the thiophene and quinoxaline rings, which was also observed in the solid state. The spectroscopic properties of the C-shaped diastereomers were compared to a model compound containing only a single thiophene-substituted quinoxaline ring. Ground state intramolecular π-π interactions in solution were detected by NMR and UV-vis spectroscopy. Red-shifted emission bands, band broadening, and large Stokes shifts were observed, which collectively suggest excited state π-π interactions that produce excimer-like emissions, as well as a remarkable positive emission solvatochromism, indicating charge-transfer character in the excited state.

Crystal structure, characterization and magnetic properties of a 1D ...

Indian Academy of Sciences (India)

Crystal structure, characterization and magnetic properties of a 1D copper(II) polymer incorporating a Schiff base with carboxylate side arm. SHYAMAPADA SHIT MADHUSUDAN NANDY CORRADO RIZZOLI CÉDRIC DESPLANCHES SAMIRAN MITRA. Regular Article Volume 128 Issue 6 June 2016 pp 913-920 ...

Using surfaces, ligands, and dimensionality to obtain desired nanostructure properties

Science.gov (United States)

Nagpal, Prashant; Singh, Vivek; Ding, Yuchen

2014-03-01

Nanostructured materials are intensively investigated to obtain material properties different from their bulk counterparts. It has been demonstrated that nanoscaled semiconductor can have interesting size, shape and morphology dependent optoelectronic properties. But the effect of surfaces, ligands and dimensionality (0D quantum dots to 2D nanosheets) has been largely unexplored. Here, we will show how tuning the surface and dimensionality can affect the electronic states of the semiconductor, and how these states can play an important role in their fundamental photophysical properties or thermal transport. Using the specific case for silicon, we will show how ``new'' surface states in small uniform can lead to light absorption/emission without phonon assistance, while hindering the phonon-drag of charge carriers leading to low Seebeck coefficient for thermoelectric applications. These measurements will shed light on designing appropriate surface, size, and dimensionality for desired applications of nanostructured films.

Preparation, Characterization, and Properties of In Situ Formed Graphene Oxide/Phenol Formaldehyde Nanocomposites

Directory of Open Access Journals (Sweden)

Weihua Xu

2013-01-01

Full Text Available Graphene oxide (GO has shown great potential to be used as fillers to develop polymer nanocomposites for important applications due to their special 2D geometrical structure as well as their outstanding mechanical, thermal, and electrical properties. In this work, GO was incorporated into phenol formaldehyde (PF resin by in situ polymerization. The morphologies and structures of GO sheets were characterized by FTIR, XRD, and AFM methods. The structure and properties of the GO/PF nanocomposites were characterized using FTIR, XRD, DSC, and TGA methods. Effects of GO content, reactive conditions, and blending methods on the structure and properties of GO/PF nanocomposites were studied. It was found that due to the well dispersion of GO sheets in polymer matrix and the strong interfacial interaction between the GO sheets and PF matrix, the thermal stability and thermal mechanical properties of the GO/PF nanocomposites were greatly enhanced.

Intramolecular didehydro-Diels-Alder reaction and its impact on the structure-function properties of environmentally sensitive fluorophores.

Science.gov (United States)

Brummond, Kay M; Kocsis, Laura S

2015-08-18

Reaction discovery plays a vital role in accessing new chemical entities and materials possessing important function.1 In this Account, we delineate our reaction discovery program regarding the [4 + 2] cycloaddition reaction of styrene-ynes. In particular, we highlight our studies that lead to the realization of the diverging reaction mechanisms of the intramolecular didehydro-Diels-Alder (IMDDA) reaction to afford dihydronaphthalene and naphthalene products. Formation of the former involves an intermolecular hydrogen atom abstraction and isomerization, whereas the latter is formed via an unexpected elimination of H2. Forming aromatic compounds by a unimolecular elimination of H2 offers an environmentally benign alternative to typical oxidation protocols. We also include in this Account ongoing work focused on expanding the scope of this reaction, mainly its application to the preparation of cyclopenta[b]naphthalenes. Finally, we showcase the synthetic utility of the IMDDA reaction by preparing novel environmentally sensitive fluorophores. The choice to follow this path was largely influenced by the impact this reaction could have on our understanding of the structure-function relationships of these molecular sensors by taking advantage of a de novo construction and functionalization of the aromatic portion of these compounds. We were also inspired by the fact that, despite the advances that have been made in the construction of small molecule fluorophores, access to rationally designed fluorescent probes or sensors possessing varied and tuned photophysical, spectral, and chemical properties are still needed. To this end, we report our studies to correlate fluorophore structure with photophysical property relationships for a series of solvatochromic PRODAN analogs and viscosity-sensitive cyanoacrylate analogs. The versatility of this de novo strategy for fluorophore synthesis was demonstrated by showing that a number of functional groups could be installed at

Thermomechanical and Photophysical Properties of Crystal-Violet-Dye/H2O Based Dissolutions via the Pulsed Laser Photoacoustic Technique

Directory of Open Access Journals (Sweden)

Vicente Torres-Zúñiga

2014-01-01

Full Text Available Different thermoelastic parameters, for example, the acoustic attenuation and the speed of sound, are fundamental for instrumental calibration and quantitative characterization of organic-based dissolutions. In this work, these parameters as functions of the concentration of an organic dye (crystal-violet: CV in distillated water (H2O based dissolutions are investigated. The speed of sound was measured by the pulsed-laser photoacoustic technique (PLPA, which consists in the generation of acoustic-waves by the optical absorption of pulsed light in a given material (in this case a liquid sample. The thermally generated sound-waves traveling through a fluid are detected with two piezoelectric sensors separated by a known distance. An appropriate processing of the photoacoustic signals allows an adequate data analysis of the generated waves within the system, providing an accurate determination of the speed of sound as function of the dye-concentration. The acoustic attenuation was calculated based on the distance of the two PZT-microphones to an acoustic-source point and performing linear-fitting of the experimental data (RMS-amplitudes as function of the dye-concentration. An important advantage of the PLPA-method is that it can be implemented with poor or null optical transmitting materials permitting the characterization of the mechanical and concentration/aggregate properties of dissolved organic compounds.

Nondestructive techniques for characterizing mechanical properties of structural materials: An overview

Science.gov (United States)

Vary, A.; Klima, S. J.

1985-01-01

An overview of nondestructive evaluation (NDE) is presented to indicate the availability and application potentials of techniques for quantitative characterization of the mechanical properties of structural materials. The purpose is to review NDE techniques that go beyond the usual emphasis on flaw detection and characterization. Discussed are current and emerging NDE techniques that can verify and monitor entrinsic properties (e.g., tensile, shear, and yield strengths; fracture toughness, hardness, ductility; elastic moduli) and underlying microstructural and morphological factors. Most of the techniques described are, at present, neither widely applied nor widely accepted in commerce and industry because they are still emerging from the laboratory. The limitations of the techniques may be overcome by advances in applications research and instrumentation technology and perhaps by accommodations for their use in the design of structural parts.

Rock mass mechanical property estimations for the Yucca Mountain Site Characterization Project

International Nuclear Information System (INIS)

Lin, M.; Hardy, M.P.; Bauer, S.J.

1993-06-01

Rock mass mechanical properties are important in the design of drifts and ramps. These properties are used in evaluations of the impacts of thermomechanical loading of potential host rock within the Yucca Mountain Site Characterization Project. Representative intact rock and joint mechanical properties were selected for welded and nonwelded tuffs from the currently available data sources. Rock mass qualities were then estimated using both the Norwegian Geotechnical Institute (Q) and Geomechanics Rating (RMR) systems. Rock mass mechanical properties were developed based on estimates of rock mass quality, the current knowledge of intact properties, and fracture/joint characteristics. Empirical relationships developed to correlate the rock mass quality indices and the rock mass mechanical properties were then used to estimate the range of rock mass mechanical properties

Photosensitivity to Triflusal: Formation of a Photoadduct with Ubiquitin Demonstrated by Photophysical and Proteomic Techniques

Directory of Open Access Journals (Sweden)

E Nuin

2016-08-01

Full Text Available Triflusal is a platelet aggregation inhibitor chemically related to acetylsalicylic acid, which is used for the prevention and/or treatment of vascular thromboembolisms, which acts as a prodrug. Actually, after oral administration it is absorbed primarily in the small intestine, binds to plasma proteins (99% and is rapidly biotransformed in the liver into its deacetylated active metabolite 2-hydroxy-4-trifluoromethylbenzoic acid (HTB. In healthy humans, the half-life of triflusal is ca. 0.5 h, whereas for HTB it is ca. 35 h. From a pharmacological point of view, it is interesting to note that HTB is itself highly active as a platelet anti-aggregant agent. Indeed, studies on the clinical profile of both drug and metabolite have shown no significant differences between them.It has been evidenced that HTB displays ability to induce photoallergy in humans. This phenomenon involves a cell-mediated immune response, which is initiated by covalent binding of a light-activated photosensitizer (or a species derived therefrom to a protein. In this context, small proteins like ubiquitin could be appropriate models for investigating covalent binding by means of MS/MS and peptide fingerprint analysis. In previous work, it was shown that HTB forms covalent photoadducts with isolated lysine. Interestingly, ubiquitin contains seven lysine residues that could be modified by a similar reaction. With this background, the aim of the present work is to explore adduct formation between the triflusal metabolite and ubiquitin as model protein upon sunlight irradiation, combining proteomic and photophysical (fluorescence and laser flash photolysis techniques.Photophysical and proteomic analysis demonstrate monoadduct formation as the major outcome of the reaction. Interestingly, addition can take place at any of the -amino groups of the lysine residues of the protein and involves replacement of the trifluoromethyl moiety with a new amide function. This process can in

Tunable photophysical processes of porphyrin macrocycles on the surface of ZnO nanoparticles

KAUST Repository

Parida, Manas R.

2015-01-23

We investigated the impact of the molecular structure of cationic porphyrins on the degree of electrostatic interactions with zinc oxide nanoparticles (ZnO NPs) using steady-state and time-resolved fluorescence and transient absorption spectroscopy. Our results demonstrate that the number of cationic pyridinium units has a crucial impact on the photophysics of the porphyrin macrocycle. Fluorescence enhancement, relative to initial free porphyrin fluorescence, was found to be tuned from 3.4 to 1.3 times higher by reducing the number of cationic substituents on the porphyrin from 4 to 2. The resulting enhancement of the intensity of the fluorescence is attributed to the decrease in the intramolecular charge transfer (ICT) character between the porphyrin cavity and its meso substituent. The novel findings reported in this work provide an understanding of the key variables involved in nanoassembly, paving the way toward optimizing the interfacial chemistry of porphyrin-ZnO NP assembly for photodynamic therapy and energy conversion.

Characterization of thermal and hydrodynamic properties for microencapsulated phase change slurry (MPCS)

International Nuclear Information System (INIS)

Chen, Lin; Wang, Ting; Zhao, Yan; Zhang, Xin-Rong

2014-01-01

Highlights: • Microencapsulated phase change slurry (MPCS) is reviewed and characterized for heat transfer and storage systems. • Basic formation, materials, properties are categorized and systematically analyzed. • Generalization and modelization of complex MPCS properties are made. • MPCS is identified to be one promising substitute in future energy systems. • Future research topics and applications are also specified. - Abstract: Microencapsulated phase change slurry (MPCS) is a new kind of multi-phase fluid that are proposed and utilized in heat transfer and heat storage systems. Different from traditional organic (paraffin or non-parafin) or inorganic phase change slurries, MPCS is able to maintain both high latent heat capacity and heat transfer rate under controlled volume changes and safe operation conditions. Consequently, in recent decade, MPCS has been widely proposed and tested in textile, building, cooling and heating, solar and thermal storage systems, etc. Based on those recent findings and application developments, characterizations of thermal and hydrodynamic properties for MPCS are made in this study. The basic objective of this paper is to summarize the features of MPCS properties and the establishment of models for MPCS properties and morphologies. The review and analysis are based on recent representative experimental studies, which are categorized into: properties, heat transfer characteristics, stability and applications. Due to the various materials and methods and carry fluids properties, no single model can cover the properties for all MPCS. In this study, each property is reviewed with its specific model and application regions. Basic trends are compared with other kinds of phase change materials. Finally, by investigating those results the future trends of MPCS are presented

Electromagnetic NDT to characterize usage properties of flat steel products - Part 2

International Nuclear Information System (INIS)

Altpeter, I.; Dobmann, G.; Szielasko, K.

2015-01-01

The Fraunhofer Institute for Non-destructive Testing (IZFP) in Saarbruecken, Germany, started its activities in materials characterization of flat steel products in the eighties of the last century in the basic program of the European Community of Coal and Steel (ECCS). Throughout the years, continuous research and development were performed. The objective of the work, presented within this three-part series of reports, is to discuss the history of an innovation which began in 1988 with R&D in the area of texture characterization in steel sheets produced for car-body manufacturing (Part 1). In the following years the activities were to automate online property determination in terms of yield strength, tensile strength, planar, and vertical-anisotropy-factors. Again, steel sheets were the focus of the developments and the first NDT systems that came into industrial application for this project. Parallel research was performed to characterize the mechanical properties and hardness of heavy steel plates, mainly produced for pipeline manufacturing and off-shore applications (Part 2) The final report in the series (Part 3) will discuss steel sheet characterization and presents the successful development of a combination-transducer which combines ultrasonics with electromagnetic NDT. (author)

Electromagnetic NDT to characterize usage properties of flat steel products - Part 3

International Nuclear Information System (INIS)

Altpeter, I.; Dobmann, G.; Szielasko, K.

2015-01-01

The Fraunhofer Institute for Nondestructive Testing (IZFP) in Saarbruecken, Germany, started its activities in materials characterization of flat steel products in the eighties of the last century in the basic program of the European Community of Coal and Steel (ECCS). Throughout the years, continuous research and development were performed. The objective of the work, presented within this three-part series of reports, is to discuss the history of an innovation that began in 1988 with R&D in the area of texture characterization in steel sheets produced for car-body manufacturing (Part 1). In the following years the activities were to automate online property determination in terms of yield strength, tensile strength, planar- and vertical-anisotropy factors. Again, steel sheets were the focus of the developments and first NDT systems came into industrial application. Parallel research was performed to characterize the mechanical properties and hardness on heavy steel plates, mainly produced for pipeline manufacturing and offshore applications (Part 2). The final report in the series (Part 3) discusses steel sheet characterization and presents the successful development of a combination transducer that combines ultrasonics with electromagnetic NDT. (author)

Electromagnetic NDT to characterize usage properties of flat steel products - Part 3

Energy Technology Data Exchange (ETDEWEB)

Altpeter, I.; Dobmann, G.; Szielasko, K., E-mail: iab.altlau@t-online.de, E-mail: gerd.dobmann@t-online.de, E-mail: klaus.szielasko@izfp.fraunhofer.de [Fraunhofer Inst. - IZFP, Saarbruecken (Germany)

2015-11-15

The Fraunhofer Institute for Nondestructive Testing (IZFP) in Saarbruecken, Germany, started its activities in materials characterization of flat steel products in the eighties of the last century in the basic program of the European Community of Coal and Steel (ECCS). Throughout the years, continuous research and development were performed. The objective of the work, presented within this three-part series of reports, is to discuss the history of an innovation that began in 1988 with R&D in the area of texture characterization in steel sheets produced for car-body manufacturing (Part 1). In the following years the activities were to automate online property determination in terms of yield strength, tensile strength, planar- and vertical-anisotropy factors. Again, steel sheets were the focus of the developments and first NDT systems came into industrial application. Parallel research was performed to characterize the mechanical properties and hardness on heavy steel plates, mainly produced for pipeline manufacturing and offshore applications (Part 2). The final report in the series (Part 3) discusses steel sheet characterization and presents the successful development of a combination transducer that combines ultrasonics with electromagnetic NDT. (author)

Electromagnetic NDT to characterize usage properties of flat steel products - Part 2

Energy Technology Data Exchange (ETDEWEB)

Altpeter, I.; Dobmann, G.; Szielasko, K., E-mail: iab.altlau@t-online.de, E-mail: gerd.dobmann@t-online.de, E-mail: klaus.szielasko@izfp.fraunhofer.de [Fraunhofer Inst. - IZFP, Saarbruecken (Germany)

2015-09-15

The Fraunhofer Institute for Non-destructive Testing (IZFP) in Saarbruecken, Germany, started its activities in materials characterization of flat steel products in the eighties of the last century in the basic program of the European Community of Coal and Steel (ECCS). Throughout the years, continuous research and development were performed. The objective of the work, presented within this three-part series of reports, is to discuss the history of an innovation which began in 1988 with R&D in the area of texture characterization in steel sheets produced for car-body manufacturing (Part 1). In the following years the activities were to automate online property determination in terms of yield strength, tensile strength, planar, and vertical-anisotropy-factors. Again, steel sheets were the focus of the developments and the first NDT systems that came into industrial application for this project. Parallel research was performed to characterize the mechanical properties and hardness of heavy steel plates, mainly produced for pipeline manufacturing and off-shore applications (Part 2) The final report in the series (Part 3) will discuss steel sheet characterization and presents the successful development of a combination-transducer which combines ultrasonics with electromagnetic NDT. (author)

Rationalizing the photophysical properties of BODIPY laser dyes via aromaticity and electron-donor-based structural perturbations

Energy Technology Data Exchange (ETDEWEB)

Waddell, Paul G.; Liu, Xiaogang; Zhao, Teng; Cole, Jacqueline M.

2015-05-01

The absorption and fluorescence properties of six boron dipyrromethene (BODIPY) laser dyes with simple non-aromatic substituents are rationalized by relating them to observable structural perturbations within the molecules of the dyes. An empirical relationship involving the structure and the optical properties is derived using a combination of single-crystal X-ray diffraction data, quantum chemical calculations and electronic constants: i.e. the tendency of the pyrrole bond lengths towards aromaticity and the UV-vis absorption and fluorescence wavelengths correlating with the electron-donor properties of the substituents. The effect of molecular conformation on the solid-state optical properties of the dyes is also discussed. The findings in this study also demonstrate the usefulness and limitations of using crystal structure data to develop structure-property relationships in this class of optical materials, contributing to the growing effort to design optoelectronic materials with tunable properties via molecular engineering.

Effects of alkyl or alkyloxy side chains in poly[4,6-bis(3´-dodecylthien-2´-yl)thieno-[3,4-c][1,2,5]thiadiazole-5´,5´-diyl-alt-2,5-di(alkyl or alkyloxy)-1,4-phenylene]: synthesis, photophysics, and spectroelectrochemical and photovoltaic properties

Czech Academy of Sciences Publication Activity Database

Cimrová, Věra; Pokorná, Veronika; Výprachtický, Drahomír

2017-01-01

Roč. 118, 2 June (2017), s. 180-191 ISSN 0032-3861 R&D Projects: GA ČR(CZ) GA13-26542S Institutional support: RVO:61389013 Keywords : low-bandgap thienothiadiazole copolymers * photophysics * spectroelectrochemistry Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.684, year: 2016

Photophysical studies of zinc phthalocyanine and chloroaluminum phthalocyanine incorporated into liposomes in the presence of additives

Directory of Open Access Journals (Sweden)

S.M.T. Nunes

2004-02-01

Full Text Available The photophysical properties of zinc phthalocyanine (ZnPC and chloroaluminum phthalocyanine (AlPHCl incorporated into liposomes of dimyristoyl phosphatidylcholine in the presence and absence of additives such as cholesterol or cardiolipin were studied by time-resolved fluorescence, laser flash photolysis and steady-state techniques. The absorbance of the drugs changed linearly with drug concentration, at least up to 5.0 µM in homogeneous and heterogeneous media, indicating that aggregation did not occur in these media within this concentration range. The incorporation of the drugs into liposomes increases the dimerization constant by one order of magnitude (for ZnPC, 3.6 x 10(4 to 1.0 x 10(5 M-1 and for AlPHCl, 3.7 x 10(4 to 1.5 x 10(5 M-1, but this feature dose does not rule out the use of this carrier, since the incorporation of these hydrophobic drugs into liposomes permits their systemic administration. Probe location in biological membranes and predominant positions of the phthalocyanines in liposomes were inferred on the basis of their fluorescence and triplet state properties. Both phthalocyanines are preferentially distributed in the internal regions of the liposome bilayer. The additives affect the distribution of these drugs within the liposomes, a fact that controls their delivery when both are used in a biological medium, retarding their release. The addition of the additives to the liposomes increases the internalization of phthalocyanines. The interaction of the drugs with a plasma protein, bovine serum albumin, was examined quantitatively by the fluorescence technique. The results show that when the drugs were incorporated into small unilamellar liposomes, the association with albumin was enhanced when compared with organic media, a fact that should increase the selectivity of tumor targeting by these phthalocyanines (for ZnPC, 0.71 x 10(6 to 1.30 x 10(7 M-1 and for AlPHCl, 4.86 x 10(7 to 3.10 x 10(8 M-1.

Synthesis, Characterization, and Electrochemical Properties of Polyaniline Thin Films

Science.gov (United States)

Rami, Soukaina

Conjugated polymers have been used in various applications (battery, supercapacitor, electromagnetic shielding, chemical sensor, biosensor, nanocomposite, light-emitting-diode, electrochromic display etc.) due to their excellent conductivity, electrochemical and optical properties, and low cost. Polyaniline has attracted the researchers from all disciplines of science, engineering, and industry due to its redox properties, environmental stability, conductivity, and optical properties. Moreover, it is a polymer with fast electroactive switching and reversible properties displayed at low potential, which is an important feature in many applications. The thin oriented polyaniline films have been fabricated using self-assembly, Langmuir-Blodgett, in-situ self-assembly, layer-by-layer, and electrochemical technique. The focus of this thesis is to synthesize and characterize polyaniline thin films with and without dyes. Also, the purpose of this thesis is to find the fastest electroactive switching PANI electrode in different electrolytic medium by studying their electrochemical properties. These films were fabricated using two deposition techniques: in-situ self-assembly and electrochemical deposition. The characterization of these films was done using techniques such as Fourier Transform Infrared Spectroscopy (FTIR), UV-spectroscopy, Scanning Electron Microscope (SEM), and X-Ray Diffraction (XRD). FTIR and UV-spectroscopy showed similar results in the structure of the polyaniline films. However, for the dye incorporated films, since there was an addition in the synthesis of the material, peak locations shifted, and new peaks corresponding to these materials appeared. The 1 layer PANI showed compact film morphology, comparing to other PANI films, which displayed a fiber-like structure. Finally, the electrochemical properties of these thin films were studied using cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) in

Determination of photophysical parameters of cyanines using different techniques. Application to DODCI (3-3' dietiloxacarbocyanine iodide)

International Nuclear Information System (INIS)

Duchowicz, R.; Scaffardi, L.; Di Paolo, R.E.; Tocho, J.O.

1990-01-01

A number of fluorescence and absorption techniques were developed for the determination of photo-physical parameters of photo-isomerizable cyanines. The application of these techniques, such as saturated fluorescence, double excitation fluorescence and temperature dependent absorption, to the specific case of 3-3' dietiloxadicarbocyanine iodide (DODCI), allowed the particular study of photo-isomer's exited state along with its decay processes. Fluorescence efficiency and the mean life of the photo-isomer as a function of temperature were obtained. The activation energy and the pre-exponential factor for the non-radioactive decay processes were determined. For the first time, the fluorescence spectrum of the transient isomer form was registered free of the emission of the normal species. (Author). 6 refs., 9 figs

Computational methods for 2D materials: discovery, property characterization, and application design.

Science.gov (United States)

Paul, J T; Singh, A K; Dong, Z; Zhuang, H; Revard, B C; Rijal, B; Ashton, M; Linscheid, A; Blonsky, M; Gluhovic, D; Guo, J; Hennig, R G

2017-11-29

The discovery of two-dimensional (2D) materials comes at a time when computational methods are mature and can predict novel 2D materials, characterize their properties, and guide the design of 2D materials for applications. This article reviews the recent progress in computational approaches for 2D materials research. We discuss the computational techniques and provide an overview of the ongoing research in the field. We begin with an overview of known 2D materials, common computational methods, and available cyber infrastructures. We then move onto the discovery of novel 2D materials, discussing the stability criteria for 2D materials, computational methods for structure prediction, and interactions of monolayers with electrochemical and gaseous environments. Next, we describe the computational characterization of the 2D materials' electronic, optical, magnetic, and superconducting properties and the response of the properties under applied mechanical strain and electrical fields. From there, we move on to discuss the structure and properties of defects in 2D materials, and describe methods for 2D materials device simulations. We conclude by providing an outlook on the needs and challenges for future developments in the field of computational research for 2D materials.

TCNQ-embedded heptacene and nonacene: Synthesis, characterization and physical properties

KAUST Repository

Ye, Qun

2013-01-01

Incorporation of 7,7,8,8-tetracyanoquinodimethane (TCNQ) moieties into the acene backbone has been successfully achieved and two heptacene-TCNQ derivatives and one nonacene-TCNQ derivative have been synthesized and well characterized. Two TCNQ moieties have been embedded into heptacene and nonacene backbones for the first time. All the three compounds have good stability and solubility due to the presence of TCNQ moieties. Single crystal analysis revealed a bent butterfly-like conformation of these molecules. Their charge transport properties have been characterized using organic field effect transistors (OFETs). © 2013 The Royal Society of Chemistry.

Preparation and Characterization of Ion-Irradiated Nanodiamonds as Photoacoustic Contrast Agents.

Science.gov (United States)

Fang, Chia-Yi; Chang, Cheng-Chun; Mou, Chung-Yuan; Chang, Huan-Cheng

2015-02-01

Highly radiation-damaged or irradiated nanodiamonds (INDs) are a new type of nanomaterial developed recently as a potential photoacoustic (PA) contrast agent for deep-tissue imaging. This work characterized in detail the photophysical properties of these materials prepared by ion irradiation of natural diamond powders using various spectroscopic methods. For 40-nm NDs irradiated with 40-keV He+ at a dose of 3 x 10(15) ions/cm2, an average molar extinction coefficient of 4.2 M-1 cm-1 per carbon atom was measured at 1064 nm. Compared with gold nanorods of similar dimensions (10 nm x 67 nm), the INDs have a substantially smaller (by > 4 orders of magnitude) molar extinction coefficient per particle. However, the deficit is readily compensated by the much higher thermal stability, stronger hydrophilic interaction with water, and a lower nanobubble formation threshold (~30 mJ/cm2) of the sp3-carbon-based nanomaterial. No sign of photodamage was detected after high-energy (>100 mJ/cm2) illumination of the INDs for hours. Cell viability assays at the IND concentration of up to 100 µg/mL showed that the nanomaterial is non-cytotoxic and potentially useful for long-term PA bioimaging applications.

Semiconductor interfaces of polycrystalline CdTe thin-film solar cells. Characterization and modification of electronic properties

International Nuclear Information System (INIS)

Fritsche, J.

2003-01-01

In this thesis for the first time the electronic properties of the semiconductor interfaces in polycrystalline CdTe thin-film solar cells, as well as the morphological and electronic properties of the single semiconductor surfaces were systematically characterized by surface-sensitive measuring methods. The morphological surface properties were analyzed by scanning force microscopy. As substrate materials with SnO 2 /ITO covered glass was applied, where the CdS and CdTe layers were deposited. Furthermore the electronic and morphological material properties of differently treated SnO 2 surfaces were characterized. Beside the studies with scanning force microscopy sputtering depth profiles and X-ray photoelectron spectroscopy were measured

Characterization of porosity in support of mechanical property analysis

International Nuclear Information System (INIS)

Price, R.H.; Martin, R.J. III; Boyd, P.J.

1993-01-01

The general applicability of laboratory data for engineering purposes is a prime concern for the design and licensing of a potential repository of high level nuclear waste at Yucca Mountain. In order for the results of experiments to be applicable to the repository scale, the data must be scaled to in situ size and conditions. Previous laboratory investigations of tuff have shown that porosity has a dominant, general effect on mechanical properties. As a result, it is very important for the interpretation of mechanical property data that porosity is measured on each sampled test. Porosity alone, however, does not address all of the issues important to mechanical behavior. Variability in size and distribution of pore space produces significantly different mechanical properties. A nondestructive technique for characterizing the internal structure of the sample prior to testing is being developed and the results are being analyzed. The information obtained from this technique can help in both qualitative and quantitative interpretation of test results

Synthesis and overall nonlinear optical characterization of poly(hexa-2,4-diynylen-1,6-dioxydibenzoate) containing 2,2′-(4-((4-nitrophenyl)ethynyl)phenylazanediyl)diethanol

International Nuclear Information System (INIS)

Castañón-Alonso, Sandra L.; Morales-Saavedra, Omar G.; Báez-Pimiento, Sandro; Ortega-Martínez, Roberto; Rodríguez-Rosales, Antonio A.; Hernández-Rojas, María E.

2012-01-01

Highlights: ► Synthesis of a novel polydiacetylene containing tolan units as NLO-chromophores. ► Quadratic and cubic NLO-characterizations were performed in prepared film samples. ► Outstanding NLO-coefficients were evaluated via the Z-Scan and SHG-techniques. ► High T g -values of this polymer indicates suitable properties for material processing. - Abstract: A new polymer, poly(p-propargyloxybenzoate) containing a polar tolan as nonlinear optically active chromophore was synthesized and characterized. This polymer shows a T g -value of ∼98 °C and is soluble in typical organic solvents. These properties allowed us to fabricate mechanically stable and high quality semi-transparent thin films by spin coating of N-methylpirrolidone based solutions; obtained samples were adequate for linear and nonlinear photophysical characterizations. In order to explore the quadratic nonlinear optical (NLO) properties, molecular chromophore ordering was electrically induced within the polymeric films via the corona poling method. According to the Maker fringes technique, oriented films with an order parameter of ∼0.25 were able to display large and stable off-resonant second-order NLO-effects such as second harmonic generation (SHG, - 532 nm); the estimated χ zzz (2) and χ zxx (2) macroscopic NLO-coefficients were in the order of 186.8 and 71.2 pm V −1 , respectively. On the other hand, the cubic NLO-properties of these films were also studied via the Z-Scan technique, where the deposited films displayed an outstanding NLO refractive (n 2 ) and absorptive (β) performance. Indeed, due to the high conjugation degree and intra-molecular charge transfer (ICT) properties, poled and unpoled polymer films displayed huge n 2 -values in the order of 10 −8 m 2 W −1 with negative sign and NLO saturable absorption β-coefficients in the order of 10 −1 m W −1 . The large quadratic and cubic NLO-coefficients obtained for this novel polymer evidence its potentiality in

Responsive copolymers for enhanced petroleum recovery

Energy Technology Data Exchange (ETDEWEB)

McCormick, Charles; Hester, Roger

2000-06-13

The objectives of this work were to: synthesize responsive, amphiphilic systems; characterize molecular structure and solution behavior; measure rheological properties of the aqueous fluids including behavior in fixed geometry flow profiles and beds; and to tailor final polymer compositions for in situ rheology control under simulated reservoir conditions. This report focuses on the first phase of the research emphasizing synthesis and the development of photophysical techniques and rheological means of following segmental organization at the structural level.

Characterization of elevated temperature properties of heat exchanger and steam generator alloys

International Nuclear Information System (INIS)

Wright, J.K.; Carroll, L.J.; Cabet, C.; Lillo, T.M.; Benz, J.K.; Simpson, J.A.; Lloyd, W.R.; Chapman, J.A.; Wright, R.N.

2012-01-01

The Next Generation Nuclear Plant project is considering Alloy 800H and Alloy 617 for steam generator and intermediate heat exchangers. It is envisioned that a steam generator would operate with reactor outlet temperatures from 750 to 800 °C, while an intermediate heat exchanger for primary to secondary helium would operate up to an outlet temperature of 950 °C. Although both alloys are of interest due in part to their technical maturity, a number of specific properties require further characterization for design of nuclear components. Strain rate sensitivity of both alloys has been characterized and is found to be significant above 600 °C. Both alloys also exhibit dynamic strain aging, characterized by serrated flow, over a wide range of temperatures and strain rates. High temperature tensile testing of Alloy 617 and Alloy 800H has been conducted over a range of temperatures. Dynamic strain aging is a concern for these materials since it is observed to result in reduced ductility for many solid solution alloys. Creep, fatigue, and creep–fatigue properties of Alloy 617 have been measured as well, with the goal of determining the influence of the temperature, strain rate and atmosphere on the creep–fatigue life of Alloy 617. Elevated temperature properties and implications for codification of the alloys will be described.

Modeling and characterization of through-the-thickness properties of 3D woven composites

Science.gov (United States)

Hartranft, Dru; Pravizi-Majidi, Azar; Chou, Tsu-Wei

1995-01-01

The through-the-thickness properties of three-dimensionally (3D) woven carbon/epoxy composites have been studied. The investigation aimed at the evaluation and development of test methodologies for the property characterization in the thickness direction, and the establishment of fiber architectures were studied: layer-to-layer Angle Interlock, through-the-thickness Orthogonal woven preform with surface pile was also designed and manufactured for the fabrication of tensile test coupons with integrated grips. All the preforms were infiltrated by the resin transfer molding technique. The microstructures of the composites were characterized along the warp and fill (weft) directions to determine the degree of yarn undulations, yarn cross-sectional shapes, and microstructural dimensions. These parameters were correlated to the fiber architecture. Specimens were designed and tested for the direct measurement of the through-the-thickness tensile, compressive and shear properties of the composites. Design optimization was conducted through the analysis of the stress fields within the specimen coupled with experimental verification. The experimentally-derived elastic properties in the thickness direction compared well with analytical predictions obtained from a volume averaging model.

Synthesis, characterization, and property studies of (La, Ag) FeO{sub 3} (0.0 {<=} x {<=} 0.3) perovskites

Energy Technology Data Exchange (ETDEWEB)

Bellakki, Manjunath B.; Kelly, Brandon J. [Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523 (United States); Manivannan, V., E-mail: mani@engr.colosate.ed [Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523 (United States)

2010-01-07

Applying a solution - based combustion process, Ag-doped LaFeO{sub 3} orthoferrites were synthesized. The samples were characterized by multiple techniques to establish structure - property relationships. Specifically, for structural characterization, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Fourier transmission infrared spectroscopy (FTIR), Thermo-gravimetric analysis (TGA), and X-ray photoelectron microscopy (XPS) were carried out. For properties, squid magnetometer measurements (for magnetic properties), titrations (for chemical analysis), and diffuse reflectance (for optical band gap properties) measurements were carried out to elucidate structure-property relationship.

Poly-β-hydroxybutyrate sensitizing effect on the photophysical properties of environment friendly fluorescent films containing europium complex

Energy Technology Data Exchange (ETDEWEB)

Yang, Chaolong, E-mail: yclzjun@163.com [School of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054 (China); Zhang, Pan; Zhou, Hualin [School of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054 (China); Xu, Jing [Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Azaaoba 6-3, Aoba-ku, Sendai (Japan); Li, Youbing [School of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054 (China); Lu, Mangeng [Key Laboratory of Polymer Materials for Electronics, Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650 (China); Lei, Lei; Zhang, Qiang; Zhang, Yi; Chen, Shaopeng [School of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054 (China)

2016-10-15

A series of environment friendly Eu/PHB fluorescent films through doped the Eu-complex precursor Eu(TTA){sub 2}(Tpy-OCH{sub 3})(2H{sub 2}O) into polymer matrices poly-β-hydroxybutyrate (PHB) with doping percentage at 1, 3, 5, and 7 (mass) were designed, fabricated and characterized. TGA and PL results indicated the Eu-complex precursor was immobilized in PHB matrix through the interaction between the Eu-complex. DSC results indicated the crystallinity of Eu/PHB films decreased with the increase of Eu-complex doping percentage. The emission spectra of the Eu-complex and Eu/PHB films recorded at room temperature exhibited the characteristic bands arising from the {sup 5}D{sub 0}/{sup 7}F{sub J}. The fact that the quantum efficiencies (η) of the doped film increased significantly revealed that the PHB matrix acts as an efficient co-sensitizer for Eu{sup 3+} ions luminescent center and therefore enhances the quantum efficiency of the emitter {sup 5}D{sub 0} level. In particular, all Eu/PHB films can be excited by visible light (410 nm), and also showed good photoluminescent properties. So the new Eu/PHB fluorescent films showed considerable promise for polymer light-emitting diode, active polymer optical fiber and biomedical analysis applications.

Poly-β-hydroxybutyrate sensitizing effect on the photophysical properties of environment friendly fluorescent films containing europium complex

International Nuclear Information System (INIS)

Yang, Chaolong; Zhang, Pan; Zhou, Hualin; Xu, Jing; Li, Youbing; Lu, Mangeng; Lei, Lei; Zhang, Qiang; Zhang, Yi; Chen, Shaopeng

2016-01-01

A series of environment friendly Eu/PHB fluorescent films through doped the Eu-complex precursor Eu(TTA) 2 (Tpy-OCH 3 )(2H 2 O) into polymer matrices poly-β-hydroxybutyrate (PHB) with doping percentage at 1, 3, 5, and 7 (mass) were designed, fabricated and characterized. TGA and PL results indicated the Eu-complex precursor was immobilized in PHB matrix through the interaction between the Eu-complex. DSC results indicated the crystallinity of Eu/PHB films decreased with the increase of Eu-complex doping percentage. The emission spectra of the Eu-complex and Eu/PHB films recorded at room temperature exhibited the characteristic bands arising from the 5 D 0 / 7 F J . The fact that the quantum efficiencies (η) of the doped film increased significantly revealed that the PHB matrix acts as an efficient co-sensitizer for Eu 3+ ions luminescent center and therefore enhances the quantum efficiency of the emitter 5 D 0 level. In particular, all Eu/PHB films can be excited by visible light (410 nm), and also showed good photoluminescent properties. So the new Eu/PHB fluorescent films showed considerable promise for polymer light-emitting diode, active polymer optical fiber and biomedical analysis applications.

Characterization and Some Properties of Functionalized Graft Copolymer

International Nuclear Information System (INIS)

Hegazy El-Sayed, A.; Kamal, H.; Mahmoud, Gh.A.; Khalifa, N.A.

2000-01-01

The study involved the investigation and characterization of membranes prepared by graft copolymerization of acrylonitrile (AN) and vinyl acetate (VAc) binary monomers onto low density polyethylene (LDPE) and isotactic polypropylene (IPP). The mutual gamma-irradiation method was used as a grafting technique. The effects of grafting and chemical treatments on the thermal properties and crystallinity of prepared graft copolymer have been investigated using DSC, TGA and XRD. IR spectra recorded before and after grafting and also for the chemically treated membranes to elucidate the structural changes occurred due to grafting and chemical treatments

Photo-physical properties of dimers formed by tri-aryl pyrylium salts: experimental and theoretical study

International Nuclear Information System (INIS)

Lampre, Isabelle

1996-01-01

This research thesis reports the study of dimers formed in solution by aggregation of tri-aryl pyrylium salts, in order to establish a direct correlation between properties and electronic structure of components, on the one hand, and molecular pattern, on the other hand. The author adopted a multidisciplinary approach by using experimental techniques and calculations based on the excitonic theory and methods of quantum chemistry. First, the properties of the first excited states of cationic chromophores have been studied (characterisation of electronic transitions, relaxation at the singlet excited state, formation of triplet state). Then, the author analysed dimerisation processes and showed that each dimer is formed by two pairs of ions. She discusses some original optical properties of dimers. The geometry of dimers is theoretically determined by minimising the system interaction potential energy. Electronic transitions are then determined as linear combinations of transitions of two monomers. Properties are thus calculated and are in agreement with those deduced from spectral analysis. The experimentally noticed polarisation change and large Stokes displacement are then explained in terms of emission for a localised state on a chromophore [fr

Physical properties and characterization of Ag doped CdS thin films

International Nuclear Information System (INIS)

Shah, N.A.; Nazir, A.; Mahmood, W.; Syed, W.A.A.; Butt, S.; Ali, Z.; Maqsood, A.

2012-01-01

Highlights: ► CdS thin films were grown. ► By ion exchange, Ag was doped. ► Physical properties were investigated. - Abstract: Thin films of cadmium sulfide with very well defined preferential orientation and relatively high absorption coefficient were fabricated by thermal evaporation technique. The research is focused to the fabrication and characterization of the compositional data of CdS thin films obtained by using X-ray diffraction, scanning electron microscope along with energy dispersive X-ray spectroscopy. The optical properties were studied by using a UV-VIS-NIR spectrophotometer. The effects of silver-doping by ion exchange process on the properties of as-deposited CdS thin films have been investigated.

Hybrid Organic/Inorganic Perovskite–Polymer Nanocomposites: Toward the Enhancement of Structural and Electrical Properties

KAUST Repository

Privitera, Alberto; Righetto, Marcello; de Bastiani, Michele; Carraro, Francesco; Rancan, Marzio; Armelao, Lidia; Granozzi, Gaetano; Bozio, Renato; Franco, Lorenzo

2017-01-01

Hybrid organic/inorganic perovskite nanoparticles (NPs) have garnered remarkable research attention because of their promising photophysical properties. New and interesting properties emerge after combining perovskite NPs with semiconducting materials. Here, we report the synthesis and investigation of a composite material obtained by mixing CH3NH3PbBr3 nanocrystals with the semiconducting polymer poly(3-hexylthiophene) (P3HT). By the combination of structural techniques and optical and magnetic spectroscopies we observed multiple effects of the perovskite NPs on the P3HT: (i) an enlargement of P3HT crystalline domains, (ii) a strong p-doping of the P3HT, and (iii) an enhancement of interchain order typical of H-aggregates. These observations open a new avenue toward innovative perovskite NP-based applications.

Hybrid Organic/Inorganic Perovskite–Polymer Nanocomposites: Toward the Enhancement of Structural and Electrical Properties

KAUST Repository

Privitera, Alberto

2017-11-30

Hybrid organic/inorganic perovskite nanoparticles (NPs) have garnered remarkable research attention because of their promising photophysical properties. New and interesting properties emerge after combining perovskite NPs with semiconducting materials. Here, we report the synthesis and investigation of a composite material obtained by mixing CH3NH3PbBr3 nanocrystals with the semiconducting polymer poly(3-hexylthiophene) (P3HT). By the combination of structural techniques and optical and magnetic spectroscopies we observed multiple effects of the perovskite NPs on the P3HT: (i) an enlargement of P3HT crystalline domains, (ii) a strong p-doping of the P3HT, and (iii) an enhancement of interchain order typical of H-aggregates. These observations open a new avenue toward innovative perovskite NP-based applications.

Physico-chemical studies of the experimental and theoretical properties of organic nonlinear optical material 4-chloro-4'methoxy benzylideneaniline

Science.gov (United States)

George, Merin; John, Nimmy L.; Saravana Kumar, M.; Subashini, A.; Sajan, D.

2017-01-01

The FT-IR, FT-Raman and UV-visible spectral analysis of 4-chloro 4'-methoxy benzylidene aniline were done experimentally and interpreted with the aid of normal coordinate analysis based on density functional theory (DFT) at the B3LYP/6-311++G (d, p) level of theory. Natural Bond orbital analysis was performed to understand the charge transfer interactions and reactive sites within the system. HOMO-LUMO analysis and first static and dynamic hyperpolarizability calculations were carried out in order to confirm the NLO activity of CMOBA. Photophysical characterization was done to understand the fluorescence emission and lifetime of CMOBA leading to application in blue OLEDs. The Molecular Electrostatic Potential Map was simulated to identify the active sites for electrophilic and nucleophilic attack or the active sites of the molecule which can bind to proteins. Molecular docking analysis revealed its potential as an inhibitor for different proteins which are responsible for cancer and many inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease, Crohn's disease and psoriasis. Experimental studies of invitro antiproliferative effect by MTT assay verified the anticancer properties of CMOBA.

Influence of different water-ethanol solvent systems on the spectroscopic and physico-chemical properties of the macrocyclic compounds pheophytin and chlorophyll a

International Nuclear Information System (INIS)

Moreira, Leonardo M.; Rodrigues, Maira R.; Oliveira, Hueder P. M. de; Lima, Adriana; Soares, Rafael R. S.; Batistela, Vagner R.; Gerola, Adriana P.; Hioka, Noboru; Severino, Divinomar; Baptista, Mauricio S.; Machado, Antonio Eduardo da Hora

2010-01-01

This work focus on the influence of solvent on the photophysical properties of chlorophyll a and pheophytin. Both compounds are related to the photosynthesis process and are considered prototypes of photosensitizers in Photodynamic Therapy. Fluorescence measurements were developed using water/ethanol mixtures at different compositions, since both solvents could be employed in biological applications. The spectroscopic properties of these compounds undergo profound changes depending on water content in the ethanol due to auto-aggregation processes. The major hydrophobicity and the lower dielectric constant of ethanol when compared with water precluded significantly the auto-aggregation process of these compounds. (author)

Investigations of the Photo-Physical Properties of Novel Photo-Voltaic and Light Emitting Materials

National Research Council Canada - National Science Library

Goodson, Theodore G

2004-01-01

.... This report highlights the distinctive optical properties of dendrimers; branched chromophore systems as well as dendrimer encapsulated metal nanoparticles which provide a novel approach toward this challenge...

Characterization of dielectric properties of nanocellulose from wood and algae for electrical insulator applications.

Science.gov (United States)

Le Bras, David; Strømme, Maria; Mihranyan, Albert

2015-05-07

Cellulose is one of the oldest electrically insulating materials used in oil-filled high-power transformers and cables. However, reports on the dielectric properties of nanocellulose for electrical insulator applications are scarce. The aim of this study was to characterize the dielectric properties of two nanocellulose types from wood, viz., nanofibrillated cellulose (NFC), and algae, viz., Cladophora cellulose, for electrical insulator applications. The cellulose materials were characterized with X-ray diffraction, nitrogen gas and moisture sorption isotherms, helium pycnometry, mechanical testing, and dielectric spectroscopy at various relative humidities. The algae nanocellulose sample was more crystalline and had a lower moisture sorption capacity at low and moderate relative humidities, compared to NFC. On the other hand, it was much more porous, which resulted in lower strength and higher dielectric loss than for NFC. It is concluded that the solid-state properties of nanocellulose may have a substantial impact on the dielectric properties of electrical insulator applications.

Characterization of thermal, hydraulic, and gas diffusion properties in variably saturated sand grades

DEFF Research Database (Denmark)

Deepagoda Thuduwe Kankanamge Kelum, Chamindu; Smits, Kathleen; Ramirez, Jamie

2016-01-01

porous media transport properties, key transport parameters such as thermal conductivity and gas diffusivity are particularly important to describe temperature-induced heat transport and diffusion-controlled gas transport processes, respectively. Despite many experimental and numerical studies focusing...... transport models (thermal conductivity, saturated hydraulic conductivity, and gas diffusivity). An existing thermal conductivity model was improved to describe the distinct three-region behavior in observed thermal conductivity–water saturation relations. Applying widely used parametric models for saturated......Detailed characterization of partially saturated porous media is important for understanding and predicting vadose zone transport processes. While basic properties (e.g., particle- and pore-size distributions and soil-water retention) are, in general, essential prerequisites for characterizing most...

CHARACTERIZATION OF NATURAL ZEOLITE AND DETERMINATION ITS ADSORPTION PROPERTIES

Directory of Open Access Journals (Sweden)

Marian HOLUB

Full Text Available Pollution of water by toxic substances is one of the major reason concerning human health as well as the environmental quality. In terms of pollution, mining activities represent a serious threat. Countries of the middle Europe, where extraction of mineral resources takes place a long period, have to solve the problems of wastewater containing whole spectra of heavy metals, which are dangerous to the environment. Finding of the new and cheap ways of wastewater contaminated by heavy metals treatment can increase the quality of the environment in the affected localities and thus prevent adverse effects on fauna, flora or human beings. Sorption techniques belong to a cost effective methods that are able to effectively remove heavy metals. For the overall understanding of the sorption process, it is necessary to characterize and determine the properties of the used adsorbents. The paper deals with characterization of natural zeolite before and after sorption process under acidic conditions. The zeolite was characterized using Fourier transform infrared spectroscopy, X – ray diffraction, scanning electron microscopy and N2 adsorption/desorption isotherms.

Emission color tuning in AlQ3 complexes with extended conjugated chromophores.

Science.gov (United States)

Pohl, Radek; Anzenbacher, Pavel

2003-08-07

[reaction: see text] A new method for the synthesis of 5-arylethynyl-8-hydroxyquinoline ligands using Sonogashira-Hagihara coupling was developed. The electronic nature of arylethynyl substituents affects the emission color and quantum yield of the resulting Al(III) complex. Photophysical properties of the metallocomplexes correspond to the electron-withdrawing/-donating character of the arylethynyl substituents. Optical properties of such Al(III) complexes correlate with the Hammett constant values of the respective substituents. This strategy offers a powerful tool for the preparation of electroluminophores with predictable photophysical properties.

Materials characterization of free volume and void properties by two-dimensional positron annihilation lifetime spectroscopy

Science.gov (United States)

Chen, Hongmin; Van Horn, J. David; Jean, Y. C.; Hung, Wei-Song; Lee, Kueir-Rarn

2013-04-01

Positron annihilation lifetime spectroscopy (PALS) has been widely used to determine the free volume and void properties in polymeric materials. Recently, a two dimensional positron annihilation lifetime spectroscopy (2DPALS) system has been developed for membrane applications. The system measures the coincident signals between the lifetime and the energy which could separate the 2γ and 3γ annihilations and improve the accuracy in the determination of the free volume and void properties. When 2D-PALS is used in coupling with a variable mono-energy slow positron beam, it could be applied to a variety of material characterization. Results of free volumes and voids properties in a multi-layer polymer membrane characterized using 2D-PALS are presented.

Novel polymeric potassium complex: Its synthesis, structural characterization, photoluminescence and electrochemical properties

Energy Technology Data Exchange (ETDEWEB)

Ceyhan, Goekhan [Chemistry Department, K.Maras Suetcue Imam University, 46100 K.Maras (Turkey); Tuemer, Mehmet, E-mail: mtumer@ksu.edu.tr [Chemistry Department, K.Maras Suetcue Imam University, 46100 K.Maras (Turkey); Koese, Muhammet; McKee, Vickie [Chemistry Department, Loughborough University, LE11 3TU Leicestershire (United Kingdom)

2012-03-15

In this paper, we obtained a novel poly(vanillinato potassium) complex (PVP) as a single crystal and characterized by analytical and spectroscopic methods. A single crystal of the PVP was obtained from the acetone solution. X-ray structural data show that crystals contain polymeric K{sup +} complex of vanillin. Each potassium ion in the polymeric structure is identical and seven-coordinate, bonded to two methoxy, two phenoxy and three aldehyde oxygen atoms from four vaniline molecules. Two aldehyde oxygen atoms are bridging between potassium ions. It crystallizes in the monoclinic system, space group P2{sub 1}/c, with lattice parameters a=9.6215(10) A, b=17.4139(19) A, c=9.6119(10) A, {beta}=100.457(2) Degree-Sign and Z=4. Thermal properties of the PVP were investigated by TGA, DTA and DSC methods. The electrochemical properties of the complex were studied in different solvents and at various scan rates. The luminescence properties of the complex in different solvents and at different pH values have been investigated. The results show that the complex exhibits more efficient luminescence property in CH{sub 3}CN and n-butanol. - Highlights: Black-Right-Pointing-Pointer Novel polymeric potassium complex was prepared and fully characterized. Black-Right-Pointing-Pointer X-ray crystal structure of complex was reported. Black-Right-Pointing-Pointer Electrochemical properties of compound were investigated. Black-Right-Pointing-Pointer Thermal and DSC measurements of complex were examined.

Fabrication, Characterization, Properties, and Applications of Low-Dimensional BiFeO3 Nanostructures

Directory of Open Access Journals (Sweden)

Heng Wu

2014-01-01

Full Text Available Low-dimensional BiFeO3 nanostructures (e.g., nanocrystals, nanowires, nanotubes, and nanoislands have received considerable attention due to their novel size-dependent properties and outstanding multiferroic properties at room temperature. In recent years, much progress has been made both in fabrications and (microstructural, electrical, and magnetic in characterizations of BiFeO3 low-dimensional nanostructures. An overview of the state of art in BiFeO3 low-dimensional nanostructures is presented. First, we review the fabrications of high-quality BiFeO3 low-dimensional nanostructures via a variety of techniques, and then the structural characterizations and physical properties of the BiFeO3 low-dimensional nanostructures are summarized. Their potential applications in the next-generation magnetoelectric random access memories and photovoltaic devices are also discussed. Finally, we conclude this review by providing our perspectives to the future researches of BiFeO3 low-dimensional nanostructures and some key problems are also outlined.

Multi-property characterization chamber for geophysical-hydrological investigations of hydrate bearing sediments

Energy Technology Data Exchange (ETDEWEB)

Seol, Yongkoo, E-mail: Yongkoo.Seol@netl.doe.gov; Choi, Jeong-Hoon; Dai, Sheng [National Energy Technology Laboratory, U.S. Department of Energy, Morgantown, West Virginia 26507 (United States)

2014-08-01

With the increase in the interest of producing natural gas from methane hydrates as well as potential risks of massive hydrate dissociation in the context of global warming, studies have recently shifted from pure hydrate crystals to hydrates in sediments. Such a research focus shift requires a series of innovative laboratory devices that are capable of investigating various properties of hydrate-bearing sediments (HBS). This study introduces a newly developed high pressure testing chamber, i.e., multi-property characterization chamber (MPCC), that allows simultaneous investigation of a series of fundamental properties of HBS, including small-strain stiffness (i.e., P- and S-waves), shear strength, large-strain deformation, stress-volume responses, and permeability. The peripheral coolant circulation system of the MPCC permits stable and accurate temperature control, while the core holder body, made of aluminum, enables X-ray computer tomography scanning to be easily employed for structural and morphological characterization of specimens. Samples of hydrate-bearing sediments are held within a rubber sleeve inside the chamber. The thick sleeve is more durable and versatile than thin membranes while also being much softer than oedometer-type chambers that are incapable of enabling flow tests. Bias introduced by the rubber sleeve during large deformation tests are also calibrated both theoretically and experimentally. This system provides insight into full characterization of hydrate-bearing sediments in the laboratory, as well as pressure core technology in the field.

Multi-property characterization chamber for geophysical-hydrological investigations of hydrate bearing sediments

International Nuclear Information System (INIS)

Seol, Yongkoo; Choi, Jeong-Hoon; Dai, Sheng

2014-01-01

With the increase in the interest of producing natural gas from methane hydrates as well as potential risks of massive hydrate dissociation in the context of global warming, studies have recently shifted from pure hydrate crystals to hydrates in sediments. Such a research focus shift requires a series of innovative laboratory devices that are capable of investigating various properties of hydrate-bearing sediments (HBS). This study introduces a newly developed high pressure testing chamber, i.e., multi-property characterization chamber (MPCC), that allows simultaneous investigation of a series of fundamental properties of HBS, including small-strain stiffness (i.e., P- and S-waves), shear strength, large-strain deformation, stress-volume responses, and permeability. The peripheral coolant circulation system of the MPCC permits stable and accurate temperature control, while the core holder body, made of aluminum, enables X-ray computer tomography scanning to be easily employed for structural and morphological characterization of specimens. Samples of hydrate-bearing sediments are held within a rubber sleeve inside the chamber. The thick sleeve is more durable and versatile than thin membranes while also being much softer than oedometer-type chambers that are incapable of enabling flow tests. Bias introduced by the rubber sleeve during large deformation tests are also calibrated both theoretically and experimentally. This system provides insight into full characterization of hydrate-bearing sediments in the laboratory, as well as pressure core technology in the field

Structure-dependent photophysical properties of singlet and triplet metal-to-ligand charge transfer states in copper(I) bis(diimine) compounds.

Science.gov (United States)

Siddique, Zainul Abedin; Yamamoto, Yuichi; Ohno, Takeshi; Nozaki, Koichi

2003-10-06

The photophysical properties of singlet and triplet metal-to-ligand charge transfer (MLCT) states of [Cu(I)(diimine)(2)](+), where diimine is 2,9-dimethyl-1,10-phenanthroline (dmphen), 2,9-dibutyl-1,10-phenanthroline (dbphen), or 6,6'-dimethyl-2,2'-bipyridine (dmbpy), were studied. On 400 nm laser excitation of [Cu(dmphen)(2)](+) in CH(2)Cl(2) solution, prompt (1)MLCT fluorescence with a quantum yield of (2.8 +/- 0.8) x 10(-5) was observed using a picosecond time-correlated single photon counting technique. The quantum yield was dependent on the excitation wavelength, suggesting that relaxation of the Franck-Condon state to the lowest (1)MLCT competes with rapid intersystem crossing (ISC). The fluorescence lifetime of the copper(I) compound was 13-16 ps, unexpectedly long despite a large spin-orbit coupling constant of 3d electrons in copper (829 cm(-1) ). Quantum chemical calculations using a density functional theory revealed that the structure of the lowest (1)MLCT in [Cu(dmphen)(2)](+) (1(1)B(1)) was flattened due to the Jahn-Teller effect in 3d(9) electronic configuration, and the dihedral angle between the two phenanthroline planes (dha) was about 75 degrees with the dha around 90 degrees in the ground state. Intramolecular reorganization energy for the radiative transition of 1(1)B(1) was calculated as 2.1 x 10(3) cm(-1), which is responsible for the large Stokes shift of the fluorescence observed (5.4 x 10(3) cm(-1)). To understand the sluggishness of the intersystem crossing (ISC) of (1)MLCT of the copper(I) compounds, the strength of the spin-orbit interaction between the lowest (1)MLCT (1(1)B(1)) and all (3)MLCT states was calculated. The ISC channels induced by strong spin-orbit interactions (ca. 300 cm(-1)) between the metal-centered HOMO and HOMO - 1 were shown to be energetically unfavorable in the copper(I) compounds because the flattening distortion caused large splitting (6.9 x 10(3) cm(-1)) between these orbitals. The possible ISC is therefore

On the elastic properties of carbon nanotube-based composites: modelling and characterization

CERN Document Server

Thostenson, E T

2003-01-01

The exceptional mechanical and physical properties observed for carbon nanotubes has stimulated the development of nanotube-based composite materials, but critical challenges exist before we can exploit these extraordinary nanoscale properties in a macroscopic composite. At the nanoscale, the structure of the carbon nanotube strongly influences the overall properties of the composite. The focus of this research is to develop a fundamental understanding of the structure/size influence of carbon nanotubes on the elastic properties of nanotube-based composites. Towards this end, the nanoscale structure and elastic properties of a model composite system of aligned multi-walled carbon nanotubes embedded in a polystyrene matrix were characterized, and a micromechanical approach for modelling of short fibre composites was modified to account for the structure of the nanotube reinforcement to predict the elastic modulus of the nanocomposite as a function of the constituent properties, reinforcement geometry and nanot...

Evaluation of the Intramolecular Charge-Transfer Properties in Solvatochromic and Electrochromic Zinc Octa(carbazolyl)phthalocyanines.

Science.gov (United States)

Majeed, Shereen A; Ghazal, Basma; Nevonen, Dustin E; Goff, Philip C; Blank, David A; Nemykin, Victor N; Makhseed, Saad

2017-10-02

2,3,9,10,16,17,23·24-Octakis-(9H-carbazol-9-yl) phthalocyaninato zinc(II) (3) and 2,3,9,10,16,17,23·24-octakis-(3,6-di-tert-butyl-9H-carbazole) phthalocyaninato zinc(II) (4) complexes were prepared and characterized by NMR and UV-vis spectroscopies, magnetic circular dichroism (MCD), matrix-assisted laser desorption ionization mass spectrometry, and X-ray crystallography. UV-vis and MCD data are indicative of the interligand charge-transfer nature of the broad band observed in 450-500 nm range for 3 and 4. The redox properties of 3 and 4 were probed by electrochemical and spectro-electrochemical methods, which are suggestive of phthalocyanine-centered first oxidation and reduction processes. Photophysics of 3 and 4 were investigated by steady-state fluorescence and time-resolved transient absorption spectroscopy demonstrating the influence of the carbazole substituents on deactivation from the first excited state in 3 and 4. Protonation of the meso-nitrogen atoms in 3 results in much faster deactivation kinetics from the first excited state. Spectroscopic data were correlated with density functional theory (DFT) and time-dependent DFT calculations on 3 and 4.

UHV mirror mounts for photophysics beamline at Indus-I

International Nuclear Information System (INIS)

Meenakshi Raja Rao, P.; Bhattacharya, S.S.; Das, N.C.; Rajasekhar, B.N.; Roy, A.P.

1995-01-01

Photophysics beamline makes use of a combination of two toroidal mirrors and one meter Seya-Namioka Monochromator in its fore optics. The fore optics monochromatises and steers the synchrotron radiation source (SRS) beam from its tangent point to the sample situated at a distance of about five meters. Slit widths of the monochromator are of the order of 100μ and the sample size is one mm 2 . Hence it is essential to impart precision rotational and translational movements of the same order of magnitude to the mirrors with the use of appropriate mirror mounts. Since Indus-1 operates at a pressure -9 mbar, the mirror mounts should be UHV compatible and the movements should be actuated under UHV. The mirrors along with the mirror mounts are enclosed in UHV chambers. The mirror chambers have been fabricated at Centre for Advanced Technology (CAT) workshops and tested up to a pressure of 10 -9 mbar. The mirror mounts are designed, fabricated and leak checked (He leak rate -10 std cc/s) The precision movements are achieved with the help of bellow sealed shaft mechanism and adjustable screws provided with the kinematic mount of the mirror frame. The performance of the mirror mount was tested at atmospheric pressure by using a laser beam and found to be good. The minimum displacement of the laser beam at slit and sample positions is ∼ 70μ which is quite adequate for optical alignment. The performance of the mirror mount under UHV conditions is being evaluated. (author). 4 refs., 3 figs

Novel technique for online characterization of cartilaginous tissue properties.

Science.gov (United States)

Yuan, Tai-Yi; Huang, Chun-Yuh; Yong Gu, Wei

2011-09-01

The goal of tissue engineering is to use substitutes to repair and restore organ function. Bioreactors are an indispensable tool for monitoring and controlling the unique environment for engineered constructs to grow. However, in order to determine the biochemical properties of engineered constructs, samples need to be destroyed. In this study, we developed a novel technique to nondestructively online-characterize the water content and fixed charge density of cartilaginous tissues. A new technique was developed to determine the tissue mechano-electrochemical properties nondestructively. Bovine knee articular cartilage and lumbar annulus fibrosus were used in this study to demonstrate that this technique could be used on different types of tissue. The results show that our newly developed method is capable of precisely predicting the water volume fraction (less than 3% disparity) and fixed charge density (less than 16.7% disparity) within cartilaginous tissues. This novel technique will help to design a new generation of bioreactors which are able to actively determine the essential properties of the engineered constructs, as well as regulate the local environment to achieve the optimal conditions for cultivating constructs.

Photo-physical characterization of fluorophore Ru(bpy32+ for optical biosensing applications

Directory of Open Access Journals (Sweden)

E.L. Sciuto

2015-12-01

Full Text Available We studied absorption, emission and lifetime of the coordination compound tris(2,2′-bipyridylruthenium(II fluorophore (Ru(bpy32+ both dissolved in water solutions and dried. Lifetime measurements were carried out using a new detector, the Silicon Photomultiplier (SiPM, which is more sensitive and physically much smaller than conventional optical detectors, such as imager and scanner. Through these analyses and a morphological characterization with transmission electron microscopy, revealed its usability for sensor applications, in particular, as dye in optical DNA-chip technology, a viable alternative to the conventional CY5 fluorophore. The use of Ru(bpy32+ would solve some of the typical disadvantages related to Cy5’s application, such as self-absorption of fluorescence and photobleaching. In addition, the Ru(bpy32+ longer lifetime may play a key role in the definition of new optical DNA-chip. Keywords: Tris(2,2′-bipyridylruthenium(II, Fluorophore, Spectroscopy, Lifetime measurements, SiPM, TEM

Phosphorescent rhenium emitters based on two electron-withdrawing diamine ligands: Structure, characterization and electroluminescent performance

Energy Technology Data Exchange (ETDEWEB)

Rui, Mei, E-mail: meirui2015@163.com [College of Science, Hebei North University, Zhangjiakou 075000, Hebei (China); Yuhong, Wang [College of Science, Hebei North University, Zhangjiakou 075000, Hebei (China); Yinting, Wang; Na, Zhang [Communication Training Base of The Headquarters of The General Staff, Zhangjiakou 075100, Hebei (China)

2014-09-15

In this paper, two diamine ligands having electron-withdrawing oxadiazole group and their corresponding Re(I) complexes were synthesized. Their geometric structure, electronic transition, photophysical property, thermal stability and electrochemical property were discussed in detail. Experimental data suggested that both complexes were promising yellow emitters with suited energy levels and good thermal stability for electroluminescent application. The correlation between emission performance and electron-withdrawing group was analyzed. It was found that electron-withdrawing group favored emission performance improvement. Their electroluminescence performance was also explored. Yellow electroluminescence was observed with maximum brightness of 1743 cd/m{sup 2}. - Highlights: • Oxadiazole derived diamine ligands and their Re(I) complexes were synthesized. • Their characters and properties were analyzed and compared in detail. • Electron-withdrawing group was proved to be positive for PL improvement. • Electroluminescence was obtained with maximum brightness of 1743 cd/m{sup 2}.

An updated taxonomy for characterizing hackers according to their threat properties

DEFF Research Database (Denmark)

Hald, Sara Ligaard; Pedersen, Jens Myrup

2012-01-01

The objective of this paper is to give an up-to-date terminology for and categorization of hackers on the Internet, and to characterize each category of hackers by their threat properties. To be able to prioritize defense efforts, security experts need an accurate taxonomy of attackers...... for the production of detailed and precise threat assessments. We take an existing taxonomy for hackers and update it to correspond to the terminology used by hackers and security experts. Also, the categories of hackers are updated to reflect the threat properties demonstrated in recent attacks, and each category...

Copper nanoparticles functionalized PE: Preparation, characterization and magnetic properties

International Nuclear Information System (INIS)

Reznickova, A.; Orendac, M.; Kolska, Z.; Cizmar, E.; Dendisova, M.; Svorcik, V.

2016-01-01

Highlights: • Polyethylene (PE) surface was activated by argon plasma discharge. • Copper nanoparticles were coated on polyethylene via dithiol interlayer. • Prepared samples exhibit excellent structural and magnetic properties. • Studied properties may be utilized in design and fabrication of electronic devices. - Abstract: We report grafting of copper nanoparticles (CuNP) on plasma activated high density polyethylene (HDPE) via dithiol interlayer pointing out to the structural and magnetic properties of those composites. The as-synthesized Cu nanoparticles have been characterized by high-resolution transmission electron microscopy (HRTEM/TEM) and UV–vis spectroscopy. Properties of pristine PE and their plasma treated counterparts were studied by different experimental techniques: X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy, energy dispersive X-ray spectroscopy (EDS), zeta potential, electron spin resonance (ESR) and SQUID magnetometry. From TEM and HRTEM analyses, it is found that the size of high purity Cu nanoparticles is (12.2 ± 5.2) nm. It was determined that in the CuNPs, the copper atoms are arranged mostly in the (111) and (200) planes. Absorption in UV–vis region by these nanoparticles is ranging from 570 to 670 nm. EDS revealed that after 1 h of grafting are Cu nanoparticles homogeneously distributed over the whole surface and after 24 h of grafting Cu nanoparticles tend to aggregate slightly. The combined investigation of magnetic properties using ESR spectrometry and SQUID magnetometry confirmed the presence of copper nanoparticles anchored on PE substrate and indicated ferromagnetic interactions.

Copper nanoparticles functionalized PE: Preparation, characterization and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Reznickova, A., E-mail: alena.reznickova@vscht.cz [Department of Solid State Engineering, University of Chemistry and Technology, 166 28 Prague 6 (Czech Republic); Orendac, M., E-mail: martin.orendac@upjs.sk [Faculty of Science, P.J. Safarik University, Park Angelinum 9, 04013 Kosice (Slovakia); Kolska, Z., E-mail: zdenka.kolska@seznam.cz [Faculty of Science, J.E. Purkyne University, 400 96 Usti nad Labem (Czech Republic); Cizmar, E., E-mail: erik.cizmar@upjs.sk [Faculty of Science, P.J. Safarik University, Park Angelinum 9, 04013 Kosice (Slovakia); Dendisova, M., E-mail: vyskovsm@vscht.cz [Department of Physical Chemistry, University of Chemistry and Technology Prague, 166 28 Prague 6 (Czech Republic); Svorcik, V., E-mail: vaclav.svorcik@vscht.cz [Department of Solid State Engineering, University of Chemistry and Technology, 166 28 Prague 6 (Czech Republic)

2016-12-30

Highlights: • Polyethylene (PE) surface was activated by argon plasma discharge. • Copper nanoparticles were coated on polyethylene via dithiol interlayer. • Prepared samples exhibit excellent structural and magnetic properties. • Studied properties may be utilized in design and fabrication of electronic devices. - Abstract: We report grafting of copper nanoparticles (CuNP) on plasma activated high density polyethylene (HDPE) via dithiol interlayer pointing out to the structural and magnetic properties of those composites. The as-synthesized Cu nanoparticles have been characterized by high-resolution transmission electron microscopy (HRTEM/TEM) and UV–vis spectroscopy. Properties of pristine PE and their plasma treated counterparts were studied by different experimental techniques: X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy, energy dispersive X-ray spectroscopy (EDS), zeta potential, electron spin resonance (ESR) and SQUID magnetometry. From TEM and HRTEM analyses, it is found that the size of high purity Cu nanoparticles is (12.2 ± 5.2) nm. It was determined that in the CuNPs, the copper atoms are arranged mostly in the (111) and (200) planes. Absorption in UV–vis region by these nanoparticles is ranging from 570 to 670 nm. EDS revealed that after 1 h of grafting are Cu nanoparticles homogeneously distributed over the whole surface and after 24 h of grafting Cu nanoparticles tend to aggregate slightly. The combined investigation of magnetic properties using ESR spectrometry and SQUID magnetometry confirmed the presence of copper nanoparticles anchored on PE substrate and indicated ferromagnetic interactions.

Characterization of antibacterial and adhesion properties of chitosan-modified glass ionomer cement.

Science.gov (United States)

Ibrahim, Marrwa A; Neo, Jennifer; Esguerra, Roxanna J; Fawzy, Amr S

2015-10-01

The aim is to investigate the effect of modifying the liquid phase of a conventional glass ionomer restorative material with different chitosan volume contents on the antibacterial properties and adhesion to dentin. The liquids of commercially available restorative glass ionomer cements (GIC) were modified with chitosan (CH) solutions at different volume contents (5%, 10%, 25%, and 50%). The GIC powders were mixed with the unmodified and the CH-modified liquids at the desired powder/liquid (P/L) ratio. For the characterization of the antibacterial properties, Streptococcus mutans biofilms were formed on GIC discs and characterized by scanning electron microscope (SEM), confocal microscopy, colony forming unit (CFU) count, and cell viability assay (MTS). The unmodified and CH-modified GICs were bonded to dentin surfaces and the micro-tensile bond strength (µTBs) was evaluated and the interface was investigated by SEM. Modification with CH solutions enhanced the antibacterial properties against S. mutans in terms of resistance to biofilm formation, CFU count, and MTS assay. Generally, significant improvement in the antibacterial properties was found with the increase in the CH volume content. Modification with 25% and 50% CH adversely affected the µTBs with predominant cohesive failure in the GIC. However, no difference was found between the control and the 5% and 10% CH-modified specimens. Incorporation of acidic solutions of chitosan in the polyacrylic acid liquid of GIC at v/v ratios of 5-10% improved the antibacterial properties of conventional glass ionomer cement against S. mutans without adversely affecting its bonding to dentin surface. © The Author(s) 2015.

Characterization and evaluation of ceramic properties of clay used in structural ceramics

International Nuclear Information System (INIS)

Reis, A.S.; Oliveira, J.N.; Della-Sagrillo, V.P.; Valenzuela-Diaz, F.R.

2014-01-01

The clay used in the manufacture of structural ceramic products must meet quality requirements that are influenced by their chemical, physical, mineralogical and microstructural characteristics, which control the ceramic properties of the final products. This paper aims to characterize the clay used in the manufacture of ceramic roof tiles and bricks. The clay was characterized through XRF, XRD, thermogravimetry and differential thermal analysis, Atterberg limits and particle size distribution. Specimens were shaped, dried at 110°C, and burned at 900 deg C in an industrial kiln. After that, they were submitted to tests of water absorption, apparent porosity, bulk density and flexural strength. The results show that the chemical composition of clay has significant amount of silica and alumina and adequate levels of kaolinite for use in structural ceramic. The ceramic properties evaluated in the specimens partially meet the requirements of the Brazilian standard-clays for structural ceramics. (author)

Microscale characterization of the viscoelastic properties of hydrogel biomaterials using dual-mode ultrasound elastography.

Science.gov (United States)

Hong, Xiaowei; Stegemann, Jan P; Deng, Cheri X

2016-05-01

Characterization of the microscale mechanical properties of biomaterials is a key challenge in the field of mechanobiology. Dual-mode ultrasound elastography (DUE) uses high frequency focused ultrasound to induce compression in a sample, combined with interleaved ultrasound imaging to measure the resulting deformation. This technique can be used to non-invasively perform creep testing on hydrogel biomaterials to characterize their viscoelastic properties. DUE was applied to a range of hydrogel constructs consisting of either hydroxyapatite (HA)-doped agarose, HA-collagen, HA-fibrin, or preosteoblast-seeded collagen constructs. DUE provided spatial and temporal mapping of local and bulk displacements and strains at high resolution. Hydrogel materials exhibited characteristic creep behavior, and the maximum strain and residual strain were both material- and concentration-dependent. Burger's viscoelastic model was used to extract characteristic parameters describing material behavior. Increased protein concentration resulted in greater stiffness and viscosity, but did not affect the viscoelastic time constant of acellular constructs. Collagen constructs exhibited significantly higher modulus and viscosity than fibrin constructs. Cell-seeded collagen constructs became stiffer with altered mechanical behavior as they developed over time. Importantly, DUE also provides insight into the spatial variation of viscoelastic properties at sub-millimeter resolution, allowing interrogation of the interior of constructs. DUE presents a novel technique for non-invasively characterizing hydrogel materials at the microscale, and therefore may have unique utility in the study of mechanobiology and the characterization of hydrogel biomaterials. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterization of hydrogeologic units using matrix properties, Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Flint, L.E.

1998-01-01

Determination of the suitability of Yucca Mountain, in southern Nevada, as a geologic repository for high-level radioactive waste requires the use of numerical flow and transport models. Input for these models includes parameters that describe hydrologic properties and the initial and boundary conditions for all rock materials within the unsaturated zone, as well as some of the upper rocks in the saturated zone. There are 30 hydrogeologic units in the unsaturated zone, and each unit is defined by limited ranges where a discrete volume of rock contains similar hydrogeologic properties. These hydrogeologic units can be easily located in space by using three-dimensional lithostratigraphic models based on relationships of the properties with the lithostratigraphy. Physical properties of bulk density, porosity, and particle density; flow properties of saturated hydraulic conductivity and moisture-retention characteristics; and the state variables (variables describing the current state of field conditions) of saturation and water potential were determined for each unit. Units were defined using (1) a data base developed from 4,892 rock samples collected from the coring of 23 shallow and 8 deep boreholes, (2) described lithostratigraphic boundaries and corresponding relations to porosity, (3) recognition of transition zones with pronounced changes in properties over short vertical distances, (4) characterization of the influence of mineral alteration on hydrologic properties such as permeability and moisture-retention characteristics, and (5) a statistical analysis to evaluate where boundaries should be adjusted to minimize the variance within layers. This study describes the correlation of hydrologic properties to porosity, a property that is well related to the lithostratigraphy and depositional and cooling history of the volcanic deposits and can, therefore, be modeled to be distributed laterally

Advanced ceramic composite for high energy resistors. Characterization of electrical and physical properties

International Nuclear Information System (INIS)

Farrokh, Fattahi; Navid, Tagizadegan; Naser, Tabatabaei; Ahmad, Rashtehizadeh

2005-01-01

There is a need to characterize and apply advanced materials to improve the performance of components used in pulse power systems. One area of innovation is the use of bulk electrically conductive ceramics for non-inductive, high energy and high power electrical resistors. Standard Ceramics Inc. has developed a unique silicon carbide structural ceramic composite which exhibits electrical conductivity. The new conductive bulk ceramic material has a controlled microstructure, which results in improved homogeneity, making the material suitable for use as a non-inductive high energy resistor. This paper describes characterization of the material's physical and electrical properties and relates them to improvements in low-inductance, high temperature, high power density and high energy density resistors. The bulk resistor approach offers high reliability through better mechanical properties and simplicity of construction

Advanced ceramic composite for high energy resistors. Characterization of electrical and physical properties

International Nuclear Information System (INIS)

Farrokh, Fattahi; Navid, Tagizadegan; Naser, Tabatabaei

2005-01-01

Full text : There is a need to characterize and apply advanced materials to improve the performance of components used in pulse power systems. One area for innovation is the use of bulk electrically conductive ceramics for non-inductive, high energy and high power electrical resistors. Standard Ceramics, Inc. has developed a unique silicon carbide structural ceramic composite which exhibits electrical conductivity. The new conductive bulk ceramic material has a controlled microstructure, which results an improved homogeneity, making the material suitable for use as a non-inductive, high energy resistor. The new material has higher density, highee peak of temperature limit and greater physical strength compared with bulk ceramics currently used for pulsed power resistors. This paper describes characterization of the material's physical and electrical properties and relates them to improvements in low-power density, as compared to existing components would be expected and derived from specific properties such as good thermal conductivity, high strength, thermal shock resistance and high temperature capability. The bulk resistor approach that weas proposed offers high reliability through better mechanical properties and simplicity of construction

Characterization-Based Molecular Design of Biofuel Additives Using Chemometric and Property Clustering Techniques

Directory of Open Access Journals (Sweden)

Subin eHada

2014-06-01

Full Text Available In this work, multivariate characterization data such as infrared (IR spectroscopy was used as a source of descriptor data involving information on molecular architecture for designing structured molecules with tailored properties. Application of multivariate statistical techniques such as principal component analysis (PCA allowed capturing important features of the molecular architecture from complex data to build appropriate latent variable models. Combining the property clustering techniques and group contribution methods (GCM based on characterization data in a reverse problem formulation enabled identifying candidate components by combining or mixing molecular fragments until the resulting properties match the targets. The developed methodology is demonstrated using molecular design of biodiesel additive which when mixed with off-spec biodiesel produces biodiesel that meets the desired fuel specifications. The contribution of this work is that the complex structures and orientations of the molecule can be included in the design, thereby allowing enumeration of all feasible candidate molecules that matched the identified target but were not part of original training set of molecules.

Fabrication and Photocatalytic Properties of ZnSe Nanorod Films

Directory of Open Access Journals (Sweden)

Jiajia Yin

2016-01-01

Full Text Available ZnSe nanorod films grown on fused quartz glass substrates via a simple two-step synthesis protocol were demonstrated to be environmentally safe and effective recyclable photocatalysts. These films showed greatly enhanced photocatalytic activity compared to pulsed laser deposition ZnSe films in the degradation of methyl orange dye solutions. The well-crystalized ZnSe nanorods had a length of 15 µm and a diameter of 200 nm and were densely grown on the substrate. The morphology, crystal structure, crystal phase, and photophysical properties of the ZnSe nanorod films were investigated using field-emission scanning electron microscopy (FE-SEM, UV-Vis spectroscopy, X-ray diffraction (XRD, transmission electron microscopy (TEM, and high resolution transmission electron microscopy (HRTEM.

A comparative study of the redox and excited state properties of (nBu4N)2[Mo6X14] and (nBu4N)2[Mo6X8(CF3COO)6] (X = Cl, Br, or I)

Czech Academy of Sciences Publication Activity Database

Kirakci, Kaplan; Kubát, Pavel; Langmaier, Jan; Polívka, T.; Fuciman, M.; Fejfarová, Karla; Lang, Kamil

2013-01-01

Roč. 42, č. 19 (2013), s. 7224-7232 ISSN 1477-9226 R&D Projects: GA ČR GA13-05114S Institutional support: RVO:61388980 ; RVO:61388955 ; RVO:68378271 Keywords : HEXANUCLEAR MOLYBDENUM CLUSTERS * TRANSITION- METAL CLUSTERS * PHOTOPHYSICAL PROPERTIES * CHLORIDE CLUSTERS Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 4.097, year: 2013

Evidence for the existence of sulfur-doped fullerenes from elucidation of their photophysical properties

Energy Technology Data Exchange (ETDEWEB)

Glenis, S.; Cooke, S.; Chen, X.; Labes, M.M. [Temple Univ., Philadelphia, PA (United States)

1996-01-01

Cage carbon atoms of fullerenes were substituted by sulfur in sulfur-doped fullerenes synthesized by the authors. The synthesis method was based on the arc evaporation of graphite in the presence of thiophene or 3-methylthiophene. Structural characterization was accomplished through mass spectrometry and fluorescence spectroscopy and crude purification regimens using column chromatography were established. 24 refs., 4 figs., 1 tab.

Spectrally selective molecular doped solids: spectroscopy, photophysics and their application to ultrafast optical pulse processing

International Nuclear Information System (INIS)

Galaup, Jean-Pierre

2005-01-01

The persistent spectral hole-burning (PSHB) phenomenon observed in molecular doped polymers cooled down to liquid helium temperatures allows the engraving of spectral structures in the inhomogeneous absorption profile of the material. This phenomenon known since 1974 has became a fruitful field for the study of the intimacy of complex molecular systems in the solid state, revealing high-resolution spectroscopy, photophysics, photochemistry and dynamics of molecular doped amorphous media, organic as well as inorganic. A PSHB molecular doped solid can be programmed in spectral domain and therefore, it can be converted in an optical processor capable to achieve user-defined optical functions. Some aspects of this field are illustrated in the present paper. An application is presented where a naphthalocyanine doped polymer film is used in a demonstrative experiment to prove that temporal aberration free re-compression of ultra-short light pulses is feasible. Perspectives for the coherent control of light fields or photochemical processes are also evoked

Characterization of elastic-viscoplastic properties of an AS4/PEEK thermoplastic composite

Science.gov (United States)

Yoon, K. J.; Sun, C. T.

1991-01-01

The elastic-viscoplastic properties of an AS4/PEEK (APC-2) thermoplastic composite were characterized at 24 C (75 F) and 121 C (250 F) by using a one-parameter viscoplasticity model. To determine the strain-rate effects, uniaxial tension tests were performed on unidirectional off-axis coupon specimens with different monotonic strain rates. A modified Bodner and Partom's model was also used to describe the viscoplasticity of the thermoplastic composite. The experimental results showed that viscoplastic behavior can be characterized quite well using the one-parameter overstress viscoplasticity model.

Photophysical studies of highly luminescent europium(III) and terbium(III) complexes functionalized with amino and mercapto groups

Energy Technology Data Exchange (ETDEWEB)

Souza, E.R.; Monteiro, J.H.S.K.; Mazali, I.O.; Sigoli, F.A., E-mail: fsigoli@iqm.unicam.br

2016-02-15

This work proposes the replacement of coordinated-water molecules from the precursor complexes [Ln(aba){sub 3}(H{sub 2}O)] and [Ln(tta){sub 3}(H{sub 2}O){sub 2}], (Ln=Eu{sup 3+}, Gd{sup 3+} or Tb{sup 3+}, aba{sup −}=aminobenzoate, tta{sup −}=thenoyltrifluoroacetonate) by the ligands mercaptobenzoate (mba{sup −}), mercaptopropionate (mpa{sup −}), phenanthroline (phen), dimethylformamide (dmf) and acetoacetanilide (aaa{sup −}), leading to anionic or neutral amino (–NH{sub 2}) or mercapto (–SH) functionalized-lantanides (III) complexes with reasonable emission quantum yields for potential application on fluorescence microscopy of biological moieties. The complexes photophysical properties were studied using luminescence spectroscopy and theoretical models to determine the transfer and back energy transfer rates and quantum yields, that were compared with experimental ones. The anionic complexes [Eu(tta){sub 3}(L)]{sup −} showed high quantum yield values and their sensitization efficiency are in the range of 39–81%. The overlay of the ground state geometries, obtained from the Sparkle/PM3 model, of the complexes [Eu(tta){sub 3}(aba)]{sup −}, [Eu(tta){sub 3}(mba)]{sup −} and [Eu(tta){sub 3}(mpa)]{sup −}, suggest similar coordination polyhedrons occupied by the europium(III). The highest transfer rates T→{sup 5}D{sub 1,0} were obtained for the anionic complexes [Eu(tta){sub 3}(L)]{sup −} which might be a result of the low triplet level energies and R{sub L} values. - Highlights: • Lanthanides functionalized-complexes. • Free mercapto and amino groups. • Covalence degree of Eu-ligands. • Energy transfer rates. • Intrinsic and absolute quantum yields and sensitization.

Standardization of Nanoparticle Characterization: Methods for Testing Properties, Stability, and Functionality of Edible Nanoparticles.

Science.gov (United States)

McClements, Jake; McClements, David Julian

2016-06-10

There has been a rapid increase in the fabrication of various kinds of edible nanoparticles for oral delivery of bioactive agents, such as those constructed from proteins, carbohydrates, lipids, and/or minerals. It is currently difficult to compare the relative advantages and disadvantages of different kinds of nanoparticle-based delivery systems because researchers use different analytical instruments and protocols to characterize them. In this paper, we briefly review the various analytical methods available for characterizing the properties of edible nanoparticles, such as composition, morphology, size, charge, physical state, and stability. This information is then used to propose a number of standardized protocols for characterizing nanoparticle properties, for evaluating their stability to environmental stresses, and for predicting their biological fate. Implementation of these protocols would facilitate comparison of the performance of nanoparticles under standardized conditions, which would facilitate the rational selection of nanoparticle-based delivery systems for different applications in the food, health care, and pharmaceutical industries.

Characterization-Based Molecular Design of Bio-Fuel Additives Using Chemometric and Property Clustering Techniques

International Nuclear Information System (INIS)

Hada, Subin; Solvason, Charles C.; Eden, Mario R.

2014-01-01

In this work, multivariate characterization data such as infrared spectroscopy was used as a source of descriptor data involving information on molecular architecture for designing structured molecules with tailored properties. Application of multivariate statistical techniques such as principal component analysis allowed capturing important features of the molecular architecture from enormous amount of complex data to build appropriate latent variable models. Combining the property clustering techniques and group contribution methods based on characterization (cGCM) data in a reverse problem formulation enabled identifying candidate components by combining or mixing molecular fragments until the resulting properties match the targets. The developed methodology is demonstrated using molecular design of biodiesel additive, which when mixed with off-spec biodiesel produces biodiesel that meets the desired fuel specifications. The contribution of this work is that the complex structures and orientations of the molecule can be included in the design, thereby allowing enumeration of all feasible candidate molecules that matched the identified target but were not part of original training set of molecules.

Characterization-Based Molecular Design of Bio-Fuel Additives Using Chemometric and Property Clustering Techniques

Energy Technology Data Exchange (ETDEWEB)

Hada, Subin; Solvason, Charles C.; Eden, Mario R., E-mail: edenmar@auburn.edu [Department of Chemical Engineering, Auburn University, Auburn, AL (United States)

2014-06-10

In this work, multivariate characterization data such as infrared spectroscopy was used as a source of descriptor data involving information on molecular architecture for designing structured molecules with tailored properties. Application of multivariate statistical techniques such as principal component analysis allowed capturing important features of the molecular architecture from enormous amount of complex data to build appropriate latent variable models. Combining the property clustering techniques and group contribution methods based on characterization (cGCM) data in a reverse problem formulation enabled identifying candidate components by combining or mixing molecular fragments until the resulting properties match the targets. The developed methodology is demonstrated using molecular design of biodiesel additive, which when mixed with off-spec biodiesel produces biodiesel that meets the desired fuel specifications. The contribution of this work is that the complex structures and orientations of the molecule can be included in the design, thereby allowing enumeration of all feasible candidate molecules that matched the identified target but were not part of original training set of molecules.

Synthesis characterization, and properties of rubber lattices; a review

International Nuclear Information System (INIS)

Khan, S.M.; Chughtai, A.; Sattar, A.

2008-01-01

Latex is a stable dispersion of polymeric material in an aqueous medium. Lattices are present in natural as well as in synthetic forms. The range of applications of latex is extensive in carpet underlay, fabric back-coating, paper and paints coatings, adhesive, binder, leather finish, floor polish, waterproof clothing, bounded fiber, pigment printing, latex thread, cement and asphalt, foam scraps binders, can closure, thickeners, box toes and shoes counters, sealant and mastics, modifiers, protein reduction, enzyme treatment and peroxide vulcanization. In this review we are presenting synthesis, characterization, properties, manufacturing and processing of latex. (author)

Characterization of Thermo-Physical Properties of EVA/ATH: Application to Gasification Experiments and Pyrolysis Modeling

Directory of Open Access Journals (Sweden)

Bertrand Girardin

2015-11-01

Full Text Available The pyrolysis of solid polymeric materials is a complex process that involves both chemical and physical phenomena such as phase transitions, chemical reactions, heat transfer, and mass transport of gaseous components. For modeling purposes, it is important to characterize and to quantify the properties driving those phenomena, especially in the case of flame-retarded materials. In this study, protocols have been developed to characterize the thermal conductivity and the heat capacity of an ethylene-vinyl acetate copolymer (EVA flame retarded with aluminum tri-hydroxide (ATH. These properties were measured for the various species identified across the decomposition of the material. Namely, the thermal conductivity was found to decrease as a function of temperature before decomposition whereas the ceramic residue obtained after the decomposition at the steady state exhibits a thermal conductivity as low as 0.2 W/m/K. The heat capacity of the material was also investigated using both isothermal modulated Differential Scanning Calorimetry (DSC and the standard method (ASTM E1269. It was shown that the final residue exhibits a similar behavior to alumina, which is consistent with the decomposition pathway of EVA/ATH. Besides, the two experimental approaches give similar results over the whole range of temperatures. Moreover, the optical properties before decomposition and the heat capacity of the decomposition gases were also analyzed. Those properties were then used as input data for a pyrolysis model in order to predict gasification experiments. Mass losses of gasification experiments were well predicted, thus validating the characterization of the thermo-physical properties of the material.

Characterization of Thermo-Physical Properties of EVA/ATH: Application to Gasification Experiments and Pyrolysis Modeling.

Science.gov (United States)

Girardin, Bertrand; Fontaine, Gaëlle; Duquesne, Sophie; Försth, Michael; Bourbigot, Serge

2015-11-20

The pyrolysis of solid polymeric materials is a complex process that involves both chemical and physical phenomena such as phase transitions, chemical reactions, heat transfer, and mass transport of gaseous components. For modeling purposes, it is important to characterize and to quantify the properties driving those phenomena, especially in the case of flame-retarded materials. In this study, protocols have been developed to characterize the thermal conductivity and the heat capacity of an ethylene-vinyl acetate copolymer (EVA) flame retarded with aluminum tri-hydroxide (ATH). These properties were measured for the various species identified across the decomposition of the material. Namely, the thermal conductivity was found to decrease as a function of temperature before decomposition whereas the ceramic residue obtained after the decomposition at the steady state exhibits a thermal conductivity as low as 0.2 W/m/K. The heat capacity of the material was also investigated using both isothermal modulated Differential Scanning Calorimetry (DSC) and the standard method (ASTM E1269). It was shown that the final residue exhibits a similar behavior to alumina, which is consistent with the decomposition pathway of EVA/ATH. Besides, the two experimental approaches give similar results over the whole range of temperatures. Moreover, the optical properties before decomposition and the heat capacity of the decomposition gases were also analyzed. Those properties were then used as input data for a pyrolysis model in order to predict gasification experiments. Mass losses of gasification experiments were well predicted, thus validating the characterization of the thermo-physical properties of the material.

Characterization of Mechanical Properties of Tissue Scaffolds by Phase Contrast Imaging and Finite Element Modeling.

Science.gov (United States)

Bawolin, Nahshon K; Dolovich, Allan T; Chen, Daniel X B; Zhang, Chris W J

2015-08-01

In tissue engineering, the cell and scaffold approach has shown promise as a treatment to regenerate diseased and/or damaged tissue. In this treatment, an artificial construct (scaffold) is seeded with cells, which organize and proliferate into new tissue. The scaffold itself biodegrades with time, leaving behind only newly formed tissue. The degradation qualities of the scaffold are critical during the treatment period, since the change in the mechanical properties of the scaffold with time can influence cell behavior. To observe in time the scaffold's mechanical properties, a straightforward method is to deform the scaffold and then characterize scaffold deflection accordingly. However, experimentally observing the scaffold deflection is challenging. This paper presents a novel study on characterization of mechanical properties of scaffolds by phase contrast imaging and finite element modeling, which specifically includes scaffold fabrication, scaffold imaging, image analysis, and finite elements (FEs) modeling of the scaffold mechanical properties. The innovation of the work rests on the use of in-line phase contrast X-ray imaging at 20 KeV to characterize tissue scaffold deformation caused by ultrasound radiation forces and the use of the Fourier transform to identify movement. Once deformation has been determined experimentally, it is then compared with the predictions given by the forward solution of a finite element model. A consideration of the number of separate loading conditions necessary to uniquely identify the material properties of transversely isotropic and fully orthotropic scaffolds is also presented, along with the use of an FE as a form of regularization.

Substituent and solvent effects on spectroscopic properties of 2-amino-1,3-dicyano-5,6,7,8-tetrahydronaphthalene derivatives

International Nuclear Information System (INIS)

Józefowicz, M.; Bajorek, A.; Pietrzak, M.; Heldt, J.R.; Heldt, J.

2014-01-01

In this article, we report the photophysical properties of six, newly synthesized donor-substituted 2-amino-1,3-dicyano-5,6,7,8-tetrahydronaphthalene fluorophores. The steady-state and time-resolved spectroscopic experiments have been used to investigate the substituent and solvent effects on the locally excited (LE) and intramolecular charge transfer (ICT) emission. We demonstrate that the spectroscopic characteristics (fluorescence quantum yields, fluorescence decay times, radiative rate constants, and ground and excited state dipole moments) of the studied D–A dyes, as well as the reorganization energies characterizing the solute–solvent interactions and intramolecular torsion motions greatly depend on different substituents and microenvironment. On the basis of the experimental results and our previous quantum-chemical calculations, it was shown that two emitting charge transfer states: non-relaxed (ICT) NR and relaxed (ICT) R exist in six biphenyl derivatives dissolved in polar solvents (e.g., THF), whereas in non-polar medium (MCH) the existence of two emissive states have been attributed to non-relaxed and relaxed, locally excited state ((LE) NR , (LE) R ). - Highlights: • Spectroscopic properties greatly depend on different substituents and microenvironment. • Investigated dyes form a typically spectrally inhomogeneous system. • Two emitting charge transfer states (ICT) NR and (ICT) R exist in polar solvents. • In non-polar medium locally excited fluorescence is possible from (LE) NR and (LE) R states

Characterization and Design of Zeolite Catalysts Solid Acidity, Shape Selectivity and Loading Properties

CERN Document Server

Niwa, Miki; Okumura, Kazu

2010-01-01

Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents. Zeolite-based catalysts are used by industrial chemical companies in the interconversion of hydrocarbons and the alkylation of aromatic compounds. The current book deals with the characterization of specific properties of Zeolites and calculations for the design of catalysts. Measurements and utilization of solid acidity, shape selectivity, and loading properties, that are three prominent properties of a Zeolite catalyst, are treated in detail. These features concern chemical vapor deposition of silica, shape selectivity, loading properties, solid activity, Brønsted or Lewis character, ammonia temperature programmed desorption, control of the pore-opening size by chemical vapor deposition of silica and XAFS analysis of metals being highly dispersed inside and outside a framework.

Petroleum electrical properties characterization; Caracterizaco de propriedades eletricas de petroleo

Energy Technology Data Exchange (ETDEWEB)

Ueti, Edson; Sens, Marcio Antonio [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil)], e-mail: ueti@cepel.br

2006-07-01

Presently, petroleum wells consist predominantly of heavy type petroleum, that is submitted to decantation and separation of water, through desalinisation process. If this process is not efficient, the metallic piping will be severely corroded during refining. Hence, the knowledge of petroleum electric properties is essential for optimizing the separation of water from petroleum, by indicating its humidity in laboratory testing conditions. The present work shows an experimental procedure based on disposable cells for electric characterization of liquid polymeric materials. The use of standard cells is unfeasible, due to the petroleum physical characteristics. The procedures for the evaluation of electric properties shown in this work are applied for dielectric constant values up to 200 kHz, as well as for the electric conductivity in direct current and the electrical strength in industrial frequency. (author)

Synthesis, crystal structure and photo physical properties of isomeric fluorinated s-shaped polyaromatic dibenzo[c,l]chrysene derivatives

Science.gov (United States)

Moriguchi, Tetsuji; Tabuchi, Daichi; Yakeya, Daisuke; Tsuge, Akihiko; Jalli, Venkataprasad; Yoza, Kenji

2018-01-01

Two s-shaped fluorinated isomeric polyaromatic dibenzo[c,l]chrysene derivatives have been synthesized by a two step process using the Wittig, Heck and iodine promoted cyclization reactions. These cyclized compounds were characterized by 1H NMR and EI-MS. Further, absolute configurations of isomeric 4a and 4b were determined by X-ray diffraction analysis. Compound 4a crystallized under monoclinic system with space group P21/c and compound 4b crystallized under monoclinic system with space group Cc. They have good solubility in common organic solvents such as dichloromethane, chloroform and THF. Photophysical properties of 4a and 4b were evaluated by using UV-Visible and Fluorescence spectrophotometer. Compounds 4a and 4b showed strong absorption maximum wavelength at 317 nm. The emission spectra of 4a and 4b displayed sharp peaks in the visible region from 417 to 441 nm. The shape of the UV-Visible and Fluorescence spectra of 4a and 4b looks almost identical. But compound 4a exhibited better fluorescence intensity than compound 4b. This difference may be due to the difference in the configuration of compounds 4a and 4b.

Photophysical, electrochemical and photovoltaic properties of thiophene-containing arylene-ethynylene/arylene-vinylene polymers

International Nuclear Information System (INIS)

Egbe, Daniel Ayuk Mbi; Huong Nguyen, Le; Muehlbacher, David; Hoppe, Harald; Schmidtke, Kathy; Serdar Sariciftci, Niyazi

2006-01-01

This work reports the properties of two types of thiophene-containing poly(arylene-ethynylene)-alt-poly(arylene-vinylene)s polymers, whose repeating units (-Ph-C≡C-Th-CH=CH-Ph-CH=CH-) n , 1, and (-Th-C≡C-Ph-C≡C-Th-CH=CH-Ph-CH=CH-) n , 2, consist respectively of a 1 : 2 and a 2 : 2 ratio of -C≡C-/-CH=CH- moieties. Although similar electrochemical data (HOMO: - 5.43 eV, LUMO: ∼- 3.15 eV, E g ec = 2.28 eV) as well as identical thin film absorption behaviour (λ a = 501 nm, E g opt = 2.10 eV) were obtained for both types of materials, significant differences in their thin film photoluminescence behaviour and photovoltaic properties were observed. While polymer 1 shows a fluorescence maximum at λ e = 568 nm (with a fluorescence quantum yield of Φ f = 7%), a total fluorescence quenching was observed in 2. Solar cells (set up: ITO/PEDOT : PSS/active layer/LiF/Al; active layer consisting of 1 or 2 as donor and PCBM as acceptor in a 1 : 3 ratio by weight) designed from 1 (best cell: V OC = 900 mV, I SC = 2.51 mA.cm -2 , FF = 53.7%, η AM1.5 = 1.21%) show far better photovoltaic performance than those from 2 (best cell: V OC = 500 mV, I SC = 1.44 mA.cm -2 , FF = 37.1%, η AM1.5 = 0.27%)

Design, synthesis and photophysical studies of dipyrromethene-based materials: insights into their applications in organic photovoltaic devices.

Science.gov (United States)

Bessette, André; Hanan, Garry S

2014-05-21

This review article presents the most recent developments in the use of materials based on dipyrromethene (DPM) and azadipyrromethenes (ADPM) for organic photovoltaic (OPV) applications. These chromophores and their corresponding BF2-chelated derivatives BODIPY and aza-BODIPY, respectively, are well known for fluorescence-based applications but are relatively new in the field of photovoltaic research. This review examines the variety of relevant designs, synthetic methodologies and photophysical studies related to materials that incorporate these porphyrinoid-related dyes in their architecture. The main idea is to inspire readers to explore new avenues in the design of next generation small-molecule and bulk-heterojunction solar cell (BHJSC) OPV materials based on DPM chromophores. The main concepts are briefly explained, along with the main challenges that are to be resolved in order to take full advantage of solar energy.

A computational modeling approach for the characterization of mechanical properties of 3D alginate tissue scaffolds.

Science.gov (United States)

Nair, K; Yan, K C; Sun, W

2008-01-01

Scaffold guided tissue engineering is an innovative approach wherein cells are seeded onto biocompatible and biodegradable materials to form 3-dimensional (3D) constructs that, when implanted in the body facilitate the regeneration of tissue. Tissue scaffolds act as artificial extracellular matrix providing the environment conducive for tissue growth. Characterization of scaffold properties is necessary to understand better the underlying processes involved in controlling cell behavior and formation of functional tissue. We report a computational modeling approach to characterize mechanical properties of 3D gellike biomaterial, specifically, 3D alginate scaffold encapsulated with cells. Alginate inherent nonlinearity and variations arising from minute changes in its concentration and viscosity make experimental evaluation of its mechanical properties a challenging and time consuming task. We developed an in silico model to determine the stress-strain relationship of alginate based scaffolds from experimental data. In particular, we compared the Ogden hyperelastic model to other hyperelastic material models and determined that this model was the most suitable to characterize the nonlinear behavior of alginate. We further propose a mathematical model that represents the alginate material constants in Ogden model as a function of concentrations and viscosity. This study demonstrates the model capability to predict mechanical properties of 3D alginate scaffolds.

Characterization of Structural and Configurational Properties of DNA by Atomic Force Microscopy.

Science.gov (United States)

Meroni, Alice; Lazzaro, Federico; Muzi-Falconi, Marco; Podestà, Alessandro

2018-01-01

We describe a method to extract quantitative information on DNA structural and configurational properties from high-resolution topographic maps recorded by atomic force microscopy (AFM). DNA molecules are deposited on mica surfaces from an aqueous solution, carefully dehydrated, and imaged in air in Tapping Mode. Upon extraction of the spatial coordinates of the DNA backbones from AFM images, several parameters characterizing DNA structure and configuration can be calculated. Here, we explain how to obtain the distribution of contour lengths, end-to-end distances, and gyration radii. This modular protocol can be also used to characterize other statistical parameters from AFM topographies.

Synthesis, characterization and magnetic properties of room-temperature nanofluid ferromagnetic graphite

OpenAIRE

Souza, N. S.; Sergeenkov, S.; Speglich, C.; Rivera, V. A. G.; Cardoso, C. A.; Pardo, H.; Mombru, A. W.; Rodrigues, A. D.; de Lima, O. F.; Araujo-Moreira, F. M.

2009-01-01

We report the chemical synthesis route, structural characterization, and physical properties of nanofluid magnetic graphite (NFMG) obtained from the previously synthesized bulk organic magnetic graphite (MG) by stabilizing the aqueous ferrofluid suspension with an addition of active cationic surfactant. The measured magnetization-field hysteresis curves along with the temperature dependence of magnetization confirmed room-temperature ferromagnetism in both MG and NFMG samples. (C) 2009 Americ...

Semiconductor quantum dots as Förster resonance energy transfer donors for intracellularly-based biosensors

Science.gov (United States)

Field, Lauren D.; Walper, Scott A.; Susumu, Kimihiro; Oh, Eunkeu; Medintz, Igor L.; Delehanty, James B.

2017-02-01

Förster resonance energy transfer (FRET)-based assemblies currently comprise a significant portion of intracellularly based sensors. Although extremely useful, the fluorescent protein pairs typically utilized in such sensors are still plagued by many photophysical issues including significant direct acceptor excitation, small changes in FRET efficiency, and limited photostability. Luminescent semiconductor nanocrystals or quantum dots (QDs) are characterized by many unique optical properties including size-tunable photoluminescence, broad excitation profiles coupled to narrow emission profiles, and resistance to photobleaching, which can cumulatively overcome many of the issues associated with use of fluorescent protein FRET donors. Utilizing QDs for intracellular FRET-based sensing still requires significant development in many areas including materials optimization, bioconjugation, cellular delivery and assay design and implementation. We are currently developing several QD-based FRET sensors for various intracellular applications. These include sensors targeting intracellular proteolytic activity along with those based on theranostic nanodevices for monitoring drug release. The protease sensor is based on a unique design where an intracellularly expressed fluorescent acceptor protein substrate assembles onto a QD donor following microinjection, forming an active complex that can be monitored in live cells over time. In the theranostic configuration, the QD is conjugated to a carrier protein-drug analogue complex to visualize real-time intracellular release of the drug from its carrier in response to an external stimulus. The focus of this talk will be on the design, properties, photophysical characterization and cellular application of these sensor constructs.

Synthesis and overall nonlinear optical characterization of poly(hexa-2,4-diynylen-1,6-dioxydibenzoate) containing 2,2 Prime -(4-((4-nitrophenyl)ethynyl)phenylazanediyl)diethanol

Energy Technology Data Exchange (ETDEWEB)

Castanon-Alonso, Sandra L., E-mail: sandracastason@yahoo.com.mx [Hospital Infantil de Mexico Federico Gomez. Dr. Marquez 162, Col. Doctores C.P. 06720, Delegacion Cuauhtemoc, Mexico, DF (Mexico); Morales-Saavedra, Omar G. [Centro Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, CCADET-UNAM, Circuito Exterior S/N, Ciudad Universitaria, C.P. 04510, Mexico, DF (Mexico); Baez-Pimiento, Sandro [Universidad del Papaloapan, Campus Loma Bonita, Av. Ferrocarril s/n, Cd. Universitaria, Loma Bonita - Oaxaca, C.P. 68400 (Mexico); Ortega-Martinez, Roberto; Rodriguez-Rosales, Antonio A. [Centro Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, CCADET-UNAM, Circuito Exterior S/N, Ciudad Universitaria, C.P. 04510, Mexico, DF (Mexico); Hernandez-Rojas, Maria E. [Area de Tecnologias Sustentables, Departamento de Energia, Universidad Autonoma Metropolitana - Azcapotzalco. Av. San Pablo No. 180, Colonia Reynosa Tamaulipas, C.P. 02200, Del. Azcapotzalco, Mexico, DF (Mexico)

2012-03-15

Highlights: Black-Right-Pointing-Pointer Synthesis of a novel polydiacetylene containing tolan units as NLO-chromophores. Black-Right-Pointing-Pointer Quadratic and cubic NLO-characterizations were performed in prepared film samples. Black-Right-Pointing-Pointer Outstanding NLO-coefficients were evaluated via the Z-Scan and SHG-techniques. Black-Right-Pointing-Pointer High T{sub g}-values of this polymer indicates suitable properties for material processing. - Abstract: A new polymer, poly(p-propargyloxybenzoate) containing a polar tolan as nonlinear optically active chromophore was synthesized and characterized. This polymer shows a T{sub g}-value of {approx}98 Degree-Sign C and is soluble in typical organic solvents. These properties allowed us to fabricate mechanically stable and high quality semi-transparent thin films by spin coating of N-methylpirrolidone based solutions; obtained samples were adequate for linear and nonlinear photophysical characterizations. In order to explore the quadratic nonlinear optical (NLO) properties, molecular chromophore ordering was electrically induced within the polymeric films via the corona poling method. According to the Maker fringes technique, oriented films with an order parameter of {approx}0.25 were able to display large and stable off-resonant second-order NLO-effects such as second harmonic generation (SHG, - 532 nm); the estimated {chi}{sub zzz}{sup (2)} and {chi}{sub zxx}{sup (2)} macroscopic NLO-coefficients were in the order of 186.8 and 71.2 pm V{sup -1}, respectively. On the other hand, the cubic NLO-properties of these films were also studied via the Z-Scan technique, where the deposited films displayed an outstanding NLO refractive (n{sub 2}) and absorptive ({beta}) performance. Indeed, due to the high conjugation degree and intra-molecular charge transfer (ICT) properties, poled and unpoled polymer films displayed huge n{sub 2}-values in the order of 10{sup -8} m{sup 2} W{sup -1} with negative sign and NLO

Graphene field emitters: A review of fabrication, characterization and properties

Energy Technology Data Exchange (ETDEWEB)

Chen, Leifeng, E-mail: chlf@hdu.edu.cn [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Yu, Hu; Zhong, Jiasong; Song, Lihui [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Jun, E-mail: wujun@hdu.edu.cn [Institute of Electron Device & Application, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018 (China); Su, Weitao [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

2017-06-15

Highlights: • The preparation, characterization and field emission properties for Gs are reviewed. • The review provides an updated progress on design and construction of Gs field emitters. • The review offers fundamental insights into understanding and design of Gs emitters. • The review can broach the subject and inspire readers in field of Gs based emitters. - Abstract: Graphenes are beneficial to electrons field emission due to its high aspect ratio, high carrier density, the larger carrier mobility, excellent electrical and thermal conductivity, excellent mechanical strength and chemical stability. In recent years, graphene or reduced oxide graphene field emitters have been successfully constructed by various methods such as chemical vapor deposition, chemical exfoliation, electrophoretic deposition, screen-printing and chemical synthesis methods. Graphene emitters are tried to construct in distribution with some angles or vertical orientation with respect to the substrate surface. The vertical alignment of graphene sheets or edges arrays can facilitate efficient electron emission from the atomically thick sheets. Therefore they have even more a low turn-on and threshold-field electronic field, high field enhancement factor, high current stability and high luminance. In this review, we shortly survey and discuss recent research progress in graphene field emission properties with particular an emphasis on their preparing method, characterization and applications in devices especially for vertical graphene and single layer graphene, also including their challenges and future prospects.

Characterizing the statistical properties of protein surfaces

Science.gov (United States)

Bak, Ji Hyun; Bitbol, Anne-Florence; Bialek, William

Proteins and their interactions form the body of the signaling transduction pathway in many living systems. In order to ensure the accuracy as well as the specificity of signaling, it is crucial that proteins recognize their correct interaction partners. How difficult, then, is it for a protein to discriminate its correct interaction partner(s) from the possibly large set of other proteins it may encounter in the cell? An important ingredient of recognition is shape complementarity. The ensemble of protein shapes should be constrained by the need for maintaining functional interactions while avoiding spurious ones. To address this aspect of protein recognition, we consider the ensemble of proteins in terms of the shapes of their surfaces. We take into account the high-resolution structures of E.coli non-DNA-binding cytoplasmic proteins, retrieved from the Protein Data Bank. We aim to characterize the statistical properties of the protein surfaces at two levels: First, we study the intrinsic dimensionality at the level of the ensemble of the surface objects. Second, at the level of the individual surfaces, we determine the scale of shape variation. We further discuss how the dimensionality of the shape space is linked to the statistical properties of individual protein surfaces. Jhb and WB acknowledge support from National Science Foundation Grants PHY-1305525 and PHY-1521553. AFB acknowledges support from the Human Frontier Science Program.

Structural characterization and mechanical properties of polypropylene reinforced natural fibers

Science.gov (United States)

Karim, M. A. A.; Zaman, I.; Rozlan, S. A. M.; Berhanuddin, N. I. C.; Manshoor, B.; Mustapha, M. S.; Khalid, A.; Chan, S. W.

2017-10-01

Recently the development of natural fiber composite instead of synthetics fiber has lead to eco-friendly product manufacturing to meet various applications in the field of automotive, construction and manufacturing. The use of natural fibers offer an alternative to the reinforcing fibers because of their good mechanical properties, low density, renewability, and biodegradability. In this present research, the effects of maleic anhydride polypropylene (MAPP) on the mechanical properties and material characterization behaviour of kenaf fiber and coir fiber reinforced polypropylene were investigated. Different fractions of composites with 10wt%, 20wt% and 30wt% fiber content were prepared by using brabender mixer at 190°C. The 3wt% MAPP was added during the mixing. The composites were subsequently molded with injection molding to prepare the test specimens. The mechanical properties of the samples were investigated according to ISO 527 to determine the tensile strength and modulus. These results were also confirmed by the SEM machine observations of fracture surface of composites and FTIR analysis of the chemical structure. As the results, the presence of MAPP helps increasing the mechanical properties of both fibers and 30wt% kenaf fiber with 3wt% MAPP gives the best result compare to others.

Characterization of hydrogeologic units using matrix properties, Yucca Mountain, Nevada

Science.gov (United States)

Flint, L.E.

1998-01-01

Determination of the suitability of Yucca Mountain, in southern Nevada, as a geologic repository for high-level radioactive waste requires the use of numerical flow and transport models. Input for these models includes parameters that describe hydrologic properties and the initial and boundary conditions for all rock materials within the unsaturated zone, as well as some of the upper rocks in the saturated zone. There are 30 hydrogeologic units in the unsaturated zone, and each unit is defined by limited ranges where a discrete volume of rock contains similar hydrogeologic properties. These hydrogeologic units can be easily located in space by using three-dimensional lithostratigraphic models based on relation- ships of the properties with the lithostratigraphy. Physical properties of bulk density, porosity, and particle density; flow properties of saturated hydraulic conductivity and moisture-retention characteristics; and the state variables (variables describing the current state of field conditions) of saturation and water potential were determined for each unit. Units were defined using (1) a data base developed from 4,892 rock samples collected from the coring of 23 shallow and 8 deep boreholes, (2) described lithostratigraphic boundaries and corresponding relations to porosity, (3) recognition of transition zones with pronounced changes in properties over short vertical distances, (4) characterization of the influence of mineral alteration on hydrologic properties such as permeability and moisture-retention characteristics, and (5) a statistical analysis to evaluate where boundaries should be adjusted to minimize the variance within layers. This study describes the correlation of hydrologic properties to porosity, a property that is well related to the lithostratigraphy and depositional and cooling history of the volcanic deposits and can, therefore, be modeled to be distributed laterally. Parameters of the hydrogeologic units developed in this study and the

Mechanical property characterization of polymeric composites reinforced by continuous microfibers

Science.gov (United States)

Zubayar, Ali

Innumerable experimental works have been conducted to study the effect of polymerization on the potential properties of the composites. Experimental techniques are employed to understand the effects of various fibers, their volume fractions and matrix properties in polymer composites. However, these experiments require fabrication of various composites which are time consuming and cost prohibitive. Advances in computational micromechanics allow us to study the various polymer based composites by using finite element simulations. The mechanical properties of continuous fiber composite strands are directional. In traditional continuous fiber laminated composites, all fibers lie in the same plane. This provides very desirable increases in the in-plane mechanical properties, but little in the transverse mechanical properties. The effect of different fiber/matrix combinations with various orientations is also available. Overall mechanical properties of different micro continuous fiber reinforced composites with orthogonal geometry are still unavailable in the contemporary research field. In this research, the mechanical properties of advanced polymeric composite reinforced by continuous micro fiber will be characterized based on analytical investigation and FE computational modeling. Initially, we have chosen IM7/PEEK, Carbon Fiber/Nylon 6, and Carbon Fiber/Epoxy as three different case study materials for analysis. To obtain the equivalent properties of the micro-hetero structures, a concept of micro-scale representative volume elements (RVEs) is introduced. Five types of micro scale RVEs (3 square and 2 hexagonal) containing a continuous micro fiber in the polymer matrix were designed. Uniaxial tensile, lateral expansion and transverse shear tests on each RVE were designed and conducted by the finite element computer modeling software ANSYS. The formulae based on elasticity theory were derived for extracting the equivalent mechanical properties (Young's moduli, shear

ZnS-Graphene nanocomposite: Synthesis, characterization and optical properties

Energy Technology Data Exchange (ETDEWEB)

Pan Shugang [Key Laboratory for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Ministry of Education, Nanjing 210094 (China); Liu Xiaoheng, E-mail: xhliu@mail.njust.edu.cn [Key Laboratory for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Ministry of Education, Nanjing 210094 (China)

2012-07-15

A ZnS-Graphene nanocomposite was prepared by a facile one-step hydrothermal method using zinc nitrate hexahydrate, ethylenediamine and carbon disulfide as precursors, graphene oxide as a template. The composite was characterized by X-ray power diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, Fourier transform infrared, Raman spectra and fluorescence spectroscopy. The results show that graphene oxide was reduced to graphene in the hydrothermal reaction process. Simultaneously, the graphene sheets in the composite are exfoliated and decorated with ZnS nanoparticles. Furthermore, Raman and fluorescence properties of the composite were observed. ZnS-Graphene nanocomposite displays surface-enhanced Raman scattering activity for graphene oxide, and fluorescence enhancement property compared with pure ZnS sample. - Graphical abstract: Approach of reaction makes the reduction of grapheme oxide and the deposition of Zns on the grapheme sheets occur simultaneously and overcomes the aggregation of the grapheme sheets and Zns. Highlights: Black-Right-Pointing-Pointer Graphene oxide is reduced to graphene in the hydrothermal reaction process. Black-Right-Pointing-Pointer ZnS nanoparticles are attached onto the almost transparent graphene sheets. Black-Right-Pointing-Pointer ZnS-Graphene system shows surface-enhanced Raman scattering (SERS) activity. Black-Right-Pointing-Pointer ZnS-Graphene system displays relatively better fluorescence property than pure ZnS.

Synthesis, Properties Characterization and Applications of Various Organobismuth Compounds

Directory of Open Access Journals (Sweden)

Jingfei Luan

2011-05-01

Full Text Available Organobismuth chemistry was emphasized in this review article due to the low price, low toxicity and low radioactivity characteristics of bismuth. As an environmentally-friendly class of organometallic compounds, different types of organobismuth compounds have been used in organic synthesis, catalysis, materials, etc. The synthesis and property characterization of many organobismuth compounds had been summarized. This review article also presented a survey of various applications of organobismuth compounds in organic transformations, as reagents or catalysts. The reactivity, reaction pathways and mechanisms of reactions with organobismuths were discussed. Less common and limiting aspects of organobismuth compounds were also briefly mentioned.

Theoretical spectral properties of PAHs: towards a detailed model of their photophysics in the ISM

International Nuclear Information System (INIS)

Malloci, Giuliano; Mulas, Giacomo; Porceddu, Ignazio

2005-01-01

In the framework of density functional theory (DFT) we computed the spectral properties of a total of about 20 polycyclic aromatic hydrocarbons (PAHs) in different charge states. From our complete atlas of PAHs, ranging in size from naphthalene (C 10 H 8 ) to dicoronylene (C 48 H 20 ), we present here a sample of results concerning both ground-state and excited-state properties. Our theoretical results are in reasonable agreement with the available experimental data. This makes them particularly precious when the latter are not easily obtainable, as is often the case for the highly reactive radicals and ions of such species. In another paper (Mulas et al., same volume) we show that our theoretical results can be reliably used to model the behaviour of these molecules in astrophysical environments

Ultrasound Imaging Techniques for Spatiotemporal Characterization of Composition, Microstructure, and Mechanical Properties in Tissue Engineering.

Science.gov (United States)

Deng, Cheri X; Hong, Xiaowei; Stegemann, Jan P

2016-08-01

Ultrasound techniques are increasingly being used to quantitatively characterize both native and engineered tissues. This review provides an overview and selected examples of the main techniques used in these applications. Grayscale imaging has been used to characterize extracellular matrix deposition, and quantitative ultrasound imaging based on the integrated backscatter coefficient has been applied to estimating cell concentrations and matrix morphology in tissue engineering. Spectral analysis has been employed to characterize the concentration and spatial distribution of mineral particles in a construct, as well as to monitor mineral deposition by cells over time. Ultrasound techniques have also been used to measure the mechanical properties of native and engineered tissues. Conventional ultrasound elasticity imaging and acoustic radiation force imaging have been applied to detect regions of altered stiffness within tissues. Sonorheometry and monitoring of steady-state excitation and recovery have been used to characterize viscoelastic properties of tissue using a single transducer to both deform and image the sample. Dual-mode ultrasound elastography uses separate ultrasound transducers to produce a more potent deformation force to microscale characterization of viscoelasticity of hydrogel constructs. These ultrasound-based techniques have high potential to impact the field of tissue engineering as they are further developed and their range of applications expands.

Theoretical investigation of the photophysics of methyl salicylate isomers

Science.gov (United States)

Massaro, Richard D.; Blaisten-Barojas, Estela

2011-10-01

The photophysics of methyl salicylate (MS) isomers has been studied using time-dependent density functional theory and large basis sets. First electronic singlet and triplet excited states energies, structure, and vibrational analysis were calculated for the ketoB, enol, and ketoA isomers. It is demonstrated that the photochemical pathway involving excited state intramolecular proton transfer (ESIPT) from the ketoB to the enol tautomer agrees well with the dual fluorescence in near-UV (from ketoB) and blue (from enol) wavelengths obtained from experiments. Our calculation confirms the existence of a double minimum in the excited state pathway along the O-H-O coordinate corresponding to two preferred energy regions: (1) the hydrogen belongs to the OH moiety and the structure of methyl salicylate is ketoB; (2) the hydrogen flips to the closest carboxyl entailing electronic rearrangement and tautomerization to the enol structure. This double well in the excited state is highly asymmetric. The Franck-Condon vibrational overlap is calculated and accounts for the broadening of the two bands. It is suggested that forward and backward ESIPT through the barrier separating the two minima is temperature-dependent and affects the intensity of the fluorescence as seen in experiments. When the enol fluoresces and returns to its ground state, a barrier-less back proton transfer repopulates the ground state of methyl salicylate ketoB. It is also demonstrated that the rotamer ketoA is not stable in an excited state close to the desired emission wavelength. This observation eliminates the conjecture that the near-UV emission of the dual fluorescence originates from the ketoA rotamer. New experimental results for pure MS in the liquid state are reported and theoretical results compared to them.

Material properties characterization - concrete

International Nuclear Information System (INIS)

England, G.L.; MacLeod, J.S.

1978-01-01

A review is presented of the six contributions in the SMiRT 4 conference to Session H5 on structural analysis of prestressed concrete reactor pressure vessels. These relate to short term stress-strain aspects of concrete loaded beyond the linear range in uniaxial and biaxial stress fields, to some time and temperature dependent properties of concrete at working stress levels, and to a programme of strain-gauge testing for the assessment of concrete properties. From the information discussed, it is clear that there are difficulties in determining material properties for concrete, and these are summarised. (UK)

Photophysical and antibacterial properties of complex systems based on smectite, a cationic surfactant and methylene blue.

Science.gov (United States)

Donauerová, Alena; Bujdák, Juraj; Smolinská, Miroslava; Bujdáková, Helena

2015-10-01

Solid or colloidal materials with embedded photosensitizers are promising agents from the medical or environmental perspective, where the direct use of photoactive solutions appears to be problematic. Colloids based on layered silicates of the saponite (Sap) and montmorillonite (Mon) type, including those modified with dodecylammonium cations (C12) and photosensitizer--methylene blue (MB) were studied. Two representatives of bacteria, namely Enterobacter cloacae and Escherichia coli, were selected for this work. A spectral study showed that MB solutions and also colloids with Sap including C12 exhibited the highest photoactivities. The antimicrobial properties of the smectite colloids were not directly linked to the photoactivity of the adsorbed MB cations. They were also influenced by other parameters, such as light vs. dark conditions, the spectrum, power and duration of the light used for the irradiation; growth phases, and the pre-treatment of microorganisms. Both the photoactivity and antimicrobial properties of the colloids were improved upon pre-modification with C12. Significantly higher antimicrobial properties were observed for the colloids based on Mon with MB in the form of molecular aggregates without significant photoactivities. The MB/Mon colloids, both modified and non-modified with C12 cations, exhibited higher antimicrobial effects than pure MB solution. Besides the direct effect of photosensitization, the surface properties of the silicate particles likely played a crucial role in the interactions with microorganisms. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of Immersion Solvent on Photovoltaic and Photophysical Properties of Porphyrin-Sensitized Solar Cells.

Science.gov (United States)

Hayashi, Hironobu; Higashino, Tomohiro; Kinjo, Yuriko; Fujimori, Yamato; Kurotobi, Kei; Chabera, Pavel; Sundström, Villy; Isoda, Seiji; Imahori, Hiroshi

2015-08-26

Memory effects in self-assembled monolayers (SAMs) of zinc porphyrin carboxylic acid on TiO2 electrodes have been demonstrated for the first time by evaluating the photovoltaic and electron transfer properties of porphyrin-sensitized solar cells prepared by using different immersion solvents sequentially. The structure of the SAM of the porphyrin on the TiO2 was maintained even after treating the porphyrin monolayer with different neat immersion solvents (memory effect), whereas it was altered by treatment with solutions containing different porphyrins (inverse memory effect). Infrared spectroscopy shows that the porphyrins in the SAM on the TiO2 could be exchanged with the same or analogous porphyrin, leading to a change in the structure of the porphyrin SAM. The memory and inverse memory effects are well correlated with a change in porphyrin geometry, mainly the tilt angle of the porphyrin along the long molecular axis from the surface normal on the TiO2, as well as with kinetics of electron transfer between the porphyrin and TiO2. Such a new structure-function relationship for DSSCs will be very useful for the rational design and optimization of photoelectrochemical and photovoltaic properties of molecular assemblies on semiconductor surfaces.

Synthesis, characterization and photophysical studies of β ...

Indian Academy of Sciences (India)

synthesized in appreciable yields through a copper(I)-catalyzed “click” reaction of zinc(II) 2-azidomethyl-. 5,10,15,20-tetraphenylporphyrin ... C to form the corresponding free-base porphyrin analogues in good yields. The newly syn- thesized products ... nificance of these two classes of heterocycles, our aim was to connect ...

A study of the structure-property relationship of azole-azine based homoleptic platinum(II) complexes and tunability of the photo-physical properties

Science.gov (United States)

Ranga Prabhath, Malaviarachchige Rabel

reveal that the solid state emission is associated with 1MMLCT transitions. Lifetime measurements revealed the existence of two decay processes: one being fluorescence and the other process, either phosphorescence or delayed fluorescence. Further a linear-relationship between the Hammett parameters of the substituents and emission wavelengths was established. This allows a reliable emission predictability for any given substituent of 5-substituted pyridyl-1,2,3-triazole platinum complexes. In conclusion, we show a new approach in achieving coarse emission tunability in pyridyl-1,2,3-triazole based platinum complexes via subtle changes in the molecular structure and the importance of metallophilic interactions in the process. During the second phase of the study, the scope was broadened to examine the effects of heterocyclic nitrogens in the ligand skeleton. Fifteen different combinations of azole-azine linked ligand systems were synthesized, by systematically increasing the number of nitrogens and changing the ring position of the nitrogens in the skeleton. Later, the homoleptic platinum complexes of the respective ligands were synthesised, and the photo-physical characteristics were studied. The above mentioned changes in the ligand structure resulted in a 264 nm emission tunability, in the thin films of the complexes. Theoretical studies on the complexes revealed that based on the structure of the ligand, different metallophilic stacking behaviours and different origins of emission (fluorescence and phosphorescence) can result, which in turn give rise to tunable emission wavelengths.

Water soluble {2-[3-(diethylamino)phenoxy]ethoxy} substituted zinc(II) phthalocyanine photosensitizers

Energy Technology Data Exchange (ETDEWEB)

Çakır, Dilek [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Göl, Cem [Gebze Institute of Technology, Department of Chemistry, PO Box 141, Gebze, 41400, Kocaeli (Turkey); Çakır, Volkan [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Durmuş, Mahmut [Gebze Institute of Technology, Department of Chemistry, PO Box 141, Gebze, 41400, Kocaeli (Turkey); Bıyıklıoğlu, Zekeriya, E-mail: zekeriya_61@yahoo.com [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Kantekin, Halit [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey)

2015-03-15

The new peripherally and non-peripherally tetra-{2-[3-(diethylamino)phenoxy] ethoxy} substituted zinc phthalocyanines (2a and 3a) were synthesized by cyclotetramerization of phthalonitrile derivatives (2 and 3). 2-[3-(diethylamino)phenoxy] ethoxy group was chosen as substituent because the quaternization of the diethylamino functionality on the structure of this group produced water soluble zinc phthalocyanines (2b and 3b). The water solubility is very important for many different applications such as photosensitizers in the photodynamic therapy of cancer because the water soluble photosensitizers can be injected directly to the body and they can transport to cancer cells through blood stream. The new compounds were characterized by using elemental analysis, UV–vis, IR, {sup 1}H NMR, {sup 13}C NMR and mass spectroscopies. The photophysical and photochemical properties of these novel photosensitizer compounds were examined in DMSO (both non-ionic and ionic complexes) and in PBS (for ionic complexes) solutions. The investigation of these properties is very important for the usage of the compounds as photosensitizers for PDT because determination of these properties is the first stage of potential of the compounds as photosensitizers. The bovine serum albumin (BSA) and DNA binding behaviour of the studied water soluble zinc (II) phthalocyanines were also investigated in PBS solutions for the determination of biological activity of these compounds. - Highlights: • Synthesis of water soluble zinc phthalocyanines. • Photophysical and photochemical properties for phthalocyanines. • Photodynamic therapy studies.

Water soluble {2-[3-(diethylamino)phenoxy]ethoxy} substituted zinc(II) phthalocyanine photosensitizers

International Nuclear Information System (INIS)

Çakır, Dilek; Göl, Cem; Çakır, Volkan; Durmuş, Mahmut; Bıyıklıoğlu, Zekeriya; Kantekin, Halit

2015-01-01

The new peripherally and non-peripherally tetra-{2-[3-(diethylamino)phenoxy] ethoxy} substituted zinc phthalocyanines (2a and 3a) were synthesized by cyclotetramerization of phthalonitrile derivatives (2 and 3). 2-[3-(diethylamino)phenoxy] ethoxy group was chosen as substituent because the quaternization of the diethylamino functionality on the structure of this group produced water soluble zinc phthalocyanines (2b and 3b). The water solubility is very important for many different applications such as photosensitizers in the photodynamic therapy of cancer because the water soluble photosensitizers can be injected directly to the body and they can transport to cancer cells through blood stream. The new compounds were characterized by using elemental analysis, UV–vis, IR, 1 H NMR, 13 C NMR and mass spectroscopies. The photophysical and photochemical properties of these novel photosensitizer compounds were examined in DMSO (both non-ionic and ionic complexes) and in PBS (for ionic complexes) solutions. The investigation of these properties is very important for the usage of the compounds as photosensitizers for PDT because determination of these properties is the first stage of potential of the compounds as photosensitizers. The bovine serum albumin (BSA) and DNA binding behaviour of the studied water soluble zinc (II) phthalocyanines were also investigated in PBS solutions for the determination of biological activity of these compounds. - Highlights: • Synthesis of water soluble zinc phthalocyanines. • Photophysical and photochemical properties for phthalocyanines. • Photodynamic therapy studies

Luminescent cyclometalated alkynylgold(III) complexes with 6-phenyl-2,2'-bipyridine derivatives: synthesis, characterization, electrochemistry, photophysics, and computational studies.

Science.gov (United States)

Au, Vonika Ka-Man; Lam, Wai Han; Wong, Wing-Tak; Yam, Vivian Wing-Wah

2012-07-16

A novel class of luminescent gold(III) complexes containing various tridentate cyclometalating ligands derived from 6-phenyl-2,2'-bipyridine and alkynyl ligands, [Au(RC^N^N)(C≡C-R')]PF(6), has been successfully synthesized and characterized. One of the complexes has also been determined by X-ray crystallography. Electrochemical studies show a ligand-centered reduction originated from the cyclometalating RC^N^N ligands as well as an alkynyl-centered oxidation. The electronic absorption and photoluminescence properties of the complexes have also been investigated. In acetonitrile at room temperature, the complexes show intense absorption at higher energy region with wavelength shorter than 320 nm, and a moderately intense broad absorption band at 374-406 nm, assigned as the metal-perturbed intraligand π-π* transition of the cyclometalating RC(∧)N(∧)N ligand, with some charge transfer character from the aryl ring to the bipyridine moiety. Most of the complexes have been observed to show vibronic-structured emission bands at 469-550 nm in butyronitile glass at 77 K, assigned to an intraligand excited state of the RC^N^N ligand, with some charge transfer character from the aryl to the bipyridyine moiety. Insights into the origin of the absorption and emission have also been provided by density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations.

Impact of Nonfullerene Acceptor Core Structure on the Photophysics and Efficiency of Polymer Solar Cells

KAUST Repository

Alamoudi, Maha

2018-03-02

Small-molecule “nonfullerene” acceptors are promising alternatives to fullerene (PC61/71BM) derivatives often used in bulk heterojunction (BHJ) organic solar cells; yet, the efficiency-limiting processes and their dependence on the acceptor structure are not clearly understood. Here, we investigate the impact of the acceptor core structure (cyclopenta-[2,1-b:3,4-b′]dithiophene (CDT) versus indacenodithiophene (IDTT)) of malononitrile (BM)-terminated acceptors, namely CDTBM and IDTTBM, on the photophysical characteristics of BHJ solar cells. Using PCE10 as donor polymer, the IDTT-based acceptor achieves power conversion efficiencies (8.4%) that are higher than those of the CDT-based acceptor (5.6%) because of a concurrent increase in short-circuit current and open-circuit voltage. Using (ultra)fast transient spectroscopy we demonstrate that reduced geminate recombination in PCE10:IDTTBM blends is the reason for the difference in short-circuit currents. External quantum efficiency measurements indicate that the higher energy of interfacial charge-transfer states observed for the IDTT-based acceptor blends is the origin of the higher open-circuit voltage.

Impact of Nonfullerene Acceptor Core Structure on the Photophysics and Efficiency of Polymer Solar Cells

KAUST Repository

Alamoudi, Maha; Khan, Jafar Iqbal; Firdaus, Yuliar; Wang, Kai; Andrienko, Denis; Beaujuge, Pierre; Laquai, Fré dé ric

2018-01-01

Small-molecule “nonfullerene” acceptors are promising alternatives to fullerene (PC61/71BM) derivatives often used in bulk heterojunction (BHJ) organic solar cells; yet, the efficiency-limiting processes and their dependence on the acceptor structure are not clearly understood. Here, we investigate the impact of the acceptor core structure (cyclopenta-[2,1-b:3,4-b′]dithiophene (CDT) versus indacenodithiophene (IDTT)) of malononitrile (BM)-terminated acceptors, namely CDTBM and IDTTBM, on the photophysical characteristics of BHJ solar cells. Using PCE10 as donor polymer, the IDTT-based acceptor achieves power conversion efficiencies (8.4%) that are higher than those of the CDT-based acceptor (5.6%) because of a concurrent increase in short-circuit current and open-circuit voltage. Using (ultra)fast transient spectroscopy we demonstrate that reduced geminate recombination in PCE10:IDTTBM blends is the reason for the difference in short-circuit currents. External quantum efficiency measurements indicate that the higher energy of interfacial charge-transfer states observed for the IDTT-based acceptor blends is the origin of the higher open-circuit voltage.

High frequency electromagnetic characterization of NEG properties for the CLIC damping rings

CERN Document Server

Koukovini-Platia, E; Zannini, C

2014-01-01

Coating materials will be used in the CLIC damping rings (DR) to suppress two-stream effects. In particular, NEG coating is necessary to suppress fast beam ion instabilities in the electron damping ring (EDR). The electromagnetic (EM) characterization of the material properties up to high frequencies is required for the impedance modeling of the CLIC DR components. The EM properties for frequencies of few GHz are determined with the waveguide method, based on a combination of experimental measurements of the complex transmission coefficient S21 and CST 3D EM simulations. The results obtained from a NEG-coated copper (Cu) waveguide are presented in this paper.

Novel metallomesogenic polyurethanes: Synthesis, characterization and properties

International Nuclear Information System (INIS)

Senthilkumar, Natarajan; Narasimhaswamy, Tanneru; Kim, Il-Jin

2012-01-01

A series of tetradentate Schiff base metallomesogenic diols were synthesized from two simple dihydroxy benzenes. The metallomesogenic diol was constructed from three ring containing mesogen linked through ester and azomethine with terminal hydroxy group. This upon complexation with copper(II) formed metallomesogenic diol with varying terminal chain length. A series of metallomesogenic polyurethanes were synthesized using these metallomesogenic diols as chain extenders for the prepolymers based on polytetramethylene glycol (PTMG) of varying molecular weight (M n = 650, 2000) and 2,4-toluene diisocyanate (TDI), or 4,4′-methylene bis(phenyl isocyanate) (MDI). The molar ratio of metallomesogenic diol and PTMG were varied in the polyurethane to find their role in liquid crystalline and mechanical properties. Extensive characterization of all metallomesogenic compounds and intermediates were carried out by FT-IR, 1 H and 13 C NMR, EPR, VSM, Mass (EI and FAB) and UV–visible spectroscopy. Hot stage polarizing microscope and differential scanning calorimetry were used to ensure the phase characteristics such as nature of phase, melting and clearing temperatures and phase range. The appearance of enantiotropic smectic A phases indicated high molecular polarizability of the core due to the metal ion. - Highlights: ► Design and synthesis of metallomesogenic diols. ► Metallomesogenic polyurethanes were prepared using these diols as chain extenders. ► Liquid crystalline and mechanical properties were studied. ► A square pyramidal structure for the copper(II) complexes have been proposed. ► Polyurethanes exhibited enantiotropic smectic A phases.

Isolation, Characterization and Anti-Inflammatory Property of Thevetia Peruviana

Directory of Open Access Journals (Sweden)

R. Thilagavathi

2010-01-01

Full Text Available Thevetia peruviana seeds contain glucosides of neriifolin, acetylneriifolin and thevetin. Seed oil distillates of Thevetia peruviana have been found to contain anti-bacterial activity. In the persent work, the fresh flowers of Thevetia peruviana was subjected to phytochemical studies. The results of the study showed that the flowers contain quercetin, kaempferol and quercetin-7-o-galactoside. The structure of the isolated compound was characterized by UV, 1H NMR and 13C NMR spectra. The anti-inflammatory character of the isolated compound was tested by in vitro method and the results of the study revealed that the isolated compound showed a biphasic property.

pH dependent photophysical studies of new europium and terbium complexes of tripodal ligand: Experimental and semiempirical approach

International Nuclear Information System (INIS)

Akbar, Rifat; Baral, Minati; Kanungo, B K

2015-01-01

The photophysical properties of adduct of a novel nonadentate tripodal ligand, 5,5′-(2-(((8-hydroxyquinolin-5-yl)methylamino)methyl)-2-methylpropane-1, 3-diyl)bis(azanediyl)bis(methylene diquinolin-8-ol, (TAME5OX), with Eu 3+ and Tb 3+ metal ions have been probed for photonics applications. The absorption spectroscopy of these complexes show remarkable spectral changes due to characteristic lanthanide transitions, which support the use of TAME5OX as a sensitive optical pH based sensor to detect Ln 3+ metal ions in biological systems. In addition, these complexes have also been shown to exhibit strong green fluorescence allowing simultaneous sensing within the visible region under physiological pH in competitive medium for both Eu 3+ and Tb 3+ ions. The intense fluorescence from these compounds were revealed to intermittently get quenched under acidic as well as basic conditions due to the photoinduced intramolecular electron transfer from excited 8-hydroxyquinoline (8-HQ) moiety to metal ion, just an opposite process. This renders these compounds the OFF–ON–OFF type of pH-dependent fluorescent sensor. The thermodynamic stability and aqueous coordination chemistry of the chelator with the said lanthanide ions have also been probed by potentiometric, UV–visible and fluorescence spectrophotometric method. TAME5OX has been found to form two protonated complexes [Ln(H 5 L)] 5+ and [Ln(H 4 L)] 4+ below pH 2.5 with both metal ions, which consecutively deprotonates through one proton process with rise of pH. The formation constants (log β 11n ) of neutral complexes have been determined to be 33.51 and 32.16 with pLn (pLn=−log[Ln 3+ ]) values of 16.14 and 19.48 for Eu 3+ and Tb 3+ ions, respectively, calculated at pH 7.4, indicating TAME5OX is a good lanthanide synthetic chelator. The emission lifetimes of the Eu 3+ and Tb 3+ complexes recorded in D 2 O and H 2 O suggest the presence of water molecules in the first coordination sphere of the metal ions. NMR

pH dependent photophysical studies of new europium and terbium complexes of tripodal ligand: Experimental and semiempirical approach

Energy Technology Data Exchange (ETDEWEB)

Akbar, Rifat [Department of Chemistry, Sant Longowal Institute of Engineering & Technology, Longowal, Punjab 148106 (India); Baral, Minati [Department of Chemistry, National Institute of Technology Kurukshetra, Haryana 136119 (India); Kanungo, B K, E-mail: b.kanungo@gmail.com [Department of Chemistry, Sant Longowal Institute of Engineering & Technology, Longowal, Punjab 148106 (India)

2015-11-15

The photophysical properties of adduct of a novel nonadentate tripodal ligand, 5,5′-(2-(((8-hydroxyquinolin-5-yl)methylamino)methyl)-2-methylpropane-1, 3-diyl)bis(azanediyl)bis(methylene diquinolin-8-ol, (TAME5OX), with Eu{sup 3+} and Tb{sup 3+} metal ions have been probed for photonics applications. The absorption spectroscopy of these complexes show remarkable spectral changes due to characteristic lanthanide transitions, which support the use of TAME5OX as a sensitive optical pH based sensor to detect Ln{sup 3+} metal ions in biological systems. In addition, these complexes have also been shown to exhibit strong green fluorescence allowing simultaneous sensing within the visible region under physiological pH in competitive medium for both Eu{sup 3+} and Tb{sup 3+} ions. The intense fluorescence from these compounds were revealed to intermittently get quenched under acidic as well as basic conditions due to the photoinduced intramolecular electron transfer from excited 8-hydroxyquinoline (8-HQ) moiety to metal ion, just an opposite process. This renders these compounds the OFF–ON–OFF type of pH-dependent fluorescent sensor. The thermodynamic stability and aqueous coordination chemistry of the chelator with the said lanthanide ions have also been probed by potentiometric, UV–visible and fluorescence spectrophotometric method. TAME5OX has been found to form two protonated complexes [Ln(H{sub 5}L)]{sup 5+} and [Ln(H{sub 4}L)]{sup 4+} below pH 2.5 with both metal ions, which consecutively deprotonates through one proton process with rise of pH. The formation constants (log β{sub 11n}) of neutral complexes have been determined to be 33.51 and 32.16 with pLn (pLn=−log[Ln{sup 3+}]) values of 16.14 and 19.48 for Eu{sup 3+} and Tb{sup 3+} ions, respectively, calculated at pH 7.4, indicating TAME5OX is a good lanthanide synthetic chelator. The emission lifetimes of the Eu{sup 3+} and Tb{sup 3+} complexes recorded in D{sub 2}O and H{sub 2}O suggest the presence

Hydrophilic olive cake extracts: Characterization by physicochemical properties and Cu(II) complexation

International Nuclear Information System (INIS)

Kolokassidou, K.; Szymczak, W.; Wolf, M.; Obermeier, C.; Buckau, G.; Pashalidis, I.

2009-01-01

Disposed olive cake generates hydrophilic components that can be mobilized in the aquatic environment. This paper deals with the characterization of such components, isolated by alkaline extraction. It is shown that these substances possess properties very much resembling humic acid, including a substantial inventory of proton exchanging groups. Extraction and purification of the hydrophilic components from the disposed olive cake was performed by the standard approach for isolation of humic acids from solid sources, i.e. alternating alkaline dissolution and acid flocculation, leaving the purified extract in the protonated form. The purified sample was characterized by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Fourier Transform Infra Red Spectroscopy (FTIR), UV-vis, Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and Asymmetrical Flow Field-Flow Fractionation (AFFFF). The complex formation properties were investigated by potentiometry using Cu(II) ion selective electrode under atmospheric conditions at I = 0.1 M NaClO 4 (aqueous solution) and pH 6. The formation constant for the CuHA complex is found to be log β = 5.3 ± 0.4 which is close to the corresponding value (log β = 5.2 ± 0.4) obtained from similar investigations with the commercially available Aldrich humic acid (this study) and corresponding published values for various humic acids. Both, structural properties and complex formation data show that the olive cake extract has considerable similarities with humic acids from different sources, pointing towards potential similarities in environmental behavior and impact.

Chemical synthesis, characterization and evaluation of antimicrobial properties of Cu and its oxide nanoparticles

CSIR Research Space (South Africa)

Motlatle, Abesach M

2016-10-01

Full Text Available of Nanoparticle Research, vol. 18: DOI: 10.1007/s11051-016-3614-8 Chemical synthesis, characterization and evaluation of antimicrobial properties of Cu and its oxide nanoparticles Motlatle AM Kesevan Pillai S Scriba MR Ray SS ABSTRACT: Cu...

A probabilistic approach to rock mechanical property characterization for nuclear waste repository design

International Nuclear Information System (INIS)

Kim, Kunsoo; Gao, Hang

1996-01-01

A probabilistic approach is proposed for the characterization of host rock mechanical properties at the Yucca Mountain site. This approach helps define the probability distribution of rock properties by utilizing extreme value statistics and Monte Carlo simulation. We analyze mechanical property data of tuff obtained by the NNWSI Project to assess the utility of the methodology. The analysis indicates that laboratory measured strength and deformation data of Calico Hills and Bullfrog tuffs follow an extremal. probability distribution (the third type asymptotic distribution of the smallest values). Monte Carlo simulation is carried out to estimate rock mass deformation moduli using a one-dimensional tuff model proposed by Zimmermann and Finley. We suggest that the results of these analyses be incorporated into the repository design

A curcumin-based TPA four-branched copper(II) complex probe for in vivo early tumor detection

Energy Technology Data Exchange (ETDEWEB)

Pi, Zongxin [Department of Chemical and Chemical Engineering, Hefei Normal University, Hefei 230001 (China); Wang, Jiafeng; Jiang, Bo [Department of Pharmacy, Anhui University of Chinese Medicine, Hefei 230038 (China); Cheng, Gang [Department of Chemical and Chemical Engineering, Hefei Normal University, Hefei 230001 (China); Zhou, Shuangsheng, E-mail: zshuangsheng@126.com [Department of Pharmacy, Anhui University of Chinese Medicine, Hefei 230038 (China); Center of Modern Experimental Technology, Anhui University, Hefei 230038 (China)

2015-01-01

A multibranched Cu(II) complex CuL{sub 2} curcumin-based was synthesized and characterized by single-crystal X-ray diffraction analysis. The photophysical properties of the complex have been investigated both experimentally and theoretically. The results show that the target complex exhibits higher quantum yield and larger two-photon absorption (TPA) cross-section in the near infrared (NIR) region compared with its free ligand. The cell imaging studies in vitro and in vivo reveal that the complex shows good photostability and excellent tumor targeting capability to tested cancerous cells, which can be potentially used for early tumor detection. - Graphical abstract: A multibranched Cu(II) complex was prepared from curcumin. The photophysical properties of the obtained complex have been investigated. The results exhibit that the complex has high capability to test cancerous cells and can distinguish between the cancerous and noncancerous cells, which should be potentially used for early tumor detection. - Highlights: • A novel multi-branched copper complex was synthesized. • The obtained compounds exhibited obvious TPA in high polar solvents. • The complex is a low toxicity at low-micromolar concentrations. • The complex exhibits larger TPA cross-section and brighter TPF imaging. • The complex has excellent targeting capability to tested cancerous cells.

Durability and photophysical properties of surfactant-covered porous silicon particles in aqueous suspensions

Energy Technology Data Exchange (ETDEWEB)

Balaguer, M.; Pastor, E.; Matveeva, E.; Chirvony, V.S. [Nanophotonics Technology Center, Universidad Politecnica de Valencia, Cami de Vera s/n, 46022 Valencia (Spain); Bychto, L. [Nanophotonics Technology Center, Universidad Politecnica de Valencia, Cami de Vera s/n, 46022 Valencia (Spain); Department of Electronics and Computer Sciences, Koszalin University of Technology, Sniadeckich 2, 75-453 Koszalin (Poland); Atienzar, P.; Miranda, M.A. [Instituto de Tecnologia Quimica CSIC-UPV, Universidad Politecnica de Valencia, Av. de los Naranjos s/n, 46022 Valencia (Spain)

2008-11-15

With the aim to impart hydrophilic properties to porous silicon (PSi) containing luminescent Si nanocrystals the PSi surface has been modified by a non-ionic surfactant (undecylenic acid) either physically (by physisorption) or chemically (through Si-C bond). PSi luminescence spectra and reversible quenching of the luminescence by molecular oxygen have been studied as a function of time elapsed after PSi surface immersion in water. The data obtained indicate that Si nanocrystal surface oxidation, which is realized in water, is accompanied by an appearance of a new type of luminescence centres, which are quenched by molecular oxygen differently than free excitons. SiO-related surface states are suggested to be responsible for the observed effect. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Influence of Nitrogen Doping on Device Operation for TiO2-Based Solid-State Dye-Sensitized Solar Cells: Photo-Physics from Materials to Devices

Directory of Open Access Journals (Sweden)

Jin Wang

2016-02-01

Full Text Available Solid-state dye-sensitized solar cells (ssDSSC constitute a major approach to photovoltaic energy conversion with efficiencies over 8% reported thanks to the rational design of efficient porous metal oxide electrodes, organic chromophores, and hole transporters. Among the various strategies used to push the performance ahead, doping of the nanocrystalline titanium dioxide (TiO2 electrode is regularly proposed to extend the photo-activity of the materials into the visible range. However, although various beneficial effects for device performance have been observed in the literature, they remain strongly dependent on the method used for the production of the metal oxide, and the influence of nitrogen atoms on charge kinetics remains unclear. To shed light on this open question, we synthesized a set of N-doped TiO2 nanopowders with various nitrogen contents, and exploited them for the fabrication of ssDSSC. Particularly, we carefully analyzed the localization of the dopants using X-ray photo-electron spectroscopy (XPS and monitored their influence on the photo-induced charge kinetics probed both at the material and device levels. We demonstrate a strong correlation between the kinetics of photo-induced charge carriers probed both at the level of the nanopowders and at the level of working solar cells, illustrating a direct transposition of the photo-physic properties from materials to devices.

Characterization of Physical and Thermal Properties of Biofield Treated Neopentyl Glycol

OpenAIRE

Trivedi, Dahryn; Trivedi, Mahendra Kumar; Branton, Alice; Nayak, Gopal

2015-01-01

Neopentyl glycol (NPG) has been extensively used as solid-solid phase change materials (PCMs) for thermal energy storage applications. The objective of the present study was to evaluate the impact of biofield treatment on physical, spectral and thermal properties of NPG. The study was performed in two groups (control and treated). The control group remained as untreated, and treatment group was subjected to Mr. Trivedi’s biofield treatment. The control and treated NPG were characterized by X-...

Characterizing scaling properties of complex signals with missed data segments using the multifractal analysis

Science.gov (United States)

Pavlov, A. N.; Pavlova, O. N.; Abdurashitov, A. S.; Sindeeva, O. A.; Semyachkina-Glushkovskaya, O. V.; Kurths, J.

2018-01-01

The scaling properties of complex processes may be highly influenced by the presence of various artifacts in experimental recordings. Their removal produces changes in the singularity spectra and the Hölder exponents as compared with the original artifacts-free data, and these changes are significantly different for positively correlated and anti-correlated signals. While signals with power-law correlations are nearly insensitive to the loss of significant parts of data, the removal of fragments of anti-correlated signals is more crucial for further data analysis. In this work, we study the ability of characterizing scaling features of chaotic and stochastic processes with distinct correlation properties using a wavelet-based multifractal analysis, and discuss differences between the effect of missed data for synchronous and asynchronous oscillatory regimes. We show that even an extreme data loss allows characterizing physiological processes such as the cerebral blood flow dynamics.

Synthesis, Structure and Fluorescence Properties of 5,17-Distyryl-25,26,27,28-tetraproproxycalix[4]arenes in the Cone Conformation

DEFF Research Database (Denmark)

Larsen, Mogens; Krebs, Frederik C; Jørgensen, Mikkel

1998-01-01

The HWE (Horner-Wadsworth-Emmons) reaction performed on the easily obtainable 5,17-diformyl- calix[4]arenes (cone) with arylmethyl phosphorus ylides yielded 5,17-distyryl-25,26,27, 28-tetrapropoxycalix[4]arenes (cone) in high yield and purely in the E/E configuration. Compounds 2-5 were prepared...... this way containing bromine. Subsequent bromine-lithium exchange and reaction with trimethoxyborane yielded the boryl- substituted 5,17-distyrylcalix[4] arenes 6-7a. The structures of 3, 5, and 7a were determined by X-ray diffraction. The photophysical properties of 2 were established by absorption...

BATMAN beam properties characterization by the beam emission spectroscopy diagnostic

Science.gov (United States)

Bonomo, F.; Ruf, B.; Barbisan, M.; Cristofaro, S.; Schiesko, L.; Fantz, U.; Franzen, P.; Pasqualotto, R.; Riedl, R.; Serianni, G.; Wünderlich, D.

2015-04-01

The ITER neutral beam heating systems are based on the production and acceleration of negative ions (H/D) up to 1 MV. The requirements for the beam properties are strict: a low core beam divergence (BATMAN (BAvarian Test MAchine for Negative ions) allows for deepening the knowledge of the determination of the beam properties. One of the diagnostics routinely used to this purpose is the Beam Emission Spectroscopy (BES): the Hα light emitted in the beam is detected and the corresponding spectra are evaluated to estimate the beam divergence and the stripping losses. The BES number of lines of sight in BATMAN has been recently increased: five horizontal lines of sight providing a vertical profile of the beam permit to characterize the negative ion beam properties in relation to the source parameters. Different methods of Hα spectra analysis are here taken into account and compared for the estimation of the beam divergence and the amount of stripping. In particular, to thoroughly study the effect of the space charge compensation on the beam divergence, an additional hydrogen injection line has been added in the tank, which allows for setting different background pressure values (one order of magnitude, from about 0.04 Pa up to the source pressure) in the beam drift region.

Structural and optical properties of novel surfactant-coated Yb-TiO2 nanoparticles

International Nuclear Information System (INIS)

Calandra, P.; Lombardo, D.; Pistone, A.; Turco Liveri, V.; Trusso, S.

2011-01-01

In this paper a novel hybrid approach to synthesise composite nanoparticles is presented. It is based on the laser ablation of a bulk target (Yb) immersed in a reversed micellar solution which contains nanoparticles of a different host material (TiO 2 nanoparticles) previously synthesised by chemical method. This approach thus exploits the advantages of the chemical synthesis through reversed micellar solution (size control, nanoparticle stabilisation), and of the laser ablation (“clean” synthesis, no side reactions). Central role is played by the microscopic processes controlling the deposition of the ablated Yb atoms onto the surface of TiO 2 nanoparticles which actually behave as nucleation seeds. The structural features of the resulting Yb-TiO 2 composite nanoparticles have been studied by Transmission Electron Microscopy, whereas their peculiar optical properties have been explored by UV–Vis spectroscopy and steady-state fluorescence. Results consistently show the formation of Yb and TiO 2 glued nanodomains to form nearly spherical and non-interacting nanoparticles with enhanced photophysical properties.

Structural and energetic characterization of the emissive RNA alphabet based on the isothiazolo[4,3-d]pyrimidine heterocycle core

KAUST Repository

Chawla, Mohit

2016-06-01

We present theoretical characterization of fluorescent non-natural nucleobases, tzA, tzG, tzC, and tzU, derived from the isothiazolo[4,3-d]pyrimidine heterocycle. Consistent with the experimental evidence, our calculations show that the non-natural bases have minimal impact on the geometry and stability of the classical Watson-Crick base pairs, allowing them to accurately mimic natural bases in a RNA duplex, in terms of H-bonding. In contrast, our calculations indicate that H-bonded base pairs involving the Hoogsteen edge are destabilized relative to their natural counterparts. Analysis of the photophysical properties of the non-natural bases allowed us to correlate their absorption/emission peaks to the strong impact of the modification on the energy of the lowest unoccupied molecular orbital, LUMO, which is stabilized by roughly 1.0-1.2 eV relative to the natural analogues, while the highest occupied molecular orbital, HOMO, is not substantially affected. As a result, the HOMO-LUMO gap is reduced from 5.3-5.5 eV in the natural bases to 4.0-4.4 eV in the modified ones, with a consequent bathochromic shift in the absorption and emission spectra. © 2016 the Owner Societies.

Structural and energetic characterization of the emissive RNA alphabet based on the isothiazolo[4,3-d]pyrimidine heterocycle core

KAUST Repository

Chawla, Mohit; Poater, Albert; Oliva, Romina; Cavallo, Luigi

2016-01-01

We present theoretical characterization of fluorescent non-natural nucleobases, tzA, tzG, tzC, and tzU, derived from the isothiazolo[4,3-d]pyrimidine heterocycle. Consistent with the experimental evidence, our calculations show that the non-natural bases have minimal impact on the geometry and stability of the classical Watson-Crick base pairs, allowing them to accurately mimic natural bases in a RNA duplex, in terms of H-bonding. In contrast, our calculations indicate that H-bonded base pairs involving the Hoogsteen edge are destabilized relative to their natural counterparts. Analysis of the photophysical properties of the non-natural bases allowed us to correlate their absorption/emission peaks to the strong impact of the modification on the energy of the lowest unoccupied molecular orbital, LUMO, which is stabilized by roughly 1.0-1.2 eV relative to the natural analogues, while the highest occupied molecular orbital, HOMO, is not substantially affected. As a result, the HOMO-LUMO gap is reduced from 5.3-5.5 eV in the natural bases to 4.0-4.4 eV in the modified ones, with a consequent bathochromic shift in the absorption and emission spectra. © 2016 the Owner Societies.

Theoretical study on photophysical properties of angular-shaped mercury(II) bis(acetylide) complexes as light-emitting materials

International Nuclear Information System (INIS)

Ran Xueqin; Feng Jikang; Wong, Wai-Yeung; Ren Aimin; Poon, Suk-Yue; Sun Chiachung

2010-01-01

An in-depth investigation on the optical and electronic properties of a series of mercury-containing and metal-free arylacetylenes with bridged heteroatoms was provided here. The geometric and electronic structures of the complexes in the ground state are studied with density functional theory and Hartree-Fock, whereas the lowest singlet and triplet excited states are optimized by singles configuration interaction (CIS) methods. At the time-dependent density functional theory (TD-DFT) level, molecular absorptions and emission properties were calculated on the basis of optimized ground- and excited-state geometries, respectively. The calculated lowest-lying absorptions of the investigated complexes are attributed to ligand-to-ligand charge transfer (LLCT), intraligand (IL) and ligand-to-metal charge transfer (LMCT). The results show that the optoelectronic properties for the complexes are affected by the transition-metal atom, various bridge heteroatoms and different end-group substituents. Moreover, the calculated data reveal that the studied molecules have improved charge-transfer rate, especially for designed molecules.

Photoluminescence properties of ‘red’ emitting La{sub 2}Zr{sub 2}O{sub 7}:Eu pyrochlore ceramics for potential phosphor application

Energy Technology Data Exchange (ETDEWEB)

Mohapatra, M., E-mail: manojm@barc.gov.in; Rajeswari, B.; Hon, N.S.; Kadam, R.M.; Natarajan, V.

2015-10-15

Lanthanum zirconate (La{sub 2}Zr{sub 2}O{sub 7}=LZO) pyrochlores doped with varying concentrations of Eu were synthesized using a low temperature gel-combustion synthesis route and characterized using X-ray diffraction, scanning electron microscopic and photoluminescence techniques. The final annealing temperature of the system could be brought down to 700 °C to produce a single phase compound. In addition, the optimum activator ion concentration for maximum luminescence yield was evaluated for the system. The site occupancy for the Eu ions was also investigated which suggested that at 500 °C, the ions were on the surface of the LZO host and later diffused into the lattice and replaced the La{sup 3+} ions on annealing at 700 °C 5 h. However, due to difference in the ionic radii, the doped RE ions were of the inversion center forming a D{sub 2d} symmetry around them. For the first time the radiative properties and the commercial utility of the LZO system have been investigated. These parameters were used to get an idea about the M–L bond covalency in the system. The radiative properties suggested the system can be used as a potential ‘red’ emitting phosphor. - Highlights: • Synthesis of lanthanum zirconate pyrochlores doped with Eu using gel-combustion route. • Optimization of dopant ion concentration and annealing temperature and evaluation of its local site symmetry. • Evaluation of various photo-physical properties for the Eu-LZO system to investigate the M–L bond covalency. • Investigation of the commercial utility of the system by calculating the color coordinates. • Comparison of the emission properties with commercial sample.

Structural and thermophysical properties characterization of continuously reinforced cast Al matrix composite

Directory of Open Access Journals (Sweden)

Brian Gordon

2010-11-01

Full Text Available In this work the process of manufacturing a continuously reinforced cast Al matrix composite and its properties are presented. The described technology permits obtaining a structural material of competitive properties compared to either heat treatable aluminum alloys or polymer composites for several types of applications. The examined thermophysical properties and structural characterization, including material anisotropy, coupled with the results of previous measurements of the mechanical properties of both Al2O3 reinforcing filaments and metallic prepregs have proven the high quality of this material and the possibility of its operation under special loading modes and environmental conditions. Microscopic examinations (LM, SEM were carried out to reveal the range of morphological homogeneity of the microstructure, the anisotropy of the filament band distribution, and simultaneously the adhesive behavior of the metal/fiber interface. The 3D morphology of the chosen microstructure components was revealed by computed tomography. The obtained results indicate that special properties of the examined prepreg materials have been strongly influenced, on the one hand, by the geometry of its internal microstructure, i.e. spatial distribution and volume fraction of the Al2O3 reinforcing filaments and, on the other hand, by a very good compatibility obtained between the individual metal prepreg components.

Characterization of conformational properties of protein/trehalose/water system by neutron scattering

CERN Document Server

Brandt, A; Mangione, A; Migliardo, F; Vertessy, B G

2002-01-01

In this contribution we report results of a small-angle neutron scattering (SANS) investigation of dUTPase/D sub 2 O solutions. Data were collected by the V4 spectrometer at the BENSC facility (Berlin, Germany). The results allow us to characterize the conformational properties of the protein in solution as a function of temperature and in the presence of trehalose, a disaccharide with a noticeable bioprotective action. (orig.)

Characterization of conformational properties of protein/trehalose/water system by neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Brandt, A. [Hahn-Meitner-Institut, BENSC (NI), Glienicker Strasse, 14109 Berlin (Germany); Magazu' , S.; Mangione, A.; Migliardo, F. [Dipartimento di Fisica and INFM, Universita' di Messina, PO Box 55, 98166 Messina (Italy); Vertessy, B.G. [Institute of Enzymology, Hungarian Academy of Sciences, P. O. Box 7, 1518 Budapest (Hungary)

2002-07-01

In this contribution we report results of a small-angle neutron scattering (SANS) investigation of dUTPase/D{sub 2}O solutions. Data were collected by the V4 spectrometer at the BENSC facility (Berlin, Germany). The results allow us to characterize the conformational properties of the protein in solution as a function of temperature and in the presence of trehalose, a disaccharide with a noticeable bioprotective action. (orig.)

A sufficiency property arising from the characterization of extremes of Markov chains

OpenAIRE

Bortot, Paola; Coles, Stuart

2000-01-01

At extreme levels, it is known that for a particular choice of marginal distribution, transitions of a Markov chain behave like a random walk. For a broad class of Markov chains, we give a characterization for the step length density of the limiting random walk, which leads to an interesting sufficiency property. This representation also leads us to propose a new technique for kernel density estimation for this class of models.

Oleic acid capped PbS nanoparticles: Synthesis, characterization and tribological properties

International Nuclear Information System (INIS)

Chen Shuang; Liu Weimin

2006-01-01

Oleic acid (OA) capped PbS nanoparticles were chemically synthesized and characterized by means of Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray electron diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The triboligical properties of the capped PbS nanoparticles as additive in liquid paraffin was investigated using a four-ball machine. The lubricating mechanisms were discussed along with the analyses results of XPS and scanning electron microscope (SEM). Results show that OA-capped PbS nanoparticles, with an average diameter of about 8 nm, are able to prevent water adsorption, oxidation and are capable of being dispersed stably in organic solvents or mineral oil. OA-capped PbS nanoparticles as an additive in liquid paraffin perform good antiwear and friction-reduction properties owing to the formation of a boundary film

Exciplex dynamics in a conjugated polymer blend of MDMO-PPV and PCNEPV

NARCIS (Netherlands)

Offermans, T.; Hal, van P.A.; Koetse, M.M.; Meskers, S.C.J.; Janssen, R.A.J.; Kafafi, Z.H.

2005-01-01

The photophysical properties of a solution processed blend of two semiconducting polymers with electron donating and electron accepting properties, respectively, as used in polymer photovoltaic devices have been investigated. In the binary mixture of

Characterization and property evaluation of U–15 wt%Pu alloy for fast reactor

International Nuclear Information System (INIS)

Kaity, Santu; Banerjee, Joydipta; Ravi, K.; Keswani, R.; Kutty, T.R.G.; Kumar, Arun; Prasad, G.J.

2013-01-01

The characterization and high temperature behaviour of U–15 wt%Pu alloy has been investigated in this study for the first time. U–15 wt%Pu alloy sample for this study was prepared by following melting and casting route. Microstructural characterization of the alloy was carried out by XRD and optical microscopy. The thermophysical properties like phase transition temperatures, coefficient of thermal expansion and hot hardness of the above alloy were determined. Eutectic temperature between T91 and U–15 wt%Pu was established. Apart from that, the fuel–cladding chemical compatibility of U–15 wt%Pu alloy with T91 grade steel was studied by diffusion couple experiment

Photophysical and photoprototropic characteristics of phenothiazine in aqueous and β-cyclodextrin media

Energy Technology Data Exchange (ETDEWEB)

Rajamohan, Rajaram, E-mail: rajmohanau@gmail.com [Department of Chemistry, S.K.P Institute of Technology, Tiruvannamalai 606611 (India); Nayaki, Sundararajulu Kothai [Chemistry Section, FEAT, Annamalai University, Annamalainagar 608002 (India); Sivakumar, Krishnamoorthy [Department of Chemistry, SCSV University, Enathur, Kanchipuram 631561 (India); Swaminathan, Meenakshisundaram [Department of Chemistry, Annamalai University, Annamalainagar 608002 (India)

2015-12-15

The photophysical and photoprototropic characteristics of phenothiazine (PTZ) in aqueous and β-cyclodextrin (β-CD) media have been investigated using absorption, steady state and time resolved fluorescence measurements. The absorbance and fluorescence intensities of the neutral and monocationic forms of PTZ are enhanced by the addition of β-cyclodextrin and it is due to the formation of 1:1 inclusion complex. The formation of complex is confirmed by the decay analysis and Job's continuous variation method in the liquid state while FT-IR spectral study and SEM image analysis in the solid state. The peak and pK{sub a}* values of PTZ in aqueous media are higher than in β-CD medium, which reveals that the >NH group of PTZ lies in the β-CD cavity. - Highlights: • Increase in the absorbance and fluorescence intensity of PTZ by the addition of β-CDx is confirmed the complex formation. • Biexponential decay is noticed for PTZ by the addition of β-CDx is due to the formation of inclusion complex. • FT-IR and SEM images analysis confirms complex between PTZ and β-CDx in solid state. • The pK{sub a} and pK{sub a}* values of PTZ in aqueous medium is higher than in β-CDx medium, which reveals that the >NH group of PTZ lies in the β-CDx cavity. • The orientation of the inclusion complex is proposed by PatchDock server.

Characterization of mechanical properties of pericardium tissue using planar biaxial tension and flexural deformation.

Science.gov (United States)

Murdock, Kyle; Martin, Caitlin; Sun, Wei

2018-01-01

Flexure is an important mode of deformation for native and bioprosthetic heart valves. However, mechanical characterization of bioprosthetic leaflet materials has been done primarily through planar tensile testing. In this study, an integrated experimental and computational cantilever beam bending test was performed to characterize the flexural properties of glutaraldehyde-treated bovine and porcine pericardium of different thicknesses. A strain-invariant based structural constitutive model was used to model the pericardial mechanical behavior quantified through the bending tests of this study and the planar biaxial tests previously performed. The model parameters were optimized through an inverse finite element (FE) procedure in order to describe both sets of experimental data. The optimized material properties were implemented in FE simulations of transcatheter aortic valve (TAV) deformation. It was observed that porcine pericardium TAV leaflets experienced significantly more flexure than bovine when subjected to opening pressurization, and that the flexure may be overestimated using a constitutive model derived from purely planar tensile experimental data. Thus, modeling of a combination of flexural and biaxial tensile testing data may be necessary to more accurately describe the mechanical properties of pericardium, and to computationally investigate bioprosthetic leaflet function and design. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization and technological properties of mineral clays used in the Southwest of Parana and West of Santa Catarina states

International Nuclear Information System (INIS)

Valdameri, C.Z.; Ciesca, D.F.; Zatta, L.; Anaissi, F.J.

2014-01-01

This paper aims to characterize clay minerals used in the ceramic industry in southwestern region of Parana and west of Santa Catarina states. The precursors used were the same used by industries in these regions for the production of bricks. The precursors were characterized,preliminary results are shown with respect to structural, chemical and physical precursors (XRD, EDS and plasticity). The specimens were characterized for technological burning properties: linear shrinkage, water absorption, flexural tension and density. The results show that the clays present Typical chemical composition of raw clay, however, the evaluation of technological properties after burning indicate negative results to be applied to the manufacture of red ceramic because did not meet the regulatory requirements. (author)

Characterization of Shear Properties for APO/MBI Syntactic Foam

Energy Technology Data Exchange (ETDEWEB)

Reser, Patrick M. [Univ. of New Mexico, Albuquerque, NM (United States); Lewis, Matthew W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Clark, Jarod [Univ. of New Mexico, Albuquerque, NM (United States); Ahuja, Nishant [Univ. of New Mexico, Albuquerque, NM (United States); Lenke, Lary R. [Univ. of New Mexico, Albuquerque, NM (United States)

2017-12-14

Triaxial compression testing is a means for mechanical characterization of a material. A unique feature of the triaxial compression test is the application of two different magnitudes of compressive pressures on the material simultaneously. The material behavior under these different compressive pressures can be monitored over time. Several important characteristics of the material, such as stress yield values and the shear failure envelope may then be determined. Also mechanical properties such as Poisson’s ratio, Young’s modulus and bulk modulus can be determined from the triaxial compression test. The triaxial compression test was employed in this investigation to characterize the shear behavior, shear failure envelope, and mechanical properties of a syntactic foam. Los Alamos National Laboratory (LANL) supplied a total of 36 samples of APO-BMI syntactic foam to the University of New Mexico, Department of Civil Engineering for testing between December 2003 and May 2004. Each sample had a diameter of 1.395±0.005 in. (3.543±0.013cm.) and a length of 2.796±0.004 in. (7.102±0.010 cm.). The samples had an average density of 0.295 g/cm3. Additional information about the material tested in this investigation can be found in the “Specimen Description” section contained in Chapter 1. The nomenclatures used in this study is presented in Chapter 1. In addition to designing and implementing triaxial compression tests capable of up to 2,000 psi. confining pressure (minor principal stress) and roughly 13,000 psi. in axial pressure (major principal stress), a pure tension test was designed and conducted on the foam material. The purpose of this pure tension test was to obtain maximum tensile stress values to enhance the characterization of the shear envelope in the stress space. The sampling procedure and specimen preparation for a standard test can be found in the American Society for Testing Materials (ASTM) D 5379/ D 5379 – 93. The above tests mentioned and

An expert system to characterize the surface morphological properties according to their functionalities

International Nuclear Information System (INIS)

Bigerelle, M; Mathia, T; Iost, A; Correvits, T; Anselme, K

2011-01-01

In this paper we propose a new methodology to characterize the morphological properties of a surface in relation with its functionality (tribological properties, surface coating adhesion, brightness, wettability...). We create a software based on experimental design and surface profile recording. Using an appropriate database structure, the roughness parameters are automatically computed at different scales. The surface files are saved in a hard disk directory and roughness parameters are computed at different scales. Finally, a statistical analysis system proposes the roughness parameter (or the pair of roughness parameters) that better describe(s) the functionality of the surface and the spatial scales at which the parameter(s) is (are) the more relevant.

An expert system to characterize the surface morphological properties according to their functionalities

Energy Technology Data Exchange (ETDEWEB)

Bigerelle, M [Laboratoire Roberval, UMR 6253, UTC/CNRS, UTC Centre de Recherches de Royallieu BP 20529, 60205 Compiegne France stol BS1 6BE (United Kingdom); Mathia, T [Laboratoire de Tribologie et Dynamique des Systemes, UMR 5513, Ecole Centrale de Lyon, 36 Av Guy de Collongue, 69134 Ecully Cedex (France); Iost, A [Laboratoire de Mecanique de Lille, UMR CNRS 8107, Arts et Metiers ParisTech - Lille, 8, boulevard Louis XIV 59046 Lille (France); Correvits, T [Laboratoire de Metrologie. Arts et Metiers ParisTech, ENSAM, 8 boulevard Louis XIV, 59046 LILLE Cedex (France); Anselme, K, E-mail: maxence.bigerelle@utc.fr [Institut De Sciences Des Materiaux De Mulhouse, CNRS LRC 7228, 15, rue Jean Starcky, Universite De Haute-Alsace, BP 2488, 68057 Mulhouse (France)

2011-08-19

In this paper we propose a new methodology to characterize the morphological properties of a surface in relation with its functionality (tribological properties, surface coating adhesion, brightness, wettability...). We create a software based on experimental design and surface profile recording. Using an appropriate database structure, the roughness parameters are automatically computed at different scales. The surface files are saved in a hard disk directory and roughness parameters are computed at different scales. Finally, a statistical analysis system proposes the roughness parameter (or the pair of roughness parameters) that better describe(s) the functionality of the surface and the spatial scales at which the parameter(s) is (are) the more relevant.

Design, synthesis and characterization of a highly luminescent Eu-complex monomer featuring thenoyltrifluoroacetone and 5-acryloxyethoxymethyl-8-hydroxyquinoline

Energy Technology Data Exchange (ETDEWEB)

Xu Cunjin [State Key Laboratory of Chemical Engineering, Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou 310027 (China); College of Material, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 310036 (China); Li Bogeng, E-mail: bgli@zju.edu.cn [State Key Laboratory of Chemical Engineering, Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou 310027 (China); Wan Jintao; Bu Zhiyang [State Key Laboratory of Chemical Engineering, Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou 310027 (China)

2011-08-15

A multi-functional ligand, 5-acryloxyethoxymethyl-8-hydroxyquinoline (Hamq), was synthesized, which contained a polymerizable C=C double bond for the copolymerization with other vinyl monomers and acted as photon antenna able to transfer energy to Eu{sup 3+} ions effectively. The triplet state energy of Hamq was determined to be 22,370 cm{sup -1} via the phosphorescence spectra of Hamq and its gadolinium complex. The title complex monomer Eu(tta){sub 2}(amq) was prepared by coordination reaction of Hamq with europium isopropoxide and 2-thenoyltrifluoroacetone (Htta) in dry organic solvents under argon atmosphere and characterized by elemental analysis and IR spectrum. The photophysical properties of the complex were studied in detail with UV-vis, luminescence spectra, luminescence lifetime and quantum yield. The complex exhibited nearly monochromatic red emission at 612 nm, a remarkable luminescence quantum yield at room temperature (30.6%) upon ligand excitation and a long {sup 5}D{sub 0} lifetime (389 {mu}s), which indicated that the ligand Hamq could sensitize the luminescence of Eu(III) ion efficiently in Eu(tta){sub 2}(amq), resulting in a strong luminescence of its copolymer poly[MMA-co-Eu(TTA){sub 2}(amq)] under UV excitation. The excellent luminescence properties of the complex made it not only a promising light-conversion molecular device but also an excellent luminescent monomer. - Highlights: >iWe designed and synthesized a highly luminescent Eu-complex monomer. > Quantum yield and lifetime of the complex are 30.6% and 389 {mu}s, respectively. > Excellent luminescence of the complex made it an excellent luminescent monomer.

BATMAN beam properties characterization by the beam emission spectroscopy diagnostic

International Nuclear Information System (INIS)

Bonomo, F.; Ruf, B.; Schiesko, L.; Fantz, U.; Franzen, P.; Riedl, R.; Wünderlich, D.; Barbisan, M.; Pasqualotto, R.; Serianni, G.; Cristofaro, S.

2015-01-01

The ITER neutral beam heating systems are based on the production and acceleration of negative ions (H/D) up to 1 MV. The requirements for the beam properties are strict: a low core beam divergence (< 0.4 °) together with a low source pressure (≤ 0.3 Pa) would permit to reduce the ion losses along the beamline, keeping the stripping particle losses below 30%. However, the attainment of such beam properties is not straightforward. At IPP, the negative ion source testbed BATMAN (BAvarian Test MAchine for Negative ions) allows for deepening the knowledge of the determination of the beam properties. One of the diagnostics routinely used to this purpose is the Beam Emission Spectroscopy (BES): the H α light emitted in the beam is detected and the corresponding spectra are evaluated to estimate the beam divergence and the stripping losses. The BES number of lines of sight in BATMAN has been recently increased: five horizontal lines of sight providing a vertical profile of the beam permit to characterize the negative ion beam properties in relation to the source parameters. Different methods of H α spectra analysis are here taken into account and compared for the estimation of the beam divergence and the amount of stripping. In particular, to thoroughly study the effect of the space charge compensation on the beam divergence, an additional hydrogen injection line has been added in the tank, which allows for setting different background pressure values (one order of magnitude, from about 0.04 Pa up to the source pressure) in the beam drift region

Properties and Characterization of Kenaf-Filled Natural Rubber Latex Foam

Directory of Open Access Journals (Sweden)

Ahmad Fikri Abdul Karim

2015-12-01

Full Text Available Kenaf powder was incorporated with natural rubber latex (NRL compound and foamed to make natural rubber latex foam (NRLF by using a well known technique called the Dunlop method. Different loadings of kenaf powder were added to NRL compound and was foamed to make NRLF. The mechanical properties, density, compression, thermal, and micro-structural characterization of control NRLF and kenaf incorporated NRLF were studied. Increasing content of kenaf reduced the tensile strength, elongation at break, and compressive strength of a NRLF. Modulus at 100% elongation and density of the NRLF increased with an increase in filler loading. Higher kenaf loading indicated higher elasticity of kenaf-filled NRLF, but the recovery percentage of kenaf-filled NRLF decreased with increasing kenaf loading. From thermogravimetric analysis (TGA result, an increase in the amount of kenaf loading from 1 to 7 phr increased the thermal stability of kenaf-filled NRLF. Morphological and micro-structural characterization performed by using scanning electron microscopy (SEM showed that kenaf powder filled up the micro-sized pores in the open cell structure of kenaf-filled NRLF.

Graphene oxide-modified ZnO particles: synthesis, characterization, and antibacterial properties

Directory of Open Access Journals (Sweden)

Zhong LL

2015-08-01

Full Text Available Linlin Zhong, Kyusik Yun Department of Bionanotechnology, Gachon University, Gyeonggi-do, Republic of Korea Abstract: Nanosized ZnO particles with diameters of 15 nm were prepared with a solution precipitation method at low cost and high yield. The synthesis of the particles was functionalized by the organic solvent dimethylformamide, and the particles were covalently bonded to the surface of graphene oxide. The morphology of the graphene oxide sheets and ZnO particles was confirmed with field emission scanning electron microscopy and biological atomic force microscopy. Fourier transform infrared spectroscopy and X-ray diffraction were used to analyze the physical and chemical properties of the ZnO/graphene oxide composites that differed from those of the individual components. Enhanced electrochemical properties were detected with cyclic voltammetry, with a redox peak of the composites at 0.025 mV. Excellent antibacterial activity of ZnO/graphene oxide composites was observed with a microdilution method in which minimum inhibitory concentrations of 6.25 µg/mL for Escherichia coli and Salmonella typhimurium, 12.5 µg/mL for Bacillus subtilis, and 25 µg/mL for Enterococcus faecalis. After further study of the antibacterial mechanism, we concluded that a vast number of reactive oxygen species formed on the surface of composites, improving antibacterial properties. Keywords: graphene oxide, ZnO, characterization, antibacterial property

Characterization of basic physical properties of Sb2Se3 and its relevance for photovoltaics

Institute of Scientific and Technical Information of China (English)

Chao CHEN; Matthew C.BEARD; Jiang TANG; David C.BOBELA; Ye YANG; Shuaicheng LU; Kai ZENG; Cong GE; Bo YANG; Liang GAO; Yang ZHAO

2017-01-01

Antimony selenide (Sb2Se3) is a promising absorber material for thin film photovoltaics because of its attractive material,optical and electrical properties.In recent years,the power conversion efficiency (PCE) of Sb2Se3 thin film solar cells has gradually enhanced to 5.6％.In this article,we systematically studied the basic physical properties of Sb2Se3 such as dielectric constant,anisotropic mobility,carrier lifetime,diffusion length,defect depth,defect density and optical band tail states.We believe such a comprehensive characterization of the basic physical properties of Sb2Se3 lays a solid foundation for further optimization of solar device performance.

Bis-pyridinium quadrupolar derivatives. High Stokes shift selective probes for bio-imaging

Science.gov (United States)

Salice, Patrizio; Versari, Silvia; Bradamante, Silvia; Meinardi, Francesco; Macchi, Giorgio; Pagani, Giorgio A.; Beverina, Luca

2013-11-01

We describe the design, synthesis and characterization of five high Stokes shift quadrupolar heteroaryl compounds suitable as fluorescent probes in bio-imaging. In particular, we characterize the photophysical properties and the intracellular localization in Human Umbilical Vein Endothelial Cells (HUVEC) and Human Mesenchymal Stem Cells (HMSCs) for each dye. We show that, amongst all of the investigated derivatives, the 2,5-bis[1-(4-N-methylpyridinium)ethen-2-yl)]- N-methylpyrrole salt is the best candidates as selective mitochondrial tracker. Finally, we recorded the full emission spectrum of the most performing - exclusively mitochondrial selective - fluorescent probe directly from HUVEC stained cells. The emission spectrum collected from the stained mitochondria shows a remarkably more pronounced vibronic structure with respect to the emission of the free fluorophore in solution.

Characterization of self-similarity properties of turbulence in magnetized plasmas

International Nuclear Information System (INIS)

Scipioni, A.; Rischette, P.; Bonhomme, G.; Devynck, P.

2008-01-01

The understanding of turbulence in magnetized plasmas and its role in the cross field transport is still greatly incomplete. Several previous works reported on evidences of long-time correlations compatible with an avalanche-type of radial transport. Persistence properties in time records have been deduced from high values of the Hurst exponent obtained with the rescaled range R/S analysis applied to experimental probe data acquired in the edge of tokamaks. In this paper the limitations of this R/S method, in particular when applied to signals having mixed statistics are investigated, and the great advantages of the wavelets decomposition as a tool to characterize the self-similarity properties of experimental signals are highlighted. Furthermore the analysis of modified simulated fractional Brownian motions (fBm) and fractional Gaussian noises (fGn) allows us to discuss the relationship between high values of the Hurst exponent and long range correlations. It is shown that for such simulated signals with mixed statistics persistence at large time scales can still reflect the self-similarity properties of the original fBm and do not imply the existence of long range correlations, which are destroyed. It is thus questionable to assert the existence of long range correlations for experimental signals with non-Gaussian and mixed statistics just from high values of the Hurst exponent.

Monodentate Schiff base ligands: their structural characterization, photoluminescence, anticancer, electrochemical and sensor properties.

Science.gov (United States)

Köse, Muhammet; Ceyhan, Gökhan; Tümer, Mehmet; Demirtaş, Ibrahim; Gönül, İlyas; McKee, Vickie

2015-02-25

Two Schiff base compounds, N,N'-bis(2-methoxy phenylidene)-1,5-diamino naphthalene (L(1)) and N,N'-bis(3,4,5-trimethoxy phenylidene)-1,5-diamino naphthalene (L(2)) were synthesized and characterized by the analytical and spectroscopic methods. The electrochemical and photoluminescence properties of the Schiff bases were investigated in the different conditions. The compounds L(1) and L(2) show the reversible redox processes at some potentials. The sensor properties of the Schiff bases were examined and color changes were observed upon addition of the metal cations, such as Hg(II), Cu(II), Co(II) and Al(III). The Schiff base compounds show the bathochromic shift from 545 to 585 nm. The single crystals of the compounds (L(1)) and (L(2)) were obtained from the methanol solution and characterized structurally by the X-ray crystallography technique. The molecule L(2) is centrosymmetric whereas the L(1) has no crystallographically imposed molecular symmetry. However, the molecular structures for these compounds are quite similar, differing principally in the conformation about methoxy groups and the dihedral angle between the two aromatic rings and diamine naphthalene. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of the Properties of Photopatterned Hydrogels for Use in Regenerative Medicine

Science.gov (United States)

Fiedler, Callie Irene

The goal of this thesis was to locally photopattern cytocompatible hydrogels to exhibit a wide range of mechanical properties and to probe the fundamental parameters governing these materials printed via stereolithography (SLA). Fabricating cell-laden structures with locally defined mechanical properties is non-trivial because the use of multiple precursor materials is wasteful, slow, and can lead to cell-death. To investigate the range of mechanical properties a single precursor solution can produce, I initially formed a single-network hydrogel and cyclically in- swelled fresh precursor solution followed by photo-exposure of the swollen gel ("swelling + exposure" or SE cycle). Because transport (i.e., diffusion and swelling) can occur on the same time scale as photopolymerization reaction kinetics, I first characterized the variable modulus hydrogels in bulk to isolate the reaction kinetics. In these experiments, I demonstrated the ability modify the mechanical and chemical (i.e., compressive modulus, toughness, crosslink density, swelling ratio) properties by up to 10-fold using only 2-4 SE cycles. I then used the understanding gained via these bulk experiments to locally photopattern the elastic modulus of a cytocompatible hydrogel with pixel-limited resolution (˜10s mum) employing a custom SLA system. Here I demonstrated the ability to fabricate hydrogels with a 500% elastic moduli increase with respect to the unpatterned hydrogel using atomic force microscopy. I monitored monomer attachment to the existing matrix as a function of SE cycle using confocal fluorescence microscopy to characterize the shape and size of printed features. I validated that the dependence of these features on material and processing conditions could be explained by a first-order reaction/diffusion model. With this understanding, I fabricated SLA 3D printed, soft, cytocompatible hydrogels (˜10s kPa) with ˜250 mum channels in addition to fabricating 3D printed stiff, cytocompatible

Synthesis, characterization, photophysics and electroluminescence based on a series of pyran-containing emitters

Energy Technology Data Exchange (ETDEWEB)

Yang Lifen [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China); Guan Min [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China); Bian Zuqiang [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China)]. E-mail: bianzq@pku.edu.cn; Xie Junqi [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China); Chen Tianpeng [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China); Huang Chunhui [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China)]. E-mail: chhuang@pku.edu.cn

2006-04-03

Four unsymmetric as well as symmetric carbazole or oxadiazole modified pyran-containing compounds have been synthesized and characterized. These compounds are 4-(dicyanomethylene)-2-methyl-6-(4-(carbazolo-9-yl)phenyl)-4H-pyran (10), 4-(dicyanomethylene)-2,6-bis(4-(carbazolo-9-yl)phenyl)-4H-pyran (11), 4-(dicyanomethylene)-2-methyl-6-(4-tert-phenyl)-1,3,4-oxdiazole-4-phenyl)-4 H-pyran (12), and 4-(dicyanomethylene)-2,6-bis(4-tert-phenyl)-1,3, 4-oxdiazole-4-phenyl-4H-pyran (13). Photoluminescent measurements indicated that their maximal emissions can be tuned from 543 to 590 nm in acetone solution. Electroluminescent studies based on these compounds as dopants resulted in greenish yellow light emission. It was found that the device based on the bis-condensed symmetric compound (11) with the configuration of indium tin oxide / Copper (II) phthalocyanine (5 nm) / N,N'-bis-(1-naphthl)-diphenyl-1,1'-biphenyl-4,4'-diamine (40 nm) / compound (11) : tris-(8-quinolinolato)aluminium (Alq{sub 3}) (1%) (30 nm) / 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (5 nm) / Alq{sub 3} (40 nm) / Mg : Ag (9 : 1) (200 nm) / Ag (80 nm) has achieved the highest luminance (6869 cd/m{sup 2}) and efficiency (1.32 lm/W and 2.52 cd/A) among the four emitters.

New sensitive and selective calixarene-based fluorescent sensors for the detection of Cs"+ in an organo aqueous medium

International Nuclear Information System (INIS)

Kumar, Naresh; Pham-Xuan, Qui; Depauw, Alexis; Leray, Isabelle; Hemadi, Miryana; Ha-Duong, Nguyet-Thanh; Lefevre, Jean-Pierre; Ha-Thi, Minh-Huong

2017-01-01

Herein, new fluorescent sensors based on calix[4]arene-bis-crown-6 containing extended coumarin as a fluoro-phore were synthesized and their photophysical properties were characterized. These compounds display intense absorption and emission spectra in the visible region due to extension of the coumarin system. Moreover, complexation properties of these ligands were reported, and the Calix-COU-Benz-CN ligand was able to selectively detect cesium ions in an organo aqueous solvent. Upon the addition of cesium, a blue-shift in the absorption spectra and an enhancement of the emission spectra were observed. This ligand was incorporated in a micro fluidic device for the detection of Cs"+ ions, and a detection limit of 1.4 mM was achieved for these ions. (authors)

Synthesis, characterization and optical properties of hybridized CdS-PVA nanocomposites

International Nuclear Information System (INIS)

Wang Hongmei; Chen Zhe; Fang Pengfei; Wang Shaojie

2007-01-01

Hybrid nanocomposites of CdS nanoparticles embedded in poly(vinyl alcohol)(PVA) matrixes had been prepared and characterized. The -OH groups acted as the coordination sites for cadmium ion aggregations and nanosized CdS particles were successfully grown in situ at these sites with the release of S 2- ions from thioacetamide. The density and size of the nanoparticles were found to be a function of molar quantity of cadmium ion used. X-ray diffraction results showed that the obtained CdS nanoparticles were hexagonal phase. Ionic clustering within the PVA matrix occurred and had provided a confined medium for particles growth in uniform size. The optical properties of the prepared CdS-PVA hybrid nanocomposites were characterized by absorption and emission spectroscopies. The absorption spectra showed a blue shift as compared to bulk CdS band-gap. The photoluminescence studies indicated the emission peak observed in samples could be assigned to the optical transition of the first excitonic state of the CdS nanoparticles

Properties of field functionals and characterization of local functionals

Science.gov (United States)

Brouder, Christian; Dang, Nguyen Viet; Laurent-Gengoux, Camille; Rejzner, Kasia

2018-02-01

Functionals (i.e., functions of functions) are widely used in quantum field theory and solid-state physics. In this paper, functionals are given a rigorous mathematical framework and their main properties are described. The choice of the proper space of test functions (smooth functions) and of the relevant concept of differential (Bastiani differential) are discussed. The relation between the multiple derivatives of a functional and the corresponding distributions is described in detail. It is proved that, in a neighborhood of every test function, the support of a smooth functional is uniformly compactly supported and the order of the corresponding distribution is uniformly bounded. Relying on a recent work by Dabrowski, several spaces of functionals are furnished with a complete and nuclear topology. In view of physical applications, it is shown that most formal manipulations can be given a rigorous meaning. A new concept of local functionals is proposed and two characterizations of them are given: the first one uses the additivity (or Hammerstein) property, the second one is a variant of Peetre's theorem. Finally, the first step of a cohomological approach to quantum field theory is carried out by proving a global Poincaré lemma and defining multi-vector fields and graded functionals within our framework.

Integral parameters for characterizing water, energy, and aeration properties of soilless plant growth media

Science.gov (United States)

Chamindu Deepagoda, T. K. K.; Chen Lopez, Jose Choc; Møldrup, Per; de Jonge, Lis Wollesen; Tuller, Markus

2013-10-01

Over the last decade there has been a significant shift in global agricultural practice. Because the rapid increase of human population poses unprecedented challenges to production of an adequate and economically feasible food supply for undernourished populations, soilless greenhouse production systems are regaining increased worldwide attention. The optimal control of water availability and aeration is an essential prerequisite to successfully operate plant growth systems with soilless substrates such as aggregated foamed glass, perlite, rockwool, coconut coir, or mixtures thereof. While there are considerable empirical and theoretical efforts devoted to characterize water retention and aeration substrate properties, a holistic, physically-based approach considering water retention and aeration concurrently is lacking. In this study, the previously developed concept of integral water storage and energy was expanded to dual-porosity substrates and an analog integral oxygen diffusivity parameter was introduced to simultaneously characterize aeration properties of four common soilless greenhouse growth media. Integral parameters were derived for greenhouse crops in general, as well as for tomatoes. The integral approach provided important insights for irrigation management and for potential optimization of substrate properties. Furthermore, an observed relationship between the integral parameters for water availability and oxygen diffusivity can be potentially applied for the design of advanced irrigation and management strategies to ensure stress-free growth conditions, while conserving water resources.

Preparation, characterization, and thermal properties of microencapsulated phase change material for thermal energy storage

Energy Technology Data Exchange (ETDEWEB)

Alkan, Cemil; Sari, Ahmet; Karaipekli, Ali [Department of Chemistry, Gaziosmanpasa University, 60240 Tokat (Turkey); Uzun, Orhan [Department of Physics, Gaziosmanpasa University, 60240 Tokat (Turkey)

2009-01-15

This study is focused on the preparation, characterization, and determination of thermal properties of microencapsulated docosane with polymethylmethacrylate (PMMA) as phase change material for thermal energy storage. Microencapsulation of docosane has been carried out by emulsion polymerization. The microencapsulated phase change material (MEPCM) was characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Thermal properties and thermal stability of MEPCM were measured by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). DSC analysis indicated that the docosane in the microcapsules melts at 41.0 C and crystallizes at 40.6 C. It has latent heats of 54.6 and -48.7 J/g for melting and crystallization, respectively. TGA showed that the MEPCM degraded in three distinguishable steps and had good chemical stability. Accelerated thermal cycling tests also indicated that the MEPCM had good thermal reliability. Based on all these results, it can be concluded that the microencapsulated docosane as MEPCMs have good potential for thermal energy storage purposes such as solar space heating applications. (author)

UHPLC/Q-TOFMS-based metabolomics for the characterization of cold and hot properties of Chinese materia medica.

Science.gov (United States)

Wang, Yang; Zhou, Shujun; Wang, Meng; Liu, Shuying; Hu, Yuanjia; He, Chengwei; Li, Peng; Wan, Jian-Bo

2016-02-17

The cold/hot property of Chinese materia medica (CMM) and the application of its corresponding knowledge in the diagnosis, differentiation and treatment of diseases have been considered to be the extremely important part of traditional Chinese medicine (TCM). As highly abstracted TCM theory, the cold/hot property of CMMs is still not fully understood and remains to be elucidated by systems biology approach. The cold and hot properties of CMM are mainly defined by the response of the body to a given CMM. Metabolomics is a promising systems biology method to profile entire endogenous metabolites and monitor their fluctuations related to an exogenous stimulus. Thus, a metabolomics approach was applied to characterize the cold and hot properties of CMMs. Mice were intragastrically administered three selected cold property CMMs (i.e., Rheum palmatum L., radix et rhizoma; Coptis chinensis Franch, rhizome and Scutellaria baicalensis Georgi, radix) and three hot property CMMs (i.e., Cinnamomum cassia (L.) J. Presl, cortex; Zingiber officinale Roscoe, rhizoma and Evodia rutaecarpa (Juss.) Benth., fructus) once daily for one week. The comprehensive metabolome changes in the plasma of mice after treatment with cold or hot property CMMs were characterized by ultra-high performance liquid chromatography/time of flight mass spectrometry (UHPLC/Q-TOF-MS), and the potential biomarkers related to cold and hot properties of CMM were explored. Metabolites perturbation in plasma occurs after treatment with cold CMMs and hot CMMs in mice, and 15 and 16 differential biomarkers were identified to be associated with the cold and hot properties of CMMs, respectively. Among them, LPC (18:0), LPC (18:1), LPC (20:4) and LPC (20:5) showed decreased trends in the cold property CMM treated groups, but increased in the hot property CMM treated groups. There is a strong connection between the cold/hot property of CMMs and lysophosphatidylcholines metabolism. This study offers new insight

Novel ion-exchange nanocomposite membrane containing in-situ formed FeOOH nanoparticles: Synthesis, characterization and transport properties

Energy Technology Data Exchange (ETDEWEB)

Heidary, Farhad; Kharat, Ali Nemati [University of Tehran, Tehran (Iran, Islamic Republic of); Khodabakhshi, Ali Reza [Faculty of Science, Arak University, Arak (Iran, Islamic Republic of)

2016-04-15

A new type of cation-exchange nanocomposite membrane was prepared via in-situ formation of FeOOH nanoparticles in a blend containing sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) and sulfonated polyvinylchloride by a simple one-step chemical method. Prepared nanocomposite membranes were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. The SEM images showed uniform dispersion of FeOOH nanoparticles throughout the polymeric matrices. The effect of additive loading on physicochemical and electrochemical properties of prepared cation-exchange nanocomposite membranes was studied. Various characterizations showed that the incorporation of different amounts of FeOOH nanoparticles into the basic membrane structure had a significant influence on the membrane performance and could improve the electrochemical properties.

Electrostatic Properties and Characterization of Textile Materials Affected by Ion Flux

Directory of Open Access Journals (Sweden)

Pranas Juozas ŽILINSKAS

2013-03-01

Full Text Available This work analyzes the opportunities of wider characterization of textile materials, fabrics, upholstery fabrics, fibers, yarns or others, which may accumulate electric charge. A non-contact way for electrostatic properties measurement based on affecting those materials by ions with positive or negative charge is described. The method allows to measure simultaneously the time dependences of the surface voltage and the electric charge during the charging process and the time dependences of the surface voltage during the discharging process. From the measured dependencies the following set of parameters was measured or calculated: the surface voltage limiting value, the surface voltage semi-decay time, the maximum deposited charge, the layer capacitance, the energy of the accumulated charge and others. The surface voltage distribution measurement method when the investigated textile material is affected by ion flux was also described. To verify the applicability of the proposed methods for characterization of textile materials in order to determine the above-mentioned parameters of cotton, linen, wool, viscose, acetate, polyester, polyester coated with polytetrafluoroethylene, a series of experiments were performed. The surface voltage distribution measurement method based on affecting textile materials by ions with positive charge was described and a surface voltage distribution of a polyester-cotton upholstery fabric produced by a Jacquard mechanism was presented. The performed experiments demonstrate the possibilities of method application for comparison of the electrostatic properties of different textile materials used for the same tasks or the same materials produced by different technological processes.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3828

Manganese ferrite prepared using reverse micelle process: Structural and magnetic properties characterization

Energy Technology Data Exchange (ETDEWEB)

Hashim, Mohd, E-mail: md.hashim09@gmail.com [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India); Shirsath, Sagar E. [Spin Device Technology Centre, Department of Engineering, Shinshu University, Nagano 380-8553 (Japan); Meena, S.S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Mane, M.L. [Department of Physics, S.G.R.G. Shinde Mahavidyalaya, Paranda 413502, MS (India); Kumar, Shalendra [School of Materials Science and Engineering, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of); Bhatt, Pramod [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kumar, Ravi [Centre for Material Science Engineering, National Institute of Technology, Hamirpur, HP (India); Prasad, N.K.; Alla, S.K. [Deptartment of Metallurgical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Shah, Jyoti; Kotnala, R.K. [National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Mohammed, K.A. [Department of Mathematics & Physics Sciences, College of Arts and Sciences, University of Nizwa, Nizwa (Oman); Şentürk, Erdoğan [Department of Physics, Sakarya University, Esentepe, 54187 Sakarya (Turkey); Alimuddin [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India)

2015-09-05

Highlights: • Preparation of Mn{sup 3+} substituted MnFe{sub 2}O{sub 4} ferrite by Reverse microemulsion process. • Characterization by XRD, SEM, VSM, Mössbauer spectroscopy and dielectric measurements techniques. • Magnetic properties of MnFe{sub 2}O{sub 4} enhanced after Mn{sup 3+} substitution. • The dielectric constant and ac conductivity increased with Mn{sup 3+} substitution. - Abstract: Reverse microemulsion process was employed to prepare of nanocrystalline Mn{sup 3+} substituted MnFe{sub 2−x}Mn{sub x}O{sub 4} ferrites. The structural, magnetic and dielectric properties were studied for different concentrations of Mn{sup 3+}. The structural and microstructural properties were analyzed using X-ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy techniques. The phase identification of the materials was studied by Rietveld refined XRD patterns which reveals single phase with cubic symmetry for the samples. The lattice parameters were ranged in between 8.369 and 8.379 Å and do not show any significant change with the substitution of Mn{sup 3+}. The average particles size was found to be around 11 ± 3 nm. Magnetization results obtained from the vibrating sample magnetometer (VSM) confirm that the substitution of Mn{sup 3+} in MnFe{sub 2}O{sub 4} ferrite caused an increase in the saturation magnetization and coercivity. The dependence of Mössbauer parameters on Mn{sup 3+} substitution has been analyzed. Magnetic behavior of the samples were also studied at field cooled (FC) and zero field cooled (ZFC) mode. The dependence of Mössbauer parameters on Mn{sup 3+} substitution was also analyzed. All the magnetic characterization shows that Mn{sup 3+} substitution enhance the magnetic behavior of MnFe{sub 2}O{sub 4} ferrite nanoparticles.

Thermoelectric Characterization of Electronic Properties of GaMnAs Nanowires

Directory of Open Access Journals (Sweden)

Phillip M. Wu

2012-01-01

Full Text Available Nanowires with magnetic doping centers are an exciting candidate for the study of spin physics and proof-of-principle spintronics devices. The required heavy doping can be expected to have a significant impact on the nanowires' electron transport properties. Here, we use thermopower and conductance measurements for transport characterization of Ga0.95Mn0.05As nanowires over a broad temperature range. We determine the carrier type (holes and concentration and find a sharp increase of the thermopower below temperatures of 120 K that can be qualitatively described by a hopping conduction model. However, the unusually large thermopower suggests that additional mechanisms must be considered as well.

Characterization and bulk properties of oxides

International Nuclear Information System (INIS)

Sonder, E.; Connolly, T.F.

1979-06-01

The bulk properties of oxides are divided into two classes, intrinsic properties which depend solely on the identity of the material, and extrinsic ones, which differ for different samples of the same compound. Sources of tabulated numerical values of intrinsic properties are given and modern developments in information storage and retrieval are discussed. Extrinsic properties are shown to depend on defects and trace impurities in the samples. Techniques of trace impurity analysis are discussed and realistic limits of detection and accuracies are given for routine analyses

Molecular Engineering, Photophysical and Electrochemical Characterizations of Novel Ru(II) and BODIPY Sensitizers for Mesoporous TiO2 Solar Cells

Science.gov (United States)

Cheema, Hammad Arshad

To realize the dream of a low carbon society and ensure the wide spread application of renewable energy sources such as solar energy, photovoltaic devices should be highly efficient, cost-effective and stable for at least 20 years. Dye sensitized solar cells (DSCs) are photovoltaic cells that mimic the natural photosynthesis. In a DSC, the dye absorbs photons from incident light and converts those photons to electric charges, which are then extracted to the outer circuit through semiconductor TiO2, whereas the mediator regenerates the oxidized dye. A sensitizer is the pivotal component in the device in terms of determining the spectral response, color, photocurrent density, long term stability, and thickness of a DSC. The breakthrough report by O'Regan and Gratzel in 1991 has garnered more than 18,673 citations (as of October 9, 2014), which indicates the immense scientific interest to better understand and improve the fundamental science of this technology. With the aforementioned in mind, this study has focused on the molecular engineering of novel sensitizers to provide a better understanding of structure-property relationships of novel sensitizers for DSCs. The characterization of sensitizers (HD-1-mono, HD-2-mono and HD-2) for photovoltaic applications showed that the photocurrent response of DSCs can be increased by using mono-ancillary ligand instead of bis-ancillary ligands, which is of great commercial value considering the difference in the molecular weights of both dyes. The results of this work were published in Journal of Materials Chemistry A (doi:10.1039/c4ta01942c) and ACS Applied Materials and Interfaces (doi: 10.1021/am502400b). Furthermore, structure-property relationships were investigated in Ru (II) sensitizers HL-41 and HL-42 in order to elucidate the steric effects of electron donating ancillary ligands on photocurrent and photovoltage, as discussed in Chapter 4. It was found that the electron donating group (ethoxy) ortho to the CH=CH spacer

Identifying and selecting edible luminescent probes as sensors of food quality

Directory of Open Access Journals (Sweden)

Maria G. Corradini

2016-06-01

Full Text Available Foods contain a plethora of aromatic molecules—natural colors, synthetic dyes, flavors, vitamins, antioxidants, etc.—that are luminescent, exhibiting prompt fluorescence or delayed phosphorescence. Although food autofluorescence has been used to detect specific contaminants (e.g., aflatoxins or to authenticate specific foods (olive oil, much of the potential of using the optical luminescence of intrinsic molecules for sensing properties of foods is unrealized. We summarize here work characterizing the photophysical properties of some edible, and potentially GRAS (generally-recognized-as-safe, chromophores and especially their sensitivity to, and thus potential for sensing, various physical—viscosity, mobility/rigidity—or chemical—polarity, pH—properties of food known to reflect or be indicative of food quality, stability, and safety. A thorough-going characterization of and robust protocols for interpretation of the luminescent signals from edible chromophores can expand the repertoire of analytical techniques available to monitor quality, and even safety, of the food supply at various stages of production, distribution and storage or even at point of sale.

Development of Ta3N5 as an Efficient Visible Light-responsive Photocatalyst for Water Oxidation

KAUST Repository

Nurlaela, Ela

2015-01-01

phase sample. The photophysical properties of Ta3N5, such as the absorption coefficient, carrier mobility, and carrier lifetime, have been experimentally measured by synthesizing Ta3N5 thin films. Very low kinetic properties with very low transport

Magnetic refrigeration cycle analysis using selected thermodynamic property characterizations for gadolinium gallium garnet

International Nuclear Information System (INIS)

Murphy, R.W.

1992-01-01

Magneto-thermodynamic property characterizations were selected, adapted, and compared to material property data for gadolinium gallium garnet in the temperature range 4--40 K and magnetic field range 0--6 T. The most appropriate formulations were incorporated into a model in which methods similar to those previously developed for other materials and temperature ranges were used to make limitation and relative performance assessments of Carnot, ideal regenerative, and pseudo-constant field regenerative cycles. Analysis showed that although Carnot cycle limitations on available temperature lift for gadolinium gallium garnet are not as severe as those for materials previously examined, substantial improvements in cooling capacity/temperature lift combinations can be achieved using regenerative cycles within specified fields limits if significant loss mechanisms are mitigated

A series of copper complexes with carbazole and oxadiazole moieties: Synthesis, characterization and luminescence performance

Energy Technology Data Exchange (ETDEWEB)

Bai Weiyang, E-mail: baiwy02@163.com [College of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054 (China); Sun Li [Graduate University of Chinese Academy of Sciences, Beijing 100049 (China)

2012-10-15

In this paper, various moieties of ethyl, carbazole and oxadiazole are attached to 2-thiazol-4-yl-1H-benzoimidazole to form a series of diamine ligands. Their corresponding Cu(I) complexes are also synthesized using bis(2-(diphenylphosphanyl)phenyl) ether as the auxiliary ligand. Crystal structures, thermal property, electronic nature and luminescence property of these Cu(I) complexes are discussed in detail. These Cu(I) complexes are found to be efficient green-emitting ones in solutions and the emissive parameters are improved largely by the incorporation of substituent moieties. Detailed analysis suggests that the effective suppression of solvent-induced exciplex quenching is responsible for this phenomenon. On the other hand, the introduction of substituent moieties exerts no obvious influence on molecular structure, thermal stability and emitting-energy of the Cu(I) complexes, owing to their absence from inner coordination sphere. - Highlights: Black-Right-Pointing-Pointer Diamine ligands with various moieties and Cu(I) complexes are synthesized. Black-Right-Pointing-Pointer Crystal structures and photophysical property are discussed in detail. Black-Right-Pointing-Pointer The incorporation of substituent moieties improves luminescence performance. Black-Right-Pointing-Pointer Solvent-induced exciplex quenching is suppressed by substituent moieties.

Synthesis, characterization, and biocompatible properties of alanine-grafted chitosan copolymers.

Science.gov (United States)

Park, Gyu Han; Kang, Min-Sil; Knowles, Jonathan C; Gong, Myoung-Seon

2016-04-01

In order to overcome major problems regarding the lack of affinity to solvents and limited reactivity of the free amines of chitosan, introduction of appropriate spacer arms having terminal amine function is considered of interest. L-Alanine-N-carboxyanhydride was grafted onto chitosan via anionic ring-opening polymerization. The chemical and structural characterizations of L-alanine-grafted chitosan (Ala-g-Cts) were confirmed through Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy ((1)H NMR). In addition, the viscoelastic properties of Ala-g-Cts were examined by means of a rotational viscometer, and thermal analysis was carried out with a thermogravimetric analyzer and differential scanning calorimetry. Morphological changes in the chitosan L-alanine moiety were determined by x-ray diffraction. To determine the feasibility of using these films as biomedical materials, we investigated the effects of their L-alanine content on physical and mechanical properties. The biodegradation results of crosslinked Ala-g-Cts films were evaluated in phosphate-buffered solution containing lysozyme at 37℃. Proliferation of MC3T3-E1 cells on crosslinked Ala-g-Cts films was also investigated with use of the CCK-8 assay. © The Author(s) 2016.

Optical properties of humic substances and CDOM: relation to structure.

Science.gov (United States)

Boyle, Erin S; Guerriero, Nicolas; Thiallet, Anthony; Del Vecchio, Rossana; Blough, Neil V

2009-04-01

The spectral dependencies of absorption and fluorescence emission (emission maxima (lamdamax), quantum yields (phi), and mean lifetimes (taum)) were acquired for a commercial lignin, Suwannee River humic (SRHA) and fulvic (SRFA) acids, and a series solid phase extracts (C18) from the Middle Atlantic Bight (MAB extracts). These parameters were compared with the relative average size and total lignin phenol content (TLP). TLP was strongly correlated with absorption at 280 and 355 nm for the MAB extracts, SRHA, and SRFA. The spectral dependence of lamdamax, phi), and taum was very similar for all samples, suggesting a common photophysical and thus structural basis. A strong decrease of phi and taum with increasing average size indicates that intramolecular interactions must be important. When combined with previous work, the results lead us to conclude that the optical properties commonly associated with terrestrial humic substances and chromophoric dissolved organic matter arise primarily from an ensemble of partially oxidized lignins derived from vascular plant sources. Theyfurther provide additional support for an electronic interaction model in which intramolecular energy transfer, excited-state electron transfer, as well as charge transfer likely play important roles in producing the observed optical and photochemical properties of these materials.

Influence of different water-ethanol solvent systems on the spectroscopic and physico-chemical properties of the macrocyclic compounds pheophytin and chlorophyll a; Influencia de diferentes sistemas de solvente agua-etanol sobre as propriedades fisico-quimicas e espectroscopicas dos compostos macrociclicos feofitina e clorofila a

Energy Technology Data Exchange (ETDEWEB)

Moreira, Leonardo M.; Rodrigues, Maira R.; Oliveira, Hueder P. M. de [Universidade Camilo Castelo Branco, Sao Jose dos Campos, SP (Brazil); Lima, Adriana [Universidade do Vale do Paraiba, Sao Jose dos Campos, SP (Brazil); Soares, Rafael R. S.; Batistela, Vagner R.; Gerola, Adriana P.; Hioka, Noboru [Universidade Estadual de Maringa (UEM), PR (Brazil). Dept. de Quimica; Severino, Divinomar; Baptista, Mauricio S. [Universidade de Sao Paulo, (USP), SP (Brazil). Inst. de Quimica; Machado, Antonio Eduardo da Hora [Universidade Federal de Uberlandia (UFU), MG (Brazil). Inst. de Quimica

2010-07-01

This work focus on the influence of solvent on the photophysical properties of chlorophyll a and pheophytin. Both compounds are related to the photosynthesis process and are considered prototypes of photosensitizers in Photodynamic Therapy. Fluorescence measurements were developed using water/ethanol mixtures at different compositions, since both solvents could be employed in biological applications. The spectroscopic properties of these compounds undergo profound changes depending on water content in the ethanol due to auto-aggregation processes. The major hydrophobicity and the lower dielectric constant of ethanol when compared with water precluded significantly the auto-aggregation process of these compounds. (author)

Synthesis, characterization and luminescent properties of lanthanide complexes with an unsymmetrical tripodal ligand

Energy Technology Data Exchange (ETDEWEB)

Yan Zhenzhong [State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Tang Yu [State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)], E-mail: tangyu@lzu.edu.cn; Liu Weisheng; Tan Minyu [State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)

2008-09-15

Solid complexes of lanthanide nitrates with a new unsymmetrical tripodal ligand, bis[(2'-benzylaminoformyl)phenoxyl)ethyl](ethyl)amine (L) have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Sm(III), Eu(III), Tb(III) and Dy(III) nitrate complexes in solid state were also investigated. Under the excitation of UV light, these complexes exhibited characteristic emission of central metal ions.

Synthesis, characterization and magnetic properties of selected Laves and MAX phases

International Nuclear Information System (INIS)

Hamm, Christin Maria

2017-01-01

In this work the rare-earth free Laves phases Ti 2 M 3 Si with M = Mn, Fe, Co, Ni were synthesized by microwave heating and were structurally and magnetically characterized. Furthermore, the solid solution Ti 2 (Co 1-x Fe x ) 3 Si was synthesized by arc melting and spark plasma sintering, as well as their magnetic behavior was studied. In addition to the Laves phases, the focus was on the synthesis and characterization of aluminum-based MAX phases. For the first time the ternary carbides were prepared by microwave heating. The phase-pure representation of MAX phases was particularly challenging for synthetic solid-state chemistry. The susceptor-assisted microwave heating allows the synthesis of high-quality samples, which was shown in this work on M 2 AlC (M = Ti, V, Cr) and V 4 AlC 3 . Furthermore, for the first time, the doping of these materials with Mn and Fe was successful. In addition to the structural characterization of the new phases, the microstructure and magnetic properties are discussed in this work. Using these doped compounds as well as the compound V 4 AlC 3 , it has been shown that field-activated synthesis, particularly susceptor-assisted microwave heating, are a very good synthesis method for compounds which are hard or sometimes not synthesized by conventional methods.

Synthesis, characterization and magnetic properties of monodisperse Ni, Zn-ferrite nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Kumar, Sanjeev, E-mail: sanjeevkumar.dubey2@gmail.com [University of Petroleum and Energy Studies, Dehradun, Uttarakhand (India); Kumar, Pankaj [University of Petroleum and Energy Studies, Dehradun, Uttarakhand (India); Singh, Vaishali [University School of Basic and Applied Science (India); Kumar Mandal, Uttam [University of Chemical Technology, GGS Indraprastha University, Sector 16, Dwarka, Delhi 110403 (India); Kumar Kotnala, Ravinder [National Physical laboratory, New Delhi 110012 (India)

2015-04-01

Synthesization of monodisperse Ni, Zn-ferrite (Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}, x=1, 0.8, 0.6, 0.5, 0.4, 0.2, 0.0) nanocrystals has been achieved by the inverse microemulsion method using CTAB as surfactant and kerosene as an oil phase. The detailed characterization of the synthesized nanocrystals and measurement of the magnetic properties has been done by techniques like X-ray diffraction (XRD), field emission transmission electron microscopy (FETEM), Fourier transform infrared spectroscopy (FITR) and Vibrating Sample Magnetometer (VSM) respectively. The relationship between the structure and composition of the nanocrystals with magnetic properties has been investigated. The nanocrystals size is found to be in the range 1–5 nm. The effect of Zn substitution on size and magnetic properties has been studied. It has been observed that magnetism changed from ferromagnetic at X= 0 to super paramagnetic to paramagnetic at X=1 as Zn concentration increased. The Curie temperature is found to decrease with an increase in Zn concentration. - Highlights: • Reverse microemulsion route is very facile route for synthesis of Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} ferrite. • Presence of Zn changes the structural and magnetic properties of the Zn substituted NiFe{sub 2}O{sub 4.} • The lattice constant increases with the increase in Zn substitution. • The curie temperature decreases with Zn concentration appreciably. • Magnetic behavior varies from ferromagnetic at x=0 to superparamagnetic to paramagnetic at x=1.

Synthesis, characterization, spectroscopic properties and DFT study of a new pyridazinone family

Science.gov (United States)

Arrue, Lily; Rey, Marina; Rubilar-Hernandez, Carlos; Correa, Sebastian; Molins, Elies; Norambuena, Lorena; Zarate, Ximena; Schott, Eduardo

2017-11-01

Nitrogen compounds are widely investigated due to their pharmacological properties such as antihypertensive, antinociceptive, antibacterial, antifungal, analgesic, anticancer and inhibition activities and lately even as pesticide. In this context, we present the synthesis of new compounds: (E)-6-(3,4-dimethoxyphenyl)-3-(3-(3,4-dimethoxyphenyl)acryloyl)-1-(4-R-phenyl)- 5,6-dihydropyridazin-4(1H)-one (with R = sbnd H(1), -Cl(2), -Br(3), sbnd I(4) and sbnd COOH(5)) that was carried out by reaction of (1E, 6E)-1,7-bis(3,4-dimethoxyphenyl)hepta-1,6-diene-3,5-dione with a substituted phenylamine with general formula p-R-C6H4sbnd NH2 (R = sbnd H (1), sbnd Cl (2), -Br(3), sbnd I(4) and sbnd COOH(5)). This is the first synthesis report of a pyridazinone using as precursors a curcuminoid derivative and a diazonium salt formed in situ. All compounds were characterized by EA, FT-IR, UV-Vis, Emission,1H- and13C-NMR spectroscopy and the crystalline and molecular structure of 4 was solved by X-rays diffraction method. DFT and TD-DFT quantum chemical calculations were also employed to characterize the compounds and provide a rational explanation to the spectroscopic properties. To assess the biological activity of the systems, we focused on pesticide tests on compound 2, which showed an inhibitory effect in plant growth of Agrostis tenuis Higland.

WET TORREFACTION OF MISCANTHUS – CHARACTERIZATION OF HYDROCHARS IN VIEW OF HANDLING, STORAGE AND COMBUSTION PROPERTIES

Directory of Open Access Journals (Sweden)

Mateusz Wnukowski

2015-06-01

Full Text Available Properties of miscanthus hydrochars obtained through wet torrefaction were studied. The process was carried out in three different temperatures – 180, 200 and 220 °C and with four different ratios of water to biomass – 3:1, 6:1, 12:1 and 16:1. The obtained solid products were characterized with respect to their fuel properties. The best results were obtained for the temperature of 220 °C and showed a noticeable improvement in fuel properties – especially grindability and lowered ash content. The influence of water to biomass ratio was not so explicit and while high ratio showed an improvement in all mentioned properties, low ratio allowed to achieve the highest energy yield. The results obtained for miscanthus wet torrefaction and the literature data for dry torrefaction were compared.

Fulltext PDF

Indian Academy of Sciences (India)

photophysical characterization, spectroscopic, electro- chemistry and preliminary ... Microanalyses were carried out with a Fisons elemental analyzer and ..... that were assigned to the anthracenyl carbons signals. The proton NMR spectrum of ...

Characterizing Economic and Social Properties of Trust and Reputation Systems in P2P Environment

Institute of Scientific and Technical Information of China (English)

Yu-Feng Wang; Yoshiaki Hori; Kouichi Sakurai

2008-01-01

Considering the fact that P2P (Peer-to-Peer) systems are self-organized and autonomous, social-control mechanism (like trust and reputation) is essential to evaluate the trustworthiness of participating peers and to combat the selfish, dishonest and malicious peer behaviors. So, naturally, we advocate that P2P systems that gradually act as an important information infrastructure should be multi-disciplinary research topic, and reflect certain features of our society. So, from economic and social perspective, this paper designs the incentive-compatible reputation feedback scheme based on well-known economic model, and characterizes the social features of trust network in terms of efficiency and cost. Specifically, our framework has two distinctive purposes: first, from high-level perspective, we argue trust system is a special kind of social network, and an accurate characterization of the structural properties of the network can be of fundamental importance to understand the dynamics of the system. Thus, inspired by the concept of weighted small-world, this paper proposes new measurements to characterize the social properties of trust system, that is, highg lobal and local efficiency, and low cost; then, from relative low-level perspective, we argue that reputation feedback is a special kind of information, and it is not free. So, based on economic model, VCG (Vickrey-Clarke-Grove)-like reputation remuneration mechanism is proposed to stimulate rational peers not only to provide reputation feedback, but truthfully offer feedback. Furthermore, considering that trust and reputation is subjective, we classify the trust into functional trust and referral trust, and extend the referral trust to include two factors: similarity and truthfulness, which can efficiently reduce the trust inference error. The preliminary simulation results show the benefits of our proposal and the emergence of certain social properties in trust network.

A simple method to characterize the electrical and mechanical properties of micro-fibres

International Nuclear Information System (INIS)

Castellanos-Gomez, A

2013-01-01

A procedure to characterize the electrical and mechanical properties of micro-fibres is presented here. As the required equipment can be found in many teaching laboratories, it can be carried out by physics and mechanical/electrical engineering students. The electrical resistivity, mass density and Young's modulus of carbon micro-fibres have been determined using this procedure, obtaining values in very good agreement with the reference values. Young's modulus has been obtained by measuring the resonance frequency of carbon fibre-based cantilevers. In this way, one can avoid common approaches based on tensile or bending tests which are difficult to implement for microscale materials. Despite the simplicity of the experiments proposed here, they can be used to trigger in the students interest regarding the electrical and mechanical properties of microscale materials. (paper)

V2O5 xerogel-poly(ethylene oxide) hybrid material: Synthesis, characterization, and electrochemical properties

International Nuclear Information System (INIS)

Guerra, Elidia M.; Ciuffi, Katia J.; Oliveira, Herenilton P.

2006-01-01

In this work, we report the synthesis, characterization, and electrochemical properties of vanadium pentoxide xerogel-poly(ethylene oxide) (PEO) hybrid materials obtained by varying the average molecular weight of the organic component as well as the components' ratios. The materials were characterized by X-ray diffraction, ultraviolet/visible and infrared spectroscopies, thermogravimetric analysis, scanning electron microscopy, electron paramagnetic resonance, and cyclic voltammetry. Despite the presence of broad and low intensity peaks, the X-ray diffractograms indicate that the lamellar structure of the vanadium pentoxide xerogel is preserved, with increase in the interplanar spacing, giving evidence of a low-crystalline structure. We found that the electrochemical behaviour of the hybrid materials is quite similar to that found for the V 2 O 5 xerogel alone, and we verified that PEO leads to stabilization and reproducibility of the Li + electrochemical insertion/de-insertion into the V 2 O 5 xerogel structure, which makes these materials potential components of lithium ion batteries. - Graphical abstract: The synthesis, structural and electrochemical properties of vanadium pentoxide xerogel-poly(ethylene oxide) hybrid materials have been described. Despite the presence of broad and low intensity peaks, the X-ray diffractograms indicate that the lamellar structure of the vanadium pentoxide xerogel is preserved. The cyclic voltammetry technique demonstrated that PEO intercalation provides an improvement in the electrochemical properties, mainly with respect to the lithium electroinsertion process into the oxide matrix

Efficient near-infrared emission of π-extended cyclometalated iridium complexes based on pyrene in solution-processed polymer light-emitting diode

Science.gov (United States)

Liu, Yu; Hao, Zhaoran; Meng, Fanyuan; Wang, Pu; Yang, Liang; Wang, Yafei; Pei, Yong; Su, Shijian

2018-05-01

A novel iridium complex grafting hole-transporting triphenylamine (TPA) unit onto cyclometalated ligand, namely t-BuPyrPyTPA)2Ir(acac), was successfully synthesized and characterized. The photophysical, electrochemical and DFT/TD-DFT calculation, as well as electroluminescence properties of this iridium complex were fully investigated. Meanwhile, the PLEDs employing (t-BuPyrPyTPA)2Ir(acac) as dopant presented stable NIR emission peaked at 697 nm and a shoulder at 764 nm with a highest external quantum efficiency (EQE) of 0.56% at 4 wt% dopant concentration. These results demonstrate that expanding the conjugation length of the ligand is an effective way to achieve NIR emission.

Alternative Thieno[3,2-b][1]benzothiophene Isoindigo Polymers for Solar Cell Applications

KAUST Repository

Neophytou, Marios

2018-03-05

This work reports the synthesis, characterization, photophysical, and photovoltaic properties of five new thieno[3,2-b][1]benzothiophene isoindigo (TBTI)-containing low bandgap donor-acceptor conjugated polymers with a series of comonomers and different side chains. When TBTI is combined with different electron-rich moieties, even small structural variations can have significant impact on thin film morphology of the polymer:phenyl C70 butyric acid methyl ester (PCBM) blends. More importantly, high-resolution electron energy loss spectroscopy is used to investigate the phase-separated bulk heterojunction domains, which can be accurately and precisely resolved, enabling an enhanced correlation between polymer chemical structure, photovoltaic device performance, and morphology.

Perylenediimide--metal ion dyads for photo-induced electron transfer

DEFF Research Database (Denmark)

Qvortrup, Katrine; Bond, Andrew D; Nielsen, Anne

2008-01-01

A novel perylene diimide incorporating a tetradentate ligand was synthesized and the photophysical properties of its Cu(+), Cu(2+), and Fe(3+) complexes were investigated by fluorescence experiments....

Characterization of Mechanical Properties and Residual Stress in API 5L X80 Steel Welded Joints

Science.gov (United States)

de Sousa Lins, Amilton; de Souza, Luís Felipe Guimarães; Fonseca, Maria Cindra

2018-01-01

The use of high-strength and low-alloy steels, high design factors and increasingly stringent safety requirements have increased the operating pressure levels and, consequently, the need for further studies to avoid and prevent premature pipe failure. To evaluate the possibility of improving productivity in manual arc welding of this type of steel, this work characterizes the mechanical properties and residual stresses in API 5L X80 steel welded joints using the SMAW and FCAW processes. The residual stresses were analyzed using x-ray diffraction with the sin2 ψ method at the top and root of the welded joints in the longitudinal and transverse directions of the weld bead. The mechanical properties of the welded joints by both processes were characterized in terms of tensile strength, impact toughness and Vickers microhardness in the welded and shot peening conditions. A predominantly compressive residual stress was found, and shot peening increased the tensile strength and impact toughness in both welded joints.

Synthesis and characterization of NiO nanoparticles by thermal decomposition of nickel linoleate and their optical properties

Energy Technology Data Exchange (ETDEWEB)

Kalam, Abul, E-mail: abul_k33@yahoo.com [Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413, P.O. Box 9004 (Saudi Arabia); Al-Sehemi, Abdullah G.; Al-Shihri, Ayed S. [Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413, P.O. Box 9004 (Saudi Arabia); Du Gaohui [Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Ahmad, Tokeer [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India)

2012-06-15

Well dispersed nickel oxide nanoparticles have been synthesized successfully by direct calcination of nickel linoleate. The structure, morphology and properties of the nanoparticles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and ultraviolet-visible spectroscopy. Transmission electron microscopic studies show that nickel oxide nanoparticles are uniform with an average size of 14-20 nm. The optical band gap of 3.8 eV is obtained using UV-Visible spectroscopy which exhibits the red shift compared with the bulk counterpart. - Highlights: Black-Right-Pointing-Pointer Synthesis of metal oxide nanoparticles by using metal complexes as precursors. Black-Right-Pointing-Pointer Characterization of isolated nanoparticles using XRD, FTIR, SEM, TEM and HRTEM data. Black-Right-Pointing-Pointer The expected optical properties of these nanoparticles are clarified.

Synthesis, Crystal Structure and Luminescence Property of a New Silver(I) Dimer with Isonicotinic Acid

International Nuclear Information System (INIS)

Yuan, Qi; Liu, Bing

2005-01-01

The absorption spectrum was calculated from reflection spectrum by the Kubelka.Munk function. The energy gap of the title compound determined by extrapolation from the linear portion of the absorption edge in a (α/S) versus energy plot is 1.91 eV, which suggests that the title compound behaves as semiconductor. Isonicotinic acid (Iso), namely 4.pyridinecarboxylate, a multi.functional chelating and/or bridging ligand, has proved to be very powerful for the construction of multi. dimensional metal.organic coordination networks. Furthermore, The isonicotinic acid complexes has raised many interests in fluorescence probing with numerous potential applications for studies of microsecond diffusion and dynamics of membranes. Metal centers are potential carriers of electrochemical, magnetic, catalytic, or optical properties that may be introduced into the inorganic.organic hybrid materials. d"1"0 metals with rich photophysical and photochemical character have focused attentions to synthesize polynuclear complexes. Considering the versatile coordination abilities of Iso, we employ the ligand to coordinate with silver nitrate to fabricate a coordination complex with excellent fluorescence property. Herein we report the synthesis, crystal structure and fluorescence property of a new d"1"0 coordination dimer [Ag_2(Iso)_2(NO_3)_2

Characterization of Skeletonema costatum Intracellular Organic Matter and Study of Nanomechanical Properties under Different Solution Conditions

KAUST Repository

Gutierrez, Leonardo

2016-06-17

In the current investigation, a rigorous characterization of the high molecular weight (HMW) compounds of Skeletonema costatum (SKC) intracellular organic matter (IOM), including nanomechanical properties, was conducted. HMW SKC-IOM was characterized as a mixture of polysaccharides, proteins, and lipids. Atomic force microscopy (AFM) provided crucial information of this isolate at a nanoscale resolution. HMW SKC-IOM showed highly responsive to solution chemistry: fully extended chains at low ionic strength, and compressing structures with increasing electrolyte concentration in solution. Interestingly, two regions of different nanomechanical properties were observed: (a) Region #1: located farther from the substrate and showing extended polymeric chains, and (b) Region #2: located <10 nm above the substrate and presenting compressed structures. The polymer length, polymer grafting density, and compressibility of these two regions were highly influenced by solution conditions. Results suggest that steric interactions originating from HMW SKC-IOM polymeric structure would be a dominant interacting mechanism with surfaces. The current investigation has successfully applied models of polymer physics to describe the complex HMW SKC-IOM structural conformation at different solution conditions. The detailed methodology presented provides a tool to characterize and understand biopolymers interactions with surfaces, including filtration membranes, and can be extended to other environmentally relevant organic compounds.

Ionoluminescence properties of polystyrene-hosted fluorophore films induced by helium ions of energy 50-350 keV

Science.gov (United States)

Chakraborty, Subha; Huang, Mengbing

2017-10-01

We report on measurements and analysis of ionoluminescence properties of pure polystyrene films and polystyrene films doped with four types of fluorophores in low kinetic energies (50-350 keV) of ion irradiation. We have developed a theoretical model to understand the experimentally observed ionoluminescence behaviors in terms of scintillation yield from individual ion tracks, photophysical energy transfer mechanisms, and irradiation-induced defects. A comparison of the model and experimental results suggests that singlet up-conversion resulting from triplet-triplet annihilation processes may be responsible for enhanced singlet emission of the fluorophores at high ion beam flux densities. Energy transfer from the polystyrene matrix to the fluorophore molecules has been identified as an effective pathway to increasing the fluorescence efficiency in the doped scintillator films.

Preparation and thermal properties characterization of carbonate salt/carbon nanomaterial composite phase change material

International Nuclear Information System (INIS)

Tao, Y.B.; Lin, C.H.; He, Y.L.

2015-01-01

Highlights: • Nanocomposite phase change materials were prepared and characterized. • Larger specific surface area is more efficient to enhance specific heat. • Columnar structure is more efficient to enhance thermal conductivity. • Thermal conductivity enhancement is the key. • Single walled carbon nanotube is the optimal nanomaterial additive. - Abstract: To enhance the performance of high temperature salt phase change material, four kinds of carbon nanomaterials with different microstructures were mixed into binary carbonate eutectic salts to prepare carbonate salt/nanomaterial composite phase change material. The microstructures of the nanomaterial and composite phase change material were characterized by scanning electron microscope. The thermal properties such as melting point, melting enthalpy, specific heat, thermal conductivity and total thermal energy storage capacity were characterized. The results show that the nanomaterial microstructure has great effects on composite phase change material thermal properties. The sheet structure Graphene is the best additive to enhance specific heat, which could be enhanced up to 18.57%. The single walled carbon nanotube with columnar structure is the best additive to enhance thermal conductivity, which could be enhanced up to 56.98%. Melting point increases but melting enthalpy decreases with nanomaterial specific surface area increase. Although the additives decrease the melting enthalpy of composite phase change material, they also enhance the specific heat. As a combined result, the additives have little effects on thermal energy storage capacity. So, for phase change material performance enhancement, more emphasis should be placed on thermal conductivity enhancement and single walled carbon nanotube is the optimal nanomaterial additive

Bismuth Silver Oxysulfide for Photoconversion Applications: Structural and Optoelectronic Properties

KAUST Repository

Baqais, Amal Ali Abdulallh; Curutchet, Antton; Ziani, Ahmed; Ait Ahsaine, Hassan; Sautet, Philippe; Takanabe, Kazuhiro; Le Bahers, Tangui

2017-01-01

Single-phase bismuth silver oxysulfide, BiAgOS, was prepared by a hydrothermal method. Its structural, morphological and optoelectronic properties were investigated and compared with bismuth copper oxysulfide (BiCuOS). Rietveld refinement of the powder X-ray diffraction (XRD) measurements revealed that the BiAgOS and BiCuOS crystals have the same structure as ZrSiCuAs: the tetragonal space group P4/nmm. X-ray photoelectron spectroscopy (XPS) analyses confirmed that the BiAgOS has a high purity, in contrast with BiCuOS, which tends to have Cu vacancies. The Ag has a monovalent oxidation state, whereas Cu is present in the oxidation states of +1 and +2 in the BiCuOS system. Combined with experimental measurements, density functional theory calculations employing the range-separated hybrid HSE06 exchange-correlation functional with spin-orbit coupling quantitatively elucidated photophysical properties such as ab-sorption coefficients, effective masses and dielectric constants. BiCuOS and BiAgOS were found to have indirect bandgaps of 1.1 and 1.5 eV, respectively. Both possess high dielectric constants and low electron and hole effective masses. Therefore, these materials are expected to have high exciton dissociation capabilities and excellent carrier diffusion properties. This study reveals that BiAgOS is a promising candidate for photoconversion applications.

Bismuth Silver Oxysulfide for Photoconversion Applications: Structural and Optoelectronic Properties

KAUST Repository

Baqais, Amal Ali Abdulallh

2017-09-18

Single-phase bismuth silver oxysulfide, BiAgOS, was prepared by a hydrothermal method. Its structural, morphological and optoelectronic properties were investigated and compared with bismuth copper oxysulfide (BiCuOS). Rietveld refinement of the powder X-ray diffraction (XRD) measurements revealed that the BiAgOS and BiCuOS crystals have the same structure as ZrSiCuAs: the tetragonal space group P4/nmm. X-ray photoelectron spectroscopy (XPS) analyses confirmed that the BiAgOS has a high purity, in contrast with BiCuOS, which tends to have Cu vacancies. The Ag has a monovalent oxidation state, whereas Cu is present in the oxidation states of +1 and +2 in the BiCuOS system. Combined with experimental measurements, density functional theory calculations employing the range-separated hybrid HSE06 exchange-correlation functional with spin-orbit coupling quantitatively elucidated photophysical properties such as ab-sorption coefficients, effective masses and dielectric constants. BiCuOS and BiAgOS were found to have indirect bandgaps of 1.1 and 1.5 eV, respectively. Both possess high dielectric constants and low electron and hole effective masses. Therefore, these materials are expected to have high exciton dissociation capabilities and excellent carrier diffusion properties. This study reveals that BiAgOS is a promising candidate for photoconversion applications.

Electrospun V2O5 composite fibers: Synthesis, characterization and ammonia sensing properties

International Nuclear Information System (INIS)

Modafferi, V.; Trocino, S.; Donato, A.; Panzera, G.; Neri, G.

2013-01-01

In the present work, vanadium oxide (V 2 O 5 ) fibers have been investigated for monitoring ammonia (NH 3 ) at ppb levels in air. A simple sol gel-based electrospinning process has been applied for the synthesis of vanadium oxide/polyvinyl acetate (PVAc) and vanadium oxide/polyvinylpyrrolidone (PVP) composite fibers. Composite fibers doped with platinum (Pt) have been also prepared. The pure and Pt-doped metal oxide phase has been subsequently obtained by removing the polymer binder at high temperature in air. The samples have been widely studied to characterize their morphological and microstructural properties by X-Ray Diffraction, Fourier Transform InfraRed spectroscopy, X-ray Photoelectron Spectroscopy, and Scanning Electron Microscopy investigations. The application of the produced fibers in highly sensitive ammonia resistive sensors has been demonstrated. The influence of the nature of polymer binder and platinum addition on the sensing performances of the V 2 O 5 fibers has been investigated and discussed.V 2 O 5 fibers produced by using PVP as a polymer binder have shown higher sensitivity toward ammonia at ppb concentrations than fibers obtained with PVAc. Pt-doped samples have shown a lower response compared to un-doped samples. - Highlights: • Synthesis of vanadium oxide composite fibers by electrospinning • Physical and chemical characterization of prepared samples • Investigation of the sensing properties to ppb concentrations of ammonia in air

Photophysics of C60 Colloids

Science.gov (United States)

2012-11-28

nonlinear-optical properties and excited-state dynamics of pristine, oxygen- doped , and photopolymerized C-60 in the solid-state," Physical Review B...C45 (2009). 139. E. A. Brujan, "Numerical investigation on the dynamics of cavitation nanobubbles," Microfluidics and Nanofluidics 11(5), 511-517

On the near UV photophysics of a phenylalanine residue: conformation-dependent ππ* state deactivation revealed by laser spectroscopy of isolated neutral dipeptides.

Science.gov (United States)

Loquais, Yohan; Gloaguen, Eric; Alauddin, Mohammad; Brenner, Valérie; Tardivel, Benjamin; Mons, Michel

2014-10-28

The primary step of the near UV photophysics of a phenylalanine residue is investigated in one- and two-color pump-probe R2PI nanosecond experiments carried out on specific conformers of the Ac-Gly-Phe-NH2 molecule and related neutral compounds isolated in a supersonic expansion. Compared to toluene, whose ππ* state photophysics is dominated by intersystem crossing with a lifetime of ∼80 ns at the origin, the first ππ* state of Phe in the peptide environment is systematically found to be shorter-lived. The lifetime at the origin of transition is found to be significantly shortened in the presence of a primary amide (-CONH2) group (20-60 ns, depending on the conformer considered), demonstrating the existence of an additional non-radiative relaxation channel related to this chemical group. The quenching effect induced by the peptide environment is still more remarkable beyond the origin of the ππ* state, since vibronic bands of one of the 4 conformers observed (the 27-ribbon conformation) become barely detectable in the ns R2PI experiment, suggesting a significant conformer-selective lifetime shortening (below 100 ps). These results on dipeptides, which extend previous investigations on shorter Phe-containing molecules (N-Ac-Phe-NH2 and N-Ac-Phe-NH-Me), confirm the existence of conformer-dependent non-radiative deactivation processes, whose characteristic timescales range from tens of ns down to hundreds of ps or below. This dynamics is assigned to two distinct mechanisms: a first one, consistent with an excitation energy transfer from the optically active ππ* state to low-lying amide nπ* excited states accessed through conical intersections, especially in the presence of a C-terminal primary amide group (-CONH2); a second one, responsible for the short lifetimes in 2(7) ribbon structures, would be more specifically triggered by phenyl ring vibrational excitations. Implications in terms of spectroscopic probing of Phe in a peptide environment, especially

Characterization and electrocatalytic properties of sonochemical synthesized PdAg nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Godinez-Garcia, Andres, E-mail: agodinez@qro.cinvestav.mx [Depto. Materiales, Centro de Investigacion y de Estudios Avanzados del IPN, Libramiento norponiente 2000, Fracc. Real de Juriquilla, C.P. 76230 Santiago de Queretaro, Qro. (Mexico); Perez-Robles, Juan Francisco [Depto. Materiales, Centro de Investigacion y de Estudios Avanzados del IPN, Libramiento norponiente 2000, Fracc. Real de Juriquilla, C.P. 76230 Santiago de Queretaro, Qro. (Mexico); Martinez-Tejada, Hader Vladimir [Grupo de Energia y Termodinamica, Universidad Pontificia Bolivariana, Medellin, Antioquia C.P. 050031 (Colombia); Solorza-Feria, Omar [Depto. Quimica, CINVESTAV-IPN, Av. IPN 2508, A. P. 14-740, 07360 D.F. Mexico (Mexico)

2012-06-15

High intensity ultrasound was used in the synthesis of PdAg nanoparticles. PdAg nanoparticles were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), scanning transmission electron microscopy (STEM) and high-resolution transmission electron microscopy (HRTEM). Catalytic properties for oxygen reduction reaction (ORR) were determined by electrochemical techniques of cyclic voltammetry (CV) and thin-film rotating disk electrode (TF-RDE). Finally the electrocatalyst was tested as a cathode in a single polymer electrolyte membrane fuel cell (PEMFC). Sonochemical synthesis (SS) decreased the overpotential required for the ORR and increased the double-layer capacitance (DLC) respect to the sodium borohydride reduction method due to a better distribution on vulcan carbon support. The electrocatalytic activity of the nanometric bimetallic electrocatalyst for the ORR in acid media showed a favorable multielectron charge transfer process (n = 4e{sup -}) to water formation. The performance of the membrane electrode assembly (MEA) prepared with dispersed PdAg/C as a cathode catalyst in a single PEMFC is lower in comparison to platinum. - Highlights: Black-Right-Pointing-Pointer Sonochemical synthesized PdAg nanoparticles supported on carbon were produced. Black-Right-Pointing-Pointer The material showed catalytic properties for the oxygen reduction reaction (ORR). Black-Right-Pointing-Pointer The ORR favored the pathway to water formation.

Hydrogen storage in carbon nano-materials. Elaboration, characterization and properties

International Nuclear Information System (INIS)

Luxembourg, D.

2004-10-01

This work deals with hydrogen storage for supplying fuel cells. Hydrogen storage by adsorption in carbon nano-tubes and nano-fibers is a very controversial issue because experimental results are very dispersed and adsorption mechanisms are not yet elucidated. Physi-sorption cannot explain in fact all the experimental results. All the potential adsorption sites, physical and chemical, are discussed as detailed as possible in a state of the art. Experimental works includes the steps of elaboration, characterization, and measurements of the hydrogen storage properties. Nano-fibers are grown using a CVD approach. Single wall carbon nano-tubes (SWNT) synthesis is based on the vaporization/condensation of a carbon/catalysts mixture in a reactor using a fraction of the available concentrated solar energy at the focus of the 1000 kW solar facility of IMP-CNRS at Odeillo. Several samples are produced using different synthesis catalysts (Ni, Co, Y, Ce). SWNT samples are purified using oxidative and acid treatments. Hydrogen storage properties of these materials are carefully investigated using a volumetric technique. The applied pressure is up to 6 MPa and the temperature is 253 K. Hydrogen uptake of the investigated materials are less than 1 % wt. at 253 K and 6 MPa. (author)

Coumarin amide derivatives as fluorescence chemosensors for cyanide anions

Energy Technology Data Exchange (ETDEWEB)

Wu, Qianqian [School of Material Science and Engineering, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, Shandong (China); Liu, Zhiqiang [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, Shandong (China); Cao, Duxia, E-mail: duxiacao@ujn.edu.cn [School of Material Science and Engineering, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, Shandong (China); Guan, Ruifang, E-mail: mse_guanrf@ujn.edu.cn [School of Material Science and Engineering, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, Shandong (China); Wang, Kangnan; Shan, Yanyan; Xu, Yongxiao; Ma, Lin [School of Material Science and Engineering, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, Shandong (China)

2015-07-01

Four coumarin amide derivatives with 4-methyl coumarin or pyrene as terminal group have been synthesized. Their photophysical properties and recognition properties for cyanide anions have been examined. The results indicate that the compounds can recognize cyanide anions with obvious absorption and fluorescence spectra change, at the same time, obvious color and fluorescence change can be observed by naked eye. The in situ hydrogen nuclear magnetic resonance spectra and photophysical properties change confirm that Michael additions between the chemosensors and cyanide anions take place at the 4-position of coumarin. - Highlights: • Four coumarin amide derivatives with 4-methyl coumarin or pyrene as terminal group were synthesized. • The compounds can recognize cyanide anions with obvious absorption and fluorescence spectra change. • Michael additions between the chemosensors and cyanide anions take place at the 4-position of coumarin.

Characterization of Hydrologic and Thermal Properties at Brady Geothermal Field, NV

Science.gov (United States)

Patterson, J.; Cardiff, M. A.; Lim, D.; Coleman, T.; Wang, H. F.; Feigl, K. L.

2017-12-01

Understanding and predicting the temperature evolution of geothermal reservoirs is a primary focus for geothermal power plant operators ensuring continued financial sustainability of the resource. Characterization of reservoir properties - such as thermal diffusivity and hydraulic conductivity - facilitates modeling efforts to develop a better understanding of temperature evolution. As part of the integrated "PoroTomo" experiment, borehole pressure measurements were collected in three monitoring wells of various depths under varying operational conditions at the Brady Geothermal Field near Reno, NV. During normal operational conditions, a vertical profile of borehole temperature to 330 m depth was collected using distributed temperature sensing (DTS) for a period of 5 days. Borehole pressure data indicates 2D flow and shows rapid responses to changes in pumping /injection rates, likely indicating fault-dominated flow. The temperature data show that borehole temperature recovery following cold water slug injection is variable with depth. Late time vertical temperature profiles show the borehole following a shallow geotherm to a depth of approximately 275 meters, below which the temperature declines until a depth of approximately 320 meters, with a stable zone of cold water forming below this, possibly indicating production-related thermal drawdown. A validated heat transfer model is used in conjunction with the temperature data to determine depth-dependent reservoir thermal properties. Hydraulic reservoir properties are determined through inversion of the collected pressure data using MODFLOW. These estimated thermal and hydraulic properties are synthesized with existing structural and stratigraphic datasets at Brady. The work presented herein was funded in part by the Office of Energy Efficiency and Renewable Energy (EERE), U.S. Department of Energy, under Award Number DE-EE0006760.

Transition metal borides. Synthesis, characterization and superconducting properties

International Nuclear Information System (INIS)