WorldWideScience

Sample records for self-assembled monolayer organic

  1. Multifunctional Self-Assembled Monolayers for Organic Field-Effect Transistors

    Science.gov (United States)

    Cernetic, Nathan

    Organic field effect transistors (OFETs) have the potential to reach commercialization for a wide variety of applications such as active matrix display circuitry, chemical and biological sensing, radio-frequency identification devices and flexible electronics. In order to be commercially competitive with already at-market amorphous silicon devices, OFETs need to approach similar performance levels. Significant progress has been made in developing high performance organic semiconductors and dielectric materials. Additionally, a common route to improve the performance metric of OFETs is via interface modification at the critical dielectric/semiconductor and electrode/semiconductor interface which often play a significant role in charge transport properties. These metal oxide interfaces are typically modified with rationally designed multifunctional self-assembled monolayers. As means toward improving the performance metrics of OFETs, rationally designed multifunctional self-assembled monolayers are used to explore the relationship between surface energy, SAM order, and SAM dipole on OFET performance. The studies presented within are (1) development of a multifunctional SAM capable of simultaneously modifying dielectric and metal surface while maintaining compatibility with solution processed techniques (2) exploration of the relationship between SAM dipole and anchor group on graphene transistors, and (3) development of self-assembled monolayer field-effect transistor in which the traditional thick organic semiconductor is replaced by a rationally designed self-assembled monolayer semiconductor. The findings presented within represent advancement in the understanding of the influence of self-assembled monolayers on OFETs as well as progress towards rationally designed monolayer transistors.

  2. Organic surfaces exposed by self-assembled organothiol monolayers: Preparation, characterization, and application

    Science.gov (United States)

    Kind, Martin; Wöll, Christof

    2009-07-01

    Organic surfaces play a major role in materials science. Most surfaces that we touch in our daily lives are made from organic materials, e.g., vegetables, fruit, skin, wood, and textiles made from natural fibers. In the context of biology, organic surfaces play a prominent role too, proteins docking onto cell surfaces are a good example. To better understand the characteristics of organic surfaces, including physico-chemical properties like wettability or chemical reactivities and physical properties like friction and lubrication, a structurally well-defined model system that can be investigated with numerous analytical techniques is desirable. In the last two decades, one particular system, self-assembled monolayers or SAMs, have demonstrated their suitability for this purpose. In particular, organothiols consisting of an organic molecule with an attached SH-group are well suited to fabricating structurally well-defined adlayers of monolayer thickness on gold substrates using a simple preparation procedure. These ultrathin monolayers expose an organic surface with properties that can be tailored by varying the type of organothiol employed. After a short introduction into the preparation of SAMs, this article provides an overview of the possibilities and limitations of organic surfaces exposed by Au-thiolate SAMs. Applications are as diverse as the metallization of organic surfaces, a fundamental problem in materials science, and the fabrication of surfaces that resist the adsorption of proteins. In addition to a number of different case studies, we will also discuss the most powerful analytical techniques needed to characterize these important model systems.

  3. Metal complexation and monolayer self-assembly of the bio-organic semiconductor Alizarin

    Energy Technology Data Exchange (ETDEWEB)

    Uppal, Neeti [Dept. Earth and Environmental Sciences, Ludwig-Maximilians-Universitaet Muenchen (LMU) and Center for NanoSciences (CeNS), Muenchen (Germany); Institut fuer Physik, Universitaet Augsburg (Germany); Gast, Norbert [Dept. Earth and Environmental Sciences, Ludwig-Maximilians-Universitaet Muenchen (LMU) and Center for NanoSciences (CeNS), Muenchen (Germany); Zentrum Neue Technologien, Deutsches Museum, Muenchen (Germany); Bueno, Martin [Fakultaet Feinwerk- und Mikrotechnik, Physikalische Technik, Hochschule Muenchen (Germany); Heckl, Wolfgang M. [Dept. of Physics, Technische Universitaet Muenchen (TUM), Garching (Germany); Zentrum Neue Technologien, Deutsches Museum, Muenchen (Germany); Trixler, Frank [Dept. Earth and Environmental Sciences, Ludwig-Maximilians-Universitaet Muenchen (LMU) and Center for NanoSciences (CeNS), Muenchen (Germany); Dept. of Physics, Technische Universitaet Muenchen (TUM), Garching (Germany); Zentrum Neue Technologien, Deutsches Museum, Muenchen (Germany)

    2010-07-01

    Organic Solid/Solid Wetting Deposition (OSWD) (Trixler et al.: Chem.Eur.J. 13 (2007), 7785) enables to deposit insoluble molecules such as organic pigments and semiconductors on substrate surfaces under ambient conditions. We explore the potential of OSWD to grow and manipulate monolayers of biomolecules and their chelates on graphite and use Alizarin as a model system - a natural organic compound which occurs mainly as an anthraquinone glycoside in plants. Our investigations via Scanning Tunneling Microscopy (STM), Tunneling Spectroscopy (TS) and Molecular Modelling reveal that OSWD works also with bio-organic molecules and chelate complexes and show that the advantages of OSWD (self-assembly under ambient conditions in a non-solvent environment, nanomanipulation via molecular extraction) can all be tapped.

  4. Regulating charge injection in ambipolar organic field-effect transistors by mixed self-assembled monolayers.

    Science.gov (United States)

    Xu, Yong; Baeg, Kang-Jun; Park, Won-Tae; Cho, Ara; Choi, Eun-Young; Noh, Yong-Young

    2014-08-27

    We report on a technique using mixed self-assembled monolayers (SAMs) to finely regulate ambipolar charge injection in polymer organic field-effect transistors. Differing from the other works that employ single SAM specifically for efficient charge injection in p-type and n-type transistors, we blend two different SAMs of alkyl- and perfluoroalkyl thiols at different ratios and apply them to ambipolar OFETs and inverter. Thanks to the utilization of ambipolar semiconductor and one SAM mixture, the device and circuit fabrications are facile with only one step for semiconductor deposition and another for SAM treatment. This is much simpler with respect to the conventional scheme for the unipolar-device-based complementary circuitry that demands separate deposition and processing for individual p-channel and n-channel transistors. Our results show that the mixed-SAM treatments not only improve ambipolar charge injection manifesting as higher hole- and electron-mobility and smaller threshold voltage but also gradually tune the device characteristics to reach a desired condition for circuit application. Therefore, this simple but useful approach is promising for ambipolar electronics.

  5. Alkanephosphonates on hafnium-modified gold: a new class of self-assembled organic monolayers.

    Science.gov (United States)

    Jespersen, Michael L; Inman, Christina E; Kearns, Gregory J; Foster, Evan W; Hutchison, James E

    2007-03-14

    A new method for assembling organic monolayers on gold is reported that employs hafnium ions as linkers between a phosphonate headgroup and the gold surface. Monolayers of octadecylphosphonic acid (ODPA) formed on gold substrates that had been pretreated with hafnium oxychloride are representative of this new class of organic thin films. The monolayers are dense enough to completely block assembly of alkanethiols and resist displacement by alkanethiols. The composition and structure of the monolayers were investigated by contact angle goniometry, XPS, PM-IRRAS, and TOF-SIMS. From these studies, it was determined that this assembly strategy leads to the formation of ODPA monolayers similar in quality to those typically formed on metal oxide substrates. The assembly method allows for the ready generation of patterned surfaces that can be easily prepared by first patterning hafnium on the gold surface followed by alkanephosphonate assembly. Using the bifunctional (thiol-phosphonate) 2-mercaptoethylphosphonic acid (2-MEPA), we show that this new assembly chemistry is compatible with gold-thiol chemistry and use TOF-SIMS to show that the molecule attaches through the phosphonate functionality in the patterned region and through the thiol in the bare gold regions. These results demonstrate the possibility of functionalizing metal substrates with monolayers typically formed on metal oxide surfaces and show that hafnium-gold chemistry is complementary and orthogonal to well-established gold-thiol assembly strategies.

  6. Novel self-assembled phosphonic acids monolayers applied in N-channel perylene diimide (PDI) organic field effect transistors

    Science.gov (United States)

    Cheng, Heng; Huai, Jinyue; Cao, Li; Li, Zhefeng

    2016-08-01

    Phosphoric acid (PA) self-assembled monolayers (SAMs) have been developed for applications in organic field-effect transistors (OFETs). This efficient interface modification is helpful for semiconductor layer to form crystal thin film during vapor deposition. Results show that the PDI-i8C based OFETs with PA SAMs exhibit field-effect mobilities up to 0.014 cm2 V-1 s-1 (with ODPA as SAMs), which is over 500 times higher than the device without SAMs. Also, transistors with Naph6PA as SAMs show up to 1.5 × 10-3 cm2 V-1 s-1. By studying the morphology of semiconductor layer and SAMs surface, it is found that ODPA bilayer structure plays a key role in inducing PDI-i8C to form orderly crystal thin film.

  7. Applications of self-assembled monolayers in materials chemistry

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Self-assembly provides a simple route to organise suitable organic molecules on noble metal and selected nanocluster surfaces by using monolayers of long chain organic molecules with various functionalities like –SH, –COOH, –NH2, silanes etc. These surfaces can be effectively used to build-up interesting ...

  8. Applications of self-assembled monolayers in materials chemistry

    Indian Academy of Sciences (India)

    Self-assembly provides a simple route to organise suitable organic molecules on noble metal and selected nanocluster surfaces by using monolayers of long chain organic molecules with various functionalities like -SH, -COOH, -NH2, silanes etc. These surfaces can be effectively used to build-up interesting nano level ...

  9. Self-Assembled Monolayers for Dental Implants

    Directory of Open Access Journals (Sweden)

    Sidónio C. Freitas

    2018-01-01

    Full Text Available Implant-based therapy is a mature approach to recover the health conditions of patients affected by edentulism. Thousands of dental implants are placed each year since their introduction in the 80s. However, implantology faces challenges that require more research strategies such as new support therapies for a world population with a continuous increase of life expectancy, to control periodontal status and new bioactive surfaces for implants. The present review is focused on self-assembled monolayers (SAMs for dental implant materials as a nanoscale-processing approach to modify titanium surfaces. SAMs represent an easy, accurate, and precise approach to modify surface properties. These are stable, well-defined, and well-organized organic structures that allow to control the chemical properties of the interface at the molecular scale. The ability to control the composition and properties of SAMs precisely through synthesis (i.e., the synthetic chemistry of organic compounds with a wide range of functional groups is well established and in general very simple, being commercially available, combined with the simple methods to pattern their functional groups on complex geometry appliances, makes them a good system for fundamental studies regarding the interaction between surfaces, proteins, and cells, as well as to engineering surfaces in order to develop new biomaterials.

  10. Effect of TiO2 modification with amino-based self-assembled monolayer on inverted organic solar cell

    Science.gov (United States)

    Tozlu, Cem; Mutlu, Adem; Can, Mustafa; Havare, Ali Kemal; Demic, Serafettin; Icli, Sıddık

    2017-11-01

    The effects of surface modification of titanium dioxide (TiO2) on the performance of inverted type organic solar cells (i-OSCs) was investigated in this study. A series of benzoic acid derivatized self-assembled monolayer (SAM) molecules of 4‧-[(hexyloxy)phenyl]amino-3,5-biphenyl dicarboxylic acid (CT17) and 4‧-[1-naphthyl (phenyl)amino]biphenyl-4-carboxylic acid (CT19) were utilized to modify the interface between TiO2 buffer layer and poly-3 hexylthiophene (P3HT):[6,6]-phenyl C61 butyric acid methyl ester (PC61BM) active layer having the device structure of ITO/TiO2/SAM/P3HT:PC61BM/MoO3/Ag. The work function and surface wetting properties of TiO2 buffer layer served as electron transporting layer between ITO and PC61BM active layer were tuned by SAM method. The solar cell of the SAM modified devices exhibited better performance. The power conversion efficiency (PCE) of i-OSCs devices with bare TiO2 electrodes enhanced from 2.00% to 2.21% and 2.43% with CT17 and CT19 treated TiO2 electrodes, respectively. The open circuit voltage (Voc) of the SAM treated TiO2 devices reached to 0.60 V and 0.61 V, respectively, while the Voc of untreated TiO2 was 0.57 V. The water contact angle of i-OSCs with CT17 and CT19 SAMs was also higher than the value of the unmodified TiO2 electrode. These results show that inserting a monolayer at the interface between organic and inorganic layers is an useful alternative method to improve the performance of i-OSCs.

  11. Self Assembly and Pyroelectric Poling for Organics

    Science.gov (United States)

    2015-07-06

    and semiconducting molecular phosphonic acid (PA) self-assembled monolayers (SAMs) have been developed for applications in organic field-effect...SAM structure and electronic performance of various commonly used organic semiconducting small molecules/polymers. Mechanisms for improving device...Fig. 3). This study represents a major advancement in understanding the mechanisms at play between SAMs and linear organic semiconducting molecules. A

  12. Impact of self-assembled monolayer on low frequency noise of organic thin film transistors

    International Nuclear Information System (INIS)

    Ke Lin; Dolmanan, Surani Bin; Shen Lu; Vijila, Chellappan; Chua, Soo Jin; Png, R.-Q.; Chia, P.-J.; Chua, L.-L.; Ho, Peter K-H.

    2008-01-01

    Bottom-contact organic field-effect transistors (FETs) based on regioregular poly(3-hexylthiophene) were fabricated with different surface treatments and were evaluated using a low frequency noise (LFN) spectroscopy. The oxygen-plasma (OP) treated device shows the highest mobility with the lowest current fluctuation. Octadecyltrichlorosilane and perfluorodecyldimetylchlorosilane treated device gives a higher noise compared with the OP treated device. Hexamethyldisilazane treated devices show the highest noise but the lowest mobility. The LFN results are correlated with organic FET device mobility and stability, proved by channel material crystallinity and degree of dislocations analysis. LFN measurement provides a nondisruptive and direct methodology to characterize device performance

  13. Surface Decoration on Polymeric Gate Dielectrics for Flexible Organic Field-Effect Transistors via Hydroxylation and Subsequent Monolayer Self-Assembly.

    Science.gov (United States)

    Yan, Yan; Huang, Long-Biao; Zhou, Ye; Han, Su-Ting; Zhou, Li; Sun, Qijun; Zhuang, Jiaqing; Peng, Haiyan; Yan, He; Roy, V A L

    2015-10-28

    A simple photochemical reaction based on confined photocatalytic oxidation (CPO) treatment and hydrolysis was employed to efficiently convert C-H bonds into C-OH groups on polymeric material surfaces, followed by investigation of monolayer self-assembly decoration on polymeric dielectrics via chemical bonding for the organic field-effect transistors (OFETs) applications. This method is a low temperature process and has negligible etching effect on polymeric dielectric layers. Various types of self-assembled monolayers have been tested and successfully attached onto the hydroxylated polymeric dielectric surfaces through chemical bonding, ensuring the stability of decorated functional films during the subsequent device fabrication consisting of solution processing of the polymer active layer. With the surface decoration of functional groups, both n-type and p-type polymers exhibit enhanced carrier mobilities in the unipolar OFETs. In addition, enhanced and balanced mobilities are obtained in the ambipolar OFETs with the blend of polymer semiconductors. The anchored self-assembled monolayers on the dielectric surfaces dramatically preclude the solvent effect, thus enabling an improvement of carrier mobility up to 2 orders of magnitude. Our study opens a way of targeted modifications of polymeric surfaces and related applications in organic electronics.

  14. A self-assembled monolayer-assisted surface microfabrication and release technique

    NARCIS (Netherlands)

    Kim, B.J.; Liebau, M.; Huskens, Jurriaan; Reinhoudt, David; Brugger, J.P.

    2001-01-01

    This paper describes a method of thin film and MEMS processing which uses self-assembled monolayers as ultra-thin organic surface coating to enable a simple removal of microfabricated devices off the surface without wet chemical etching. A 1.5-nm thick self-assembled monolayer of

  15. Infrared spectroscopy of self-assembled monolayer films on silicon

    Science.gov (United States)

    Rowell, N. L.; Tay, Lilin; Boukherroub, R.; Lockwood, D. J.

    2007-07-01

    Infrared vibrational spectroscopy in an attenuated total reflection (ATR) geometry has been employed to investigate the presence of organic thin layers on Si-wafer surfaces. The phenomena have been simulated to show there can be a field enhancement with the presented single-reflection ATR (SR-ATR) approach which is substantially larger than for conventional ATR or specular reflection. In SR-ATR, a discontinuity of the field normal to the film contributes a field enhancement in the lower index thin film causing a two order of magnitude increase in sensitivity. SR-ATR was employed to characterize a single monolayer of undecylenic acid self-assembled on Si(1 1 1) and to investigate a two monolayer system obtained by adding a monolayer of bovine serum albumin protein.

  16. Phosphonate self-assembled monolayers as organic linkers in solid-state quantum dot sensetized solar cells

    KAUST Repository

    Ardalan, Pendar

    2010-06-01

    We have employed X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-vis) spectroscopy, infrared (IR) spectroscopy, water contact angle (WCA) measurements, ellipsometry, and electrical measurements to study the effects of self-assembled monolayers (SAMs) with phosphonic acid headgroups on the bonding and performance of cadmium sulfide (CdS) solid-state quantum dot sensitized solar cells (QDSSCs). ∼2 to ∼6 nm size CdS quantum dots (QDs) were grown on the SAM-passivated TiO2 surfaces by successive ionic layer adsorption and reaction (SILAR). Our results show differences in the bonding of the CdS QDs at the TiO2 surfaces with a SAM linker. Moreover, our data indicate that presence of a SAM increases the CdS uptake on TiO2 as well as the performance of the resulting devices. Importantly, we observe ∼2 times higher power conversion efficiencies in the devices with a SAM compared to those that lack a SAM. © 2010 IEEE.

  17. Investigating organic multilayers by spectroscopic ellipsometry: specific and non-specific interactions of polyhistidine with NTA self-assembled monolayers

    Directory of Open Access Journals (Sweden)

    Ilaria Solano

    2016-04-01

    Full Text Available Background: A versatile strategy for protein–surface coupling in biochips exploits the affinity for polyhistidine of the nitrilotriacetic acid (NTA group loaded with Ni(II. Methods based on optical reflectivity measurements such as spectroscopic ellipsometry (SE allow for label-free, non-invasive monitoring of molecule adsorption/desorption at surfaces.Results: This paper describes a SE study about the interaction of hexahistidine (His6 on gold substrates functionalized with a thiolate self-assembled monolayer bearing the NTA end group. By systematically applying the difference spectra method, which emphasizes the small changes of the ellipsometry spectral response upon the nanoscale thickening/thinning of the molecular film, we characterized different steps of the process such as the NTA-functionalization of Au, the adsorption of the His6 layer and its eventual displacement after reaction with competitive ligands. The films were investigated in liquid, and ex situ in ambient air. The SE investigation has been complemented by AFM measurements based on nanolithography methods (nanografting mode.Conclusion: Our approach to the SE data, exploiting the full spectroscopic potential of the method and basic optical models, was able to provide a picture of the variation of the film thickness along the process. The combination of δΔi+1,i(λ, δΨi+1,i(λ (layer-addition mode and δΔ†i',i+1(λ, δΨ†i',i+1(λ (layer-removal mode difference spectra allowed us to clearly disentangle the adsorption of His6 on the Ni-free NTA layer, due to non specific interactions, from the formation of a neatly thicker His6 film induced by the Ni(II-loading of the NTA SAM.

  18. Self-assembly of amphiphilic janus particles into monolayer capsules for enhanced enzyme catalysis in organic media.

    Science.gov (United States)

    Cao, Wei; Huang, Renliang; Qi, Wei; Su, Rongxin; He, Zhimin

    2015-01-14

    Encapsulation of enzymes during the creation of an emulsion is a simple and efficient route for enhancing enzyme catalysis in organic media. Herein, we report a capsule with a shell comprising a monolayer of silica Janus particles (JPs) (referred to as a monolayer capsule) and a Pickering emulsion for the encapsulation of enzyme molecules for catalysis purposes in organic media using amphiphilic silica JPs as building blocks. We demonstrate that the JP capsules had a monolayer shell consisting of closely packed silica JPs (270 nm). The capsules were on average 5-50 μm in diameter. The stability of the JP capsules (Pickering emulsion) was investigated with the use of homogeneous silica nanoparticles as a control. The results show that the emulsion stabilized via amphiphilic silica JPs presented no obvious changes in physical appearance after 15 days, indicating the high stability of the emulsions and JP capsules. Furthermore, the lipase from Candida sp. was chosen as a model enzyme for encapsulation within the JP capsules during their formation. The catalytic performance of lipase was evaluated according to the esterification of 1-hexanol with hexanoic acid. It was found that the specific activity of the encapsulated enzymes (28.7 U mL(-1)) was more than 5.6 times higher than that of free enzymes in a biphasic system (5.1 U mL(-1)). The enzyme activity was further increased by varying the volume ratio of water to oil and the JPs loadings. The enzyme-loaded capsule also exhibited high stability during the reaction process and good recyclability. In particular, the jellification of agarose in the JP capsules further enhanced their operating stability. We believe that the monolayer structure of the JP capsules, together with their high stability, rendered the capsules to be ideal enzyme carriers and microreactors for enzyme catalysis in organic media because they created a large interfacial area and had low mass transfer resistance through the monolayer shell.

  19. Self-assembled monolayers of metallosalophenes on gold

    NARCIS (Netherlands)

    Beulen, M.W.J.; van Veggel, F.C.J.M.; Reinhoudt, David

    2000-01-01

    Salophene complexes of transition metals exhibit a reversible electro- chemistry. We have synthesized salophene complexes with sulfur-containing substituents aimed at the formation of self-assembled monolayers on a gold surface. Such monolayers have interesting cation complexating properties. The

  20. Microstructure and Phase Behavior of a Quinquethiophene-Based Self-Assembled Monolayer as a Function of Temperature

    NARCIS (Netherlands)

    Flesch, Heinz-Georg; Mathijssen, Simon G. J.; Gholamrezaie, Fatemeh; Moser, Armin; Neuhold, Alfred; Novak, Jiri; Ponomarenko, Sergei A.; Shen, Quan; Teichert, Christian; Hlawacek, Gregor; Puschnig, Peter; Ambrosch-Draxl, Claudia; Resel, Roland; de Leeuw, Dago M.

    2011-01-01

    The self-assembly of monolayers is a highly promising approach in organic electronics, but most systems show weak device performances, probably because of a lack of long-range order of the molecules. The present self-assembled monolayer was formed by a molecule that contains a dimethyl-chlorosilyl

  1. Self-assembled monolayer exchange reactions as a tool for channel interface engineering in low-voltage organic thin-film transistors.

    Science.gov (United States)

    Lenz, Thomas; Schmaltz, Thomas; Novak, Michael; Halik, Marcus

    2012-10-02

    In this work, we compared the kinetics of monolayer self-assembly long-chained carboxylic acids and phosphonic acids on thin aluminum oxide surfaces and investigated their dielectric properties in capacitors and low-voltage organic thin-film transistors. Phosphonic acid anchor groups tend to substitute carboxylic acid molecules on aluminum oxide surfaces and thus allow the formation of mixed or fully exchanged monolayers. With different alkyl chain substituents (n-alkyl or fluorinated alkyl chains), the exchange reaction can be monitored as a function of time by static contact angle measurements. The threshold voltage in α,α'-dihexyl-sexithiophene thin-film transistors composed of such mixed layer dielectrics correlates with the exchange progress and can be tuned from negative to positive values or vice versa depending on the dipole moment of the alkyl chain substituents. The change in the dipole moment with increasing exchange time also shifts the capacitance of these devices. The rate constants for exchange reactions determined by the time-dependent shift of static contact angle, threshold voltage, and capacitance exhibit virtually the same value thus proving the exchange kinetics to be highly controllable. In general, the exchange approach is a powerful tool in interface engineering, displaying a great potential for tailoring of device characteristics.

  2. Self-assembled monolayers on metal oxides : applications in nanotechnology

    NARCIS (Netherlands)

    Yildirim, O.

    2010-01-01

    The thesis describes the use of phosph(on)ate-based self-assembled monolayers (SAMs) to modify and pattern metal oxides. Metal oxides have interesting electronic and magnetic properties such as insulating, semiconducting, metallic, ferromagnetic etc. and SAMs can tailor the surface properties. FePt

  3. Functionalization of Organic Semiconductors and Other Carbon-based Materials by Self-Assembled Monolayers (SAMs) and Charge Transport in Organic Field-effect Transistors (OFETs)

    Science.gov (United States)

    Lee, Bumsu

    In the first part of the thesis, studies of the charge carrier transport in organic semiconductors performed using organic field-effect transistors (OFETs) with polymeric gate dielectric (parylene) are presented. By combining OFET and ultraviolet photoelectron spectroscopy (UPS) studies, the effect of bias-stress instability at the semiconductor/insulator interface have been investigated and understood. The effect is understood in terms of the transfer of holes from an accumulation channel of the semiconductor to localized states of the insulator that depends on energetic overlap between HOMO band tails of the semiconductor and the insulator. Second, surface functionalization of various materials such as organic single crystals, conjugated semiconductor polymers, graphene and carbon nanotubes (CNTs) with Self-Assembled Monolayers (SAMs) is described. In most cases, an enhanced surface conductivity is observed as a result of SAM treatment. Especially, fluorinated alkyl-silane (FTS) SAM induces the highest density of p-type charge carriers (in excess of an order of 1013cm-2), which leads to a strong surface hole-doping of these materials. In this thesis, (1) the mechanism of SAM nucleation, growth process and doping effect at the surface of organic single crystals and graphene is revealed. SAM nucleation occurs predominantly at molecular step edges or defect sites present at the surface and a consecutive lateral growth proceeds by cross-linking between SAM molecules. The strong hole-doping is explained by an interfacial charge transfer that during SAM formation. In addition, conductive atomic force microscopy (C-AFM) confirms that conducting paths along the step edges are formed by FTS nucleation at the early stage of FTS growth on rubrene. (2) it is reported that conductivity of solution-deposited thin film of conjugated polymers increases by up to six orders of magnitude, reaching (1.1 ± 0.1) × 103 Scm-1 for poly (2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b

  4. Injection-modulated polarity conversion by charge carrier density control via a self-assembled monolayer for all-solution-processed organic field-effect transistors

    Science.gov (United States)

    Roh, Jeongkyun; Lee, Taesoo; Kang, Chan-Mo; Kwak, Jeonghun; Lang, Philippe; Horowitz, Gilles; Kim, Hyeok; Lee, Changhee

    2017-04-01

    We demonstrated modulation of charge carrier densities in all-solution-processed organic field-effect transistors (OFETs) by modifying the injection properties with self-assembled monolayers (SAMs). The all-solution-processed OFETs based on an n-type polymer with inkjet-printed Ag electrodes were fabricated as a test platform, and the injection properties were modified by the SAMs. Two types of SAMs with different dipole direction, thiophenol (TP) and pentafluorobenzene thiol (PFBT) were employed, modifying the work function of the inkjet-printed Ag (4.9 eV) to 4.66 eV and 5.24 eV with TP and PFBT treatments, respectively. The charge carrier densities were controlled by the SAM treatment in both dominant and non-dominant carrier-channel regimes. This work demonstrates that control of the charge carrier densities can be efficiently achieved by modifying the injection property with SAM treatment; thus, this approach can achieve polarity conversion of the OFETs.

  5. Self-assembled organic monolayers terminated in perfluoroalkyl pentafluoro-lambda(6)-sulfanyl (-SF5) chemistry on gold.

    Science.gov (United States)

    Winter, R; Nixon, P G; Gard, G L; Graham, D J; Castner, D G; Holcomb, N R; Grainger, D W

    2004-07-06

    Recently synthesized (Winter, R.; Nixon, P. G.; Gard, G. L.; Radford, D. H.; Holcomb, N. R.; Grainger, D. W. J. Fluorine Chem. 2001, 107, 23-30) SF5-terminated perfluoroalkyl thiols (SF5(CF2)nCH2CH2SH, where n = 2, 4, and 6) and a symmetric SF5-terminated dialkyl disulfide ([SF5-CH=CH-(CH2)8-S-]2) were assembled as thin films chemisorbed onto gold surfaces. The adsorbed monolayer films of these SF5-containing molecules on polycrystalline gold were compared using ellipsometry, contact angle, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and infrared spectroscopy (FTIR) surface analytical methods. The resulting SF5-dialkyl disulfide monolayer film shows moderate angle dependence in depth-dependent XPS analysis, suggesting a preferentially oriented film. The SF5-terminated perfluoroalkyl thiols exhibit angular-dependent XPS compositional variance depending on perfluoroalkyl chain length, consistent with improved film assembly (increasingly hydrophobic, fewer defects, and more vertical chain orientation increasing film thickness) with increasing chain length. Tof-SIMS measurements indicate that both full parent ions for these film-forming molecules and the unique SF5 terminal group are readily detectable from the thin films without substantial contamination from other adsorbates.

  6. Photobleaching-activated micropatterning on self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Scrimgeour, Jan; Kodali, Vamsi K; Kovari, Daniel T; Curtis, Jennifer E, E-mail: jennifer.curtis@physics.gatech.ed [School of Physics and Petit Institute for Bioengineering and Biosciences (IBB), Georgia Institute of Technology, 837 State St, Atlanta, GA 30332 (United States)

    2010-05-19

    Functional chemical micropatterns were fabricated by exploiting the photobleaching of dye-coupled species near methacrylate self-assembled monolayers. Using this approach we have demonstrated that multiple chemistries can be coupled to the monolayer using a standard fluorescence microscope. The surface bound functional groups remain active and patterns with feature sizes down to 3 {mu}m can be readily achieved with excellent signal-to-noise ratio. Control over the ligand binding density was demonstrated to illustrate the convenient route provided by this platform for fabricating complex spatial gradients in ligand density.

  7. Work functions of self-assembled monolayers on metal surfaces by first-principles calculations

    NARCIS (Netherlands)

    Rusu, P.C.; Brocks, G.

    2006-01-01

    Using first-principles calculations we show that the work function of noble metals can be decreased or increased by up to 2 eV upon the adsorption of self-assembled monolayers of organic molecules. We identify the contributions to these changes for several (fluorinated) thiolate molecules adsorbed

  8. Self-assembly patterning of organic molecules on a surface

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Minghu; Fuentes-Cabrera, Miguel; Maksymovych, Petro; Sumpter, Bobby G.; Li, Qing

    2017-04-04

    The embodiments disclosed herein include all-electron control over a chemical attachment and the subsequent self-assembly of an organic molecule into a well-ordered three-dimensional monolayer on a metal surface. The ordering or assembly of the organic molecule may be through electron excitation. Hot-electron and hot-hole excitation enables tethering of the organic molecule to a metal substrate, such as an alkyne group to a gold surface. All-electron reactions may allow a direct control over the size and shape of the self-assembly, defect structures and the reverse process of molecular disassembly from single molecular level to mesoscopic scale.

  9. Self assembled monolayers of octadecyltrichlorosilane for dielectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vijay, E-mail: cirivijaypilani@gmail.com [Centre for Nanoscience and Engineering, Indian Institute of Science-Bangalore (India); Mechanical Engineering Department, Birla Institute of Technology and Science-Pilani (India); Puri, Paridhi; Nain, Shivani [Mechanical Engineering Department, Birla Institute of Technology and Science-Pilani (India); Bhat, K. N. [Centre for Nanoscience and Engineering, Indian Institute of Science-Bangalore (India); Sharma, N. N. [Mechanical Engineering Department, Birla Institute of Technology and Science-Pilani (India); School of Automobile, Mechanical & Mechatronics, Manipal University-Jaipur (India)

    2016-04-13

    Treatment of surfaces to change the interaction of fluids with them is a critical step in constructing useful microfluidics devices, especially those used in biological applications. Selective modification of inorganic materials such as Si, SiO{sub 2} and Si{sub 3}N{sub 4} is of great interest in research and technology. We evaluated the chemical formation of OTS self-assembled monolayers on silicon substrates with different dielectric materials. Our investigations were focused on surface modification of formerly used common dielectric materials SiO{sub 2}, Si{sub 3}N{sub 4} and a-poly. The improvement of wetting behaviour and quality of monolayer films were characterized using Atomic force microscope, Scanning electron microscope, Contact angle goniometer, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) monolayer deposited oxide surface.

  10. Sulfonation of alkyl phenyl ether self-assembled monolayers.

    Science.gov (United States)

    Katash, Irit; Luo, Xianglin; Sukenik, Chaim N

    2010-02-02

    The sulfonation of phenyl ether decorated self-assembled monolayers (SAMs) was studied with an eye toward creating surfaces with a particularly high negative charge density based on a close-packed array of phenyl rings with more than one sulfonic acid group per molecule. The product distribution and kinetics of this process were studied by ultraviolet, infrared, and photoelectron spectroscopies and by monitoring changes in the thickness and wetting properties of the SAM. The sulfonation chemistry could be effected without undermining monolayer integrity and the isomer distribution of ortho- and para-monosulfonated material, along with the percentages of mono- and disulfonated molecules could be established throughout the process. As doubly sulfonated molecules appeared, the reaction slowed drastically. Ultimately, sulfonation stops completely with approximately 60% of the molecules disulfonated and 20% each of the two monosulfonated isomers. This striking constraint on monolayer reactivity and the relationship between the surface chemistry and variations in SAM structure are discussed.

  11. Self assembly of highly-ordered nanoparticle monolayers.

    Energy Technology Data Exchange (ETDEWEB)

    Bigioni, T. P.; Lin, X.-M.; Nguyen, T. T.; Corwin, E. I.; Witten, T. A.; Jaeger, H. M.; Univ. of Chicago

    2006-01-01

    When a drop of a colloidal solution of nanoparticles dries on a surface, it leaves behind coffee-stain-like rings of material with lace-like patterns or clumps of particles in the interior. These non-uniform mass distributions are manifestations of far-from-equilibrium effects, such as fluid flows and solvent fluctuations during late-stage drying. However, recently a strikingly different drying regime promising highly uniform, long-range-ordered nanocrystal monolayers has been found. Here we make direct, real-time and real-space observations of nanocrystal self-assembly to reveal the mechanism. We show how the morphology of drop-deposited nanoparticle films is controlled by evaporation kinetics and particle interactions with the liquid-air interface. In the presence of an attractive particle-interface interaction, rapid early-stage evaporation dynamically produces a two-dimensional solution of nanoparticles at the liquid-air interface, from which nanoparticle islands nucleate and grow. This self-assembly mechanism produces monolayers with exceptional long-range ordering that are compact over macroscopic areas, despite the far-from-equilibrium evaporation process. This new drop-drying regime is simple, robust and scalable, is insensitive to the substrate material and topography, and has a strong preference for forming monolayer films. As such, it stands out as an excellent candidate for the fabrication of technologically important ultra thin film materials for sensors, optical devices and magnetic storage media.

  12. Functional Molecular Junctions Derived from Double Self-Assembled Monolayers.

    Science.gov (United States)

    Seo, Sohyeon; Hwang, Eunhee; Cho, Yunhee; Lee, Junghyun; Lee, Hyoyoung

    2017-09-25

    Information processing using molecular junctions is becoming more important as devices are miniaturized to the nanoscale. Herein, we report functional molecular junctions derived from double self-assembled monolayers (SAMs) intercalated between soft graphene electrodes. Newly assembled molecular junctions are fabricated by placing a molecular SAM/(top) electrode on another molecular SAM/(bottom) electrode by using a contact-assembly technique. Double SAMs can provide tunneling conjugation across the van der Waals gap between the terminals of each monolayer and exhibit new electrical functions. Robust contact-assembled molecular junctions can act as platforms for the development of equivalent contact molecular junctions between top and bottom electrodes, which can be applied independently to different kinds of molecules to enhance either the structural complexity or the assembly properties of molecules. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. XPS and electrochemical evaluation of two-dimensional organic films obtained by chemical modification of self-assembled monolayers of (3-mercaptopropyl)trimethoxysilane on copper surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sinapi, Fabrice; Delhalle, Joseph; Mekhalif, Zineb

    2002-12-01

    In this study, a protective film consisting of an ultrathin two-dimensional polymer was prepared by hydrolysis of a (3-mercaptopropyl)trimethoxysilane (ethanol, 10{sup -3} M) self-assembled monolayer grafted onto copper and a subsequent modification with 3(heptofluoroisopropoxy)propyltrichlorosilane (toluene, 10{sup -3} M). Each stage of the preparation was characterized by X-ray photoelectron spectroscopy (XPS) while copper's corrosion-inhibitive properties were assessed by cyclic voltammetry measurements carried on in a 0.1 M NaOH medium. A remarkable enhancement of the copper's corrosion protection was obtained by the formation of lateral siloxane linkages between MPTS molecules absorbed followed by the grafting of the second molecular layer.

  14. Template-Directed Self-Assembly of Alkanethiol Monolayers: Selective Growth on Preexisting Monolayer Edges

    NARCIS (Netherlands)

    Sharpe, R.B.A.; Burdinski, Dirk; Huskens, Jurriaan; Zandvliet, Henricus J.W.; Reinhoudt, David; Poelsema, Bene

    2007-01-01

    Self-assembled monolayers were investigated for their suitability as two-dimensional scaffolds for the selective growth of alkanethiol edge structures. Heterostructures with chemical contrast could be grown, whose dimensions were governed by both the initial pattern sizes and the process time.

  15. A self assembled monolayer based microfluidic sensor for urea detection

    Science.gov (United States)

    Srivastava, Saurabh; Solanki, Pratima R.; Kaushik, Ajeet; Ali, Md. Azahar; Srivastava, Anchal; Malhotra, B. D.

    2011-07-01

    Urease (Urs) and glutamate dehydrogenase (GLDH) have been covalently co-immobilized onto a self-assembled monolayer (SAM) comprising of 10-carboxy-1-decanthiol (CDT) via EDC-NHS chemistry deposited onto one of the two patterned gold (Au) electrodes for estimation of urea using poly(dimethylsiloxane) based microfluidic channels (2 cm × 200 μm × 200 μm). The CDT/Au and Urs-GLDH/CDT/Au electrodes have been characterized using Fourier transform infrared (FTIR) spectroscopy, contact angle (CA), atomic force microscopy (AFM) and electrochemical cyclic voltammetry (CV) techniques. The electrochemical response measurement of a Urs-GLDH/CDT/Au bioelectrode obtained as a function of urea concentration using CV yield linearity as 10 to 100 mg dl-1, detection limit as 9 mg dl-1 and high sensitivity as 7.5 μA mM-1 cm-2.

  16. Graphene growth by conversion of aromatic self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Turchanin, Andrey [Institute of Physical Chemistry, Friedrich Schiller University Jena (Germany); Jena Center for Soft Matter (JCSM), Jena (Germany); Center for Energy and Environmental Chemistry Jena (CEEC), Jena (Germany); Abbe Center of Photonics (ACP), Jena (Germany)

    2017-11-15

    Despite present diversity of graphene production methods there is still a high demand for improvement of the existing production schemes or development of new. Here a method is reviewed to produce graphene employing aromatic self-assembled monolayers (SAMs) as molecular precursors. This method is based on electron irradiation induced crosslinking of aromatic SAMs resulting in their conversion into carbon nanomembranes (CNMs) with high thermal stability and subsequent pyrolysis of CNMs into graphene in vacuum or in the inert atmosphere. Depending on the production conditions, such as chemical structure of molecular precursors, irradiation and annealing parameters, various properties of the produced graphene sheets including shape, crystallinity, thickness, optical properties and electric transport can be adjusted. The assembly of CNM/graphene van der Waals heterostructures opens a flexible route to non-destructive chemical functionalization of graphene for a variety of applications in electronic and photonic devices. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Nanoscale Nitrogen Doping in Silicon by Self-Assembled Monolayers.

    Science.gov (United States)

    Guan, Bin; Siampour, Hamidreza; Fan, Zhao; Wang, Shun; Kong, Xiang Yang; Mesli, Abdelmadjid; Zhang, Jian; Dan, Yaping

    2015-07-31

    This Report presents a nitrogen-doping method by chemically forming self-assembled monolayers on silicon. Van der Pauw technique, secondary-ion mass spectroscopy and low temperature Hall effect measurements are employed to characterize the nitrogen dopants. The experimental data show that the diffusion coefficient of nitrogen dopants is 3.66 × 10(-15) cm(2) s(-1), 2 orders magnitude lower than that of phosphorus dopants in silicon. It is found that less than 1% of nitrogen dopants exhibit electrical activity. The analysis of Hall effect data at low temperatures indicates that the donor energy level for nitrogen dopants is located at 189 meV below the conduction band, consistent with the literature value.

  18. Mixed carboranethiol self-assembled monolayers on gold surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, Adem [Micro and Nanotechnology Department, Graduate School of Natural and Applied Science, Middle East Technical University, Ankara 06800 (Turkey); Sohrabnia, Nima [Department of Chemistry, Middle East Technical University, Ankara 06800 (Turkey); Yilmaz, Ayşen [Micro and Nanotechnology Department, Graduate School of Natural and Applied Science, Middle East Technical University, Ankara 06800 (Turkey); Department of Chemistry, Middle East Technical University, Ankara 06800 (Turkey); Danışman, M. Fatih, E-mail: danisman@metu.edu.tr [Micro and Nanotechnology Department, Graduate School of Natural and Applied Science, Middle East Technical University, Ankara 06800 (Turkey); Department of Chemistry, Middle East Technical University, Ankara 06800 (Turkey)

    2017-08-15

    Highlights: • M1 binds to the gold surface preferentially when co-deposited with M9 or O1. • Contact angles show similar trends regardless of the gold substrate roughness. • Contact angles were lower, with higher hysteresis, on template stripped gold. • Mixed carboranethiol SAMs have similar morphological properties regardless of mixing ratio. - Abstract: Carboranethiol self-assembled monolayers on metal surfaces have been shown to be very convenient systems for surface engineering. Here we have studied pure and mixed self-assembled monolayers (SAMs) of three different carboranethiol (CT) isomers on gold surfaces. The isomers were chosen with dipole moments pointing parallel to (m-1-carboranethiol, M1), out of (m-9-carboranethiol, M9) and into (o-1-carboranethiol, O1) the surface plane, in order to investigate the effect of dipole moment orientation on the film properties. In addition, influence of the substrate surface morphology on the film properties was also studied by using flame annealed (FA) and template stripped (TS) gold surfaces. Contact angle measurements indicate that in M1/M9 and M1/O1 mixed SAMs, M1 is the dominant species on the surface even for low M1 ratio in the growth solution. Whereas for O1/M9 mixed SAMs no clear evidence could be observed indicating dominance of one of the species over the other one. Though contact angle values were lower and hysteresis values were higher for SAMs grown on TS gold surfaces, the trends in the behavior of the contact angles with changing mixing ratio were identical for SAMs grown on both substrates. Atomic force microscopy images of the SAMs on TS gold surfaces indicate that the films have similar morphological properties regardless of mixing ratio.

  19. Ordering and dynamics of oligo(phenylene ethynylene) self-assembled monolayers on Au(111)

    NARCIS (Netherlands)

    Wu, Hairong; Sotthewes, Kai; Schön, Peter Manfred; Vancso, Gyula J.; Zandvliet, Henricus J.W.

    2015-01-01

    Self-assembled monolayers of 4-[4′-(phenylethynyl)-phenylethynyl]-benzenethiolate (PPB-S) molecules on flame annealed Au(111) have been investigated by ultra-high vacuum scanning tunneling microscopy. We have found a hitherto unknown self-assembled monolayer phase. This phase consists of a

  20. Monitoring the hydration of DNA self-assembled monolayers using an extensional nanomechanical resonator

    DEFF Research Database (Denmark)

    Cagliani, Alberto; Kosaka, Priscila; Tamayo, Javier

    2012-01-01

    We have fabricated an ultrasensitive nanomechanical resonator based on the extensional vibration mode to weigh the adsorbed water on self-assembled monolayers of DNA as a function of the relative humidity. The water adsorption isotherms provide the number of adsorbed water molecules per nucleotide...... for monolayers of single stranded (ss) DNA and after hybridization with the complementary DNA strand. Our results differ from previous data obtained with bulk samples, showing the genuine behavior of these self-assembled monolayers. The hybridization cannot be inferred from the water adsorption isotherms due...... on the interaction between water and self-assembled monolayers of nucleic acids....

  1. High-Performance n-Channel Organic Transistors Using High-Molecular-Weight Electron-Deficient Copolymers and Amine-Tailed Self-Assembled Monolayers.

    Science.gov (United States)

    Wang, Yang; Hasegawa, Tsukasa; Matsumoto, Hidetoshi; Mori, Takehiko; Michinobu, Tsuyoshi

    2018-03-01

    While high-performance p-type semiconducting polymers are widely reported, their n-type counterparts are still rare in terms of quantity and quality. Here, an improved Stille polymerization protocol using chlorobenzene as the solvent and palladium(0)/copper(I) as the catalyst is developed to synthesize high-quality n-type polymers with number-average molecular weight up to 10 5 g mol -1 . Furthermore, by sp 2 -nitrogen atoms (sp 2 -N) substitution, three new n-type polymers, namely, pBTTz, pPPT, and pSNT, are synthesized, and the effect of different sp 2 -N substitution positions on the device performances is studied for the first time. It is found that the incorporation of sp 2 -N into the acceptor units rather than the donor units results in superior crystalline microstructures and higher electron mobilities. Furthermore, an amine-tailed self-assembled monolayer (SAM) is smoothly formed on a Si/SiO 2 substrate by a simple spin-coating technique, which can facilitate the accumulation of electrons and lead to more perfect unipolar n-type transistor performances. Therefore, a remarkably high unipolar electron mobility up to 5.35 cm 2 V -1 s -1 with a low threshold voltage (≈1 V) and high on/off current ratio of ≈10 7 is demonstrated for the pSNT-based devices, which are among the highest values for unipolar n-type semiconducting polymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Copper pattern on self-assembled monolayer through microcontact printing.

    Science.gov (United States)

    Liu, Zheng-Chun; Yang, Fei-Peng; Xu, Xiao-Wen; Guo, Can; Liu, Jian-Xin

    2010-05-01

    Cu pattern on 3-mercaptopropyltrimethoxysilane self-assembled monolayers (MPTS-SAMs) modified glass substrate was achieved by a combination of hydrophobic treatment through microcontact printing, activation and electroless plating. The MPTS-SAMs modified glass substrate was selectively deactivated by microcontact printing 1-hexadecanethiol ethanol solution. X-ray photoelectron spectroscopy (XPS) and water contact angle measurements confirmed that a selectively deactivated pattern was obtained, which was attributed to the formation of disulfide linkages between MPTS and 1-hexadecanethiol. The substrate was selectively activated by dipping into Ag colloids solution and then applied for electroless Cu plating. XPS spectra suggested an ideal catalytic pattern on the substrate due to the deposition of Ag particles on the MPTS and the formation of S-Ag bonds. SEM showed that the microstructure of Cu pattern on MPTS-SAMs was in good agreement with the corresponding silicon master with a resolution of 10 microm. The average electrical resistivity was about 1.8 x 10(-6) omegacm, measured by four-point probe technique. The results suggested that microcontact printing deactivating reagents on SAMs is a potential technique for Cu patterns preparation.

  3. Electrochemical and structural characterization of self-assembled thiol monolayers on gold

    NARCIS (Netherlands)

    Sondag-Huethorst, J.A.M.

    1994-01-01

    Self-assembled alkanethiol monolayers on gold are used as model systems in a fundamental study of the potential-dependent wetting and of the galvanic metal deposition. For using such monolayers as model systems, well-defined and ordered monolayers are required. In order to control the

  4. Permethylated 12-Vertex p-Carborane Self-Assembled Monolayers

    Czech Academy of Sciences Publication Activity Database

    Scholz, F.; Nothofer, H. G.; Wessels, J. M.; Nelles, G.; Wrochem von, F.; Roy, S.; Chen, X.; Michl, Josef

    2011-01-01

    Roč. 115, č. 46 (2011), s. 22998-23007 ISSN 1932-7447 Grant - others:National Science Foundation(US) CHE-0848477 Institutional research plan: CEZ:AV0Z40550506 Keywords : p-carbone * monolayer * scanning tunneling microscopy * ultraviolet photoelectron spectroscopy * X-ray photoelectron Subject RIV: CC - Organic Chemistry Impact factor: 4.805, year: 2011

  5. Ionic Self Assembled Monolayer (ISAM) Processes for Electronic Materials and Devices

    National Research Council Canada - National Science Library

    Miller, Mike

    1997-01-01

    .... Ionic self-assembled monolayer (ISAM) techniques for the fabrication of multilayer nanoparticle/polymer structures offer low manufacturing costs, advantages of processing at ambient temperature and pressure, ability to produce devices...

  6. Controlled modification of octadecyltrichlorosilane self-assembled monolayer by CO2 plasma

    International Nuclear Information System (INIS)

    Delorme, Nicolas; Bardeau, Jean-Francois; Bulou, Alain; Poncin-Epaillard, Fabienne

    2006-01-01

    CO 2 -plasma is used to introduce functional groups on the uppermost surface of an alkoxy silane self-assembled monolayer (Sam). The structural and chemical modifications of the material surface were monitored by X-ray reflectometry, atomic force microscopy, X-ray photoelectrons spectroscopy and water contact angle measurements. Optimization of the plasma parameters is performed in order to achieve a maximum functionalization and to prevent degradation of the SAM. Finally, the ability of grafting organic compounds onto the plasma modified SAMS was demonstrated by the formation of an alkoxysilane bilayer

  7. Effect of water-DNA interactions on elastic properties of DNA self-assembled monolayers.

    Science.gov (United States)

    Domínguez, Carmen M; Ramos, Daniel; Mendieta-Moreno, Jesús I; Fierro, José L G; Mendieta, Jesús; Tamayo, Javier; Calleja, Montserrat

    2017-04-03

    DNA-water interactions have revealed as very important actor in DNA mechanics, from the molecular to the macroscopic scale. Given the particularly useful properties of DNA molecules to engineer novel materials through self-assembly and by bridging organic and inorganic materials, the interest in understanding DNA elasticity has crossed the boundaries of life science to reach also materials science and engineering. Here we show that thin films of DNA constructed through the self-assembly of sulfur tethered ssDNA strands demonstrate a Young's modulus tuning range of about 10 GPa by simply varying the environment relative humidity from 0% up to 70%. We observe that the highest tuning range occurs for ssDNA grafting densities of about 3.5 × 10 13 molecules/cm 2 , where the distance between the molecules maximizes the water mediated interactions between the strands. Upon hybridization with the complementary strand, the DNA self-assembled monolayers significantly soften by one order of magnitude and their Young's modulus dependency on the hydration state drastically decreases. The experimental observations are in agreement with molecular dynamics simulations.

  8. Morphology control of perovskite light-emitting diodes by using amino acid self-assembled monolayers

    Science.gov (United States)

    Wang, Nana; Cheng, Lu; Si, Junjie; Liang, Xiaoyong; Jin, Yizheng; Wang, Jianpu; Huang, Wei

    2016-04-01

    Amino acid self-assembled monolayers are used in the fabrication of light-emitting diodes based on organic-inorganic halide perovskites. The monolayers of amino acids provide modified interfaces by anchoring to the surfaces of ZnO charge-transporting layers using carboxyl groups, leaving the amino groups to facilitate the nucleation of MAPbBr3 perovskite films. This surface-modification strategy, together with chlorobenzene-assisted fast crystallization method, results in good surface coverage and reduced defect density of the perovskite films. These efforts lead to green perovskite light emitting diodes with a low turn-on voltage of 2 V and an external quantum efficiency of 0.43% at a brightness of ˜5000 cd m-2.

  9. Morphology control of perovskite light-emitting diodes by using amino acid self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Nana; Cheng, Lu; Wang, Jianpu, E-mail: iamjpwang@njtech.edu.cn [Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials - SICAM, Nanjing Tech University - NanjingTech, 30 South Puzhu Road, Nanjing 211816 (China); Si, Junjie; Liang, Xiaoyong [State Key Laboratory of Silicon Materials, Center for Chemistry of High-Performance and Novel Materials, and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Jin, Yizheng [Center for Chemistry of High-Performance and Novel Materials, State Key Laboratory of Silicon Materials, and Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Huang, Wei [Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials - SICAM, Nanjing Tech University - NanjingTech, 30 South Puzhu Road, Nanjing 211816 (China); Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023 (China)

    2016-04-04

    Amino acid self-assembled monolayers are used in the fabrication of light-emitting diodes based on organic-inorganic halide perovskites. The monolayers of amino acids provide modified interfaces by anchoring to the surfaces of ZnO charge-transporting layers using carboxyl groups, leaving the amino groups to facilitate the nucleation of MAPbBr{sub 3} perovskite films. This surface-modification strategy, together with chlorobenzene-assisted fast crystallization method, results in good surface coverage and reduced defect density of the perovskite films. These efforts lead to green perovskite light emitting diodes with a low turn-on voltage of 2 V and an external quantum efficiency of 0.43% at a brightness of ∼5000 cd m{sup −2}.

  10. Multifunctional phosphonic acid self-assembled monolayers on metal oxides as dielectrics, interface modification layers and semiconductors for low-voltage high-performance organic field-effect transistors.

    Science.gov (United States)

    Ma, Hong; Acton, Orb; Hutchins, Daniel O; Cernetic, Nathan; Jen, Alex K-Y

    2012-11-07

    Insulating and semiconducting molecular phosphonic acid (PA) self-assembled monolayers (SAMs) have been developed for applications in organic field-effect transistors (OFETs) for low-power, low-cost flexible electronics. Multifunctional SAMs on ultrathin metal oxides, such as hafnium oxide and aluminum oxide, are shown to enable (1) low-voltage (sub 2 V) OFETs through dielectric and interface engineering on rigid and plastic substrates, (2) simultaneous one-component modification of source-drain and dielectric surfaces in bottom-contact OFETs, and (3) SAM-FETs based on molecular monolayer semiconductors. The combination of excellent dielectric and interfacial properties results in high-performance OFETs with low-subthreshold slopes down to 75 mV dec(-1), high I(on)/I(off) ratios of 10(5)-10(7), contact resistance down to 700 Ω cm, charge carrier mobilities of 0.1-4.6 cm(2) V(-1) s(-1), and general applicability to solution-processed and vacuum-deposited n-type and p-type organic and polymer semiconductors.

  11. Gas sensing with self-assembled monolayer field-effect transistors

    NARCIS (Netherlands)

    Andringa, Anne-Marije; Spijkman, Mark-Jan; Smits, Edsger C. P.; Mathijssen, Simon G. J.; van Hal, Paul A.; Setayesh, Sepas; Willard, Nico P.; Borshchev, Oleg V.; Ponomarenko, Sergei A.; Blom, Paul W. M.; de Leeuw, Dago M.

    A new sensitive gas sensor based on a self-assembled monolayer field-effect transistor (SAMFET) was used to detect the biomarker nitric oxide. A SAMFET based sensor is highly sensitive because the analyte and the active channel are separated by only one monolayer. SAMFETs were functionalised for

  12. Self-assembly of hydrofluorinated Janus graphene monolayer

    DEFF Research Database (Denmark)

    Jin, Yakang; Xue, Qingzhong; Zhu, Lei

    2016-01-01

    With remarkably interesting surface activities, two-dimensional Janus materials arouse intensive interests recently in many fields. We demonstrate by molecular dynamic simulations that hydrofluorinated Janus graphene (J-GN) can self-assemble into Janus nanoscroll (J-NS) at room temperature. The van...

  13. Distinct self-assembly of dithiol monolayers on Au(1 1 1) in water and hexane

    Science.gov (United States)

    Sharif, Aisyah M.; Laffir, Fathima R.; Buckley, D. Noel; Silien, Christophe

    2014-09-01

    The self-assembly of 1,4-benzenedimethanethiol on Au(1 1 1), at low concentration in water and in hexane which are respectively polar and non-polar solvent, has been studied by scanning tunneling microscopy (STM). The data reveal that, on clean Au(1 1 1), a complete and ordered self-assembled monolayer (SAM) of lying-down dithiols can form within a few seconds in water. While in hexane the adsorption is initially impeded by the rapid growth of an ordered hexane film that is gradually replaced by disordered domains of dithiol until completion of a saturated monolayer. Complemented by X-ray photoelectron spectroscopy measurements, the STM images resolve the progression of the self-assembly in both these polar and non-polar solvent, and highlight how the self-assembly depends on the trio solvent, dithiol, and substrate.

  14. Required Equipment for Photo-Switchable Donor-Acceptor (D-A) Dyad Interfacial Self-Assembled Monolayers for Organic Photovoltaic Cells

    Science.gov (United States)

    2014-01-24

    Accessory, 6) a Jelight Co. UVO cleaner, and 7) a Laurell Technologies Spin Coater . These instruments were used to characterize a variety of...goniometer/tensiometer, UVO cleaner, spin coater U U U UU Luis Echegoyen (915) 747-7573 (HBCU) - Required Equipment for Photo-switchable Donor...are exposed to the spin coated photoactive layer over the ITO monolayer, the effectiveness of this monolayer will be difficult to study. We need

  15. Correlation of Effective Dispersive and Polar Surface Energies in Heterogeneous Self-Assembled Monolayer Coatings

    DEFF Research Database (Denmark)

    Zhuang, Yanxin; Hansen, Ole

    2009-01-01

    grown oil oxidized (100) silicon Surfaces in a vapor phase process using five different precursors. Experimentally, effective surface energy components of the fluorocarbon self-assembled monolayers were determined from measured contact angles using the Owens-Wendt-Rabel-Kaelble method. We show......We show, theoretically, that the measured effective dispersive and polar surface energies of a heterogeneous Surface are correlated; the correlation, however, differs whether a Cassic or an Israelachvili and Gee model is assumed. Fluorocarbon self-assembled monolayers with varying coverage were...

  16. Surface characterization of sulfur and alkanethiol self-assembled monolayers on Au(111)

    International Nuclear Information System (INIS)

    Vericat, C; Vela, M E; Benitez, G A; Gago, J A Martin; Torrelles, X; Salvarezza, R C

    2006-01-01

    In the last two decades surface science techniques have decisively contributed to our present knowledge of alkanethiol self-assembled monolayers (SAMs) on solid surfaces. These organic layers have been a challenge for surface scientists, in particular because of the soft nature of the organic material (which can be easily damaged by irradiation), the large number of atoms present in the molecules, and the complex physical chemistry involved in the self-assembly process. This challenge has been motivated by the appealing technological applications of SAMs that cover many fields of the emerging area of nanotechnology. Sulfur (S) is closely related to alkanethiols and can be used to understand basic aspects of the surface structure of SAMs. In this review we focus on the atomic/molecular structures of S-containing SAMs on Au(111). Particular emphasis is given to the substrate, adsorption sites, chemical state of the S-metal bond and also to the experimental and theoretical tools used to study these structures at the atomic or molecular levels. (topical review)

  17. Self-assembled monolayers of alpha-cyclodextrin derivatives on gold and their host-guest behavior

    Czech Academy of Sciences Publication Activity Database

    Perl, A.; Kumprecht, Lukáš; Kraus, Tomáš; Armspach, D.; Matt, D.; Reinhoudt, D.N.; Huskens, J.

    2009-01-01

    Roč. 25, č. 3 (2009), s. 1534-1539 ISSN 0743-7463 R&D Projects: GA AV ČR IAA400550810; GA ČR GA203/06/1550; GA MŠk OC 172 Institutional research plan: CEZ:AV0Z40550506 Keywords : cyklodextrins * self-assembled monolayers Subject RIV: CC - Organic Chemistry Impact factor: 3.898, year: 2009

  18. Tailoring self-assembled monolayers at the electrochemical interface

    Indian Academy of Sciences (India)

    Administrator

    gmail.com. Abstract. The main focus ... facilitates the packing of the molecules in the monolayers and serves as a linker between the head ..... applications of pharmaceutical and food industries. It has been shown recently that SAMs and mixed.

  19. Self-assembled monolayers of shape-persistent macrocycles on graphite: interior design and conformational polymorphism

    Directory of Open Access Journals (Sweden)

    Joscha Vollmeyer

    2014-11-01

    Full Text Available Three shape-persistent naphthylene–phenylene–acetylene macrocycles of identical backbone structures and extraannular substitution patterns but different (empty, apolar, polar nanopore fillings are self-assembled at the solid/liquid interface of highly oriented pyrolytic graphite and 1,2,4-trichlorobenzene. Submolecularly resolved images of the resulting two-dimensional (2D crystalline monolayer patterns are obtained by in situ scanning tunneling microscopy. A concentration-dependent conformational polymorphism is found, and open and more dense packing motifs are observed. For all three compounds alike lattice parameters are found, therefore the intermolecular macrocycle distances are mainly determined by their size and symmetry. This is an excellent example that the graphite acts as a template for the macrocycle organization independent from their specific interior.

  20. Self-assembled monolayers of shape-persistent macrocycles on graphite: interior design and conformational polymorphism.

    Science.gov (United States)

    Vollmeyer, Joscha; Eberhagen, Friederike; Höger, Sigurd; Jester, Stefan-S

    2014-01-01

    Three shape-persistent naphthylene-phenylene-acetylene macrocycles of identical backbone structures and extraannular substitution patterns but different (empty, apolar, polar) nanopore fillings are self-assembled at the solid/liquid interface of highly oriented pyrolytic graphite and 1,2,4-trichlorobenzene. Submolecularly resolved images of the resulting two-dimensional (2D) crystalline monolayer patterns are obtained by in situ scanning tunneling microscopy. A concentration-dependent conformational polymorphism is found, and open and more dense packing motifs are observed. For all three compounds alike lattice parameters are found, therefore the intermolecular macrocycle distances are mainly determined by their size and symmetry. This is an excellent example that the graphite acts as a template for the macrocycle organization independent from their specific interior.

  1. Interactions of Na+, K+, Mg2+, and Ca 2+ with benzene self-assembled monolayers

    DEFF Research Database (Denmark)

    Pedersen, Morten Rimmen; Matthiesen, Jesper; Bovet, Nicolas Emile

    2014-01-01

    Interactions between cations and organic molecules are found throughout nature, from the functionality and structure of proteins in humans and animals to the exchange of ions in minerals in soil and oil reservoirs with the fluid phases. We have explored the behavior of the s-block elements...... that are most common in the natural world, namely, Na+, K+, Mg 2+, and Ca2+. Specifically, we investigated how these ions affect the interactions between surfaces covered by self-Assembled monolayers (SAMs) terminated with benzene molecules. We used a flat oxidized silicon substrate and an atomic force...... but forms bridges between the layers, leading to higher adhesion than in pure water. In Na+ and Mg2+ solutions, adhesion is quite similar to that in pure water, indicating a lack of interaction between these two ions and the surfaces, or at least that the interaction is too weak to be detected by our...

  2. Triazolobithiophene Light Absorbing Self-Assembled Monolayers: Synthesis and Mass Spectrometry Applications

    Directory of Open Access Journals (Sweden)

    Denis Séraphin

    2011-10-01

    Full Text Available The synthesis of five light absorbing triazolobithiophenic thiols, which were utilized for producing self-assembled monolayers (SAMs on gold surfaces, is presented. The monolayer formation was monitored by cyclic voltammetry, indicating excellent surface coverage. The new triazolobithiophenic compounds exhibited an absorption maximum around 340 nm, which is close to the emission wavelength of a standard nitrogen laser. Consequently these compounds could be used to aid ionization in laser desorption mass spectrometry (MS.

  3. Crystalline self-assembly into monolayers of folded oligomers at the air-water interface

    DEFF Research Database (Denmark)

    Lederer, K.; Godt, A.; Howes, P.B.

    2000-01-01

    Insertion of the 115-bis(ethynylene)benzene unit as a rigid spacer into a linear alkyl chain, thus separating the two resulting stems by 9 Angstrom, induces chain folding at the air-water interface. These folded molecules self-assemble into crystalline monolayers at this interface, with the plane...

  4. Sensitive detection of plastic explosives with self-assembled monolayer-coated microcantilevers

    Science.gov (United States)

    Pinnaduwage, L. A.; Boiadjiev, V.; Hawk, J. E.; Thundat, T.

    2003-08-01

    We report the detection of 10-30 parts-per-trillion levels of pentaerythritol tetranitrate and hexahydro-1,3,5-triazine within 20 s of exposure to a silicon microcantilever with its gold surface modified with a self-assembled monolayer of 4-mercaptobenzoic acid. These measurements correspond to a limit of detection of a few fg.

  5. UV/Vis and NIR Light-Responsive Spiropyran Self-Assembled Monolayers

    NARCIS (Netherlands)

    Ivashenko, Oleksii; Herpt, Jochem T. van; Feringa, Ben L.; Rudolf, Petra; Browne, Wesley R.

    2013-01-01

    Self-assembled monolayers of a 6-nitro BIPS spiropyran (SP) modified with a disulfide-terminated aliphatic chain were prepared on polycrystalline gold surfaces and characterized by UV/vis absorption, surface-enhanced Raman scattering (SEAS), and X-ray photoelectron spectroscopies (XPS). The SAMs

  6. Electron tunneling through alkanedithiol self-assembled monolayers in large-area molecular junctions

    NARCIS (Netherlands)

    Akkerman, Hylke B.; Naber, Ronald C. G.; Jongbloed, Bert; van Hal, Paul A.; Blom, Paul W. M.; de Leeuw, Dago M.; de Boer, Bert

    2007-01-01

    The electrical transport through self-assembled monolayers of alkanedithiols was studied in large-area molecular junctions and described by the Simmons model [Simmons JIG (1963) J Appi Phys 34:1793-1803 and 2581-2590] for tunneling through a practical barrier, i.e., a rectangular barrier with the

  7. Orientation modulation of a synthetic polypeptide in self-assembled monolayers: a TOF-SIMS study.

    Science.gov (United States)

    Leufgen, Kirsten; Mutter, Manfred; Vogel, Horst; Szymczak, Wilfried

    2003-07-23

    Structure and orientation of molecules are key properties of functionalized surfaces. Using time-of-flight secondary ion mass spectrometry (TOF-SIMS), here we investigate how to modulate these parameters upon the immobilization process varying the conditions of self-assembly. The molecule of interest, a template-assembled synthetic protein (TASP), consists of a central peptide ring with orthogonally arranged residues. Thioalkane chains allow the directed self-assembly of the molecule on a gold surface; four serine residues on the opposite side of the ring can be used as anchoring sites for various functional sensing molecules. The TASP conformation and its orientation in self-assembled monolayers (SAMs) play a central role for the accessibility of these serine residues. To study the influence of the self-assembly conditions, two series of samples were prepared. Pure TASP monolayers of different surface densities are compared to mixed TASP/alkanethiol monolayers prepared by sequential adsorption varying sequence and particular incubation times as well as by coadsorption modifying incubation times and TASP/alkanethiol mass ratios. Switching the TASP orientation from a state where the molecules are lying flat on the surface to an upright orientation turned out to be possible by inserting the TASP into a preformed alkanethiol monolayer of an appropriate surface density. This study demonstrates that TOF-SIMS is an excellent tool not only to investigate the surface composition, but also the molecular structure of functionalized surfaces.

  8. N-type self-assembled monolayer field-effect transistors

    NARCIS (Netherlands)

    Ringk, A.; Li, X.; Gholamrezaie, F.; Smits, E.C.P.; Neuhold, A.; Moser, A.; Gelinck, G.H.; Resel, R.; Leeuw, D.M. de; Strohriegl, P.

    2012-01-01

    Within this work we present the synthesis and applications of a novel material designed for n-type self-assembled monolayer field-effect transistors (SAMFETs). Our novel perylene bisimide based molecule was obtained in six steps and is functionalized with a phosphonic acid linker which enables a

  9. Binary self-assembled monolayers: Apparent exponential dependence of resistance on average molecular length

    NARCIS (Netherlands)

    Katsouras, I.; Geskin, V.; Kronemeijer, A.J.; Blom, P.W.M.; Leeuw, D.M. de

    2011-01-01

    We investigate the electrical transport through mixed self-assembled monolayers of alkanemonothiols and alkanedithiols in large-area molecular junctions. To disentangle the role of the molecular length and the interfacial composition, monothiol-monothiol, dithiol-dithiol, and monothiol-dithiol

  10. Binary self-assembled monolayers : Apparent exponential dependence of resistance on average molecular length

    NARCIS (Netherlands)

    Katsouras, Ilias; Geskin, Victor; Kronemeijer, Auke J.; Blom, Paul W. M.; de Leeuw, Dago M.

    We investigate the electrical transport through mixed self-assembled monolayers of alkanemonothiols and alkanedithiols in large-area molecular junctions. To disentangle the role of the molecular length and the interfacial composition, monothiol-monothiol, dithiol-dithiol, and monothiol-dithiol

  11. Linear hydrogen adsorbate structures on graphite induced by self-assembled molecular monolayers

    DEFF Research Database (Denmark)

    Nilsson, Louis; Sljivancanin, Zeljko; Balog, Richard

    2012-01-01

    Combined scanning tunnelling microscopy measurements and density functional theory calculations reveal a method to induce linear structures of hydrogen adsorbates on graphite by covering the surface with a self-assembled molecular monolayer of cyanuric acid and exposing it to atomic hydrogen...

  12. Trapping dynamics of diindenoperylene (DIP) in self-assembled monolayers using molecular simulation

    KAUST Repository

    Kaushik, Ananth P.

    2011-07-01

    All-atom Molecular Dynamics simulation methods employing a well-tested intermolecular potential model, MM3 (Molecular Mechanics 3), demonstrate the propensity for diindenoperylene (DIP) molecules to insert between molecules of a self-assembled monolayer (SAM) during a deposition process intended to grow a thin film of this organic semiconductor molecule onto the surface of self-assembled monolayers. The tendency to insert between SAM molecules is fairly prevalent at normal growth temperatures and conditions, but is most strongly dependent on the density and the nature of the SAM. We posit the existence of an optimal density to favor surface adsorption over insertion for this system. DIP is less likely to insert in fluorinated SAMs, like FOTS (fluorooctatrichlorosilane), than its unfluorinated analog, OTS (octatrichlorosilane). It is also less likely to insert between shorter SAMs (e.g., less insertion in OTS than ODTS (octadecyltrichlorosilane)). Very short length, surface-coating molecules, like HDMS (hexamethyldisilazane), are more likely to scatter energetic incoming DIP molecules with little insertion on first impact (depending on the incident energy of the DIP molecule). Grazing angles of incidence of the depositing molecules generally favor surface adsorption, at least in the limit of low coverage, but are shown to be dependent on the nature of the SAM. The validity of these predictions is confirmed by comparison of the predicted sticking coefficients of DIP at a variety of incident energies on OTS, ODTS, and FOTS SAMs with results obtained experimentally by Desai et al. (2010) [23]. The simulation predictions of the tendency of DIP to insert can be explained, in large part, in terms of binding energies between SAM and DIP molecules. However, we note that entropic and stochastic events play a role in the deposition outcomes. Preliminary studies of multiple deposition events, emulating growth, show an unexpected diffusion of DIP molecules inserted within the

  13. Tailoring self-assembled monolayers at the electrochemical interface

    Indian Academy of Sciences (India)

    Administrator

    SAM could be studied by this method. The IR beam is reflected at a small grazing angle from the monolayer surface and the intensity of the reflected beam is recorded. .... strates a strong decrease in capacity. 3.7b Blocking of electron transfer kinetics: With the decrease in the current for the SAM-covered electrode, one can ...

  14. Distinct self-assembly of dithiol monolayers on Au(1 1 1) in water and hexane

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, Aisyah M. [Department of Physics and Energy, University of Limerick (Ireland); Materials and Surface Science Institute, University of Limerick (Ireland); Laffir, Fathima R. [Materials and Surface Science Institute, University of Limerick (Ireland); Buckley, D. Noel [Department of Physics and Energy, University of Limerick (Ireland); Materials and Surface Science Institute, University of Limerick (Ireland); Silien, Christophe, E-mail: christophe.silien@ul.ie [Department of Physics and Energy, University of Limerick (Ireland); Materials and Surface Science Institute, University of Limerick (Ireland)

    2014-09-30

    Highlights: • The self-assembly of 1,4-benzenedimethanethiol in water and in hexane is studied. • The initial phase of assembly is revealed for each solvent using STM and XPS. • Water stabilizes an ordered lying-down phase. • Hexane coadsorbs with benzenedimethanethiol and promotes standing-up absorption. - Abstract: The self-assembly of 1,4-benzenedimethanethiol on Au(1 1 1), at low concentration in water and in hexane which are respectively polar and non-polar solvent, has been studied by scanning tunneling microscopy (STM). The data reveal that, on clean Au(1 1 1), a complete and ordered self-assembled monolayer (SAM) of lying-down dithiols can form within a few seconds in water. While in hexane the adsorption is initially impeded by the rapid growth of an ordered hexane film that is gradually replaced by disordered domains of dithiol until completion of a saturated monolayer. Complemented by X-ray photoelectron spectroscopy measurements, the STM images resolve the progression of the self-assembly in both these polar and non-polar solvent, and highlight how the self-assembly depends on the trio solvent, dithiol, and substrate.

  15. Ozone Oxidation of Self-Assembled Monolayers on SiOx-Coated Zinc Selenide Surfaces

    Science.gov (United States)

    McIntire, T. M.; Ryder, O. S.; Finlayson-Pitts, B. J.

    2008-12-01

    Airborne particles are important for visibility, human health, climate, and atmospheric reactions. Atmospheric particles contain a significant fraction of organics and such compounds present on airborne particles are susceptible to oxidation by atmospheric oxidants, such as OH, ozone, halogen atoms, and nitrogen trioxide. Oxidized organics associated with airborne particles are thought to be polar, hygroscopic species with enhanced cloud-nucleating properties. Oxide layers on silicon, or SiO2-coated substrates, act as models of environmentally relevant surfaces such as dust particles upon which organics adsorb. We have shown previously that ozone oxidation of unsaturated self-assembled monolayers (SAMs) on silicon attenuated total reflectance (ATR) crystals leads to the formation of carbonyl groups and micron-sized, hydrophobic organic aggregates surrounded by carbon depleted substrate that do not have increased water uptake as previously assumed. Reported here are further ATR-FTIR studies of the oxidation of alkene SAMs on ZnSe and SiO2-coated ZnSe. These substrates have the advantage that they transmit below 1500 cm-1, allowing detection of additional product species. These experiments show that the loss of C=C and formation of carbonyl groups is also accompanied by formation of a peak at 1110 cm-1, attributed to the secondary ozonide. Details concerning the products and mechanism of ozonolysis of alkene SAMs on surfaces based on these new data are presented and the implications for the oxidation of alkenes on airborne dust particles are discussed.

  16. Electronic properties of organic monolayers and molecular devices

    Indian Academy of Sciences (India)

    E-mail: dominique.vuillaume@iemn.univ-lille1.fr. Abstract. We review some of our recent experimental results on charge transport in or- ganic nanostructures such as self-assembled monolayer and monolayers of organic semicon- ductors. We describe a molecular rectifying junction made from a sequential self-assembly.

  17. Self-assembled monolayers on gold nanospheres studied by optical second-harmonic generation

    Science.gov (United States)

    Yamaguchi, T.; Kajikawa, K.

    2008-08-01

    Recently plasmonic biosensors consisting of gold nanoparticles have been developed. In order to understand the response of the biosensors, we have investigated how are gold nanospheres immobilized on a surface covered by a self-assembled monolayer (SAM) which is formed by immersion of the substrate in a solution, by use of surface second-harmonic generation (SHG). The surface immobilized gold nanospheres (SIGNs) are supported by a self-assembled monolayer (SAM) of aminoundecanthiol on a gold thin film. The SIGN substrate was immersed in an ethanol solution of hemicyanine-terminated alkanethiol. The capping angles of the hemicyanine SAM with respect to the top of the SIGN were evaluated from polarization dependence of SHG intensity. The SIGNs are not fully covered with the SAM, and the capping angle is found to be approximately 120 degrees.

  18. Controlling the stereochemistry and regularity of butanethiol self-assembled monolayers on Au(111)

    DEFF Research Database (Denmark)

    Yan, Jiawei; Ouyang, Runhai; Jensen, Palle Skovhus

    2014-01-01

    The rich stereochemistry of the self-assembled monolayers (SAMs) of four butanethiols on Au(111) is described, the SAMs containing up to 12 individual C, S, or Au chiral centers per surface unit cell. This is facilitated by synthesis of enantiomerically pure 2-butanethiol (the smallest unsubstitu......The rich stereochemistry of the self-assembled monolayers (SAMs) of four butanethiols on Au(111) is described, the SAMs containing up to 12 individual C, S, or Au chiral centers per surface unit cell. This is facilitated by synthesis of enantiomerically pure 2-butanethiol (the smallest...... when R is achiral, while adatom binding leads to rectangular plane groups that suppress long-range expression of chirality. Binding as RS• also inhibits the pitting intrinsically associated with adatom binding, desirably producing more regularly structured SAMs....

  19. Memory characteristics of a self-assembled monolayer of Pt nanoparticles as a charge trapping layer

    International Nuclear Information System (INIS)

    Choi, Hyejung; Kim, Tae-Wook; Jung, Seung-Jae; Chang, Man; Lee, Takhee; Hwang, Hyunsang; Choi, Byung-Sang

    2008-01-01

    A self-assembled monolayer of Pt nanoparticles (NPs) was studied as a charge trapping layer for non-volatile memory (NVM) applications. Pt NPs with a narrow size distribution (diameter ∼4 nm) were synthesized via an alcohol reduction method. The monolayer of these Pt NPs was immobilized on a SiO 2 substrate using poly(4-vinylpyridine) (P4VP) as a surface modifier. A metal-oxide-semiconductor (MOS) type memory device with Pt NPs exhibits a relatively large memory window of 5.8 V under ± 7 V for program/erase voltage. These results indicate that the self-assembled Pt NPs can be utilized for NVM devices

  20. Carboranedithiols: Building Blocks for Self-Assembled Monolayers on Copper Surfaces

    Czech Academy of Sciences Publication Activity Database

    Baše, Tomáš; Bastl, Zdeněk; Havránek, Vladimír; Macháček, Jan; Langecker, Jens; Malina, Václav

    2012-01-01

    Roč. 28, č. 34 (2012), s. 12518-12526 ISSN 0743-7463 R&D Projects: GA ČR GAP205/10/0348; GA AV ČR KAN100400702 Institutional support: RVO:61388980 ; RVO:61388955 ; RVO:61389005 ; RVO:67985882 Keywords : copper surfaces * carboranethiols * cluster * chemisorption * self-assembled monolayer Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 4.187, year: 2012

  1. Self-assembled monolayers in organic electronics

    NARCIS (Netherlands)

    Gholamrezaie, Fatemeh

    2012-01-01

    In de afgelopen jaren hebben organische (plastic) halfgeleiders steeds meer aandacht gekregen vanwege mogelijk gebruik in elektronische toepassingen zoals zonnecellen, LED’s en veldeffect transistors. Ze kunnen goedkoop op grote schaal gefabriceerd worden en hebben goede mechanische eigenschappen.

  2. Study of cluster ion emission from self assembled monolayers of alkanethiols under keV ion bombardment

    OpenAIRE

    Arezki, Bahia

    2007-01-01

    This work focuses on the emission processes of metal-organic clusters MmMen, (M is the organic molecule and Me the metal atom) ejected from self assembled monolayers (SAMs) of alkanethiols on gold after keV ion bombardment. These aggregates are often observed upon energetic ion bombardment of strongly bound molecules like SAMs. The explanation of this effect remains elusive, especially for large clusters as those observed in our study. The emission of these clusters is investigated using ToF-...

  3. On the lipid head group hydration of floating surface monolayers bound to self-assembled molecular protein layers

    DEFF Research Database (Denmark)

    Lösche, M.; Erdelen, C.; Rump, E.

    1994-01-01

    The structure of monomolecular layers of the protein streptavidin, specifically bound to biotin-functionalized lipid monolayers at aqueous surfaces, has been characterized. Neutron and X-ray reflectivity measurements allowed an assessment of the organization of these self-assembled systems...... with molecular resolution. Emphasis here is placed on the hydration of the lipid head groups in the bound state. For three functionalized lipids with spacers of different lengths between the biotin and their chains it was observed that the head groups were dehydrated in monolayers of the pure lipids, which were...... kept at low surface pressure before protein adsorption. The introduction of dipole moments at the interface by the admixture of phospholipids or the application of lateral pressure on the lipid monolayer before protein adsorption were found to impose an extension of the spacer moieties. The biotin...

  4. Sulfamide chemistry applied to the functionalization of self-assembled monolayers on gold surfaces

    Directory of Open Access Journals (Sweden)

    Loïc Pantaine

    2017-04-01

    Full Text Available Aniline-terminated self-assembled monolayers (SAMs on gold surfaces have successfully reacted with ArSO2NHOSO2Ar (Ar = 4-MeC6H4 or 4-FC6H4 resulting in monolayers with sulfamide moieties and different end groups. Moreover, the sulfamide groups on the SAMs can be hydrolyzed showing the partial regeneration of the aniline surface. SAMs were characterized by water contact angle (WCA measurements, Fourier-transform infrared reflection absorption spectroscopy (IRRAS and X-ray photoelectron spectroscopy (XPS.

  5. Lanthanide Selective Sorbents: Self-Assembled Monolayers on Mesoporous Supports (SAMMS)

    Energy Technology Data Exchange (ETDEWEB)

    Fryxell, Glen E.; Wu, Hong; Lin, Yuehe; Shaw, Wendy J.; Birnbaum, Jerome C.; Linehan, John C.; Nie, Zimin; Kemner, Kenneth M.; Kelly, Shelley

    2004-11-01

    Through the marriage of mesoporous ceramics with self-assembled monolayer chemistry, the genesis of a powerful new class of environmental sorbent materials has been realized. By coating the mesoporous ceramic backbone with a monolayer terminated with a lanthanide-specific ligand, it is possible to couple high lanthanide binding affinity with the high loading capacity (resulting from the extremely high surface area of the support). This lanthanide-specific ligand field is created by pairing a “hard” anionic Lewis base with a suitable synergistic ligand, in a favorable chelating geometry. Details of the synthesis, characterization, lanthanide binding studies, binding kinetics, competition experiments and sorbent regeneration studies are summarized.

  6. Chemically Transformable Configurations of Mercaptohexadecanoic Acid Self-Assembled Monolayers Adsorbed on Au(111)

    International Nuclear Information System (INIS)

    van Buuren, T; Bostedt, C; Nelson, A J; Terminello, L J; Vance, A L; Fadley, C S; Willey, T M

    2003-01-01

    Carboxyl terminated Self-Assembled Monolayers (SAMs) are commonly used in a variety of applications, with the assumption that the molecules form well ordered monolayers. In this work, NEXAFS verifies well ordered monolayers can be formed using acetic acid in the solvent. Disordered monolayers with unbound molecules present in the result using only ethanol. A stark reorientation occurs upon deprotonation of the endgroup by rinsing in a KOH solution. This reorientation of the endgroup is reversible with tilted over, hydrogen bound carboxyl groups while carboxylate-ion endgroups are upright. C1s photoemission shows that SAMs formed and rinsed with acetic acid in ethanol, the endgroups are protonated, while without, a large fraction of the molecules on the surface are carboxylate terminated

  7. The Structures of Self-Assembled Monolayer Films of Organosulfur Compounds Adsorbed on Gold Single Crystals: Electron Diffraction Studies.

    Science.gov (United States)

    1988-01-01

    AD-M193 125 THE STRUCTURES OF SELF-RSSENSLED MOMOLAYER FILMS OF 1/1 ORGANOSULFUR COMPOUND..(U) HRlYARD UNJY CAMBRIDGE MASS DEPT OF CHEMISTRY L STRONG...VV L- ___ THE STRUCTURES OF SELF-ASSEMBLED MONOLAYER FILMS OF ORGANOSULFUR COMPOUNDS ADSORBED ON GOLD SINGLE CRYSTALS: ELECTRON DIFFRACTION STUDIES...true sulfide phase. V V ’A. LA8700876 REVISED The Structures of Self-Assembled Monolayer Films of Organosulfur Compounds Adsorbed on Gold Single

  8. Study of polymorphism using patterned self-assembled monolayers approach on metal substrates

    Science.gov (United States)

    Quiñones, Rosalynn; Brown, Ryanne T.; Searls, Noah; Richards-Waugh, Lauren

    2018-01-01

    Polymorphism is a molecule's ability to possess altered physical crystalline structures and has become an active interest in pharmaceuticals due to its ability to influence a drug's physical and chemical properties. Crystal stability and solubility are crucial in determining a drug's pharmacokinetics and pharmacodynamics. Changes in these properties due to polymorphisms have contributed to recalls and modifications in industrial production. For this study, the effects of surface interactions with pharmaceuticals were examined through surface modification methodology using organic phosphonic and sulfonic acid self-assembled monolayers (SAMs) developed on a nickel or zinc oxide metal substrate. Drugs analyzed included carbamazepine, cimetidine, tolfenamic acid, and flufenamic acid. All drugs were thermodynamically applied to the reformed surface to aid in recrystallization. It was hypothesized and confirmed that intermolecular bonds, especially hydrogen bonds between the SAMs and pharmaceutical drugs, were the force that assisted in polymorph development. The study was successful in revealing multiple forms for each drug, including their commercial form and at least one additional form using micro FT-IR, Raman spectroscopy, and PXRD. Visual comparisons of crystal polymorphisms were performed with IR microscopy.

  9. Multiparametric characterization of nonelectroactive self-assembled monolayers during their formation.

    Science.gov (United States)

    Kokoschka, Malte; Henry, John B; Bandarenka, Aliaksandr S

    2013-08-06

    The formation of nonelectroactive self-assembled monolayers (SAMs) at the electrode/electrolyte interface was characterized with simultaneous impedance, gravimetric, and direct current measurements. In the presence of specifically adsorbing inorganic ions, this provides key information about the formation of SAMs. Gravimetric measurements allow an estimation of the adsorbate surface coverage; and completion of the assembly process can then be monitored in real-time. Electrochemical impedance spectroscopy measurements play a multifunctional role: they enable elucidation of the physical models of the interface, provide the information about the effective capacitance of SAMs thus probing the dielectric properties of the adsorbed layers, and evaluate the ability of charged electrolyte components to approach the electrode surface through the SAM (using adsorbing/desorbing SO4(2-) as an electroactive probe). The latter is important to assess the extent of defects in the formed organic layers. Finally, monitoring the direct current during SAM formation together with the collected gravimetric data can give additional important information about the process. A series of n-mercaptoalcohols with different hydrocarbon chain length adsorbing at Au electrodes was used as the model object to evaluate the proposed approach.

  10. In situ sulfonation of alkyl benzene self-assembled monolayers: product distribution and kinetic analysis.

    Science.gov (United States)

    Katash, Irit; Luo, Xianglin; Sukenik, Chaim N

    2008-10-07

    The sulfonation of aromatic rings held at the surface of a covalently anchored self-assembled monolayer has been analyzed in terms of the rates and isomer distribution of the sulfonation process. The observed product distributions are similar to those observed in solution, though the data obtained suggest that the reaction rate and the ortho/para product ratio depend on the length of the tether anchoring the aryl ring to the monolayer interface. It was also found that the interface becomes progressively more disordered and the observed reaction rates decrease as the reaction progresses. There is no evidence for a bias in favor of reaction at the more exposed para-position nor is there evidence for an enhanced reaction rate due to the increased disorder and/or improved wetting as the reaction proceeds. This is the first detailed study of electrophilic aromatic substitution at a monolayer interface. It introduces new approaches to the spectroscopic analysis of reactions on self-assembled monolayers and provides a new general approach to the analysis of isomeric product distribution in such a setting.

  11. Inhibition of copper corrosion by the formation of Schiff base self-assembled monolayers

    Science.gov (United States)

    Zhang, Jing; Liu, Zheng; Han, Guo-Cheng; Chen, Shi-Liang; Chen, Zhencheng

    2016-12-01

    Self-assembled monolayers (SAMs) of 4-((2-thiophenecarboxylic acid hydrazide) methylene) benzoic acid (HD2) (denoted as HD2-SAMs) were formed on copper surface. The SAMs were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. Polarization curve and weight loss methods indicated that the highest inhibition efficiency was 93.9% for CO2-saturated simulative oilfield water at a self-assembled time of 3 h. Potential-time curve, electrochemical impedance tests showed that HD2-SAMs on copper surface exhibited excellent inhibition effect at 30 °C. The adsorption behavior of HD2-SAMs on the copper surface followed the Langmuir adsorption isotherm, which was indicative of typically chemical adsorption. Quantum chemistry calculation showed that O and N atoms can interact with Cu atoms by coordination bonds which were the mainly active area of the adsorption of HD2 molecules.

  12. Electrical resistivity of nanoporous gold modified with thiol self-assembled monolayers

    International Nuclear Information System (INIS)

    Hakamada, Masataka; Kato, Naoki; Mabuchi, Mamoru

    2016-01-01

    Highlights: • Nanoporous gold is modified with thiol-containing self-assembled monolayers. • The electrical resistivity of the thiol-modified nanoporous gold increases. • The electrical resistivity increases with increasing thiol concentration. • Monolayer tail groups enhance the atmosphere dependence of electrical resistivity. - Abstract: The electrical resistivity of nanoporous gold (NPG) modified with thiol self-assembled monolayers (SAMs) has been measured at 298 K using a four-probe method. We found that the adsorption of thiol SAMs increases the electrical resistivity of NPG by up to 22.2%. Dependence of the electrical resistivity on the atmosphere (air or water) was also observed in SAMs-modified NPG, suggesting that the electronic states of the tail groups affect the electrons of the binding sulfur and adjacent surface gold atoms. The present results suggest that adsorption of thiol molecules can influence the behavior of the conducting electrons in NPG and that modification of NPG with SAMs may be useful for environmental sensing.

  13. Electrical resistivity of nanoporous gold modified with thiol self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Hakamada, Masataka, E-mail: hakamada.masataka.3x@kyoto-u.ac.jp; Kato, Naoki, E-mail: katou.naoki.75w@st.kyoto-u.ac.jp; Mabuchi, Mamoru, E-mail: mabuchi@energy.kyoto-u.ac.jp

    2016-11-30

    Highlights: • Nanoporous gold is modified with thiol-containing self-assembled monolayers. • The electrical resistivity of the thiol-modified nanoporous gold increases. • The electrical resistivity increases with increasing thiol concentration. • Monolayer tail groups enhance the atmosphere dependence of electrical resistivity. - Abstract: The electrical resistivity of nanoporous gold (NPG) modified with thiol self-assembled monolayers (SAMs) has been measured at 298 K using a four-probe method. We found that the adsorption of thiol SAMs increases the electrical resistivity of NPG by up to 22.2%. Dependence of the electrical resistivity on the atmosphere (air or water) was also observed in SAMs-modified NPG, suggesting that the electronic states of the tail groups affect the electrons of the binding sulfur and adjacent surface gold atoms. The present results suggest that adsorption of thiol molecules can influence the behavior of the conducting electrons in NPG and that modification of NPG with SAMs may be useful for environmental sensing.

  14. Fabrication of Silicon nanostructures by UHV-STM lithography in Self-Assembled Monolayers

    International Nuclear Information System (INIS)

    Sundermann, M.; Brechling, A.; Rott, K.; Meyners, D.; Kleineberg, U.; Heinzmann, U.; Knueller, A.; Eck, W.; Goelzhueuser, A.; Grunze, M.

    2002-01-01

    Our approach utilizes UHV-STM writing in Self-Assembled Monolayers (SAM). SAMs form highly-ordered ultrathin (∼2-3 nm) monomolecular layers on top of pre-activated Si(100) or Si(111) surfaces. After patterning by UHV-STM writing in constant-current mode at different write parameters (gap voltage, electron dose) the modified Self-Assembled Monolayer serves as an etch mask for an anisotropic wet etch transfer (two-step etch process in aqueous solutions of 5 % HF and 1 M KOH), of the write structure into the silicon substrate. The corresponding silicon nano-structures have been analyzed afterwards by AFM or SEM to characterize the pattern accuracy. We have studied the suitability of three different types of SAMs on silicon single-crystals. Alkyl-chain-type SAMs like Octadecylsilane (ODS) monolayer have been formed by immersion of hydroxylated Si(100) in Octadecyltrichlorosilane (CH 3 (CH 27 SiCl 3 ) while SAMs with aromatic spacer groups such as Hydroxybiphenyl (HBP, (C 6 H 6 ) 2 OH) and Ethoxybiphenyl silane (EBP, (C 6 H 6 ) 2 O(CH 2 ) 3 Si(OCH 3 ) 3 ) are formed on Si(111). (Authors)

  15. Luminescent Organic Semiconducting Langmuir Monolayers.

    Science.gov (United States)

    Agina, Elena V; Mannanov, Artur A; Sizov, Alexey S; Vechter, Olga; Borshchev, Oleg V; Bakirov, Artem V; Shcherbina, Maxim A; Chvalun, Sergei N; Konstantinov, Vladislav G; Bruevich, Vladimir V; Kozlov, Oleg V; Pshenichnikov, Maxim S; Paraschuk, Dmitry Yu; Ponomarenko, Sergei A

    2017-05-31

    In recent years, monolayer organic field-effect devices such as transistors and sensors have demonstrated their high potential. In contrast, monolayer electroluminescent organic field-effect devices are still in their infancy. One of the key challenges here is to create an organic material that self-organizes in a monolayer and combines efficient charge transport with luminescence. Herein, we report a novel organosilicon derivative of oligothiophene-phenylene dimer D2-Und-PTTP-TMS (D2, tetramethyldisiloxane; Und, undecylenic spacer; P, 1,4-phenylene; T, 2,5-thiophene; TMS, trimethylsilyl) that meets these requirements. The self-assembled Langmuir monolayers of the dimer were investigated by steady-state and time-resolved photoluminescence spectroscopy, atomic force microscopy, X-ray reflectometry, and grazing-incidence X-ray diffraction, and their semiconducting properties were evaluated in organic field-effect transistors. We found that the best uniform, fully covered, highly ordered monolayers were semiconducting. Thus, the ordered two-dimensional (2D) packing of conjugated organic molecules in the semiconducting Langmuir monolayer is compatible with its high-yield luminescence, so that 2D molecular aggregation per se does not preclude highly luminescent properties. Our findings pave the way to the rational design of functional materials for monolayer organic light-emitting transistors and other optoelectronic devices.

  16. Low-temperature poly(oxymethylene) direct bonding via self-assembled monolayer

    Science.gov (United States)

    Fu, Weixin; Ma, Bo; Kuwae, Hiroyuki; Shoji, Shuichi; Mizuno, Jun

    2018-02-01

    A direct bonding of poly(oxymethylene) (POM) was feasible at 100 °C by using self-assembled monolayer (SAM) as a surface modification method. (3-aminopropyl)triethoxysilane (APTES) and (3-glycidyloxypropyl)trimethoxysilane (GOPTS) were used in our work. X-ray photoelectron spectroscopy showed that both APTES and GOPTS modified the POM surface successfully. Bonding strength evaluation revealed that surface modification was affected by pretreatment (VUV/O3) process time. In addition, the bonding condition with highest strength had an average strength of 372 kPa. This technology is expected to be used in packaging for micro-/nano-electromechanical systems, such as biomedical devices.

  17. Self-assembly monolayer of mercaptopropyltrimethoxysilane for electroless deposition of Ag

    Energy Technology Data Exchange (ETDEWEB)

    Liu Zhengchun; He Quanguo; Xiao Pengfeng; Liang Bo; Tan Jianxin; He Nongyue; Lu Zuhong

    2003-11-15

    Mercaptopropyltrimethoxysilane (MPTS) was used to form self-assembly monolayers (SAMs) on glass slides, which was verified by using X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES). Electroless plating of Ag was performed on the SAMs-modified glass slide. XPS study showed that Ag colloids formed in solution were successfully and hard anchored on SAMs through chemical bonds. Scanning electron microscopy (SEM) analysis illustrated that Ag film on the SAMs-modified glass showed more predominant in durability of temperature than that on conventionally modified glass.

  18. Method for selective immobilization of macromolecules on self assembled monolayer surfaces

    Science.gov (United States)

    Laskin, Julia [Richland, WA; Wang, Peng [Billerica, MA

    2011-11-29

    Disclosed is a method for selective chemical binding and immobilization of macromolecules on solid supports in conjunction with self-assembled monolayer (SAM) surfaces. Immobilization involves selective binding of peptides and other macromolecules to SAM surfaces using reactive landing (RL) of mass-selected, gas phase ions. SAM surfaces provide a simple and convenient platform for tailoring chemical properties of a variety of substrates. The invention finds applications in biochemistry ranging from characterization of molecular recognition events at the amino acid level and identification of biologically active motifs in proteins, to development of novel biosensors and substrates for stimulated protein and cell adhesion.

  19. Photopatterning of self assembled monolayers on oxide surfaces for the selective attachment of biomolecules.

    Science.gov (United States)

    Hazarika, Pompi; Behrendt, Jonathan M; Petersson, Linn; Wingren, Christer; Turner, Michael L

    2014-03-15

    The immobilization of functional biomolecules to surfaces is a critical process for the development of biosensors for disease diagnostics. In this work we report the patterned attachment of single chain fragment variable (scFv) antibodies to the surface of metal oxides by the photodeprotection of self-assembled monolayers, using near-UV light. The photodeprotection step alters the functionality at the surface; revealing amino groups that are utilized to bind biomolecules in the exposed regions of the substrate only. The patterned antibodies are used for the detection of specific disease biomarker proteins in buffer and in complex samples such as human serum. © 2013 Elsevier B.V. All rights reserved.

  20. Self-assembled monolayer of graphene/Pt as counter electrode for efficient dye-sensitized solar cell.

    Science.gov (United States)

    Gong, Feng; Wang, Hong; Wang, Zhong-Sheng

    2011-10-21

    Monolayer of PDDA/graphene/PDDA/H(2)PtCl(6) is fabricated on conductive glass using electrostatic layer-by-layer self-assembly technique, which is then converted to graphene/Pt monolayer for use as counter electrode in dye-sensitized solar cell (DSSC). As compared to the sputtered Pt counter electrode, the self-assembled monolayer reduces the Pt amount by about 1000-fold but exhibits comparable photovoltaic performance. This finding provides a new route to fabrication of cheap and efficient counter electrodes for flow-line production of DSSCs. This journal is © the Owner Societies 2011

  1. Self-assembling bilayers of palladiumthiolates in organic media

    Indian Academy of Sciences (India)

    Unknown

    length. There is evidence to suggest that the alkyl chains are orientationally disordered especially prior to melting. Keywords. Self-assembling bilayers; palladiumthiolates; lamellar structures. 1. Introduction. Lipid bilayers have long been recognized as being central to molecular organization. Synthetic analogues mimicking ...

  2. Probing molecular interactions with methylene blue derivatized self-assembled monolayers

    Directory of Open Access Journals (Sweden)

    Eleni Koutsoumpeli

    2015-12-01

    Full Text Available The emergence of stratified and personalised medicine and the associated need for highly multiplexed detection strategies are driving the development of innovative sensor technology. Electronic immunosensor arrays capable of label-free and highly parallel monitoring of ligand binding have emerged as a particularly promising technology capable of meeting these new diagnostic challenges. In this study, we present an approach for interrogating molecular interactions electronically using redox active molecular monolayers. Specifically, we have synthesised self-assembled molecular monolayers assembled from long-chain alkanethiols (LCAT incorporating oligoethyleneglycol (OEG linkers that can be derivatized with a range of functional groups, including the redox active molecule methylene blue. Critically, we show that the electron transport properties of this redox-active monolayer are highly sensitive to the electrochemical environment, including the local concentration of protons and the electrostatic potential at the plane of electron transfer. Using a combination of cyclic voltammetry and QCM-D to study in detail the behaviour of the monolayer during functionalisation and analyte binding, we demonstrate that these redox properties can be exploited for the electrochemical sensing of molecular interactions (biotin–avidin in our case on SAMs. Given the versatility of LCAT-OEG monolayers, in terms of linker lengths, choice of functional group, and ability to create mixed component layers and the straight-forward assembly of mixed SAMs of high quality, our electrochemical sensing approach forms an excellent and generic label-free platform for probing a wide range of molecular interactions.

  3. Electrochemical release of amine molecules from carbamate-based, electroactive self-assembled monolayers.

    Science.gov (United States)

    Hong, Daewha; Kang, Kyungtae; Hong, Seok-Pyo; Shon, Hyun Kyong; Son, Jin Gyeong; Lee, Tae Geol; Choi, Insung S

    2012-01-10

    In this paper, carbamate-based self-assembled monolayers (SAMs) of alkanethiolates on gold were suggested as a versatile platform for release of amine-bearing molecules in response to the electrical signal. The designed SAMs underwent the electrochemical oxidation on the gold surface with simultaneous release of the amine molecules. The synthesis of the thiol compounds was achieved by coupling isocyanate-containing compounds with hydroquinone. The electroactive thiol was mixed with 11-mercaptoundecanol [HS(CH(2))(11)OH] to form a mixed monolayer, and cyclic votammetry was used for the characterization of the release behaviors. The mixed SAMs showed a first oxidation peak at +540 mV (versus Ag/AgCl reference electrode), indicating the irreversible conversion from carbamate to hydroquinone groups with simultaneous release of the amine molecules. The analysis of ToF-SIMS further indicated that the electrochemical reaction on the gold surface successfully released amine molecules.

  4. Lanthanide Selective Sorbents: Self-Assembled Monolayers on Mesoporous Supports (SAMMS)

    Energy Technology Data Exchange (ETDEWEB)

    Fryxell, Glen E.; Wu, Hong; Lin, Yuehe; Shaw, Wendy J.; Birnbaum, Jerome C.; Linehan, John C.; Nie, Zimin; Kemner, K. M.; Kelly, Shelley

    2004-11-01

    Through the marriage of mesoporous ceramics with self-assembled monolayer chemistry, the genesis of a powerful new class of environmental sorbent materials has been realized. By coating the mesoporous ceramic backbone with a monolayer terminated with a lanthanide-specific ligand, it is possible to couple high lanthanide binding affinity with the high loading capacity (resulting from the extremely high surface area of the support). This lanthanide-specific ligand field is created by pairing a ''hard'' anionic Lewis base with a suitable synergistic ligand, in a favorable chelating geometry. Details of the synthesis, characterization, lanthanide binding studies, binding kinetics, competition experiments and sorbent regeneration studies are summarized

  5. High-Efficiency Colloidal Quantum Dot Photovoltaics via Robust Self-Assembled Monolayers

    KAUST Repository

    Kim, Gi-Hwan

    2015-11-11

    © 2015 American Chemical Society. The optoelectronic tunability offered by colloidal quantum dots (CQDs) is attractive for photovoltaic applications but demands proper band alignment at electrodes for efficient charge extraction at minimal cost to voltage. With this goal in mind, self-assembled monolayers (SAMs) can be used to modify interface energy levels locally. However, to be effective SAMs must be made robust to treatment using the various solvents and ligands required for to fabricate high quality CQD solids. We report robust self-assembled monolayers (R-SAMs) that enable us to increase the efficiency of CQD photovoltaics. Only by developing a process for secure anchoring of aromatic SAMs, aided by deposition of the SAMs in a water-free deposition environment, were we able to provide an interface modification that was robust against the ensuing chemical treatments needed in the fabrication of CQD solids. The energy alignment at the rectifying interface was tailored by tuning the R-SAM for optimal alignment relative to the CQD quantum-confined electron energy levels. This resulted in a CQD PV record power conversion efficiency (PCE) of 10.7% with enhanced reproducibility relative to controls.

  6. Click functionalization of phenyl-capped bithiophene on azide-terminated self-assembled monolayers

    International Nuclear Information System (INIS)

    Zheng, Yijun; Cui, Jiaxi; Ikeda, Taichi

    2015-01-01

    Graphical abstract: - Highlights: • Electrochemically-active self-assembled monolayers with phenyl-capped bithiophene were prepared. • Post-functionalization method based on click chemistry solved the solubility issue of phenyl-capped thiophene alkanethiol. • The capture and release of the counter anions during the redox reaction were detectable by E-QCM. - Abstract: We immobilized tetra(ethylene glycol)-substituted phenyl-capped bithiophene with alkyne terminals (Ph2TPh-alkyne) on azide-terminated self-assembled monolayers (N 3 -SAMs) by Cu-catalyzed azide-alkyne cycloaddition reaction. Ph2TPh-functionalized SAMs on a gold substrate showed reversible electrochemical response. The surface densities of the azide groups in N 3 -SAMs and Ph2TPh units in Ph2TPh-functionalized SAMs were estimated to be 7.3 ± 0.3 × 10 −10 mol cm −2 and 4.6 ± 0.3 × 10 −10 mol cm −2 , respectively, by quartz crystal microbalance (QCM). Most of Ph2TPh-alkynes are considered to be anchored on N 3 -SAMs via both terminal groups. Ph2TPh-functionalized SAMs exhibited reversible redox peaks in cyclic voltammetry (CV). In redox reaction, reversible capture and release of the counter anion could be monitored by electrochemical QCM (E-QCM).

  7. Click functionalization of phenyl-capped bithiophene on azide-terminated self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Yijun; Cui, Jiaxi [Max Planck Institute for Polymer Research (MPIP), Ackermannweg 10, Mainz 55128 (Germany); Ikeda, Taichi, E-mail: IKEDA.Taichi@nims.go.jp [Max Planck Institute for Polymer Research (MPIP), Ackermannweg 10, Mainz 55128 (Germany); Polymer Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044 (Japan)

    2015-11-15

    Graphical abstract: - Highlights: • Electrochemically-active self-assembled monolayers with phenyl-capped bithiophene were prepared. • Post-functionalization method based on click chemistry solved the solubility issue of phenyl-capped thiophene alkanethiol. • The capture and release of the counter anions during the redox reaction were detectable by E-QCM. - Abstract: We immobilized tetra(ethylene glycol)-substituted phenyl-capped bithiophene with alkyne terminals (Ph2TPh-alkyne) on azide-terminated self-assembled monolayers (N{sub 3}-SAMs) by Cu-catalyzed azide-alkyne cycloaddition reaction. Ph2TPh-functionalized SAMs on a gold substrate showed reversible electrochemical response. The surface densities of the azide groups in N{sub 3}-SAMs and Ph2TPh units in Ph2TPh-functionalized SAMs were estimated to be 7.3 ± 0.3 × 10{sup −10} mol cm{sup −2} and 4.6 ± 0.3 × 10{sup −10} mol cm{sup −2}, respectively, by quartz crystal microbalance (QCM). Most of Ph2TPh-alkynes are considered to be anchored on N{sub 3}-SAMs via both terminal groups. Ph2TPh-functionalized SAMs exhibited reversible redox peaks in cyclic voltammetry (CV). In redox reaction, reversible capture and release of the counter anion could be monitored by electrochemical QCM (E-QCM).

  8. Fabrication of a Polyaniline Ultramicroelectrode via a Self Assembled Monolayer Modified Gold Electrode

    Science.gov (United States)

    Bolat, Gulcin; Kuralay, Filiz; Eroglu, Gunes; Abaci, Serdar

    2013-01-01

    Herein, we report a simple and inexpensive way for the fabrication of an ultramicroelectrode and present its characterization by electrochemical techniques. The fabrication of polyaniline UME involves only two steps: modification of a gold (Au) electrode by self assembled monolayers (SAM) and then electrodeposition of polyaniline film on this thiol-coated Au electrode by using cyclic voltammetry and constant potential electrolysis methods. Two types of self-assembled monolayers (4-mercapto-1-butanol, MB, and 11-mercaptoundecanoic acid, MUA) were used, respectively, to see the effect of chain length on microelectrode formation. Microelectrode fabrication and utility of the surface was investigated by cyclic voltammetric measurements in a redox probe. The thus prepared polyaniline microelectrode was then used for DNA immobilization. Discrimination between double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA) was obtained with enhanced electrochemical signals compared to a polyaniline-coated Au electrode. Different modifications on the electrode surfaces were examined using scanning electron microscopy (SEM). PMID:23797740

  9. Effect of density and structure on dynamics within self-assembled monolayers

    Science.gov (United States)

    Stevens, Derrick; Scott, Mary; Bochinski, Jason; Clarke, Laura

    2009-03-01

    Previously, we have observed interacting dynamics within self-assembled alkylsiloxane monolayers, and characterized this motion via sensitive dielectric spectroscopy (along with more traditional techniques such as ellipsometry, contact angle, and force microscopy). In these monolayers, molecules are covalently bound to the surface and thus cannot spontaneously change density, as in an adsorbate system. We identified this relaxation as akin to the polyethylene-like glass transition observed in polymers with phase-segregated alkyl side chains [1]. As a next step, we deliberately manipulated the physical structure of the monolayers (via different film growth procedures and/or post-deposition heat treating) and the monolayer density (from ˜10% to full coverage), and observed the resultant changes in dynamics. This experimental system may prove a useful model for more complex materials, such as glassy polymers or traditional molecular glasses, where density cannot be explicitly tuned. As density increases, the steepness index increases, indicating a more complex or fragile relaxation. At low densities, the motion has an almost-Arrhenius dependence on temperature. [1] M.C. Scott, D.R. Stevens, J.R. Bochinski, L.I. Clarke, ACS Nano. DOI: 10.1021/nn800543j.

  10. Monoatomic and cluster beam effect on ToF-SIMS spectra of self-assembled monolayers on gold

    International Nuclear Information System (INIS)

    Tuccitto, N.; Torrisi, V.; Delfanti, I.; Licciardello, A.

    2008-01-01

    Self-assembled monolayers represent well-defined systems that is a good model surface to study the effect of primary ion beams used in secondary ion mass spectrometry. The effect of polyatomic primary beams on both aliphatic and aromatic self-assembled monolayers has been studied. In particular, we analysed the variation of the relative secondary ion yield of both substrate metal-cluster (Au n - ) in comparison with the molecular ions (M - ) and clusters (M x Au y - ) by using Bi + , Bi 3 + , Bi 5 + beams. Moreover, the differences in the secondary ion generation efficiency are discussed. The main effect of the cluster beams is related to an increased formation of low-mass fragments and to the enhancement of the substrate related gold-clusters. The results show that, at variance of many other cases, the static SIMS of self-assembled monolayers does not benefit of the use of polyatomic primary ions.

  11. Ultrasensitive electrochemical biosensor based on the oligonucleotide self-assembled monolayer-mediated immunosensing interface

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Dengyou; Luo, Qimei [Science College of Hunan Agricultural University, Changsha 410128 (China); Deng, Fawen [The Fourth Hospital of Chansha, Changsha 410006 (China); Li, Zhen [Science College of Hunan Agricultural University, Changsha 410128 (China); Li, Benxiang, E-mail: 172170960@qq.com [Science College of Hunan Agricultural University, Changsha 410128 (China); Shen, Zhifa, E-mail: shenzhifa@wmu.edu.cn [Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035 (China)

    2017-06-08

    Highly sensitive and selective quantitation of a variety of proteins over a wide concentration range is highly desirable for increased accuracy of biomarker detection or for multidisease diagnostics. In the present contribution, using human immunoglobulin G (HIgG) as the model target protein, an electrochemical ultrasensitive immunosensing platform was developed based on the oligonucleotide self-assembled monolayer-mediated (OSAM) sensing interface. For this immunosensor, the “signal-on” signaling mechanism and enzymatic signal amplification effect were integrated into one sensing architecture. Moreover, the thiolated flexible single-stranded DNAs immobilized onto gold electrode surface not only performs the wobbling motion to facilitate the electron transfer between the electrode surface and biosensing layer but also fundamentally prohibiting the direct interaction of proteins with gold substrate. Thus, the electrochemical signal could be efficiently enhanced and the unspecific adsorption or cross-reaction might be eliminated. As a result, utilizing the newly-proposed immunosensor, the HIgG can be detected down to 0.5 ng/mL, and the high detection specificity is offered. The successful design of OSAM and the highly desirable detection capability of new immunosensor are expected to provide a perspective for fabricating new robust immunosensing platform and for promising potential of oligonucleotide probe in biological research and biomedical diagnosis. - Highlights: • An electrochemical ultrasensitive immunosensing platform was developed based on the oligonucleotide self-assembled monolayer (OASM). • OASM severs as a flexible monolayer to promote electron transfer and prohibits the direct interaction of proteins with gold substrate. • The electrochemical signal is efficiently enhanced and the unspecific adsorption or cross-reaction is eliminated. • Target protein can be detected down to 0.5 ng/mL, and the high detection specificity can be obtained.

  12. Fabrication and tribological properties of self-assembled monolayer of n-alkyltrimethoxysilane on silicon: Effect of SAM alkyl chain length

    Science.gov (United States)

    Huo, Lixia; Du, Pengcheng; Zhou, Hui; Zhang, Kaifeng; Liu, Peng

    2017-02-01

    It is well known that the self-assembled organic molecules on a solid surface exhibit the friction-reducing performance. However, the effect of the molecular size of the self-assembled organic molecules has not been established. In the present work, self-assembled monolayers (SAMs) of n-alkyltrimethoxysilanes with different alkyl chain lengths (C6, C12, or C18) were fabricated on silicon substrate. The water contact angles of the SAMs increased from 26.8° of the hydroxylated silicon substrate to near 60° after self-assembly. The atomic force microscopy (AFM) analysis results showed that the mean roughness (Ra) of the SAMs decreased with increasing the alkyl chain length. The tribological properties of the SAMs sliding against Al2O3 ball were evaluated on an UMT-2 tribometer, and the worn surfaces of the samples were analyzed by means of Nano Scratch Tester and surface profilometry. It was found that lowest friction coefficient and smallest width of wear were achieved with the SAMs of C12 alkyl chain (C12-SAM). The superior friction reduction and wear resistance of the SAMs in comparison with the bare silicon substrate are attributed to good adhesion of the self-assembled films to the substrate, especially the C12-SAM with desirable alkyl chain length.

  13. In situ stress measurements during the electrochemical adsorption/desorption of self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Zangmeister, C.D. [Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Bertocci, U.; Beauchamp, C.R. [Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Stafford, G.R. [Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)], E-mail: gery.stafford@nist.gov

    2008-10-01

    This paper examines the surface stress associated with the electrochemical desorption of 4-mercaptobenzoic acid (4-MBA) from (1 1 1) textured Au in aqueous 0.1 mol L{sup -1} KOH. Self-assembled monolayers of varying coverage were adsorbed onto the Au electrode surface from a 0.1 mol L{sup -1} aqueous KOH solution containing 1 mmol L{sup -1} 4-MBA. Adsorption follows Langmuir kinetics and fully formed monolayers, corresponding to 0.29 coverage with respect to the Au surface, are formed in about 120 min. XP spectra confirm the formation of the Au-S bond while FTIR spectra indicate that the 4-MBA is orientated with the carboxylate pointed away from the surface. The one-electron reductive desorption of 4-MBA occurs at a potential of -0.9 to -1.0 V vs. SSE, depending on coverage, and causes a surface stress change in the tensile direction, indicating that 4-MBA adsorption induces a compressive surface stress to the Au. At short immersion times and low monolayer coverage, the surface stress increases with coverage as the stress response is primarily governed by the Au-S bond density. SAM desorption following longer immersion times produces large stress changes with little corresponding change in SAM coverage. We attribute the additional compressive stress to stabilization of the Au-S bonding regions and the coulombic repulsion between neighboring molecules, both associated with ordering of the 4-MBA on the Au surface.

  14. Effects of monolayer Bi on the self-assembly of DBBA on Au(111)

    Science.gov (United States)

    Tian, Guo; Shen, Yixian; He, Bingchen; Yu, Zhengqing; Song, Fei; Lu, Yunhao; Wang, Pingshan; Gao, Yongli; Huang, Han

    2017-11-01

    The initial growth behaviors of nonplanar 10,10‧-dibromo-9,9‧-bianthryl (DBBA) molecules on the Au(111) substrates, which is either pristine or Bi-3 × √3-Au(111), at low deposition rates have been systematically investigated using low temperature scanning tunneling microscopy (LT-STM) and density functional theories (DFT) calculations. The effects of such substrates on the subsequent graphene nanoribbons (GNRs) formation are addressed. On clean Au(111), DBBA molecules self-assemble into highly ordered commensurate single-molecule chains along Au at a coverage of 0.8 monolayer (ML), and collectively transit into long-range ordered commensurate double-molecule chains along Au but with many single-molecule vacancies at a coverage of 1.2 ML, revealing the delicate competing between intermolecular interactions and molecule-substrate interfacial interactions. The interfacial interactions are further tuned by introducing bismuth to form a Bi-3 × √3-Au(111)surface, where DBBA molecules self-assemble into an unique hexamer phase due to the enhanced intermolecular interactions via Csbnd H…π and halogen bonds. DFT calculations confirm the proposed molecular configuration change of single DBBA molecule when adsorbed on different substrates. The calculated difference in Csbnd Br bond gives further insight into why no GNRs formed on Bi-3 × √3-Au(111).

  15. Inhibition of copper corrosion by the formation of Schiff base self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing [Department of Chemical and Biological Engineering, Guilin University of Technology, Guilin 541004 (China); Liu, Zheng, E-mail: lisa4.6@163.com [Department of Chemical and Biological Engineering, Guilin University of Technology, Guilin 541004 (China); Han, Guo-Cheng, E-mail: hangc1981@163.com [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin 541004 (China); Chen, Shi-Liang [Department of Chemical and Biological Engineering, Guilin University of Technology, Guilin 541004 (China); Chen, Zhencheng [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin 541004 (China)

    2016-12-15

    Highlights: • The highest inhibition efficiency was 93.9% for CO{sub 2}-saturated simulative oilfield water. • HD2-SAMs on copper surface exhibited excellent inhibition effect at 30 °C. • The adsorption behavior of HD2-SAM followed the Langmuir adsorption isotherm. • The adsorption behavior of HD2-SAM is a typically chemical adsorption. - Abstract: Self-assembled monolayers (SAMs) of 4-((2-thiophenecarboxylic acid hydrazide) methylene) benzoic acid (HD2) (denoted as HD2-SAMs) were formed on copper surface. The SAMs were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. Polarization curve and weight loss methods indicated that the highest inhibition efficiency was 93.9% for CO{sub 2}-saturated simulative oilfield water at a self-assembled time of 3 h. Potential-time curve, electrochemical impedance tests showed that HD2-SAMs on copper surface exhibited excellent inhibition effect at 30 °C. The adsorption behavior of HD2-SAMs on the copper surface followed the Langmuir adsorption isotherm, which was indicative of typically chemical adsorption. Quantum chemistry calculation showed that O and N atoms can interact with Cu atoms by coordination bonds which were the mainly active area of the adsorption of HD2 molecules.

  16. Control of hydroxyapatite coating by self-assembled monolayers on titanium and improvement of osteoblast adhesion.

    Science.gov (United States)

    Shen, Juan; Qi, Yongcheng; Jin, Bo; Wang, Xiaoyan; Hu, Yamin; Jiang, Qiying

    2017-01-01

    Self-assembly technique was applied to introduce functional groups and form hydroxyl-, amine-, and carboxyl-terminal self-assembled monolayers (SAMs). The SAMs were grafted onto titanium substrates to obtain a molecularly smooth functional surface. Subsequent hydrothermal crystal growth formed homogeneous and crack-free crystalline hydroxyapatite (HA) coatings on these substrates. AFM and XPS were used to characterize the SAM surfaces, and XRD, SEM, and TEM were used to characterize the HA coatings. Results show that highly crystalline, dense, and oriented HA coatings can be formed on the OH-, NH 2 -, and COOH-SAM surfaces. The SAM surface with -COOH exhibited stronger nucleating ability than that with -OH and -NH 2 . The nucleation and growth processes of HA coatings were effectively controlled by varying reaction time, pH, and temperature. By using this method, highly crystalline, dense, and adherent HA coatings were obtained. In addition, in vitro cell evaluation demonstrated that HA coatings improved cell adhesion as compared with pristine titanium substrate. The proposed method is considerably effective in introducing the HA coatings on titanium surfaces for various biomedical applications and further usage in other industries. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 124-135, 2017. © 2015 Wiley Periodicals, Inc.

  17. Second harmonic generation from hemicyanine self-assembled monolayer on near-hemispherical gold nanoparticles

    Science.gov (United States)

    Tanaka, Daisuke; Yamaguchi, Tatsuya; Gupta, Gaurav; Okawa, Haruki; Hashimoto, Kazuhiko; Kajikawa, Kotaro

    2011-10-01

    Second-harmonic generation (SHG) was observed from hemicyanine-terminated alkanethiolate self-assembled monolayers (SAMs) formed on near-hemispherical gold nanoparticles (GNPs) prepared by annealing a vacuum-evaporated thin gold film deposited on a quartz glass substrate. The hemicyanine SAMs were formed on the near-hemispherical GNP by immersion of the substrate in an ethanol solution of hemicyanine-terminated alkanedisulfide. Polarized SHG measurements with the support of theoretical calculations revealed that the near-hemispherical GNP surfaces are fully covered with the hemicyanine SAMs. This result is in contrast to our previous study that showed that the hemicyanine SAM does not form fully over the spherical GNPs immobilized on a quartz glass substrate.

  18. Molecular suction pads: self-assembled monolayers of subphthalocyaninatoboron complexes on gold.

    Science.gov (United States)

    Glebe, Ulrich; Baio, Joe E; Árnadóttir, Líney; Siemeling, Ulrich; Weidner, Tobias

    2013-04-15

    Subphthalocyaninatoboron complexes with six long-chain alkylthio substituents in their periphery are applicable for the formation of self-assembled monolayers (SAMs) on gold. Such films are prepared from solution with the axially chlorido-substituted derivatives and characterised by near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results are in accord with the formation of SAMs assembled by the chemisorption of both covalently bound thiolate-type as well as coordinatively bound thioether units. The adsorbate molecules adopt an essentially flat adsorption geometry on the substrate, resembling a suction pad on a surface. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Surface-Enhanced Raman Spectroelectrochemistry of TTF-Modified Self-Assembled Monolayers.

    Science.gov (United States)

    Paxton, Walter F; Kleinman, Samuel L; Basuray, Ashish N; Stoddart, J Fraser; Van Duyne, Richard P

    2011-05-19

    Surface-enhanced Raman spectroscopy (SERS) was used to monitor the response of a self-assembled monolayer (SAM) of a tetrathiafulvalene (TTF) derivative on a gold film-over-nanosphere electrode. The electrochemical response observed was rationalized in terms of the interactions between TTF moieties as the oxidation state was changed. Electrochemical oxidation to form the monocation caused the absorbance of the TTF unit to coincide with both the laser excitation wavelength and the localized surface plasmon resonance (LSPR), resulting in surface-enhanced resonance Raman scattering (SERRS). The vibrational frequency changes that accompany electron transfer afford a high-contrast mechanism that can be used to determine the oxidation state of the TTF unit in an unambiguous manner.

  20. Specific ion effects on the hydrophobic interaction of benzene self-assembled monolayers

    DEFF Research Database (Denmark)

    Dobberschütz, Sören; Pedersen, Morten Rimmen; Hassenkam, Tue

    2015-01-01

    The interaction of aromatic compounds with various ions in aqueous solutions plays a role in a number of fields, as diverse as protein folding and enhanced oil recovery, among others. Therefore, we have investigated the effect of the four electrolytes, KCl, NaCl, MgCl2 and CaCl2, on the hydrophobic...... interaction of benzene self-assembled monolayers. Using the jump to contact phenomenon of an atomic force microscope (AFM) tip as an indicator of attractive forces between the surfaces of a sample and the tip, we discovered lower frequencies in the snap in as well as narrower distributions for the snap....... Bridging capillaries, i.e. nanometre scale gas bubbles, are some of the factors contributing to the long range hydrophobic interaction. The results demonstrate how ions influence the attraction of hydrophobic entities in aqueous solutions....

  1. Suppression of the coffee-ring effect by self-assembling graphene oxide and monolayer titania

    International Nuclear Information System (INIS)

    Sun Pengzhan; Wang Kunlin; Zhong Minlin; Wei Jinquan; Wu Dehai; Zhu Hongwei; Ma Renzhi; Sasaki, Takayoshi

    2013-01-01

    The in situ self-assembly of two types of typical two-dimensional (2D) nanomaterials (i.e., graphene oxide (GO) and monolayer titania (TO)) is realized using a simple drop-casting method. Within the as-prepared hybrid films, the GO and TO nanosheets arrange alternately into a lamellar structure. Notably, the hybridization of GO and TO suppresses the formation of coffee-rings when drop-cast, which is attributed to the strong interactions between the GO and TO nanosheets. Finally, the mechanism for the in situ hybridization of these two types of nanosheets into heterogeneous lamellar films and the suppression of the coffee-ring effect are discussed. These results demonstrate the potential applications of drop-cast hybrid films for high-quality membrane deposition from liquid phases. (paper)

  2. Calculation of Electrochemical Reorganization Energies for Redox Molecules at Self-Assembled Monolayer Modified Electrodes.

    Science.gov (United States)

    Ghosh, Soumya; Hammes-Schiffer, Sharon

    2015-01-02

    Electrochemical electron transfer reactions play an important role in energy conversion processes with many technological applications. Electrodes modified by self-assembled monolayers (SAMs) exhibit reduced double layer effects and are used in molecular electronics. An important quantity for calculating the electron transfer rate constant is the reorganization energy, which is associated with changes in the solute geometry and the environment. In this Letter, an approach for calculating the electrochemical reorganization energy for a redox molecule attached to or near a SAM modified electrode is presented. This integral equations formalism polarizable continuum model (IEF-PCM) approach accounts for the detailed electronic structure of the molecule, as well as the contributions from the electrode, SAM, and electronic and inertial solvent responses. The calculated total reorganization energies are in good agreement with experimental data for a series of metal complexes in aqueous solution. This approach will be useful for calculating electron transfer rate constants for molecular electrocatalysts.

  3. Multiple-trapping in pentacene field-effect transistors with a nanoparticles self-assembled monolayer

    Directory of Open Access Journals (Sweden)

    Keanchuan Lee

    2012-06-01

    Full Text Available A silver nanoparticles self-assembled monolayer (SAM was incorporated in pentacene field-effect transistor and its effects on the carrier injection and transport were investigated using the current-voltage (I − V and impedance spectroscopy (IS measurements. The I − V results showed that there was a significant negative shift of the threshold voltage, indicating the hole trapping inside the devices with about two orders higher in the contact resistance and an order lower in the effective mobility when a SAM was introduced. The IS measurements with the simulation using a Maxwell-Wagner equivalent circuit model revealed the existence of multiple trapping states for the devices with NPs, while the devices without NPs exhibited only a single trap state.

  4. Adsorption behavior of DNA-wrapped carbon nanotubes on self-assembled monolayer surfaces.

    Science.gov (United States)

    Zangmeister, Rebecca A; Maslar, James E; Opdahl, Aric; Tarlov, Michael J

    2007-05-22

    We have examined the adsorption of DNA-wrapped single-walled carbon nanotubes (DNA-SWNTs) on hydrophobic, hydrophilic, and charged surfaces of alkylthiol self-assembled monolayers (SAMs) on gold. Our goal is to understand how DNA-SWNTs interact with surfaces of varying chemical functionality. These samples were characterized using reflection absorption FTIR (RAIRS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. We have found that DNA-SWNTs preferentially adsorb to positively charged amine-terminated SAMs and to bare gold surfaces versus hydrophobic methyl-terminated or negatively charged carboxylic acid-terminated SAMs. Examination of the adsorption on gold of single-strand DNA (ssDNA) of the same sequence used to wrap the SWNTs suggests that the DNA wrapping plays a role in the adsorption behavior of DNA-SWNTs.

  5. One-pot reaction for the preparation of biofunctionalized self-assembled monolayers on gold surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Raigoza, Annette F.; Fies, Whitney; Lim, Amber; Onyirioha, Kristeen; Webb, Lauren J., E-mail: lwebb@cm.utexas.edu

    2017-02-01

    Highlights: • One-pot synthesis of α-helical-terminated self-assembled monolayers on Au(111). • Synthesis of high density, structured, and covalently bound α-helices on Au(111). • Characterization by surface-averaged and single molecule techniques. • Peptide-terminated surfaces for fabrication of biomaterials and sensors. - Abstract: The Huisgen cycloaddition reaction (“click” chemistry) has been used extensively to functionalize surfaces with macromolecules in a straightforward manner. We have previously developed a procedure using the copper(I)-catalyzed click reaction to tether synthetic α-helical peptides carrying two alkyne groups to a well-ordered azide-terminated alkanethiol self-assembled monolayer (SAM) on a Au(111) surface. While convenient, click-based strategies potentially pose significant problems from reagents, solvents, and reaction temperatures that may irreversibly damage some molecules or substrates. Tuning click chemistry conditions would allow individual optimization of reaction conditions for a wide variety of biomolecules and substrate materials. Here, we explore the utility of simultaneous SAM formation and peptide-attachment chemistry in a one-pot reaction. We demonstrate that a formerly multistep reaction can be successfully carried out concurrently by mixing azide-terminated alkanethiols, CuCl, and a propargylglycine-containing peptide over a bare gold surface in ethanol and reacting at 70 °C. X-ray photoelectron spectroscopy (XPS), surface infrared spectroscopy, surface circular dichroic (CD) spectroscopy, and scanning tunneling microscopy (STM) were used to determine that this one-pot reaction strategy resulted in a high density of surface-bound α-helices without aggregation. This work demonstrates the simplicity and versatility of a SAM-plus-click chemistry strategy for functionalizing Au surfaces with structured biomolecules.

  6. Biomimetic synthesis of enamel-like hydroxyapatite on self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Li Hong [Department of Materials Science and Engineering, Jinan University, Guangzhou, 510632 (China); Huang Weiya [Department of Chemistry, Jinan University, Guangzhou, 510632 (China); Zhang Yuanming [Department of Chemistry, Jinan University, Guangzhou, 510632 (China)]. E-mail: tzhangym@jnu.edu.cn; Zhong Mei [Department of Stomatology, Affiliated Hospital of Jinan University, Guangzhou, 510632 (China)

    2007-05-16

    Hydroxyapatite (HAp) crystals mimicking tooth enamel in chemical composition and morphology were formed on sulfonic-terminated self-assembled monolayer (SAM) in 1.5SBF with F{sup -} at 50 {sup o}C for 7 days. F{sup -} ions showed a marked effect on the composition and morphology of deposited HAp crystals. In the absence of F{sup -} ions, HAp containing CO{sub 3} {sup 2-} were formed on SAM, and worm-like crystals of 200-300 nm in length aggregated to form a spherical morphology. When F{sup -} was added, HAp crystals containing both CO{sub 3} {sup 2-} and F{sup -} were formed on SAM. Needle-shaped crystals of high aspect ratio and 1-2 {mu}m in length grew elongated along the c-axial direction. In addition, these needle-shaped crystals grew in bundles, mimicking HAp crystals in tooth enamel. After the process of ripening, the needles in bundle grew to large size of up to 10 {mu}m in length, and still kept no crystal-crystal fusion like enamel HAp crystals. The formation of enamel-like HAp can be attributed to the substitute of F{sup -} for OH{sup -} by disturbing the normal progress of HAp formation on SAM. The results suggest potential applications in preparing a novel dental material by a simple method. -- Graphical abstract: Hydroxyapatite (HAp) crystals mimicking tooth enamel in chemical composition and morphology were formed on self-assembled monolayer (SAM) by a biomimetic process. The needle-shaped crystals grew in bundles, mimicking HAp crystals in tooth enamel. Display Omitted.

  7. Electrochemical characterization of a 1,8-octanedithiol self-assembled monolayer (ODT-SAM) on a Au(1 1 1) single crystal electrode

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Raya, Daniel; Madueno, Rafael; Sevilla, Jose Manuel; Blazquez, Manuel [Departamento de Quimica Fisica y Termodinamica Aplicada, Universidad de Cordoba, Campus de Rabanales, Ed. Marie Curie, E-14071 Cordoba (Spain); Pineda, Teresa [Departamento de Quimica Fisica y Termodinamica Aplicada, Universidad de Cordoba, Campus de Rabanales, Ed. Marie Curie, E-14071 Cordoba (Spain)], E-mail: tpineda@uco.es

    2008-11-15

    Recently, it has becoming increasingly important to control the organization of self-assembled monolayers (SAMs) of {omega}-functionalized thiols for its potential applications in the construction of more complex molecular architectures. In this paper, we report on the spontaneous formation of a SAM of octanedithiol (ODT) as a function of the modification time. Electrochemical techniques such as cyclic voltammetry, double layer capacitance and electrochemical impedance spectroscopy are used for the characterization of this monolayer. The increase in modification time brings about changes in the octanedithiol self-assembled monolayer (ODT-SAM) reductive desorption voltammograms that indicate an evolution toward a more ordered and compact monolayer. This trend has also been found by following the changes in the electron transfer processes of the redox probe K{sub 3}Fe(CN){sub 6}. In fact, the ODT-SAM formed at low-modification time does not significantly perturb the electrochemical response as it is typical of either a low coverage or of the presence of large defects in the layer. Upon increasing the modification time, the voltammograms of the redox probe adopt a sigmoidal shape indicating the existence of pinholes in the monolayer distributed as an array of microelectrodes. The surface coverage as well as the size and distribution of these pinholes have been determined by the impedance technique that gives a more reliable evaluation of these monolayer structural parameters.

  8. Electrochemical characterization of a 1,8-octanedithiol self-assembled monolayer (ODT-SAM) on a Au(111) single crystal electrode

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Raya, Daniel; Madueno, Rafael; Sevilla, Jose Manuel; Blazquez, Manuel; Pineda, Teresa [Departamento de Quimica Fisica y Termodinamica Aplicada, Universidad de Cordoba, Campus de Rabanales, Cordoba (Spain)

    2008-11-15

    Recently, it has becoming increasingly important to control the organization of self-assembled monolayers (SAMs) of {omega}-functionalized thiols for its potential applications in the construction of more complex molecular architectures. In this paper, we report on the spontaneous formation of a SAM of octanedithiol (ODT) as a function of the modification time. Electrochemical techniques such as cyclic voltammetry, double layer capacitance and electrochemical impedance spectroscopy are used for the characterization of this monolayer. The increase in modification time brings about changes in the octanedithiol self-assembled monolayer (ODT-SAM) reductive desorption voltammograms that indicate an evolution toward a more ordered and compact monolayer. This trend has also been found by following the changes in the electron transfer processes of the redox probe K{sub 3}Fe(CN){sub 6}. In fact, the ODT-SAM formed at low-modification time does not significantly perturb the electrochemical response as it is typical of either a low coverage or of the presence of large defects in the layer. Upon increasing the modification time, the voltammograms of the redox probe adopt a sigmoidal shape indicating the existence of pinholes in the monolayer distributed as an array of microelectrodes. The surface coverage as well as the size and distribution of these pinholes have been determined by the impedance technique that gives a more reliable evaluation of these monolayer structural parameters. (author)

  9. "SAMs meet MEMS": surface modification with self-assembled monolayers for the dry-demolding of photoplastic MEMS/NEMS

    NARCIS (Netherlands)

    Kim, B.J.; Kim, G.M.; Liebau, M.; Huskens, Jurriaan; Reinhoudt, David; Brugger, J.P.

    2001-01-01

    In this contribution we demonstrate the use of self-assembled monolayers (SAMs) as anti-adhesion coating to assist the removal of photoplastic MEMS/NEMS with a patterned metal layer from the surface without wet chemical sacrificial layer etching, so-called 'dry-demolding'. The SAMs functionality

  10. Sulfonic acid-functionalized golf nanoparticles: A colloid-bound catalyst for soft lithographic application on self-assembled monolayers

    NARCIS (Netherlands)

    Li, X.; Paraschiv, V.; Huskens, Jurriaan; Reinhoudt, David

    2003-01-01

    In this report, we present a new lithographic approach to prepare patterned surfaces. Self-assembled monolayers (SAMs) of the acid-labile trimethylsilyl ether (TMS-OC11H22S)2 (TMS adsorbate) was formed on gold. 5-Mercapto-2-benzimidazole sulfonic acid sodium salt (MBS-Na+) was used as a ligand for

  11. Scanning Tunneling Microscopic Observation of Adatom-Mediated Motifs on Gold-Thiol Self-assembled Monolayers at High Coverage

    DEFF Research Database (Denmark)

    Wang, Yun; Chi, Qijin; Hush, Noel S.

    2009-01-01

    Self-assembled monolayers (SAMs) formed by chemisorption of a branched-chain alkanethiol, 2-methyl-1-propanethiol, on Au(111) surfaces were studied by in situ scanning tunneling microscopy (STM) under electrochemical potential control and analyzed using extensive density functional theory (DFT...

  12. Charge Transport Across Insulating Self-Assembled Monolayers: Non-equilibrium Approaches and Modeling To Relate Current and Molecular Structure

    NARCIS (Netherlands)

    Mirjani, F.; Thijssen, J.M.; Whitesides, G.M.; Ratner, M.A.

    2014-01-01

    This paper examines charge transport by tunneling across a series of electrically insulating molecules with the structure HS(CH2)4CONH(CH2)2R) in the form of self-assembled monolayers (SAMs), supported on silver. The molecules examined were studied experimentally by Yoon et al. (Angew. Chem. Int.

  13. UV/vis and NIR light-responsive spiropyran self-assembled monolayers.

    Science.gov (United States)

    Ivashenko, Oleksii; van Herpt, Jochem T; Feringa, Ben L; Rudolf, Petra; Browne, Wesley R

    2013-04-02

    Self-assembled monolayers of a 6-nitro BIPS spiropyran (SP) modified with a disulfide-terminated aliphatic chain were prepared on polycrystalline gold surfaces and characterized by UV/vis absorption, surface-enhanced Raman scattering (SERS), and X-ray photoelectron spectroscopies (XPS). The SAMs obtained are composed of the ring-closed form (i.e., spiropyran) only. Irradiation with UV light results in conversion of the monolayer to the merocyanine form (MC), manifested in the appearance of an N(+) contribution in the N 1s region of the XPS spectrum of the SAMs, the characteristic absorption band of the MC form in the visible region at 555 nm, and the C-O stretching band in the SERS spectrum. Recovery of the initial state of the monolayer was observed both thermally and after irradiation with visible light. Several switching cycles were performed and monitored by SERS spectroscopy, demonstrating the stability of the SAMs during repeated switching between SP and MC states. A key finding in the present study is that ring-opening of the surface-immobilized spiropyrans can be induced by irradiation with continuous wave NIR (785 nm) light as well as by irradiation with UV light. We demonstrate that ring-opening by irradiation at 785 nm proceeds by a two-photon absorption pathway both in the SAMs and in the solid state. Hence, spiropyran SAMs on gold can undergo reversible photochemical switching from the SP to the MC form with both UV and NIR and the reverse reaction induced by irradiation with visible light or heating. Furthermore, the observation of NIR-induced switching with a continuous wave source holds important consequences in the study of photochromic switches on surfaces using SERS and emphasizes the importance of the use of multiple complementary techniques in characterizing photoresponsive SAMs.

  14. Polymer blend lithography: A versatile method to fabricate nanopatterned self-assembled monolayers

    Directory of Open Access Journals (Sweden)

    Cheng Huang

    2012-09-01

    Full Text Available A rapid and cost-effective lithographic method, polymer blend lithography (PBL, is reported to produce patterned self-assembled monolayers (SAM on solid substrates featuring two or three different chemical functionalities. For the pattern generation we use the phase separation of two immiscible polymers in a blend solution during a spin-coating process. By controlling the spin-coating parameters and conditions, including the ambient atmosphere (humidity, the molar mass of the polystyrene (PS and poly(methyl methacrylate (PMMA, and the mass ratio between the two polymers in the blend solution, the formation of a purely lateral morphology (PS islands standing on the substrate while isolated in the PMMA matrix can be reproducibly induced. Either of the formed phases (PS or PMMA can be selectively dissolved afterwards, and the remaining phase can be used as a lift-off mask for the formation of a nanopatterned functional silane monolayer. This “monolayer copy” of the polymer phase morphology has a topographic contrast of about 1.3 nm. A demonstration of tuning of the PS island diameter is given by changing the molar mass of PS. Moreover, polymer blend lithography can provide the possibility of fabricating a surface with three different chemical components: This is demonstrated by inducing breath figures (evaporated condensed entity at higher humidity during the spin-coating process. Here we demonstrate the formation of a lateral pattern consisting of regions covered with 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS and (3-aminopropyltriethoxysilane (APTES, and at the same time featuring regions of bare SiOx. The patterning process could be applied even on meter-sized substrates with various functional SAM molecules, making this process suitable for the rapid preparation of quasi two-dimensional nanopatterned functional substrates, e.g., for the template-controlled growth of ZnO nanostructures.

  15. Polymer blend lithography: A versatile method to fabricate nanopatterned self-assembled monolayers.

    Science.gov (United States)

    Huang, Cheng; Moosmann, Markus; Jin, Jiehong; Heiler, Tobias; Walheim, Stefan; Schimmel, Thomas

    2012-01-01

    A rapid and cost-effective lithographic method, polymer blend lithography (PBL), is reported to produce patterned self-assembled monolayers (SAM) on solid substrates featuring two or three different chemical functionalities. For the pattern generation we use the phase separation of two immiscible polymers in a blend solution during a spin-coating process. By controlling the spin-coating parameters and conditions, including the ambient atmosphere (humidity), the molar mass of the polystyrene (PS) and poly(methyl methacrylate) (PMMA), and the mass ratio between the two polymers in the blend solution, the formation of a purely lateral morphology (PS islands standing on the substrate while isolated in the PMMA matrix) can be reproducibly induced. Either of the formed phases (PS or PMMA) can be selectively dissolved afterwards, and the remaining phase can be used as a lift-off mask for the formation of a nanopatterned functional silane monolayer. This "monolayer copy" of the polymer phase morphology has a topographic contrast of about 1.3 nm. A demonstration of tuning of the PS island diameter is given by changing the molar mass of PS. Moreover, polymer blend lithography can provide the possibility of fabricating a surface with three different chemical components: This is demonstrated by inducing breath figures (evaporated condensed entity) at higher humidity during the spin-coating process. Here we demonstrate the formation of a lateral pattern consisting of regions covered with 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS) and (3-aminopropyl)triethoxysilane (APTES), and at the same time featuring regions of bare SiO(x). The patterning process could be applied even on meter-sized substrates with various functional SAM molecules, making this process suitable for the rapid preparation of quasi two-dimensional nanopatterned functional substrates, e.g., for the template-controlled growth of ZnO nanostructures [1].

  16. Fabrication and tribological properties of self-assembled monolayer of n-alkyltrimethoxysilane on silicon: Effect of SAM alkyl chain length

    International Nuclear Information System (INIS)

    Huo, Lixia; Du, Pengcheng; Zhou, Hui; Zhang, Kaifeng; Liu, Peng

    2017-01-01

    Highlights: • n-Alkyltrimethoxysilanes with various chain lengths were self-assembled on silicon. • Effect of alkyl chain lengths (C6, C12, or C18) on the SAMs was investigated. • Surface roughness of the SAMs decreased with increasing the alkyl chain lengths. • The C 12 -SAM possessed superior friction reduction and wear resistance. - Abstract: It is well known that the self-assembled organic molecules on a solid surface exhibit the friction-reducing performance. However, the effect of the molecular size of the self-assembled organic molecules has not been established. In the present work, self-assembled monolayers (SAMs) of n-alkyltrimethoxysilanes with different alkyl chain lengths (C 6 , C 12 , or C 18 ) were fabricated on silicon substrate. The water contact angles of the SAMs increased from 26.8° of the hydroxylated silicon substrate to near 60° after self-assembly. The atomic force microscopy (AFM) analysis results showed that the mean roughness (R a ) of the SAMs decreased with increasing the alkyl chain length. The tribological properties of the SAMs sliding against Al 2 O 3 ball were evaluated on an UMT-2 tribometer, and the worn surfaces of the samples were analyzed by means of Nano Scratch Tester and surface profilometry. It was found that lowest friction coefficient and smallest width of wear were achieved with the SAMs of C 12 alkyl chain (C 12 -SAM). The superior friction reduction and wear resistance of the SAMs in comparison with the bare silicon substrate are attributed to good adhesion of the self-assembled films to the substrate, especially the C 12 -SAM with desirable alkyl chain length.

  17. Fabrication and tribological properties of self-assembled monolayer of n-alkyltrimethoxysilane on silicon: Effect of SAM alkyl chain length

    Energy Technology Data Exchange (ETDEWEB)

    Huo, Lixia [National Key Laboratory of Science and Technology on Vacuum Technology and Physics, Lanzhou Institute of Physics, Lanzhou, Gansu 730010 (China); Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Gansu 730000 (China); Du, Pengcheng [Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Gansu 730000 (China); Zhou, Hui; Zhang, Kaifeng [National Key Laboratory of Science and Technology on Vacuum Technology and Physics, Lanzhou Institute of Physics, Lanzhou, Gansu 730010 (China); Liu, Peng, E-mail: pliu@lzu.edu.cn [Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Gansu 730000 (China)

    2017-02-28

    Highlights: • n-Alkyltrimethoxysilanes with various chain lengths were self-assembled on silicon. • Effect of alkyl chain lengths (C6, C12, or C18) on the SAMs was investigated. • Surface roughness of the SAMs decreased with increasing the alkyl chain lengths. • The C{sub 12}-SAM possessed superior friction reduction and wear resistance. - Abstract: It is well known that the self-assembled organic molecules on a solid surface exhibit the friction-reducing performance. However, the effect of the molecular size of the self-assembled organic molecules has not been established. In the present work, self-assembled monolayers (SAMs) of n-alkyltrimethoxysilanes with different alkyl chain lengths (C{sub 6}, C{sub 12}, or C{sub 18}) were fabricated on silicon substrate. The water contact angles of the SAMs increased from 26.8° of the hydroxylated silicon substrate to near 60° after self-assembly. The atomic force microscopy (AFM) analysis results showed that the mean roughness (R{sub a}) of the SAMs decreased with increasing the alkyl chain length. The tribological properties of the SAMs sliding against Al{sub 2}O{sub 3} ball were evaluated on an UMT-2 tribometer, and the worn surfaces of the samples were analyzed by means of Nano Scratch Tester and surface profilometry. It was found that lowest friction coefficient and smallest width of wear were achieved with the SAMs of C{sub 12} alkyl chain (C{sub 12}-SAM). The superior friction reduction and wear resistance of the SAMs in comparison with the bare silicon substrate are attributed to good adhesion of the self-assembled films to the substrate, especially the C{sub 12}-SAM with desirable alkyl chain length.

  18. Kinetic energy distributions of molecular and cluster ions sputtered from self-assembled monolayers of octanethiol on gold

    International Nuclear Information System (INIS)

    Arezki, Bahia; Delcorte, Arnaud; Bertrand, Patrick

    2002-01-01

    Self-assembled monolayers (SAMs) of alkanethiols are an ideal model system to study the mechanisms that lead to emission of organic species under keV ion bombardment. In this contribution, we focus on the emission processes of gold-molecule cluster ions, which are not fully understood yet. To gain insights into these processes, monolayers of octanethiol CH 3 (CH 2 ) 7 SH adsorbed on gold are investigated using time-of-flight secondary ion mass spectrometry (ToF-SIMS). First, the static SIMS conditions are verified using the degradation of the SAM signals as a function of ion fluence. Second, the kinetic energy distributions (KEDs) of fragment, parent and cluster ions ejected upon 15 keV Ga + ion bombardment are measured. The peak maxima, FWHMs and high energy tails of the distributions are analyzed for Au-thiolate clusters, as well as thiol fragments. After calibration of the energy spectra using monoatomic ions, we find that the KEDs of all the clusters containing the thiolate molecule peak at about 1.2 eV. Besides, the distributions of the gold-molecule cluster ions including Au(M-H) 2 - , the most intense cluster peak in the spectrum, are significantly narrower than that of the hydrocarbon fragments

  19. Effect of time and deposition method on quality of phosphonic acid modifier self-assembled monolayers on indium zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Sang, Lingzi [Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721 (United States); Knesting, Kristina M. [Department of Chemistry, University of Washington, Seattle, WA 98195-1700 (United States); Bulusu, Anuradha [School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Sigdel, Ajaya K. [National Renewable Energy Laboratory, Golden, CO 80401 (United States); Giordano, Anthony J.; Marder, Seth R. [School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA 30332-0400 (United States); Berry, Joseph J. [National Renewable Energy Laboratory, Golden, CO 80401 (United States); Graham, Samuel [School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Ginger, David S. [Department of Chemistry, University of Washington, Seattle, WA 98195-1700 (United States); Pemberton, Jeanne E., E-mail: pembertn@email.arizona.edu [Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721 (United States)

    2016-12-15

    Highlights: • Deposition of phosphonic acid monolayers on oxides from ethanol solutions occurs by rapid adsorption within 10 s with slower equilibration complete in 48 h. • The slower equilibration step involves molecular reorientation and vacancy filling on the oxide surface. • Soak-free deposition by spray coating and microcontact printing do not provide reproducible, fully-covered, uniform monolayers without substrate etching. • Adjustments to exposure time, substrate temperature, and solution/substrate contact efficiency are necessary to optimize soak-free methods. - Abstract: Phosphonic acid (PA) self-assembled monolayers (SAMs) are utilized at critical interfaces between transparent conductive oxides (TCO) and organic active layers in organic photovoltaic devices (OPVs). The effects of PA deposition method and time on the formation of close-packed, high-quality monolayers is investigated here for SAMs fabricated by solution deposition, micro-contact printing, and spray coating. The solution deposition isotherm for pentafluorinated benzylphosphonic acid (F{sub 5}BnPA) on indium-doped zinc oxide (IZO) is studied using polarization modulation-infrared reflection-absorption spectroscopy (PM-IRRAS) at room temperature as a model PA/IZO system. Fast surface adsorption occurs within the first min; however, well-oriented high-quality SAMs are reached only after ∼48 h, presumably through a continual process of molecular adsorption/desorption and monolayer filling accompanied by molecular reorientation. Two other rapid, soak-free deposition techniques, micro-contact printing and spray coating, are also explored. SAM quality is compared for deposition of phenyl phosphonic acid (PPA), F{sub 13}-octylphosphonic acid (F{sub 13}OPA), and pentafluorinated benzyl phosphonic acid (F{sub 5}BnPA) by solution deposition, micro-contact printing and spray coating using PM-IRRAS. In contrast to micro-contact printing and spray coating techniques, 48–168 h solution

  20. Carboranedithiols: building blocks for self-assembled monolayers on copper surfaces.

    Science.gov (United States)

    Baše, Tomáš; Bastl, Zdeněk; Havránek, Vladimír; Macháček, Jan; Langecker, Jens; Malina, Václav

    2012-08-28

    Two different positional isomers of 1,2-dicarba-closo-dodecaboranedithiols, 1,2-(HS)(2)-1,2-C(2)B(10)H(10) (1) and 9,12-(HS)(2)-1,2-C(2)B(10)H(10) (2), have been investigated as cluster building blocks for self-assembled monolayers (SAMs) on copper surfaces. These two isomers represent a convenient system in which the attachment of SH groups at different positions on the skeleton affects their acidic character and thus also determines their reactivity with a copper surface. Isomer 1 exhibited etching of polycrystalline Cu films, and a detailed investigation of the experimental conditions showed that both the acidic character of SH groups and the presence of oxygen at the copper surface play crucial roles in how the surface reaction proceeds: whether toward a self-assembled monolayer or toward copper film etching. We found that each positional isomer requires completely different conditions for the preparation of a SAM on copper surfaces. Optimized conditions for the former isomer required the exposure of a freshly prepared Cu surface to vapor of 1 in vacuum, which avoided the presence of oxygen and moisture. Adsorption from a dichloromethane solution afforded a sparsely covered Cu(0) surface; isomer 1 effectively removes the surface copper(I) oxide, forming a soluble product, but apparently binds only weakly to the clean Cu(0) surface. In contrast, adsorption of the latter, less volatile isomer proceeded better from a dichloromethane solution than from the vapor phase. Isomer 2 was even able to densely cover the copper surface cleaned up by the dichloromethane solution of 1. Both isomers exhibited high capacity to remove oxygen atoms from the surface copper(I) oxide that forms immediately after the exposure of freshly prepared copper films to ambient atmosphere. Isomer 2 showed suppression of Cu film oxidation. A number of methods including X-ray photoelectron spectroscopy (XPS), X-ray Rutherford back scattering (RBS), proton-induced X-ray emission (PIXE) analysis

  1. Evaporation dynamics of microdroplets on self-assembled monolayers of dialkyl disulfides.

    Science.gov (United States)

    Li, Guangfen; Flores, Susana Moreno; Vavilala, Chandrasekhar; Schmittel, Michael; Graf, Karlheinz

    2009-12-01

    We present a study of the static wettability and evaporation dynamics of sessile microdroplets of water on self-assembled monolayers (SAMs) prepared with unsymmetric dialkyl disulfides CH(3)-(CH(2))(11+m)-S-S-(CH(2))(11)-OH (m = 0, +/- 2, +/- 4, +/- 6) on gold-covered mica. The advancing and receding contact angles decrease linearly with increasing hydrophilicity of the SAM. The latter was changed either via the molar ratio or via the chain length of the hydroxyl-terminated alkyl chains in the monolayer. In contrast to SAMs made of thiols, the contact angle hysteresis was 10 degrees for all disulfides, irrespective of their chain lengths. During evaporation of single droplets, a transition from pinning to constant contact angle mode was observed. The transition time between the modes increases with the surface hydrophilicity, leading to longer pinning. This way, the time for complete droplet evaporation decreases by approximately 30% owing to the fact that during pinning the overall droplet area stays large for a longer time. For single droplets the measured total evaporation times agree well with the calculated ones, showing the validity of the standard evaporation model for both evaporation modes. In contrast to the results for single droplets, many droplets with different initial volumes show a power-law dependence on the total evaporation time with an exponent different from 1.5 as expected from the standard model. For disulfides with m not equal 0, the exponent is in the range of 1.40-1.47 increasing with the surface hydrophilicity. For the SAMs with m = 0 the exponent increases up to 1.61 for the most hydrophilic surface. We explain this deviation from the standard evaporation model with the presence of a liquid precursor film around the droplet, which either enhances or decelerates evaporation. Our results suggest that SAMs of dialkyl disulfides offer the possibility to tune the wettability of gold surfaces in a more controlled way than thiols do.

  2. Interactions of doxorubicin with self-assembled monolayer-modified electrodes: electrochemical, surface plasmon resonance (SPR), and gravimetric studies.

    Science.gov (United States)

    Nieciecka, Dorota; Krysinski, Pawel

    2011-02-01

    We present the results on the partitioning of doxorubicin (DOX), a potent anticancer drug, through the model membrane system, self-assembled monolayers (SAMs) on gold electrodes. The monolayers were formed from alkanethiols of comparable length with different ω-terminal groups facing the aqueous electrolyte: the hydrophobic -CH(3) groups for the case of dodecanethiol SAMs or hydrophilic -OH groups of mercaptoundecanol SAMs. The electrochemical experiments combined with the surface plasmon resonance (SPR) and gravimetric studies show that doxorubicin is likely adsorbed onto the surface of hydrophilic monolayer, while for the case of the hydrophobic one the drug mostly penetrates the monolayer moiety. The adsorption of the drug hinders further penetration of doxorubicin into the monolayer moiety.

  3. Solvent effect on the formation of self-assembled monolayer on DLC surface between n-hexane and Vertrel XF

    Energy Technology Data Exchange (ETDEWEB)

    Tan Manlin [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen University Town, Shenzhen 518055 (China)], E-mail: tanmanlin@hitsz.edu.cn; Zhang Huayu; Wang Yulei [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen University Town, Shenzhen 518055 (China); Ma Hongtao [SAE Technologies Development (Dongguan) Co. Ltd., Dongguan 523087 (China); Zhu Jiaqi [Center for Composite Materials, Harbin Institute of Technology, Harbin 150018 (China); Han Jiecai [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen University Town, Shenzhen 518055 (China); Center for Composite Materials, Harbin Institute of Technology, Harbin 150018 (China)

    2008-08-15

    Self-assembled monolayers of 1H,1H,2H,2H-perfluorodecyltrichloro-silane (FDTS) have been deposited on the diamond-like carbon (DLC) film-coated magnetic heads with two different solvents, n-hexane and Vertrel XF. In order to investigate the solvent effect on the monolayer formation, a series of FDTS monolayers were prepared by varying the solution concentrations which were respectively characterized by time-of-flight mass spectroscopy, contact angle measurements and atomic force microscopy. Results showed that high density of aggregations were present for the FDTS monolayers using the n-hexane solvent, while the monolayer formed on the DLC surface using the Vertrel XF solvent exhibited excellent quality and reproducibility and no aggregations were observed.

  4. Formation of self-assembled monolayer of curcuminoid molecules on gold surfaces

    International Nuclear Information System (INIS)

    Berlanga, Isadora; Etcheverry-Berríos, Álvaro; Mella, Andy; Jullian, Domingo; Gómez, Victoria Alejandra; Aliaga-Alcalde, Núria; Fuenzalida, Victor; Flores, Marcos

    2017-01-01

    Highlights: • Thiophene curcuminoid molecules deposited on a gold surface by immersion. • Molecular dynamic studies of the molecular arrangement approaching the surface. • XPS and STM studies showing different arrangement of the molecules on the surface. • Molecular Interaction with surface depends on the sulfur position in thiophene rings. • Temporal evolution of the molecular arrangement on the surface. - Abstract: We investigated the formation of self-assembled monolayers of two thiophene curcuminoid molecules, 2-thphCCM (1) and 3-thphCCM (2), on polycrystalline gold substrates prepared by immersion of the surfaces in a solution of the molecules during 24 h. The functionalized surfaces were studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Despite the fact that both molecules have the same composition and almost the same structure, these molecules exhibit different behavior on the gold surface, which can be explained by the different positions of the sulfur atoms in the terminal aromatic rings. In the case of molecule 1, the complete formation of a SAM can be observed after 24 h of immersion. In the case of molecule 2, the transition from flat-lying to upright configuration on the surface is still in process after 24 h of immersion. This is attributed to the fact that molecule 2 have the sulfur atoms more exposed than molecule 1.

  5. Gold nanoparticle-enhanced secondary ion mass spectrometry imaging of peptides on self-assembled monolayers.

    Science.gov (United States)

    Kim, Young-Pil; Oh, Eunkeu; Hong, Mi-Young; Lee, Dohoon; Han, Min-Kyu; Shon, Hyun Kyong; Moon, Dae Won; Kim, Hak-Sung; Lee, Tae Geol

    2006-03-15

    We demonstrate the use of gold nanoparticles (AuNPs) to enhance the secondary ion emission of peptides in time-of-flight secondary ion mass spectrometry (TOF-SIMS). The signal intensity of peptides adsorbed onto AuNPs was significantly increased when compared to that of self-assembled monolayers (SAMs). This gold nanoparticle-enhanced SIMS, termed NE-SIMS, enabled the sensitive detection of subtle modifications of peptides, such as phosphorylation. From a quantitative analysis of the amounts of adsorbed peptides and AuNPs on SAMs using quartz crystal microbalance and surface plasmon resonance spectroscopy, the ratio of peptide molecule to AuNP on amine-SAMs was revealed to be 18-19:1. When considering the ratio of peptide to matrix (1:10(3)-10(6)) employed in a matrix-enhanced SIMS, the use of AuNPs gave rise to a significantly increased secondary ion emission of peptides. Peptides were adsorbed onto patterned AuNPs on SAMs using a microfluidic system, and well-contrasted molecular ion images were obtained. NE-SIMS is expected to be applied to a chip-based analysis of modification of biomolecules in a label-free manner.

  6. Understanding gold-thiolate cluster emission from self-assembled monolayers upon kiloelectronvolt ion bombardment.

    Science.gov (United States)

    Arezki, B; Delcorte, A; Garrison, B J; Bertrand, P

    2006-04-06

    This article focuses on the emission of organometallic clusters upon kiloelectronvolt ion bombardment of self-assembled monolayers. It is particularly relevant for the elucidation of the physical processes underlying secondary ion mass spectrometry (SIMS). The experimental system, an overlayer of octanethiols on gold, was modeled by classical molecular dynamics, using a hydrocarbon potential involving bonding and nonbonding interactions (AIREBO). To validate the model, the calculated mass and energy distributions of sputtered atoms and molecules were compared to experimental data. Our key finding concerns the emission mechanism of large clusters of the form MxAuy up to M6Au5 (where M is the thiolate molecule), which were not observed under sub-kiloelectronvolt projectile bombardment. Statistically, they are predominantly formed in high-yield events, where many atoms, fragments, and (supra)molecular species are desorbed from the surface. From the microscopic viewpoint, these high-yield events mostly stem from the confinement of the projectile and recoil atom energies in a finite microvolume of the sample surface. As a result of the high local energy density, molecular aggregates desorb from an overheated liquidlike region surrounding the impact point of the projectile.

  7. Oriented antibody immobilization on self-assembled monolayers applied as impedance biosensors

    Science.gov (United States)

    Tsugimura, Kaiki; Ohnuki, Hitoshi; Wu, Haiyun; Endo, Hideaki; Tsuya, Daiju; Izumi, Mitsuru

    2017-11-01

    Oriented immobilization of antibodies on a sensor chip is crucial for enhancing both the sensitivity and antigen-binding capacity of immunosensors. Here, we report a comparative study of the effect of oriented and random antibody immobilization on the binding efficiency by electrochemical impedance spectroscopy (EIS). Oriented immobilization of anti-myoglobin immunoglobulin G (anti-Myo IgG) was achieved by bonding to an Fc receptor of protein G (PrG) on a self-assembled monolayer (SAM), which results in the myoglobin (Myo) binding sites being exposed outside the sensing surface. Random immobilization of anti-Myo IgG was achieved by direct covalent attachment to the SAM surface. Both immobilizations were applied to interdigitated electrodes to enhance the electrochemical signal, and the Myo biosensor performance was then evaluated by a series of EIS measurements. We found that (i) the rate of the normalized charge transfer resistance for the oriented sample was 3 times higher than that for the random sample and (ii) the detection limit was 0.001 ng/mL, which is the lowest recorded detection limit among Myo immunosensors based on EIS. These findings indicate that oriented antibody immobilization is crucial for preparing highly sensitive EIS-based biosensors.

  8. Chemical stability of nonwetting, low adhesion self-assembled monolayer films formed by perfluoroalkylsilanization of copper.

    Science.gov (United States)

    Hoque, E; DeRose, J A; Hoffmann, P; Bhushan, B; Mathieu, H J

    2007-03-21

    A self-assembled monolayer (SAM) has been produced by reaction of 1H,1H,2H,2H-perfluorodecyldimethylchlorosilane (PFMS) with an oxidized copper (Cu) substrate and investigated by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), friction force microscopy (FFM), a derivative of AFM, and contact angle measurement. FFM showed a significant reduction in the adhesive force and friction coefficient of PFMS modified Cu (PFMS/Cu) compared to unmodified Cu. The perfluoroalkyl SAM on Cu is found to be extremely hydrophobic, yielding sessile drop static contact angles of more than 130 degrees for pure water and a "surface energy" (which is proportional to the Zisman critical surface tension for a Cu surface with 0 rms roughness) of 14.5 mJm2(nMm). Treatment by exposure to harsh conditions showed that PFMS/Cu SAM can withstand boiling nitric acid (pH=1.8), boiling water, and warm sodium hydroxide (pH=12, 60 degrees C) solutions for at least 30 min. Furthermore, no SAM degradation was observed when PFMS/Cu was exposed to warm nitric acid solution for up to 70 min at 60 degrees C or 50 min at 80 degrees C. Extremely hydrophobic (low surface energy) and stable PFMS/Cu SAMs could be useful as corrosion inhibitors in micro/nanoelectronic devices and/or as promoters for antiwetting, low adhesion surfaces or dropwise condensation on heat exchange surfaces.

  9. High-performance and high-sensitivity applications of graphene transistors with self-assembled monolayers.

    Science.gov (United States)

    Yeh, Chao-Hui; Kumar, Vinod; Moyano, David Ricardo; Wen, Shao-Hsuan; Parashar, Vyom; Hsiao, She-Hsin; Srivastava, Anchal; Saxena, Preeti S; Huang, Kun-Ping; Chang, Chien-Chung; Chiu, Po-Wen

    2016-03-15

    Charge impurities and polar molecules on the surface of dielectric substrates has long been a critical obstacle to using graphene for its niche applications that involve graphene's high mobility and high sensitivity nature. Self-assembled monolayers (SAMs) have been found to effectively reduce the impact of long-range scatterings induced by the external charges. Yet, demonstrations of scalable device applications using the SAMs technique remains missing due to the difficulties in the device fabrication arising from the strong surface tension of the modified dielectric environment. Here, we use patterned SAM arrays to build graphene electronic devices with transport channels confined on the modified areas. For high-mobility applications, both rigid and flexible radio-frequency graphene field-effect transistors (G-FETs) were demonstrated, with extrinsic cutoff frequency and maximum oscillation frequency enhanced by a factor of ~2 on SiO2/Si substrates. For high sensitivity applications, G-FETs were functionalized by monoclonal antibodies specific to cancer biomarker chondroitin sulfate proteoglycan 4, enabling its detection at a concentration of 0.01 fM, five orders of magnitude lower than that detectable by a conventional colorimetric assay. These devices can be very useful in the early diagnosis and monitoring of a malignant disease. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Comparative Study of Electroless Copper Film on Different Self-Assembled Monolayers Modified ABS Substrate

    Directory of Open Access Journals (Sweden)

    Jiushuai Xu

    2014-04-01

    Full Text Available Copper films were grown on (3-Mercaptopropyltrimethoxysilane (MPTMS, (3-Aminopropyltriethoxysilane (APTES and 6-(3-(triethoxysilylpropylamino-1,3,5- triazine-2,4-dithiol monosodium (TES self-assembled monolayers (SAMs modified acrylonitrile-butadiene-styrene (ABS substrate via electroless copper plating. The copper films were examined using scanning electron microscopy (SEM and X-ray diffraction (XRD. Their individual deposition rate and contact angle were also investigated to compare the properties of SAMs and electroless copper films. The results indicated that the formation of copper nuclei on the TES-SAMs modified ABS substrate was faster than those on the MPTMS-SAMs and APTES-SAMs modified ABS substrate. SEM images revealed that the copper film on TES-SAM modified ABS substrate was smooth and uniform, and the density of copper nuclei was much higher. Compared with that of TES-SAMs modified resin, the coverage of copper nuclei on MPTMS and APTES modified ABS substrate was very limited and the copper particle size was too big. The adhesion property test demonstrated that all the SAMs enhanced the interfacial interaction between copper plating and ABS substrate. XRD analysis showed that the copper film deposited on SAM-modified ABS substrate had a structure with Cu(111 preferred orientation, and the copper film deposited on TES-SAMs modified ABS substrate is better than that deposited on MPTMS-SAMs or APTES-SAMs modified ABS resins in electromigrtion resistance.

  11. Model of self assembled monolayer based molecular diodes made of ferrocenyl-alkanethiols

    Science.gov (United States)

    Duche, David; Planchoke, Ujwol; Dang, Florian-Xuan; Le Rouzo, Judikael; Bescond, Marc; Simon, Jean-Jacques; Balaban, Teodor Silviu; Escoubas, Ludovic

    2017-03-01

    There has been significant work investigating the use of self assembled monolayers (SAMs) made of ferrocenyl terminated alkanethiols for realizing molecular diodes, leading to remarkably large forward-to-reverse current rectification ratios. In this study, we use a multiband barrier tunneling model to examine the electrical properties of SAM-based molecular diodes made of HSC9Fc, HSC11Fc, and HSCiFcC13-i (0 ≤ i ≤ 13). Using our simple physical model, we reproduce the experimental data of charge transport across various ferrocenyl substituted alkanethiols performed by Nijhuis, Reus, and Whitesides [J. Am. Chem. Soc. 132, 18386-184016 (2010)] and Yuan et al. [Nat. Commun. 6, 6324 (2015)]. Especially, the model allows predicting the rectification direction in HSCiFcC13-i (0 ≤ i ≤ 13) based molecular diodes depending on the position of the ferrocenyl (Fc) moiety within the molecules. We show that the asymmetry of the barrier length at both sides of the Highest Occupied Molecular Orbital of the ferrocenyl moiety strongly contributes to the rectifying properties of ferrocenyl-alkanethiol based molecular junctions. Furthermore, our results reveal that bound and quasi-bound states play an important role in the charge transport.

  12. A thermal stability study of alkane and aromatic thiolate self-assembled monolayers on copper surfaces

    Science.gov (United States)

    Carbonell, L.; Whelan, C. M.; Kinsella, M.; Maex, K.

    2004-07-01

    The thermal stability of 1-decanethiol (C10) and benzenethiol (BT) Self-Assembled Monolayers (SAMs) on metallic and oxidized copper surfaces has been investigated by thermal desorption spectrometry. High quality C10 and BT SAMs exhibit low thermal stabilities on clean copper surfaces with a maximum in decomposition occurring between 100 and 150 ∘C. The decomposition of SAMs follows different mechanisms. For the alkanethiol, a direct interaction between the alkyl group of the thiolate and the metallic copper surface is the dominant pathway for the C-S bond scission. The head group desorbs as oxidized sulfur and this is followed by the desorption of the alkyl fragments of the chain adsorbed on the clean copper surface. In the case of benzenethiol, a simultaneous desorption of the head group as oxidized sulfur and the benzene group occurs. SAM formation on the oxidized copper surface results in complete removal and/or reduction of the CuO layer. Higher SAM surface coverages on the resulting Cu/Cu 2O surface result from the enhanced surface roughness of the substrate. The decomposition mechanisms and thermal stabilities of the C10 and BT SAMs are dependent on the oxidation state of the underlying substrate and the chemical nature of the chain.

  13. Molecular simulations of mixed self-assembled monolayer coated gold nanoparticles in water.

    Science.gov (United States)

    J, Meena Devi

    2015-06-01

    Molecular dynamics simulations have been employed to study the hydration of a series of nanoparticles, each of which was coated with a mixed self-assembled monolayer (SAM) comprising methyl- and hydroxy-terminated alkane thiol chains. The mixing ratio of those chains are different for each nanoparticle. The simulations focused on the wetting behavior of the SAM-coated gold nanoparticles and the distribution and structure of their interfacial water molecules. The interactions of the mixed SAM-coated gold nanoparticles with water were analyzed by evaluating the radial distribution function, hydrogen bonds, the dipole orientations of the water molecules, and the water residence time in the interfacial region. The wettability of the mixed SAM-coated gold nanoparticles improved as the concentration of terminal hydroxy moieties was increased. The distribution and dynamics of the interfacial water molecules were found to be influenced by the mixing ratio of the terminal moieties of the SAM chains. The results of our simulations suggest that the surface interactions of the mixed SAM-coated gold nanoparticles with the aqueous medium can be modulated by systematically altering the mixing ratio of the terminal methyl and hydroxy moieties. This work may lead to new biological and technological applications and inspire the development of novel biomimetic materials. Graphical Abstract Mixed SAM-coated gold nanoparticles.

  14. Self-Assembled Monolayers of an Azobenzene Derivative on Silica and Their Interactions with Lysozyme.

    Science.gov (United States)

    Wei, Tao; Sajib, Md Symon Jahan; Samieegohar, Mohammadreza; Ma, Heng; Shing, Katherine

    2015-12-22

    The capability of the photoresponsive isomerization of azobenzene derivatives in self-assembled monolayer (SAM) surfaces to control protein adsorption behavior has very promising applications in antifouling materials and biotechnology. In this study, we performed an atomistic molecular dynamics (MD) simulation in combination with free-energy calculations to study the morphology of azobenzene-terminated SAMs (Azo-SAMs) grafted on a silica substrate and their interactions with lysozyme. Results show that the Azo-SAM surface morphology and the terminal benzene rings' packing are highly correlated with the surface density and the isomer state. Higher surface coverage and the trans-isomer state lead to a more ordered polycrystalline backbone as well as more ordered local packing of benzene rings. On the Azo-SAM surface, water retains a high interfacial diffusivity, whereas the adsorbed lysozyme is found to have extremely low mobility but a relative stable secondary structure. The moderate desorption free energy (∼60 kT) from the trans-Azo-SAM surface was estimated by using both the nonequilibrium-theorem-based Jarzynski's equality and equilibrium umbrella sampling.

  15. Formation of self-assembled monolayer of curcuminoid molecules on gold surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Berlanga, Isadora [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Etcheverry-Berríos, Álvaro; Mella, Andy; Jullian, Domingo [Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Beaucheff 851, Santiago (Chile); Gómez, Victoria Alejandra [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Aliaga-Alcalde, Núria [ICREA (Institució Catalana de Recerca i Estudis Avançats), Passeig Lluís Companys, 23, 08018, Barcelona (Spain); CSIC-ICMAB (Institut de Ciència dels Materials de Barcelona), Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra (Spain); Fuenzalida, Victor [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Flores, Marcos, E-mail: mflorescarra@ing.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); and others

    2017-01-15

    Highlights: • Thiophene curcuminoid molecules deposited on a gold surface by immersion. • Molecular dynamic studies of the molecular arrangement approaching the surface. • XPS and STM studies showing different arrangement of the molecules on the surface. • Molecular Interaction with surface depends on the sulfur position in thiophene rings. • Temporal evolution of the molecular arrangement on the surface. - Abstract: We investigated the formation of self-assembled monolayers of two thiophene curcuminoid molecules, 2-thphCCM (1) and 3-thphCCM (2), on polycrystalline gold substrates prepared by immersion of the surfaces in a solution of the molecules during 24 h. The functionalized surfaces were studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Despite the fact that both molecules have the same composition and almost the same structure, these molecules exhibit different behavior on the gold surface, which can be explained by the different positions of the sulfur atoms in the terminal aromatic rings. In the case of molecule 1, the complete formation of a SAM can be observed after 24 h of immersion. In the case of molecule 2, the transition from flat-lying to upright configuration on the surface is still in process after 24 h of immersion. This is attributed to the fact that molecule 2 have the sulfur atoms more exposed than molecule 1.

  16. Binary self-assembled monolayers modified Au nanoparticles as carriers in biological applications.

    Science.gov (United States)

    Chang, Hsun-Yun; You, Yun-Wen; Liao, Hua-Yang; Shyue, Jing-Jong

    2014-12-01

    Gold nanoparticles (AuNPs) are good nonviral carriers because of their ease of synthesis and conjugation in biochemistry, and self-assembled monolayers (SAMs) provide a tunable system to change their interfacial properties. Using homogeneously mixed carboxylic acid and amine functional groups, a series of surface potentials and isoelectric points (IEPs) could be obtained and allow systematic study of the effect of surface potential. In this work, the result of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay revealed that binary-SAM modified AuNPs have high biocompatibility with HEK293T cells. The amount of AuNPs ingested by the cells was found to increase with increasing surface potential and the difference was also confirmed with a scanning transmission electron microscope. The ability of binary-SAM modified AuNPs as carriers was examined, and the plasmid deoxyribose nucleic acid (DNA)-containing eGFP reporter gene was used as the model cargo. Fluorescence imaging revealed that the transfection efficiency generally increased with increasing surface potential. More importantly, when the IEP of the AuNPs was higher than that of the environment of the endosome but lower than that of the cytoplasm, the plasmid DNA can be protected better and released more easily during the endocytosis process hence higher efficiency is obtained with 60% NH2 and 40% COOH in the binary-SAM.

  17. Super-Hydrophobic/Icephobic Coatings Based on Silica Nanoparticles Modified by Self-Assembled Monolayers

    Directory of Open Access Journals (Sweden)

    Junpeng Liu

    2016-12-01

    Full Text Available A super-hydrophobic surface has been obtained from nanocomposite materials based on silica nanoparticles and self-assembled monolayers of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS using spin coating and chemical vapor deposition methods. Scanning electron microscope images reveal the porous structure of the silica nanoparticles, which can trap small-scale air pockets. An average water contact angle of 163° and bouncing off of incoming water droplets suggest that a super-hydrophobic surface has been obtained based on the silica nanoparticles and POTS coating. The monitored water droplet icing test results show that icing is significantly delayed by silica-based nano-coatings compared with bare substrates and commercial icephobic products. Ice adhesion test results show that the ice adhesion strength is reduced remarkably by silica-based nano-coatings. The bouncing phenomenon of water droplets, the icing delay performance and the lower ice adhesion strength suggest that the super-hydrophobic coatings based on a combination of silica and POTS also show icephobicity. An erosion test rig based on pressurized pneumatic water impinging impact was used to evaluate the durability of the super-hydrophobic/icephobic coatings. The results show that durable coatings have been obtained, although improvement will be needed in future work aiming for applications in aerospace.

  18. Self-assembled monolayers-based immunosensor for detection of Escherichia coli using electrochemical impedance spectroscopy

    International Nuclear Information System (INIS)

    Geng Ping; Zhang Xinai; Meng Weiwei; Wang Qingjiang; Zhang Wen; Jin Litong; Feng Zhen; Wu Zirong

    2008-01-01

    An electrochemical impedance immunosensor for the detection of Escherichia coli was developed by immobilizing anti-E. coli antibodies at an Au electrode. The immobilization of antibodies at the Au electrode was carried out through a stable acyl amino ester intermediate generated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydrosuccinimide (NHS), which could condense antibodies reproducibly and densely on the self-assembled monolayer (SAM). The surface characteristics of the immunosensor before and after the binding reaction of antibodies with E. coli were characterized by atomic force microscopy (AFM). The immobilization of antibodies and the binding of E. coli cells to the electrode could increase the electro-transfer resistance, which was directly detected by electrochemical impedance spectroscopy (EIS) in the presence of Fe(CN) 6 3- /Fe(CN) 6 4- as a redox probe. A linear relationship between the electron-transfer resistance and the logarithmic value of E. coli concentration was found in the range of E. coli cells from 3.0 x 10 3 to 3.0 x 10 7 cfu mL -1 with the detection limit of 1.0 x 10 3 cfu mL -1 . With preconcentration and pre-enrichment steps, it was possible to detect E. coli concentration as low as 50 cfu/mL in river water samples

  19. Self-assembly, Self-organization, Nanotechnology and vitalism

    OpenAIRE

    Bensaude Vincent, Bernadette

    2009-01-01

    International audience; Over the past decades, self-assembly has attracted a lot of research attention and transformed the relations between chemistry, materials science and biology. The paper explores the impact of the current interest in self-assembly techniques on the traditional debate over the nature of life. The first section describes three different research programs of self-assembly in nanotechnology in order to characterize their metaphysical implications: -1- Hybridization ( using ...

  20. Study of the ability of self-assembled N-vinylcarbazole monolayers to protect copper against corrosion

    Directory of Open Access Journals (Sweden)

    NAI-XING WANG

    2002-10-01

    Full Text Available N-Vinylcarbazole (NVC monolayers were self-assembled on copper surfaces. The electrochemical properties of the copper surfaces modified by NVC self-assembled monolayers (SAMs were investigated using polarization and electrochemical impedance spectroscopic (EIS methods. The polarization measurements indicated that the NVC SAMs could reduce the rates of the anodic and cathodic reaction on the surface of copper electrodes in 0.5 mol dm-3 NaCl solution. The EIS results showed the NVC formed a closely packed film that was able to inhibit copper corrosion. X-Ray photoelectron spectroscopy (XPS analysis of the copper samples and atomic adsorption analysis of the solution showed that the copper surfaces were covered by NVC SAMs, and the adsorption of NVC on the copper surfaces was accompanied with dissolution of Cu into the solution.

  1. Time and pressure dependent deformation of microcontact printed channels fabricated using self-assembled monolayers of alkanethiol on gold

    Directory of Open Access Journals (Sweden)

    M. Jalal Uddin

    2017-09-01

    Full Text Available In this work, the replication-based microcontact printing method has been presented to study the deformation effect of different printing times and printing pressures on the microcontact printed structures. Cost-effective microcontact printing channels of self-assembled monolayers of alkanethiol have been prepared on gold surface. The alkanethiol inking the polydimethylsiloxanes stamp effectively forms the self-assembled monolayers on the noble gold surface that protects the metal against etchant solution and thereby forms channel-like structures. To address the deformation issue, variations in the printing time in the range of 30 s–60 min and the printing pressure ranging from 840 to 4200 Pa have been studied. The estimation of differing the channel width and channel space with varying printing time and pressure shows the best resolution structures printed under minimal printing time at atmospheric pressure.

  2. Protective Coatings for Space System Components Fabricated Using Ionic Self Assembled Monolayer Processes

    National Research Council Canada - National Science Library

    Miler, Mike

    1997-01-01

    Self-assembled multilayer thin film fabrication methods offer unique opportunities to incorporate multiple functionalities into coatings for space system materials and structures as well as consumer products...

  3. Site-selective biofunctionalization of aluminum nitride surfaces using patterned organosilane self-assembled monolayers.

    Science.gov (United States)

    Chiu, Chi-Shun; Lee, Hong-Mao; Gwo, Shangjr

    2010-02-16

    Surface biochemical functionalization of group-III nitride semiconductors has recently attracted much interest because of their biocompatibility, nontoxicity, and long-term chemical stability under demanding physiochemical conditions for chemical and biological sensing. Among III-nitrides, aluminum nitride (AlN) and aluminum gallium nitride (AlGaN) are particularly important because they are often used as the sensing surfaces for sensors based on field-effect transistor or surface acoustic wave (SAW) sensor structures. To demonstrate the possibility of site-selective biofunctionalization on AlN surfaces, we have fabricated two-dimensional antibody micropatterns on AlN surfaces by using patterned self-assembled monolayer (SAM) templates. Patterned SAM templates are composed of two types of organosilane molecules terminated with different functional groups (amino and methyl), which were fabricated on AlN/sapphire substrates by combining photolithography, lift-off process, and self-assembly technique. Because the patterned SAM templates have different surface properties on the same surface, clear imaging contrast of SAM micropatterns can be observed by field-emission scanning electron microscopy (FE-SEM) operating at a low accelerating voltage in the range of 0.5-1.5 kV. Furthermore, the contrast in surface potential of the binary SAM microstructures was confirmed by selective adsorption of negatively charged colloidal gold nanoparticles (AuNPs). The immobilization of AuNPs was limited on the positively charged amino-terminated regions, while they were scarcely found on the surface regions terminated by methyl groups. In this work, selective immobilization of green fluorescent protein (GFP) antibodies was demonstrated by the specific protein binding of enhanced GFP (EGFP) labeling. The observed strong fluorescent signal from antibody functionalized regions on the SAM-patterned AlN surface indicates the retained biological activity of specific molecular recognition

  4. Importance of the indium tin oxide substrate on the quality of self-assembled monolayers formed from organophosphonic acids.

    Science.gov (United States)

    Chockalingam, Muthukumar; Darwish, Nadim; Le Saux, Guillaume; Gooding, J Justin

    2011-03-15

    The role of indium tin oxide (ITO) surface structure and chemistry on the formation of self-assembled monolayers (SAM) derived from organophosphonic acids has been investigated. The surface hydroxide content, crystal structure, and roughness of unmodified ITO surfaces were analyzed with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM), and contact angle measurements. Organophosphonic acid monolayer modified ITO surfaces were then characterized using electrochemistry, contact angle measurements and impedance spectroscopy. To ascertain the extent of defects, Pb was underpotentially deposited (UPD) onto the monolayer modified ITO surfaces at defect sites and regions where the monolayer was weakly bound. The extent of defects, and the location of defects, in monolayers formed on different ITO surfaces were determined from the amount of charge passed during UPD of Pb at identical conditions, followed by XPS analysis of the Pb 4f peak and imaging with scanning tunnelling microscopy (STM). The results demonstrate that the crystal structure and hydroxide ion concentration of ITO surfaces significantly influence the quality of self-assembled monolayer formation as does the surface roughness. The most well-packed stable monolayers formed only on smooth amorphous ITO substrates with homogeneous grains and high hydroxide content. Lower quality SAMs with significant defects formed on polycrystalline surfaces and the higher the roughness the more the defects. STM defect mapping revealed that the location of defects in monolayers occurred at the boundaries between grain edges on the polycrystalline surfaces. This shows that the substrate characteristics have a strong influence on the quality of monolayers formed on ITO surfaces.

  5. White-Emissive Self-Assembled Organic Microcrystals.

    Science.gov (United States)

    Li, Zhi Zhou; Liang, Feng; Zhuo, Ming Peng; Shi, Ying Li; Wang, Xue Dong; Liao, Liang Sheng

    2017-05-01

    Organic semiconductor micro-/nanocrystals with regular shapes have been demonstrated for many applications, such as organic field-effect transistors, organic waveguide devices, organic solid-state lasers, and therefore are inherently ideal building blocks for the key circuits in the next generation of miniaturized optoelectronics. In the study, blue-emissive organic molecules of 1,4-bis(2-methylstyryl)benzene (o-MSB) can assemble into rectangular microcrystals at a large scale via the room-temperature solution-exchange method. Because of the Förster resonance energy transfer, the energy of the absorbed photons by the host matrix organic molecules of o-MSB can directly transfer to the dopant organic molecules of tetracene or 1,2:8,9-dibenzopentacene (DBP), which then emit visible photons in different colors from blue to green, and to yellow. More impressively, by modulating the doping molar ratios of DBP to o-MSB, bright white-emissive organic microcrystals with well-preserved rectangular morphology can be successfully achieved with a low doping ratio of 1.5%. These self-assembled organic semiconductor microcrystals with multicolor emissions can be the white-light sources for the integrated optical circuits at micro-/nanoscale. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Monoatomic and cluster beam effect on ToF-SIMS spectra of self-assembled monolayers on gold

    Energy Technology Data Exchange (ETDEWEB)

    Tuccitto, N. [Dipartimento di Scienze Chimiche Universita degli Studi di Catania, v.le A. Doria 6, 95125, Catania (Italy)], E-mail: n.tuccitto@unict.it; Torrisi, V.; Delfanti, I.; Licciardello, A. [Dipartimento di Scienze Chimiche Universita degli Studi di Catania, v.le A. Doria 6, 95125, Catania (Italy)

    2008-12-15

    Self-assembled monolayers represent well-defined systems that is a good model surface to study the effect of primary ion beams used in secondary ion mass spectrometry. The effect of polyatomic primary beams on both aliphatic and aromatic self-assembled monolayers has been studied. In particular, we analysed the variation of the relative secondary ion yield of both substrate metal-cluster (Au{sub n}{sup -}) in comparison with the molecular ions (M{sup -}) and clusters (M{sub x}Au{sub y}{sup -}) by using Bi{sup +}, Bi{sub 3}{sup +}, Bi{sub 5}{sup +} beams. Moreover, the differences in the secondary ion generation efficiency are discussed. The main effect of the cluster beams is related to an increased formation of low-mass fragments and to the enhancement of the substrate related gold-clusters. The results show that, at variance of many other cases, the static SIMS of self-assembled monolayers does not benefit of the use of polyatomic primary ions.

  7. Reducing Staphylococcus aureus biofilm formation on stainless steel 316L using functionalized self-assembled monolayers

    International Nuclear Information System (INIS)

    Kruszewski, Kristen M.; Nistico, Laura; Longwell, Mark J.; Hynes, Matthew J.; Maurer, Joshua A.; Hall-Stoodley, Luanne; Gawalt, Ellen S.

    2013-01-01

    Stainless steel 316L (SS316L) is a common material used in orthopedic implants. Bacterial colonization of the surface and subsequent biofilm development can lead to refractory infection of the implant. Since the greatest risk of infection occurs perioperatively, strategies that reduce bacterial adhesion during this time are important. As a strategy to limit bacterial adhesion and biofilm formation on SS316L, self-assembled monolayers (SAMs) were used to modify the SS316L surface. SAMs with long alkyl chains terminated with hydrophobic (− CH 3 ) or hydrophilic (oligoethylene glycol) tail groups were used to form coatings and in an orthogonal approach, SAMs were used to immobilize gentamicin or vancomycin on SS316L for the first time to form an “active” antimicrobial coating to inhibit early biofilm development. Modified SS316L surfaces were characterized using surface infrared spectroscopy, contact angles, MALDI-TOF mass spectrometry and atomic force microscopy. The ability of SAM-modified SS316L to retard biofilm development by Staphylococcus aureus was functionally tested using confocal scanning laser microscopy with COMSTAT image analysis, scanning electron microscopy and colony forming unit analysis. Neither hydrophobic nor hydrophilic SAMs reduced biofilm development. However, gentamicin-linked and vancomycin-linked SAMs significantly reduced S. aureus biofilm formation for up to 24 and 48 h, respectively. - Highlights: ► SS316L was modified with glycol terminated SAMs in order to reduce biofilm growth. ► Antibiotics gentamicin and vancomycin were immobilized on SS316L via SAMs. ► Only the antibiotic modifications reduced biofilm development on SS316L

  8. Reducing Staphylococcus aureus biofilm formation on stainless steel 316L using functionalized self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Kruszewski, Kristen M., E-mail: kruszewskik@duq.edu [Duquesne University, Department of Chemistry and Biochemistry, 600 Forbes Avenue, Pittsburgh, PA 15282 (United States); Nistico, Laura, E-mail: lnistico@wpahs.org [Allegheny General Hospital, Center for Genomic Sciences, Allegheny-Singer Research Institute, 320 East North Avenue, 11th floor, South Tower, Pittsburgh, PA 15212 (United States); Longwell, Mark J., E-mail: mlongwel@wpahs.org [Allegheny General Hospital, Center for Genomic Sciences, Allegheny-Singer Research Institute, 320 East North Avenue, 11th floor, South Tower, Pittsburgh, PA 15212 (United States); Hynes, Matthew J., E-mail: mjhynes@go.wustl.edu [Washington University in St. Louis, Department of Chemistry, One Brookings Drive, St. Louis, MO 63130 (United States); Maurer, Joshua A., E-mail: maurer@wustl.edu [Washington University in St. Louis, Department of Chemistry, One Brookings Drive, St. Louis, MO 63130 (United States); Hall-Stoodley, Luanne, E-mail: L.Hall-Stoodley@soton.ac.uk [Southampton Wellcome Trust Clinical Research Facility/NIHR Respiratory BRU, University of Southampton Faculty of Medicine, Southampton General Hospital, Tremona Road, Southampton, Hampshire SO16 6YD (United Kingdom); Gawalt, Ellen S., E-mail: gawalte@duq.edu [Duquesne University, Department of Chemistry and Biochemistry, McGowan Institute for Regenerative Medicine, 600 Forbes Avenue, Pittsburgh, PA 15282 (United States)

    2013-05-01

    Stainless steel 316L (SS316L) is a common material used in orthopedic implants. Bacterial colonization of the surface and subsequent biofilm development can lead to refractory infection of the implant. Since the greatest risk of infection occurs perioperatively, strategies that reduce bacterial adhesion during this time are important. As a strategy to limit bacterial adhesion and biofilm formation on SS316L, self-assembled monolayers (SAMs) were used to modify the SS316L surface. SAMs with long alkyl chains terminated with hydrophobic (− CH{sub 3}) or hydrophilic (oligoethylene glycol) tail groups were used to form coatings and in an orthogonal approach, SAMs were used to immobilize gentamicin or vancomycin on SS316L for the first time to form an “active” antimicrobial coating to inhibit early biofilm development. Modified SS316L surfaces were characterized using surface infrared spectroscopy, contact angles, MALDI-TOF mass spectrometry and atomic force microscopy. The ability of SAM-modified SS316L to retard biofilm development by Staphylococcus aureus was functionally tested using confocal scanning laser microscopy with COMSTAT image analysis, scanning electron microscopy and colony forming unit analysis. Neither hydrophobic nor hydrophilic SAMs reduced biofilm development. However, gentamicin-linked and vancomycin-linked SAMs significantly reduced S. aureus biofilm formation for up to 24 and 48 h, respectively. - Highlights: ► SS316L was modified with glycol terminated SAMs in order to reduce biofilm growth. ► Antibiotics gentamicin and vancomycin were immobilized on SS316L via SAMs. ► Only the antibiotic modifications reduced biofilm development on SS316L.

  9. Fabrication, characterization, and applications of nanometer-scale features within organomercaptan self- assembled monolayers

    Science.gov (United States)

    Schoer, Jonathan Kevin

    1997-10-01

    Nanometer-scale features in organomercaptan self- assembled monolayers (SAMs) on Au(111) substrates were prepared by three methods: electrochemical enhancement of adventitious defects, electrochemical enhancement of template-molecule-induced pores, and scanning tunneling microscopy (STM)-induced patterning. The resulting features were characterized by electrochemistry, scanning electron microscopy (STM), and electrochemical STM (ECSTM). Finally, we applied STM-induced patterning methods to lithographic fabrication of features with critical dimensions resists and barrier layers to electron and mass transfer. Further, the nanometer-scale features act as nanometer- size electrodes. Measurements of the physical dimensions of nanometer- scale features by STM can be combined with microelectrode theory to calculate a value for the limiting current. Comparison of this value with that obtained directly from conventional electrochemistry provides qualitative agreement. From in-depth studies of the mechanistic aspects of STM- induced patterning of organomercaptan SAMs we determined that this process is controlled by a complex combination of parameters defined by both the instrument and the chemical and physical properties of materials in the vicinity of the tip. In particular, the patterning is dependent on the magnitude and polarity of the gap bias, the Coulomb dose, and the composition of the gap. From this information we propose a detailed multi-step model for STM-induced removal of n-alkanethiol SAMs from Au surfaces. The model is partially based on our observation that high tip bias ([>]~[+]2.30 V) results in removal of SAMs by Faradaic electrochemical processes in which the n-octadecyl mercaptan monolayer is: (1) disrupted by the tip, (2) electrochemically desorbed, and (3) removed by the scanning action of the tip. Further, we determined that at biases above a second threshold (~[+]4.0 V) the patterning becomes irreproducible because the patterning mechanism changes to

  10. Gold cleaning methods for preparation of cell culture surfaces for self-assembled monolayers of zwitterionic oligopeptides.

    Science.gov (United States)

    Enomoto, Junko; Kageyama, Tatsuto; Myasnikova, Dina; Onishi, Kisaki; Kobayashi, Yuka; Taruno, Yoko; Kanai, Takahiro; Fukuda, Junji

    2018-01-15

    Self-assembled monolayers (SAMs) have been used to elucidate interactions between cells and material surface chemistry. Gold surfaces modified with oligopeptide SAMs exhibit several unique characteristics, such as cell-repulsive surfaces, micropatterns of cell adhesion and non-adhesion regions for control over cell microenvironments, and dynamic release of cells upon external stimuli under culture conditions. However, basic procedures for the preparation of oligopeptide SAMs, including appropriate cleaning methods of the gold surface before modification, have not been fully established. Because gold surfaces are readily contaminated with organic compounds in the air, cleaning methods may be critical for SAM formation. In this study, we examined the effects of four gold cleaning methods: dilute aqua regia, an ozone water, atmospheric plasma, and UV irradiation. Among the methods, UV irradiation most significantly improved the formation of oligopeptide SAMs in terms of repulsion of cells on the surfaces. We fabricated an apparatus with a UV light source, a rotation table, and HEPA filter, to treat a number of gold substrates simultaneously. Furthermore, UV-cleaned gold substrates were capable of detaching cell sheets without serious cell injury. This may potentially provide a stable and robust approach to oligopeptide SAM-based experiments for biomedical studies. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  11. Investigation of secondary cluster ion emission from self-assembled monolayers of alkanethiols on gold with ToF-SIMS

    International Nuclear Information System (INIS)

    Schroeder, M.; Sohn, S.; Arlinghaus, H.F.

    2004-01-01

    Self-assembled monolayers (SAMs) of alkanethiols on gold are ideal model systems for studying the emission processes of secondary ions from thin organic layers on metal substrates under keV ion bombardment. In this experimental study, we focus on the emission processes of gold-hexadecanethiolate cluster ions, which are not well understood yet. For this purpose, we carried out time-of-flight secondary ion mass spectrometry (ToF-SIMS) measurements on SAMs of hexadecanethiols (HDT, CH 3 -(CH 2 ) 15 -SH) on gold substrates. The gold-hexadecanethiolate cluster ions Au x M y - show intense peaks in mass spectra of negatively charged secondary ions under 10 keV Ar + bombardment. Around the corresponding peaks, a characteristic peak pattern of additional ions is observed. We analyzed the contribution of different cluster ions formed by an attachment or a loss of several hydrogen atoms and their isotope patterns to the individual peaks of the peak pattern. We found two different types of gold-hexadecanethiolate cluster ions. The first type has only one parent ion with no hydrogen atom attached. The second type has two parent ions, one without attachment of hydrogen atoms and another with one additional hydrogen atom. Moreover, we found a universally valid sum formula, which predicts the most intense peak in the peak pattern of all gold-hexadecanethiolate cluster ions analyzed

  12. Molecular Fin Effect from Heterogeneous Self-Assembled Monolayer Enhances Thermal Conductance across Hard-Soft Interfaces.

    Science.gov (United States)

    Wei, Xingfei; Zhang, Teng; Luo, Tengfei

    2017-10-04

    Thermal transport across hard-soft interfaces is critical to many modern applications, such as composite materials, thermal management in microelectronics, solar-thermal phase transition, and nanoparticle-assisted hyperthermia therapeutics. In this study, we use equilibrium molecular dynamics (EMD) simulations combined with the Green-Kubo method to study how molecularly heterogeneous structures of the self-assembled monolayer (SAM) affect the thermal transport across the interfaces between the SAM-functionalized gold and organic liquids (hexylamine, propylamine and hexane). We focus on a practically synthesizable heterogeneous SAM featuring alternating short and long molecular chains. Such a structure is found to improve the thermal conductance across the hard-soft interface by 46-68% compared to a homogeneous nonpolar SAM. Through a series of further simulations and analyses, it is found that the root reason for this enhancement is the penetration of the liquid molecules into the spaces between the long SAM molecule chains, which increase the effective contact area. Such an effect is similar to the fins used in macroscopic heat exchanger. This "molecular fin" structure from the heterogeneous SAM studied in this work provides a new general route for enhancing thermal transport across hard-soft material interfaces.

  13. Study on the formation of self-assembled monolayers on sol-gel processed hafnium oxide as dielectric layers.

    Science.gov (United States)

    Ting, Guy G; Acton, Orb; Ma, Hong; Ka, Jae Won; Jen, Alex K-Y

    2009-02-17

    High dielectric constant (k) metal oxides such as hafnium oxide (HfO2) have gained significant interest due to their applications in microelectronics. In order to study and control the surface properties of hafnium oxide, self-assembled monolayers (SAMs) of four different long aliphatic molecules with binding groups of phosphonic acid, carboxylic acid, and catechol were formed and characterized. Surface modification was performed to improve the interface between metal oxide and top deposited materials as well as to create suitable dielectric properties, that is, leakage current and capacitance densities, which are important in organic thin film transistors. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, contact angle goniometry, atomic force microscopy (AFM), and simple metal-HfO2-SAM-metal devices were used to characterize the surfaces before and after SAM modification on sol-gel processed hafnium oxide. The alkylphosphonic acid provided the best monolayer formation on sol-gel processed hafnium oxide to generate a well-packed, ultrathin dielectric exhibiting a low leakage current density of 2x10(-8) A/cm2 at an applied voltage of -2.0 V and high capacitance density of 0.55 microF/cm2 at 10 kHz. Dialkylcatechol showed similar characteristics and the potential for using the catechol SAMs to modify HfO2 surfaces. In addition, the integration of this alkylphosphonic acid SAM/hafnium oxide hybrid dielectric into pentacene-based thin film transistors yields low-voltage operation within 1.5 V and improved performance over bare hafnium oxide.

  14. Formation and Characterization of Self-Assembled Phenylboronic Acid Derivative Monolayers toward Developing Monosaccaride Sensing-Interface

    Directory of Open Access Journals (Sweden)

    Kwangnak Koh

    2007-08-01

    Full Text Available We designed and synthesized phenylboronic acid as a molecular recognitionmodel system for saccharide detection. The phenylboronic acid derivatives that haveboronic acid moiety are well known to interact with saccharides in aqueous solution; thus,they can be applied to a functional interface of saccharide sensing through the formation ofself-assembled monolayer (SAM. In this study, self-assembled phenylboronic acidderivative monolayers were formed on Au surface and carefully characterized by atomicforce microscopy (AFM, Fourier transform infrared reflection absorption spectroscopy(FTIR-RAS, surface enhanced Raman spectroscopy (SERS, and surface electrochemicalmeasurements. The saccharide sensing application was investigated using surface plasmonresonance (SPR spectroscopy. The phenylboronic acid monolayers showed goodsensitivity of monosaccharide sensing even at the low concentration range (1.0 × 10-12 M.The SPR angle shift derived from interaction between phenylboronic acid andmonosaccharide was increased with increasing the alkyl spacer length of synthesizedphenylboronic acid derivatives.

  15. Steering the Self-Assembly of Octadecylamine Monolayers on Mica by Controlled Mechanical Energy Transfer from the AFM Tip

    Energy Technology Data Exchange (ETDEWEB)

    Benitez, J.J.; Heredia-Guerrero, J.A.; Salmeron, M.

    2010-06-24

    We have studied the effect of mechanical energy transfer from the tip of an Atomic Force Microscope on the dynamics of self-assembly of monolayer films of octadecylamine on mica. The formation of the self-assembled film proceeds in two successive stages, the first being a fast adsorption from solution that follows a Langmuir isotherm. The second is a slower process of island growth by aggregation of the molecules dispersed on the surface. We found that the dynamics of aggregation can be altered substantially by the addition of mechanical energy into the system through controlled tip-surface interactions. This leads to either the creation of pinholes in existing islands as a consequence of vacancy concentration, and to the assembly of residual molecules into more compact islands.

  16. Self-Assembly of Small Molecules for Organic Photovoltaic Applications

    Science.gov (United States)

    Aytun, Taner

    Organic photovoltaic (OPV) solar cells aim to provide efficient, flexible and lightweight photovoltaics (PV) with simple processing and low-cost. Advances in device optimization, structural and molecular design, as well as mechanistic understanding have helped increase device efficiency and performance. Within the framework of active layer optimization, systematically improving bulk heterojunction (BHJ) morphology could improve the power conversion efficiency of OPVs. However, most strategies aimed at improving morphology focus on annealing methods or the use of solvent additives. Rational approaches in supramolecular self-assembly can potentially offer additional control over the morphology of BHJ active layers and lead to improved power conversion efficiencies. In Chapter 2, the author explores the effect of molecular shape on the assembly of electron donating small molecules, and its ensuing effect on OPV performance. Two tripodal 'star-shaped' donor molecules with diketopyrrolopyrrole (DPP) side chains were used to generate solution-processed BHJ OPVs. It was found that the tripod molecules neither aggregate in solution nor form crystalline domains in thin films when a branched alkyl solubilizing group is used. On the other hand, linear alkyl chains promote the formation of one-dimensional (1D) nanowires and crystalline domains as well. This work demonstrated that the one-dimensional assembly of donor molecules enhances the performance of the corresponding solution-processed OPVs by 50%. This is attributed to the reduction of trap states in the 1D nanowires, resulting in a significant increase in the fill factor of the devices. In Chapter 3, experiments are described in which the electron donor is a hairpin-shaped molecule containing a trans-1,2-diamidocyclohexane core and two DPP conjugated segments, and a fullerene derivative as the electron acceptor. Self-assembly of the donor molecule is driven by the synergistic interaction between hydrogen bonds and pi

  17. Preparation and characterization of lanthanum-based thin films on sulfonated self-assembled monolayer of 3-mercaptopropyl trimethoxysilane

    Energy Technology Data Exchange (ETDEWEB)

    Tao Bai [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China); Cheng Xianhua [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China) and State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)]. E-mail: Xhcheng@sjtu.edu.cn

    2006-12-05

    Silane coupling regent (3-mercaptopropyl trimethoxysilane (MPTS)) is prepared on a single-crystal silicon substrate to form two-dimensional self-assembled monolayer (SAM). The terminal thiol groups (-SH) in the film is oxidized to sulfonic acid groups (-SO{sub 3}H) in situ to enhance the chemisorption property of the film. Lanthanum-based thin films are deposited on the oxidized MPTS-SAM by means of chemisorption with the -SO{sub 3}H group. The surface energy, chemical composition, phase transformation and surface morphology of the films are analyzed using contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy. The results show that MPTS is a self-assembled layer on the substrate and that the terminal -SH groups of the self-assembled MPTS films are closer to the air/silane interface than the silicon atoms. The study also shows that the treatment of SAM with 30% nitric acid (HNO{sub 3}) at 80 deg. C in sufficient duration can completely transform the terminal groups in the top-most layer into desirable sulfonate groups. Then the substrates coated with the sulfonated MPTS-SAM were immersed in the RE solution to form lanthanum-based thin films. The experimental results indicate that the lanthanum-based thin films are adsorbed on oxidized MPTS-SAM and that the lanthanum element with different states of oxidation exists in the thin films that are deposited on the surface of self-assembly monolayers. Also, shape analyses of the La{sup 3+} XPS peaks reveal that the rare-earth film can react with the substrate by chemical bonding and that some lanthanum molecules are adsorbed on the MPTS-SAM. The above results show that it is the -SO{sub 3}H group that has good chemisorption trend.

  18. Effect of substrate composition on atomic layer deposition using self-assembled monolayers as blocking layers

    International Nuclear Information System (INIS)

    Zhang, Wenyu; Engstrom, James R.

    2016-01-01

    The authors have examined the effect of two molecules that form self-assembled monolayers (SAMs) on the subsequent growth of TaN x by atomic layer deposition (ALD) on two substrate surfaces, SiO 2 and Cu. The SAMs that the authors have investigated include two vapor phase deposited, fluorinated alkyl silanes: Cl 3 Si(CH 2 ) 2 (CF 2 ) 5 CF 3 (FOTS) and (C 2 H 5 O) 3 Si(CH 2 ) 2 (CF 2 ) 7 CF 3 (HDFTEOS). Both the SAMs themselves and the TaN x thin films, grown using Ta[N(CH 3 ) 2 ] 5 and NH 3 , were analyzed ex situ using contact angle, spectroscopic ellipsometry, x-ray photoelectron spectroscopy (XPS), and low energy ion-scattering spectroscopy (LEISS). First, the authors find that both SAMs on SiO 2 are nominally stable at T s  ∼ 300 °C, the substrate temperature used for ALD, while on Cu, the authors find that HDFTEOS thermally desorbs, while FOTS is retained on the surface. The latter result reflects the difference in the head groups of these two molecules. The authors find that both SAMs strongly attenuate the ALD growth of TaN x on SiO 2 , by about a factor of 10, while on Cu, the SAMs have no effect on ALD growth. Results from LEISS and XPS are decisive in determining the nature of the mechanism of growth of TaN x on all surfaces. Growth on SiO 2 is 2D and approximately layer-by-layer, while on the surfaces terminated by the SAMs, it nucleates at defect sites, is islanded, and is 3D. In the latter case, our results support growth of the TaN x thin film over the SAM, with a considerable delay in formation of a continuous thin film. Growth on Cu, with or without the SAMs, is also 3D and islanded, and there is also a delay in the formation of a continuous thin film as compared to growth on SiO 2 . These results highlight the power of coupling measurements from both LEISS and XPS in examinations of ultrathin films formed by ALD

  19. Molecular dynamics simulations of peptide adsorption on self-assembled monolayers

    International Nuclear Information System (INIS)

    Xie Yun; Liu Meifeng; Zhou Jian

    2012-01-01

    All-atom molecular dynamics simulations are performed to investigate the neuromedin-B peptide adsorption on the self-assembled monolayers (SAMs) of SH(CH 2 ) 10 N + (CH 3 ) 2 CH 2 CH(OH)CH 2 SO 3 - (SBT), SH(CH 2 ) 10 OH and SH(CH 2 ) 10 CH 3 . The force-distance profiles show that the surface resistance to peptide adsorption is mainly generated by the water molecules tightly bound to surfaces via hydrogen bonds (hydration water molecules); but surfaces themselves may also set an energy barrier for the approaching peptide. For the SBT-SAM, the surface first exerts a relatively high repulsive force and then a rather week attractive force on the approaching peptide; meanwhile the hydration water molecules exert a strong repulsive force on the peptide. Therefore, SBT-SAM has an excellent performance on resisting protein adsorption. For the OH-SAM and CH 3 -SAM, surfaces show low or little energy barrier but strong affinity to the peptide; and the hydration water molecules apply merely a repulsive force within a much narrower range and with lower intensity compared with the case for the SBT-SAM. The analysis of structural and dynamical properties of the peptide, surface and water indicates that possible factors contributing to surface resistance include the hydrogen-bond formation capability of surfaces, mobility of water molecules near surfaces, surface packing density and chain flexibility of SAMs. There are a large number of hydrogen bonds formed between the hydration water molecules and the functional groups of the SBT-SAM, which greatly lowers the mobility of water molecules near the surface. This tightly-bound water layer effectively reduces the direct contact between the surface and the peptide. Furthermore, the SBT-SAM also has a high flexibility and a low surface packing density, which allows water molecules to penetrate into the surface to form tightly-bound networks and therefore reduces the affinity between the peptide and the surface. The results show that

  20. Coding for hydrogel organization through signal guided self-assembly.

    Science.gov (United States)

    Yan, Kun; Ding, Fuyuan; Bentley, William E; Deng, Hongbing; Du, Yumin; Payne, Gregory F; Shi, Xiao-Wen

    2014-01-21

    Complex structured soft matter may have important applications in the field of tissue engineering and biomedicine. However, the discovery of facile methods to exquisitely manipulate the structure of soft matter remains a challenge. In this report, a multilayer hydrogel is fabricated from the stimuli-responsive aminopolysaccharide chitosan by using spatially localized and temporally controlled sequences of electrical signals. By programming the imposed cathodic input signals, chitosan hydrogels with varying layer number and thickness can be fabricated. The inputs of electrical signals induce the formation of hydrogel layers while short interruptions create interfaces between each layer. The thickness of each layer is controlled by the charge transfer (Q = ∫idt) during the individual deposition step and the number of multilayers is controlled by the number of interruptions. Scanning electron micrographs (SEMs) reveal organized fibrous structures within each layer that are demarcated by compact orthogonal interlayer structures. This work demonstrates for the first time that an imposed sequence of electrical inputs can trigger the self-assembly of multilayered hydrogels and thus suggests the broader potential for creating an electrical "code" to generate complex structures in soft matter.

  1. From self-organization to self-assembly: a new materialism?

    Science.gov (United States)

    Vincent, Bernadette Bensaude

    2016-09-01

    While self-organization has been an integral part of academic discussions about the distinctive features of living organisms, at least since Immanuel Kant's Critique of Judgement, the term 'self-assembly' has only been used for a few decades as it became a hot research topic with the emergence of nanotechnology. Could it be considered as an attempt at reducing vital organization to a sort of assembly line of molecules? Considering the context of research on self-assembly I argue that the shift of attention from self-organization to self-assembly does not really challenge the boundary between chemistry and biology. Self-assembly was first and foremost investigated in an engineering context as a strategy for manufacturing without human intervention and did not raise new perspectives on the emergence of vital organization itself. However self-assembly implies metaphysical assumptions that this paper tries to disentangle. It first describes the emergence of self-assembly as a research field in the context of materials science and nanotechnology. The second section outlines the metaphysical implications and will emphasize a sharp contrast between the ontology underlying two practices of self-assembly developed under the umbrella of synthetic biology. And unexpectedly, we shall see that chemists are less on the reductionist side than most synthetic biologists. Finally, the third section ventures some reflections on the kind of design involved in self-assembly practices.

  2. Interactions of gaseous HNO3 and water with individual and mixed alkyl self-assembled monolayers at room temperature.

    Science.gov (United States)

    Nishino, Noriko; Hollingsworth, Scott A; Stern, Abraham C; Roeselová, Martina; Tobias, Douglas J; Finlayson-Pitts, Barbara J

    2014-02-14

    The major removal processes for gaseous nitric acid (HNO3) in the atmosphere are dry and wet deposition onto various surfaces. The surface in the boundary layer is often covered with organic films, but the interaction of gaseous HNO3 with them is not well understood. To better understand the factors controlling the uptake of gaseous nitric acid and its dissociation in organic films, studies were carried out using single component and mixtures of C8 and C18 alkyl self-assembled monolayers (SAMs) attached to a germanium (Ge) attenuated total reflectance (ATR) crystal upon which a thin layer of SiOx had been deposited. For comparison, diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) studies were also carried out using a C18 SAM attached to the native oxide layer on the surface of silicon powder. These studies show that the alkyl chain length and order/disorder of the SAMs does not significantly affect the uptake or dissociation/recombination of molecular HNO3. Thus, independent of the nature of the SAM, molecular HNO3 is observed up to 70-90% relative humidity. After dissociation, molecular HNO3 is regenerated on all SAM surfaces when water is removed. Results of molecular dynamics simulations are consistent with experiments and show that defects and pores on the surfaces control the uptake, dissociation and recombination of molecular HNO3. Organic films on surfaces in the boundary layer will certainly be more irregular and less ordered than SAMs studied here, therefore undissociated HNO3 may be present on surfaces in the boundary layer to a greater extent than previously thought. The combination of this observation with the results of recent studies showing enhanced photolysis of nitric acid on surfaces suggests that renoxification of deposited nitric acid may need to be taken into account in atmospheric models.

  3. Structural and chemical characterization of monofluoro-substituted oligo(phenylene-ethynylene) thiolate self-assembled monolayers on gold.

    Science.gov (United States)

    Hacker, Christina A; Batteas, James D; Garno, Jayne C; Marquez, Manuel; Richter, Curt A; Richter, Lee J; van Zee, Roger D; Zangmeister, Christopher D

    2004-07-20

    Monolayers of oligo(phenylene-ethynylene) (OPE) molecules have exhibited promise in molecular electronic test structures. This paper discusses films formed from a novel molecule within this class, 2-fluoro-4-phenylethynyl-1-[(4-acetylthio)phenylethynyl]benzene (F-OPE). The conditions of self-assembled monolayer (SAM) formation were systematically altered to fabricate reproducible high-quality molecular monolayers from the acetate-protected F-OPE molecule. Detailed characterization of the F-OPE monolayers was performed by using an array of surface probes, including reflection absorbance infrared spectroscopy (RAIRS), contact angle (CA) measurements, spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and atomic force microscopy (AFM). XPS and RAIRS established that the SAM formed without removal of the F substituent and without oxidation of the thiol. The monolayer thickness, determined from SE and AFM based nanolithography, was consistent with the formation of a densely packed monolayer. The valence electronic structure of the SAM was consistent with an aromatic structure shifted by the electron-withdrawing fluorine substituent and intermolecular coupling within an oriented array of molecules. Copyright 2004 American Chemical Society

  4. Soft landing of polyatomic ions for selective modification of fluorinated self-assembled monolayer surfaces

    Science.gov (United States)

    Luo, Hai; Miller, Scott A.; Cooks, R. Graham; Pachuta, Steven J.

    1998-03-01

    Fluorinated self-assembled monolayer (F-SAM) surfaces comprised of CF3(CF2)7(CH2)2S- groups bound to a gold substrate were modified by deposition of mass-selected polyatomic ions at collision energies of ~10 eV. The modified material was characterized in situ by low-energy ion bombardment and by independent high-resolution time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis. Modification of F-SAM surfaces using hyperthermal (CH3)2SiNCS+ (m/z 116) and (CH3)3SiOSi(CH3)2 (m/z 147) projectile ion beams incorporated the intact projectile ions m/z 116 and mlz 147, respectively, which were released upon subsequent 60 eV [multiset union] sputtering. In addition to simple cases of soft landing of intact ions into a surface, two related soft landing channels, dissociative soft landing and reactive soft landing, are also identified. Surfaces modified by prolonged exposure to 35CICH2(CH3)2SiOSi(CH3)2+ (m/z 181) and its isotopic variant 37CICH2(CH3)2SiOSi(CH3)2+ (m/z 183), yielded only fragment ions derived from the projectile ions, primarily C3H10OSi235Cl+ (m/z 153) and C3H10OSi237Cl+ (m/z 155) upon [multiset union] sputtering as well as in the 15 keV Ga+TOF-SIMS spectra. In these cases, facile fragmentation occurs upon initial ion impact with the surface, the fragment ion being trapped at the interface in an overall process which is described as dissociative soft landing. Consistent with this, the fragment ions C3H10OSi235CI+ (m/z 153) and C3H10OSi237Cl+ (m/z 155) generated as such in the ion source were deposited without fragmentation and subsequently released intact by 60 eV [multiset union] sputtering. In the cases of some projectiles, such as protonated 2,4,6-trimethylpyridine, the sputtered ions released from the modified surface included chemically transformed products due to reaction of the projectile ion at the surface. Such reactive soft landing processes occur by ion/molecule reactions at the interface, although details of their mechanism and its

  5. Study of Alkylthiolate Self-assembled Monolayers on Au(111) Using a Semilocal meta-GGA Density Functional

    DEFF Research Database (Denmark)

    Ferrighi, Lara; Pan, Yun-xiang; Grönbeck, Henrik

    2012-01-01

    We present a density functional theory study of the structure and stability of self-assembled monolayers (SAMs) of alkylthiolate on Au(111) as a function of the alkyl chain length. The most favorable structure of the SAMs involves an RS–Au–SR complex (S being sulfur, R being an alkyl chain) formed...... through sandwiching one Au adatom by two alkylthiolates (RSs). Comparing a generalized gradient (GGA-PBE) and a meta-GGA (MGGA-M06-L) exchange-correlation functional we find that only the meta-GGA functional predicts the experimentally observed attractive intermolecular interactions within the SAMs...

  6. Grafting of polypeptides on solid substrates by initiation of N-carboxyanhydride polymerization by amino-terminated self-assembled monolayers

    NARCIS (Netherlands)

    Heise, Andreas; Menzel, Henning; Yim, Hyun; Foster, Mark D.; Wieringa, Reinier Hendrik; Schouten, Arend Jan; Erb, Volker; Stamm, Manfred

    1997-01-01

    A series of mixed self-assembled monolayers of functionalized (Br(CH2)(11)SiCl3) and unfunctionalized (CH3(CH2)(10)SiCl3) alkyltrichlorosilanes of different compositions have been prepared on bulk silicon substrates. By in situ modification of these monolayers the bromo end groups were transformed

  7. Review and outlook: from single nanoparticles to self-assembled monolayers and granular GMR sensors

    Directory of Open Access Journals (Sweden)

    Alexander Weddemann

    2010-11-01

    Full Text Available This paper highlights recent advances in synthesis, self-assembly and sensing applications of monodisperse magnetic Co and Co-alloyed nanoparticles. A brief introduction to solution phase synthesis techniques as well as the magnetic properties and aspects of the self-assembly process of nanoparticles will be given with the emphasis placed on selected applications, before recent developments of particles in sensor devices are outlined. Here, the paper focuses on the fabrication of granular magnetoresistive sensors by the employment of particles themselves as sensing layers. The role of interparticle interactions is discussed.

  8. Photooxidation of self-assembled monolayers by exposure to light of wavelength 254 nm: a static SIMS study.

    Science.gov (United States)

    Brewer, Nicholas J; Janusz, Stefan; Critchley, Kevin; Evans, Stephen D; Leggett, Graham J

    2005-06-09

    Self-assembled monolayers (SAMs) of alkanethiols have been photooxidized by exposure to light from a lamp emitting light with a wavelength of 254 nm. The data confirm that SAM oxidation on exposure to UV light sources occurs in the absence of ozone, but also suggest that the mechanism is different from that observed in previous studies using broad-spectrum arc lamps. In particular, for monolayers on both gold and silver, carboxylic acid-terminated SAMs oxidize significantly faster than methyl-terminated SAMs, in contrast to earlier observations for monolayers exposed to light from a mercury arc lamp. The difference in rates of photooxidation for the two classes of monolayer is significantly greater on silver than on gold. These data support our recent suggestion that while methyl-terminated SAMs are able to pack much more closely on silver than on gold, carboxylic acid-terminated thiols are not able to adopt the same close-packed structures, and their rates of photooxidation on silver are similar to, or slightly greater than, those measured for the same adsorbates on gold. Surface potential measurements were made for carboxylic acid- and methyl-terminated SAMs using a Kelvin probe apparatus. It was found that the work functions of carboxylic acid-terminated SAMs are significantly greater than those of methyl-terminated monolayers. It is concluded that these data are consistent with the oxidation reaction being initiated by "hot" electrons generated following the interaction of photons with the metallic substrate.

  9. Substrate-mediated effects in photothermal patterning of alkanethiol self-assembled monolayers with microfocused continuous-wave lasers

    Directory of Open Access Journals (Sweden)

    Anja Schröter

    2012-01-01

    Full Text Available In recent years, self-assembled monolayers (SAMs have been demonstrated to provide promising new approaches to nonlinear laser processing. Most notably, because of their ultrathin nature, indirect excitation mechanisms can be exploited in order to fabricate subwavelength structures. In photothermal processing, for example, microfocused lasers are used to locally heat the substrate surface and initiate desorption or decomposition of the coating. Because of the strongly temperature-dependent desorption kinetics, the overall process is highly nonlinear in the applied laser power. For this reason, subwavelength patterning is feasible employing ordinary continuous-wave lasers. The lateral resolution, generally, depends on both the type of the organic monolayer and the nature of the substrate. In previous studies we reported on photothermal patterning of distinct types of SAMs on Si supports. In this contribution, a systematic study on the impact of the substrate is presented. Alkanethiol SAMs on Au-coated glass and silicon substrates were patterned by using a microfocused laser beam at a wavelength of 532 nm. Temperature calculations and thermokinetic simulations were carried out in order to clarify the processes that determine the performance of the patterning technique. Because of the strongly temperature-dependent thermal conductivity of Si, surface-temperature profiles on Au/Si substrates are very narrow ensuring a particularly high lateral resolution. At a 1/e spot diameter of 2 µm, fabrication of subwavelength structures with diameters of 300–400 nm is feasible. Rapid heat dissipation, though, requires high laser powers. In contrast, patterning of SAMs on Au/glass substrates is strongly affected by the largely distinct heat conduction within the Au film and in the glass support. This results in broad surface temperature profiles. Hence, minimum structure sizes are larger when compared with respective values on Au/Si substrates. The required

  10. Optical constants and self-assembly of phenylene ethynylene oligomer monolayers

    DEFF Research Database (Denmark)

    Marx, E.; Walzer, Karsten; Less, R.J.

    2004-01-01

    This paper studies the self-assembly on gold surfaces of 1,4-ethynylphenyl-4'-ethynylphenyl-2'-nitro-1-benzenedithiolate (EP2NO(2)), a substituted phenylene ethynylene trimer with applications in molecular electronics. We develop an ellipsometric technique to measure the optical constants...

  11. Molecular Dynamics Study of Alkanethiolate Self-Assembled Monolayer Coated Gold Nanoparticle

    Science.gov (United States)

    2007-06-01

    of Organosulfur Compounds on Au( 111). Implications for Molecular Self-Assembly on Gold 21. Plimpton, S.J., "Fast Parallel Algorithms for Short-Range... Organosulfur Compounds SHAKE Algorithm for Molecular Dynamics." Journal of Adsorbed on Gold Single Crystals: Electron Diffraction Computational Physics, 52

  12. Reflection and extinction of light by self-assembled monolayers of a quinque-thiophene derivative: A coherent scattering approach.

    Science.gov (United States)

    Gholamrezaie, Fatemeh; de Leeuw, Dago M; Meskers, Stefan C J

    2016-06-07

    Scattering matrix theory is used to describe resonant optical properties of molecular monolayers. Three types of coupling are included: exciton-exciton, exciton-photon, and exciton-phonon coupling. We use the K-matrix formalism, developed originally to describe neutron scattering spectra in nuclear physics to compute the scattering of polaritons by phonons. This perturbation approach takes into account the three couplings and allows one to go beyond molecular exciton theory without the need of introducing additional boundary conditions for the polariton. We demonstrate that reflection, absorption, and extinction of light by 2D self-assembled monolayers of molecules containing quinque-thiophene chromophoric groups can be calculated. The extracted coherence length of the Frenkel exciton is discussed.

  13. Reflection and extinction of light by self-assembled monolayers of a quinque-thiophene derivative: A coherent scattering approach

    Energy Technology Data Exchange (ETDEWEB)

    Gholamrezaie, Fatemeh; Meskers, Stefan C. J., E-mail: s.c.j.meskers@tue.nl [Molecular Materials and Nanosystems and Institute of Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Leeuw, Dago M. de [Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany)

    2016-06-07

    Scattering matrix theory is used to describe resonant optical properties of molecular monolayers. Three types of coupling are included: exciton-exciton, exciton-photon, and exciton-phonon coupling. We use the K-matrix formalism, developed originally to describe neutron scattering spectra in nuclear physics to compute the scattering of polaritons by phonons. This perturbation approach takes into account the three couplings and allows one to go beyond molecular exciton theory without the need of introducing additional boundary conditions for the polariton. We demonstrate that reflection, absorption, and extinction of light by 2D self-assembled monolayers of molecules containing quinque-thiophene chromophoric groups can be calculated. The extracted coherence length of the Frenkel exciton is discussed.

  14. Spectroscopic evaluation of surface functionalization efficiency in the preparation of mercaptopropyltrimethoxysilane self-assembled monolayers on glass.

    Science.gov (United States)

    Pallavicini, Piersandro; Dacarro, Giacomo; Galli, Matteo; Patrini, Maddalena

    2009-04-15

    Four synthetic protocols have been examined for the preparation of a self-assembled monolayer of propanethiol functions on glass surfaces, through the wet reaction of mercaptopropyltrimethoxysilane (MPTS) on glass slides, in order to determine an optimal method to obtain dense -SH monolayers for further reaction with maleimide-bearing molecules. We have also demonstrated that the surface density of reactive -SH groups can be indagated by the coupling reaction with a maleimide-functionalized rhodamine dye and by the examination of the absorption spectra of the glass slides. The reaction of MPTS in dry toluene gives the most dense surface of reactive thiols, among the examined protocols. We have also evidenced that thermal curing of the MPTS functionalized slides induces thiol coupling and -S-S- formation, resulting in a dramatically lowered availability of -SH groups.

  15. Influence of molecular packing on the corrosion inhibition properties of self-assembled octadecyltrichlorosilane monolayers on silicon

    International Nuclear Information System (INIS)

    Hsieh, Shuchen; Chao, Wei-Jay; Lin, Pei-Ying; Hsieh, Chiung-Wen

    2014-01-01

    Highlights: •Molecular packing plays an important role in determining SAM film properties. •Loose-packed OTS monolayers on silicon were corroded by exposure to KMnO 4 . •Dense-packed OTS SAM films exhibited excellent corrosion protection efficacy. -- Abstract: The corrosion inhibition properties of octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on silicon were investigated. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), contact angle (CA), and lateral force microscopy (LFM) were used to determine the OTS film formation time, packing density, and corrosion protection efficacy. The OTS films reached adsorption saturation after 15 s; however, the molecular density continued to increase up to 24 h. The films were exposed to the strong oxidant KMnO 4 , and while 15-s film samples exhibited corrosion after a 1 min exposure, samples with films grown for 24 h were protected even after 24 h

  16. Simple and robust strategy for potentiometric detection of glucose using fluorinated phenylboronic acid self-assembled monolayer.

    Science.gov (United States)

    Matsumoto, Akira; Matsumoto, Hiroko; Maeda, Yasuhiro; Miyahara, Yuji

    2013-09-01

    Field effect transistor (FET) based signal-transduction (Bio-FET) is an emerging technique for label-free and real-time basis biosensors for a wide range of targets. Glucose has constantly been of interest due to its clinical relevance. Use of glucose oxidase (GOD) and a lectin protein Concanavalin A are two common strategies to generate glucose-dependent electrochemical events. However, these protein-based materials are intolerant of long-term usage and storage due to their inevitable denaturing. A phenylboronic acid (PBA) modified self-assembled monolayer (SAM) on a gold electrode with an optimized disassociation constant of PBA, that is, 3-fluoro-4-carbamoyl-PBA possessing its pKa of 7.1, was prepared and utilized as an extended gate electrode for Bio-FET. The prepared electrode showed a glucose-dependent change in the surface potential under physiological conditions, thus providing a remarkably simple rationale for the glyco-sensitive Bio-FET. Importantly, the PBA modified electrode showed tolerance to relatively severe heat and drying treatments; conditions under which protein based materials would surely be denatured. A PBA modified SAM with optimized disassociation constant (pKa) can exhibit a glucose-dependent change in the surface potential under physiological conditions, providing a remarkably simple but robust method for the glyco-sensing. This protein-free, totally synthetic glyco-sensing strategy may offer cheap, robust and easily accessible platform that may be useful in developing countries. This article is part of a Special Issue entitled Organic Bioelectronics-Novel Applications in Biomedicine. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Self-assembled monolayers of 1-alkenes on oxidized platinum surfaces as platforms for immobilized enzymes for biosensing

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, Jose Maria; Bielen, Abraham A.M. [Laboratory of Organic Chemistry, Wageningen University, Dreijenplein 8, 6703 HB, Wageningen (Netherlands); Olthuis, Wouter [BIOS Lab on a Chip Group, MESA+ and MIRA Institutes, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Kengen, Servé W.M. [Laboratory of Microbiology, Wageningen University, 6703HB Wageningen (Netherlands); Zuilhof, Han, E-mail: han.zuilhof@wur.nl [Laboratory of Organic Chemistry, Wageningen University, Dreijenplein 8, 6703 HB, Wageningen (Netherlands); Department of Chemical and Materials Engineering, King Abdulaziz University, Jeddah 22254 (Saudi Arabia); Franssen, Maurice C.R., E-mail: maurice.franssen@wur.nl [Laboratory of Organic Chemistry, Wageningen University, Dreijenplein 8, 6703 HB, Wageningen (Netherlands)

    2016-10-15

    Highlights: • Three different oxidases are covalently attached to alkene based SAMs on PtOx. • Attached enzymes remain active and their activity is assessed by chronoamperometry. • Functionalized PtOx allows electron mediator free chronoamperometry measurements. • The thus formed enzyme electrodes are useful as biosensors for glucose and lactate. • Immobilization of human HAOX foresees in vivo lactate monitoring in humans. - Abstract: Alkene-based self-assembled monolayers grafted on oxidized Pt surfaces were used as a scaffold to covalently immobilize oxidase enzymes, with the aim to develop an amperometric biosensor platform. NH{sub 2}-terminated organic layers were functionalized with either aldehyde (CHO) or N-hydroxysuccinimide (NHS) ester-derived groups, to provide anchoring points for enzyme immobilization. The functionalized Pt surfaces were characterized by X-ray photoelectron spectroscopy (XPS), static water contact angle (CA), infrared reflection absorption spectroscopy (IRRAS) and atomic force microscopy (AFM). Glucose oxidase (GOX) was covalently attached to the functionalized Pt electrodes, either with or without additional glutaraldehyde crosslinking. The responses of the acquired sensors to glucose concentrations ranging from 0.5 to 100 mM were monitored by chronoamperometry. Furthermore, lactate oxidase (LOX) and human hydroxyacid oxidase (HAOX) were successfully immobilized onto the PtOx surface platform. The performance of the resulting lactate sensors was investigated for lactate concentrations ranging from 0.05 to 20 mM. The successful attachment of active enzymes (GOX, LOX and HAOX) on Pt electrodes demonstrates that covalently functionalized PtOx surfaces provide a universal platform for the development of oxidase enzyme-based sensors.

  18. Influencing the binding selectivity of self-assembled cyclodextrin monolayers on gold through their architecture

    NARCIS (Netherlands)

    de Jong, M.R.; Huskens, Jurriaan; Reinhoudt, David

    2001-01-01

    Cyclodextrin derivatives modified with seven thioether moieties (1) or with one thiol moiety (2) bind to gold. Monolayers on gold of 1 or mixed monolayers of 2 and mercaptoundecanol were characterized by electrochemistry, wettability, and atomic force microscopy (AFM). Monolayers of 1 are

  19. Study of the helium cross-section of unsymmetric disulfide self-assembled monolayers on Au(111)

    Energy Technology Data Exchange (ETDEWEB)

    Albayrak, Erol [Department of Materials and Metallurgical Engineering, Ahi Evran University, Kırşehir 40000 (Turkey); Karabuga, Semistan [Department of Chemistry, Kahramanmaraş Sütçü İmam University, Kahramanmaraş 46030 (Turkey); Bracco, Gianangelo [CNR-IMEM and Department of Physics, University of Genoa, Via Dodecaneso 33, Genoa 16146 (Italy); Danışman, M. Fatih, E-mail: danisman@metu.edu.tr [Department of Chemistry, Middle East Technical University, Ankara 06800 (Turkey)

    2016-12-30

    Highlights: • Unsymmetrtic disulfide (HDD and HOD) self assembled monolayers were grown on Au(111) by supersonic molecular beam deposition. • Helium scattering cross sections for these two different unsymmetric disulfides were determined. • A common low temperature film phase was observed for the studied disulfides. - Abstract: We have investigated the formation of self-assembled monolayers (SAMs) of 11-hydroxyundecyl decyl disulfide (CH{sub 3}-(CH{sub 2}){sub 9}-S-S-(CH{sub 2}){sub 11}-OH, HDD) and 11-hydroxyundecyl octadecyl disulfide (CH{sub 3}-(CH{sub 2}){sub 17}-S-S-(CH{sub 2}){sub 11}-OH, HOD) produced by supersonic molecular beam deposition (SMBD). The study has been carried out by means of helium diffraction at very low film coverage. In this regime helium single molecule cross sections have been estimated in a temperature range between 100 K and 450 K. The results show a different behavior above 300 K that has been interpreted as the starting of mobility with the formation of two thiolate moieties either linked by a gold adatom or distant enough to prevent cross section overlapping. Finally, helium diffraction patterns measured at 80 K for the SAMs grown at 200 K are discussed and the results support the proposed hypothesis of molecular dissociation based on the cross section data.

  20. Surface structure and stereochemical properties of self-assembled monolayer materials. Final Report

    International Nuclear Information System (INIS)

    Scoles, Giacinto

    2006-01-01

    This document reports the progress the authors have made in support of their proposal to generate well-characterized, well-ordered organic surfaces and to impinge upon the array of oriented organic molecules a well-collimated beam of radical atoms at a well-defined angle of incidence. Using the intensity of helium atom diffraction from the organic surface as a measure of the number of unreacted molecules at the surface, the authors will measure the rate of the reaction. They will then vary the angle of incidence of the reactive atom beam and repeat the measurement. In this manner they plan to map out the reactivity of the molecules on the surface as a function of the angle of incidence of the reactive moiety. To carry out this experiment requires that two fields of research be brought together: (1) molecular beam technology and (2) the science/art of growing well-ordered organic surfaces. The first half of this report describes recent helium diffraction results from molecular beam deposited organic monolayers (structural layer characterization work). The second half reports progress in constructing and characterizing the reactive atom (oxygen) beam source.

  1. Optical absorption signature of a self-assembled dye monolayer on graphene

    Directory of Open Access Journals (Sweden)

    Tessnim Sghaier

    2016-06-01

    Full Text Available A well-organized monolayer of alkylated perylene-3,4,9,10-tetracarboxylic-3,4,9,10-diimide (PTCDI has been formed onto CVD graphene transferred on a transparent substrate. Its structure has been probed by scanning tunnelling microscopy and its optical properties by polarized transmission spectroscopy at varying incidence. The results show that the transition dipoles of adsorbed PTCDI are all oriented parallel to the substrate. The maximum absorption is consistent with the measured surface density of molecules and their absorption cross section. The spectrum presents mainly a large red-shift of the absorption line compared with the free molecules dispersed in solution, whereas the relative strengths of the vibronic structures are preserved. These changes are attributed to non-resonant interactions with the graphene layer and the neighbouring molecules.

  2. Corrosion protection ability of self-assembled monolayer of 3-amino-5-mercapto-1,2,4-triazole on copper electrode

    Energy Technology Data Exchange (ETDEWEB)

    Rajkumar, Ganesan; Sethuraman, Mathur Gopalakrishnan, E-mail: mgsethu@rediffmail.com

    2014-07-01

    The self-assembled monolayer (SAM) of 3-amino-5-mercapto-1,2,4-triazole (AMTa) was formed on a copper surface and characterized using cyclic voltammetry, Fourier Transform Infra-red spectroscopy and scanning electron microscopy. Quantum chemical calculations suggested the stronger interaction between AMTa and copper. The protection ability of SAM has been evaluated using electrochemical impedance spectroscopy and potentiodynamic polarization measurements. The formed monolayer showed significant protection ability in 1% NaCl medium. The enhanced corrosion protection ability could be due to the compact film structure which blocks the electron transfer from the solution to AMTa monolayer modified copper substrate. - Highlights: • Self-assembled monolayer (SAM) of AMTa has been achieved on copper surface. • Monolayer formed has been duly characterized. • SAM of AMTa has been shown to offer significant protection to copper in NaCl medium.

  3. Sample preconcentration utilizing nanofractures generated by junction gap breakdown assisted by self-assembled monolayer of gold nanoparticles.

    Directory of Open Access Journals (Sweden)

    Chun-Ping Jen

    Full Text Available The preconcentration of proteins with low concentrations can be used to increase the sensitivity and accuracy of detection. A nonlinear electrokinetic flow is induced in a nanofluidic channel due to the overlap of electrical double layers, resulting in the fast accumulation of proteins, referred to as the exclusion-enrichment effect. The proposed chip for protein preconcentration was fabricated using simple standard soft lithography with a polydimethylsiloxane replica. This study extends our previous paper, in which gold nanoparticles were manually deposited onto the surface of a protein preconcentrator. In the present work, nanofractures were formed by utilizing the self-assembly of gold-nanoparticle-assisted electric breakdown. This reliable method for nanofracture formation, involving self-assembled monolayers of nanoparticles at the junction gap between microchannels, also decreases the required electric breakdown voltage. The experimental results reveal that a high concentration factor of 1.5×10(4 for a protein sample with an extremely low concentration of 1 nM was achieved in 30 min by using the proposed chip, which is faster than our previously proposed chip at the same conditions. Moreover, an immunoassay of bovine serum albumin (BSA and anti-BSA was carried out to demonstrate the applicability of the proposed chip.

  4. Electron-beam patterned self-assembled monolayers as templates for Cu electrodeposition and lift-off

    Directory of Open Access Journals (Sweden)

    Zhe She

    2012-02-01

    Full Text Available Self-assembled monolayers (SAMs of 4'-methylbiphenyl-4-thiol (MBP0 adsorbed on polycrystalline gold substrates served as templates to control electrochemical deposition of Cu structures from acidic solution, and enabled the subsequent lift-off of the metal structures by attachment to epoxy glue. By exploiting the negative-resist behaviour of MBP0, the SAM was patterned by means of electron-beam lithography. For high deposition contrast a two-step procedure was employed involving a nucleation phase around −0.7 V versus Cu2+/Cu and a growth phase at around −0.35 V versus Cu2+/Cu. Structures with features down to 100 nm were deposited and transferred with high fidelity. By using substrates with different surface morphologies, AFM measurements revealed that the roughness of the substrate is a crucial factor but not the only one determining the roughness of the copper surface that is exposed after lift-off.

  5. Biological Activation of Inert Ceramics: Recent Advances Using Tailored Self-Assembled Monolayers on Implant Ceramic Surfaces

    Directory of Open Access Journals (Sweden)

    Frederik Böke

    2014-06-01

    Full Text Available High-strength ceramics as materials for medical implants have a long, research-intensive history. Yet, especially on applications where the ceramic components are in direct contact with the surrounding tissue, an unresolved issue is its inherent property of biological inertness. To combat this, several strategies have been investigated over the last couple of years. One promising approach investigates the technique of Self-Assembled Monolayers (SAM and subsequent chemical functionalization to create a biologically active tissue-facing surface layer. Implementation of this would have a beneficial impact on several fields in modern implant medicine such as hip and knee arthroplasty, dental applications and related fields. This review aims to give a summarizing overview of the latest advances in this recently emerging field, along with thorough introductions of the underlying mechanism of SAMs and surface cell attachment mechanics on the cell side.

  6. Vascular endothelial growth factor attachment to hydroxyapatite via self-assembled monolayers promotes angiogenic activity of endothelial cells

    International Nuclear Information System (INIS)

    Solomon, Kimberly D.; Ong, Joo L.

    2013-01-01

    Currently, tissue engineered constructs for critical sized bone defects are non-vascularized. There are many strategies used in order to promote vascularization, including delivery of growth factors such as vascular endothelial growth factor (VEGF). In this study, hydroxyapatite (HA) was coated with self-assembled monolayers (SAMs). The SAMs were in turn used to covalently bind VEGF to the surface of HA. The different SAM chain length ratios (phosphonoundecanoic acid (11-PUDA):16-phosphonohexadecanoic acid (16-PHDA) utilized in this study were 0:100, 25:75, 50:50, 75:25, and 100:0. Surfaces were characterized by contact angle (CA) and atomic force microscopy, and an in vitro VEGF release study was performed. It was observed that CA and root-mean-squared roughness were not significantly affected by the addition of SAMs, but that CA was significantly lowered with the addition of VEGF. VEGF release profiles of bound VEGF groups all demonstrated less initial burst release than adsorbed control, indicating that VEGF was retained on the HA surface when bound by SAMs. An in vitro study using human aortic endothelial cells (HAECs) demonstrated that bound VEGF increased metabolic activity and caused sustained production of angiopoietin-2, an angiogenic marker, over 28 days. In conclusion, SAMs provide a feasible option for growth factor delivery from HA surfaces, enhancing angiogenic activity of HAECs in vitro. - Highlights: • Vascular endothelial growth factor (VEGF) is attached to hydroxyapatite (HA). • Self-assembled monolayers (SAMs) delay the release of VEGF from hydroxyapatite. • SAM chain length ratio affects the total mass of VEGF released. • VEGF on HA up-regulates proliferation and angiogenic activity of endothelial cells

  7. Self-assembled silver nanoparticles monolayers on mica-AFM, SEM, and electrokinetic characteristics

    International Nuclear Information System (INIS)

    Oćwieja, Magdalena; Morga, Maria; Adamczyk, Zbigniew

    2013-01-01

    A monodisperse silver particle suspension was produced by a chemical reduction method in an aqueous medium using sodium citrate. The average particle size determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), and atomic force microscopy (AFM) was 28.5 nm. The DLS measurements confirmed that the suspension was stable for the ionic strength up to 3 × 10 −2 M NaCl. The electrophoretic mobility measurements revealed that the electrokinetic charge of particles was negative for pH range 3–10, assuming −50 e for pH = 9 and 0.01 M NaCl. Using the suspension, silver particle monolayers on mica modified by poly(allylamine hydrochloride) were produced under diffusion-controlled transport. Monolayer coverage, quantitatively determined by AFM and SEM, was regulated within broad limits by adjusting the nanoparticle deposition time. This allowed one to uniquely express the zeta potential of silver monolayers, determined by the in situ streaming potential measurements, in terms of particle coverage. Such dependencies obtained for various ionic strengths and pH, were successfully interpreted in terms of the 3D electrokinetic model. A universal calibrating graph was produced in this way, enabling one to determine silver monolayer coverage from the measured value of the streaming potential. Our experimental data prove that it is feasible to produce uniform and stable silver particle monolayers of well-controlled coverage and defined electrokinetic properties.

  8. Self-assembled silver nanoparticles monolayers on mica-AFM, SEM, and electrokinetic characteristics.

    Science.gov (United States)

    Oćwieja, Magdalena; Morga, Maria; Adamczyk, Zbigniew

    2013-03-01

    A monodisperse silver particle suspension was produced by a chemical reduction method in an aqueous medium using sodium citrate. The average particle size determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), and atomic force microscopy (AFM) was 28.5 nm. The DLS measurements confirmed that the suspension was stable for the ionic strength up to 3 × 10 -2  M NaCl. The electrophoretic mobility measurements revealed that the electrokinetic charge of particles was negative for pH range 3-10, assuming -50  e for pH = 9 and 0.01 M NaCl. Using the suspension, silver particle monolayers on mica modified by poly(allylamine hydrochloride) were produced under diffusion-controlled transport. Monolayer coverage, quantitatively determined by AFM and SEM, was regulated within broad limits by adjusting the nanoparticle deposition time. This allowed one to uniquely express the zeta potential of silver monolayers, determined by the in situ streaming potential measurements, in terms of particle coverage. Such dependencies obtained for various ionic strengths and pH, were successfully interpreted in terms of the 3D electrokinetic model. A universal calibrating graph was produced in this way, enabling one to determine silver monolayer coverage from the measured value of the streaming potential. Our experimental data prove that it is feasible to produce uniform and stable silver particle monolayers of well-controlled coverage and defined electrokinetic properties.

  9. Enhancing the Microparticle Deposition Stability and Homogeneity on Planer for Synthesis of Self-Assembly Monolayer.

    Science.gov (United States)

    Shih, An-Ci; Han, Chi-Jui; Kuo, Tsung-Cheng; Cheng, Yun-Chien

    2018-03-14

    The deposition stability and homogeneity of microparticles improved with mask, lengthened nozzle and flow rate adjustment. The microparticles can be used to encapsulate monomers, before the monomers in the microparticles can be deposited onto a substrate for nanoscale self-assembly. For the uniformity of the synthesized nanofilm, the homogeneity of the deposited microparticles becomes an important issue. Based on the ANSYS simulation results, the effects of secondary flow were minimized with a lengthened nozzle. The ANSYS simulation was also used to investigate the ring-vortex generation and why the ring vortex can be eliminated by adding a mask with an aperture between the nozzle and deposition substrate. The experimental results also showed that particle deposition with a lengthened nozzle was more stable, while adding the mask stabilized deposition and diminished the ring-vortex contamination. The effects of flow rate and pressure were also investigated. Hence, the deposition stability and homogeneity of microparticles was improved.

  10. Functionalizable self-assembled trichlorosilyl-based monolayer for application in biosensor technology

    Energy Technology Data Exchange (ETDEWEB)

    De La Franier, Brian; Jankowski, Alexander; Thompson, Michael, E-mail: mikethom@chem.utoronto.ca

    2017-08-31

    This paper describes the design and synthesis of 3-(3-(trichlorosilyl)propoxy)propanoyl chloride (MEG-Cl), a compound capable of forming functionalizable monolayers on hydroxylated surfaces. The compound was synthesized in high purity, as suggested by nuclear magnetic resonance analysis, and in moderate overall yield. Contact angle measurement and X-ray photoelectron spectroscopy confirm the binding of MEG-Cl to an amorphous glass substrate and the further modification of the monolayer with a nickel (II)-binding ligand for the purpose of binding polyhistidine-tagged proteins. The compound will be useful in biosensing applications due to its ability to be easily modified with any number of nucleophilic functional groups subsequent to substrate monolayer formation.

  11. Chiral hierarchical self-assembly in Langmuir monolayers of diacetylenic lipids

    KAUST Repository

    Basnet, Prem B.

    2013-01-01

    When compressed in the intermediate temperature range below the chain-melting transition yet in the low-pressure liquid phase, Langmuir monolayers made of chiral lipid molecules form hierarchical structures. Using Brewster angle microscopy to reveal this structure, we found that as the liquid monolayer is compressed, an optically anisotropic condensed phase nucleates in the form of long, thin claws. These claws pack closely to form stripes. This appears to be a new mechanism for forming stripes in Langmuir monolayers. In the lower temperature range, these stripes arrange into spirals within overall circular domains, while near the chain-melting transition, the stripes arrange into target patterns. We attributed this transition to a change in boundary conditions at the core of the largest-scale circular domains. © 2013 The Royal Society of Chemistry.

  12. Structural and electrochemical characterization of fullerene-based surfaces of C-60 mono- or bis-adducts grafted onto self-assembled monolayers

    NARCIS (Netherlands)

    Cecchet, Francesca; Rapino, Stefania; Margotti, Massimo; Da Ros, Tatiana; Prato, Maurizio; Paolucci, Francesco; Rudolf, Petra

    2006-01-01

    Single layers Of C-60 mono- and bis-adducts have been obtained by functionalizing an acid-terminated self-assembled monolayer (SAM) of thiols on gold. X-ray photoelectron spectroscopy demonstrated the grafting onto the SAM by covalent bonding, via the formation of an amide bond, while cyclic

  13. Grafting of benzylic amide macrocycles onto acid-terminated self-assembled monolayers studied by XPS, RAIRS, and contact angle measurements

    NARCIS (Netherlands)

    Cecchet, F; Pilling, M; Hevesi, L; Schergna, S; Wong, JKY; Clarkson, GJ; Leigh, DA; Rudolf, P; Wong, Jenny K.Y.; Clarkson, Guy J.

    2003-01-01

    The grafting of benzylic amide macrocycles, the basic units of more complex mechanically interlocked architectures such as catenanes and rotaxanes, was performed via the functionalization of an acid-terminated self-assembled monolayer (SAM) of 11-mercaptoundecanoic acid (11-MUA). Both chemical and

  14. Building a Low-Cost, Six-Electrode Instrument to Measure Electrical Properties of Self-Assembled Monolayers of Gold Nanoparticles

    Science.gov (United States)

    Gerber, Ralph W.; Oliver-Hoyo, Maria

    2007-01-01

    The development of a new low-cost, six-electrode instrument for measuring the electrical properties of the self-assembled monolayers of gold particles is being described. The system can also be used to measure conductive liquids, except for those that contain aqua region.

  15. IMPACT OF POLYCYCLIC AROMATIC HYDROCARBONS OF THE ELECTROCHEMICAL RESPONSES OF A FERRICYNIDE PROBE AT TEMPLATE-MODIFIED SELF ASSEMBLED MONOLAYERS ON GOLD ELECTRODES

    Science.gov (United States)

    The impact of pyrene on the electrochemical response of the ferricyanide probe using Self Assembled Monolayer (SAM)-modified gold electrodes was investigated using Cyclic Voltammetry (CV) and Square Wave Voltammetry (SWV). These results suggest the feasibility of using SAMs, par...

  16. Host-guest interactions at self-assembled monolayers of cyclodextrins on gold

    NARCIS (Netherlands)

    Beulen, M.W.J.; Bugler, H.J.; de Jong, M.R.; Lammerink, Ben; Huskens, Jurriaan; Schönherr, Holger; Vancso, Gyula J.; Boukamp, Bernard A.; Wieder, Herbert; Offenhauser, Andreas; Knoll, Wolfgang; van Veggel, F.C.J.M.; Reinhoudt, David

    2000-01-01

    We have developed synthesis routes for the introduction of short and long dialkylsulfides onto the primary side of α-, β-, and γ-cyclodextrins. Monolayers of these cyclodextrin adsorbates were characterized by electrochemistry, wettability studies, X-ray photoelectron spectroscopy (XPS),

  17. Growth and Functionality of Cells Cultured on Conducting and Semi-Conducting Surfaces Modified with Self-Assembled Monolayers (SAMs

    Directory of Open Access Journals (Sweden)

    Rajendra K. Aithal

    2016-02-01

    Full Text Available Bioengineering of dermal and epidermal cells on surface modified substrates is an active area of research. The cytotoxicity, maintenance of cell phenotype and long-term functionality of human dermal fibroblast (HDF cells on conducting indium tin oxide (ITO and semi-conducting, silicon (Si and gallium arsenide (GaAs, surfaces modified with self-assembled monolayers (SAMs containing amino (–NH2 and methyl (–CH3 end groups have been investigated. Contact angle measurements and infrared spectroscopic studies show that the monolayers are conformal and preserve their functional end groups. Morphological analyses indicate that HDFs grow well on all substrates except GaAs, exhibiting their normal spindle-shaped morphology and exhibit no visible signs of stress or cytoplasmic vacuolation. Cell viability analyses indicate little cell death after one week in culture on all substrates except GaAs, where cells died within 6 h. Cells on all surfaces proliferate except on GaAs and GaAs-ODT. Cell growth is observed to be greater on SAM modified ITO and Si-substrates. Preservation of cellular phenotype assessed through type I collagen immunostaining and positive staining of HDF cells were observed on all modified surfaces except that on GaAs. These results suggest that conducting and semi-conducting SAM-modified surfaces support HDF growth and functionality and represent a promising area of bioengineering research.

  18. Evidence of Tailoring the Interfacial Chemical Composition in Normal Structure Hybrid Organohalide Perovskites by a Self-Assembled Monolayer.

    Science.gov (United States)

    Will, Johannes; Hou, Yi; Scheiner, Simon; Pinkert, Ute; Hermes, Ilka M; Weber, Stefan A L; Hirsch, Andreas; Halik, Marcus; Brabec, Christoph; Unruh, Tobias

    2018-02-14

    Current-voltage hysteresis is a major issue for normal architecture organo-halide perovskite solar cells. In this manuscript we reveal a several-angstrom thick methylammonium iodide-rich interface between the perovskite and the metal oxide. Surface functionalization via self-assembled monolayers allowed us to control the composition of the interface monolayer from Pb poor to Pb rich, which, in parallel, suppresses hysteresis in perovskite solar cells. The bulk of the perovskite films is not affected by the interface engineering and remains highly crystalline in the surface-normal direction over the whole film thickness. The subnanometer structural modifications of the buried interface were revealed by X-ray reflectivity, which is most sensitive to monitor changes in the mass density of only several-angstrom thin interfacial layers as a function of substrate functionalization. From Kelvin probe force microscopy study on a solar cell cross section, we further demonstrate local variations of the potential on different electron-transporting layers within a solar cell. On the basis of these findings, we present a unifying model explaining hysteresis in perovskite solar cells, giving an insight into one crucial aspect of hysteresis for the first time and paving way for new strategies in the field of perovskite-based opto-electronic devices.

  19. Self-assembled monolayer-based immunoassays for okadaic acid detection in seawater as monitoring tools.

    Science.gov (United States)

    Leonardo, Sandra; Toldrà, Anna; Rambla-Alegre, Maria; Fernández-Tejedor, Margarita; Andree, Karl B; Ferreres, Laura; Campbell, Katrina; Elliott, Christopher T; O'Sullivan, Ciara K; Pazos, Yolanda; Diogène, Jorge; Campàs, Mònica

    2018-02-01

    Rapid and cost-effective methods to monitor the presence of diarrhetic shellfish poisoning (DSP) toxins in seawater samples in an easy and reliable manner are required to protect human health and avoid economic losses to shellfish industry. Immunoassays for the detection of okadaic acid (OA) and dinophysistoxin-1 and dinophysistoxin-2 are developed by immobilising OA on self-assembled monothiols or dithiols in an ordered and oriented way, providing an effective limit of detection of ∼1 ng OA equiv./mL seawater. The immunoassays are applied to the analysis of the particulate fraction of seawater samples from two Catalan harbours (NW Mediterranean) and samples collected periodically from the Galician Rias (E Atlantic), as well as a reference mussel sample. Results are in agreement with LC-MS/MS and the certified values. OA concentration in seawater correlates with Dinophysis cell abundance, with a 1-2 weeks lag. The immunoassays provide powerful high-throughput analytical methods potentially applicable as alternative monitoring tools. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Investigation of hexadecanethiol self-assembled monolayers on cadmium tin oxide thin films

    International Nuclear Information System (INIS)

    Rhodes, Crissy L.; Brewer, Scott H.; Folmer, Jaap; Franzen, Stefan

    2008-01-01

    This study reports the use of variable angle reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy to investigate the formation of a 1-hexadecanethiol adlayer on cadmium tin oxide (CTO) thin film surfaces. These adlayers appear to be robust, ordered monolayers. The optical and electronic properties of CTO thin films chemically vapor deposited onto glass substrates were also investigated. The reflectance of the CTO films was dependent upon the incident angle of the impinging radiation and revealed a reflectance decrease indicative of a plasma frequency in the mid-IR using p-polarized radiation

  1. High-resolution TOF-SIMS study of varying chain length self-assembled monolayer surfaces.

    Science.gov (United States)

    Wolf, Kurt V; Cole, David A; Bernasek, Steven L

    2002-10-01

    A high-resolution time-of-flight secondary ionization mass spectrometer (TOF-SIMS) has been used to investigate chain length effects in hydrocarbon seff-assembled monolayer (SAM) surfaces on gold substrates. A wide range of n-alkanethiols was used to make homogeneous SAM surfaces, which included both odd and even hydrocarbon chain length thiols. Variations in coverage, extent of oxidation, and high-mass cluster formation as a function of hydrocarbon chain length of the alkanethiol SAM surfaces were investigated. Long-short chain length effects were observed for the relative coverage of the SAM surfaces, which directly influences the extent of oxidation for the thin films. The formation of gold-sulfur and gold-adsorbate cluster ions was also observed, since the mass range of the TOF-SIMS made it possible to monitor all of the cluster ions that were formed following the high-energy ion/surface interactions.

  2. Self-Organization and the Self-Assembling Process in Tissue Engineering

    Science.gov (United States)

    Eswaramoorthy, Rajalakshmanan; Hadidi, Pasha; Hu, Jerry C.

    2015-01-01

    In recent years, the tissue engineering paradigm has shifted to include a new and growing subfield of scaffoldless techniques which generate self-organizing and self-assembling tissues. This review aims to provide a cogent description of this relatively new research area, with special emphasis on applications toward clinical use and research models. Particular emphasis is placed on providing clear definitions of self-organization and the self-assembling process, as delineated from other scaffoldless techniques in tissue engineering and regenerative medicine. Significantly, during formation, self-organizing and self-assembling tissues display biological processes similar to those that occur in vivo. These help lead to the recapitulation of native tissue morphological structure and organization. Notably, functional properties of these tissues also approach native tissue values; some of these engineered tissues are already in clinical trials. This review aims to provide a cohesive summary of work in this field, and to highlight the potential of self-organization and the self-assembling process to provide cogent solutions to current intractable problems in tissue engineering. PMID:23701238

  3. Striped Phase of 3-Hexylthiophene Self-Assembled Monolayers on Au(1 11) Formed by Vapor Phase Deposition.

    Science.gov (United States)

    Kim, Youngwoo; Kang, Hungu; Tsunoi, Azuho; Hayashi, Tomohiro; Hara, Masahiko; Noh, Jaegeun

    2016-03-01

    The formation and surface structure of 3-hexylthiophene (HTP) self-assembled monolayers (SAMs) on Au(111) prepared by solution and ambient-pressure vapor deposition at room temperature (RT) for 24 h were examined by means of scanning tunneling microscopy (STM) and cyclic voltammetry (CV). STM imaging revealed that HTP SAMs formed by solution deposition have a disordered phase, whereas those formed by vapor deposition exhibit a striped phase with a unidirectional orientation. The distance between the rows in the striped phase was measured to be 1.3 ± 0.1 nm, and the hexyl molecular backbones of HTP in the SAMs on Au(111) are oriented parallel to the Au(111) surface with the head-to-head orientation. From this STM observation, we suggest that the formation of this striped phase in HTP SAMs prepared by vapor deposition were mainly driven by the optimization of van der Waals interactions between the hexyl chains on the surface. CV measurements also demonstrated that HTP SAMs show a high blocking efficiency for electron transfer reactions between electrolytes and the gold electrode, suggesting the formation of SAMs on Au(111) from the vapor phase. Our results obtained here will be very useful for understanding the formation and structure of HTP SAMs on Au(111) surfaces and how they are influenced by deposition method.

  4. Effects of Self-Assembled Monolayers on Solid-State CdS Quantum Dot Sensitized Solar Cells

    KAUST Repository

    Ardalan, Pendar

    2011-02-22

    Quantum dot sensitized solar cells (QDSSCs) are of interest for solar energy conversion because of their tunable band gap and promise of stable, low-cost performance. We have investigated the effects of self-assembled monolayers (SAMs) with phosphonic acid headgroups on the bonding and performance of cadmium sulfide (CdS) solid-state QDSSCs. CdS quantum dots ∼2 to ∼6 nm in diameter were grown on SAM-passivated planar or nanostructured TiO 2 surfaces by successive ionic layer adsorption and reaction (SILAR), and photovoltaic devices were fabricated with spiro-OMeTAD as the solid-state hole conductor. X-ray photoelectron spectroscopy, Auger electron spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, transmission electron microscopy, water contact angle measurements, ellipsometry, and electrical measurements were employed to characterize the materials and the resulting device performance. The data indicate that the nature of the SAM tailgroup does not significantly affect the uptake of CdS quantum dots on TiO2 nor their optical properties, but the presence of the SAM does have a significant effect on the photovoltaic device performance. Interestingly, we observe up to ∼3 times higher power conversion efficiencies in devices with a SAM compared to those without the SAM. © 2011 American Chemical Society.

  5. ToF-SIMS investigation of FIB-patterning of lactoferrin by using self-assembled monolayers of iron complexes

    International Nuclear Information System (INIS)

    Tuccitto, N.; Giamblanco, N.; Marletta, G.; Licciardello, A.

    2008-01-01

    Geometrically well-defined patterns of surface-immobilized proteins can be produced with several methods. We developed a method for patterning of proteins by means of specific, non-covalent interactions between a protein and a metal complex immobilized at the surface. In particular, reproducible patterns of lactoferrin have been obtained by exploiting the different adsorption properties of this protein on a OH-terminated self-assembled monolayer (SAM) or onto an iron-containing SAM present in certain regions of the pattern. The OH-terminated SAM was etched with a focused ion beam (FIB) in order to produce square regions of bare gold. These regions were selectively covered with a SAM of iron-terpyridine complex, formed via a stepwise procedure involving the initial formation of a mixed component SAM (containing the terpyridine ligand) and the subsequent reaction with an iron(II) salt in order to produce the complex. The patterned substrate was finally allowed to interact with a lactoferrin solution. It is shown that lactoferrin selectively and stably adsorbs on iron-containing layers, whereas it is not retained on the OH-terminated regions of the surface. The use of ToF-SIMS was crucial for obtaining this information, as well as for monitoring each sequential step necessary for the preparation of the patterns.

  6. Emission processes of molecule-metal cluster ions from self-assembled monolayers of octanethiols on gold and silver

    International Nuclear Information System (INIS)

    Arezki, B.; Delcorte, A.; Bertrand, P.

    2004-01-01

    In this contribution, we focus on the emission processes of molecule-metal cluster ions from self-assembled monolayers (SAMs) of octanethiols CH 3 (CH 2 ) 7 SH on gold and silver. To improve our understanding of these complex phenomena, mass spectra and kinetic energy distributions (KEDs) of these two systems have been measured and compared using time-of-flight-SIMS under 15 keV Ga + bombardment. First, the spectra obtained from SAMs/Ag exhibit positive (M-H) m Ag m+1 + and negative (M-H) m Ag m-1 - cluster ions that are generally more intense than the (M-H) m Au n - observed for SAMs/Au. This trend is attributed to the electronegativity difference between S and these two metals resulting in a more ionic Ag-S bond. Second, our results show that, like for the SAM/Au system already investigated, unimolecular dissociation of Ag-thiolate clusters in the acceleration section of the spectrometer is an important formation mechanism. The fraction of the (M-H) m Ag n +,- aggregates formed in the vacuum via this process is even significantly higher than that of the (M-H) m Au n - cluster ions. This suggests that the cluster ions ejected from SAMs/Ag are less stable than those ejected from SAMs/Au. It is also observed that the high energy parts of the KEDs are steeper than for gold, which is probably due to the same phenomenon

  7. Morphology of self assembled monolayers using liquid phase reaction on silica and their effect on the morphology of adsorbed insulin

    Science.gov (United States)

    Sharma, Indu; Pattanayek, Sudip K.; Aggarwal, Varsha; Ghosh, Subhasis

    2017-05-01

    The effect of roughness of two different categories of self-assembled monolayers (SAMs) with propyl amine and propyl groups respectively on the morphology of adsorbed insulin is observed. SAMs are obtained by liquid phase reaction of silica with organo silane coupling agents (SCA). The influence of the morphology and physical characteristics of the SAMs on the reaction time and concentration of the modifiers are explored. We have tested three SCA containing propyl amine with varying groups linked to Si present on it. In addition, we have used a silane coupling agent to prepare SAM of methyl head group. The approach of these molecules towards the surface depends on the head group and the groups linked to Si of the SCA. The morphology of the surfaces is analysed using power spectral density distribution (PSD), skewness, ellipsometry thickness and surface energy. Both chemical nature and physical morphology of the adsorbent influence the morphology of the adsorbed insulin. In general, a low number of aggregates of big size are formed on the surfaces obtained from low concentration of SAMs, while a higher number but of smaller size of aggregates are formed over surfaces obtained from 1% concentration of SAMs modifiers. The peak to valley ratio of the aggregates of insulin is strongly influenced by the size of grains of SCA over the adsorbent.

  8. Chemical Dynamics Simulations of Thermal Desorption of Protonated Dialanine from a Perfluorinated Self-Assembled Monolayer Surface.

    Science.gov (United States)

    Kohale, Swapnil C; Pratihar, Subha; Hase, William L

    2018-04-05

    Classical chemical dynamics simulation results are presented for the thermal desorption kinetics and energetics of protonated dialanine ions (ala 2 -H + ) physisorbed on/in a perfluorinated self-assembled monolayer (F-SAM) surface. Previously developed analytic potentials were used for the F-SAM and the ala 2 -H + /F-SAM intermolecular interaction, and the AMBER valence force field was used for ala 2 -H + . The activation energy, E a = 13.2 kcal/mol, determined from the simulations is consistent with previous simulations of the ala 2 -H + /F-SAM binding energy. The A-factor, 7.8 × 10 11 s -1 , is about an order of magnitude lower than those representative of small molecule desorption from metal and semiconductor surfaces. This finding is consistent with the decreased entropies of ala 2 -H + and the F-SAM upon desorption. Using the Arrhenius parameters for ala 2 -H + desorption from the F-SAM, the lifetime of ala 2 -H + adsorbed on the F-SAM at 300 K is 5 × 10 -3 s. Larger peptide ions are expected to have longer adsorption lifetimes.

  9. Understanding the effects of packing and chemical terminations on the optical excitations of azobenzene-functionalized self-assembled monolayers

    Science.gov (United States)

    Cocchi, Caterina; Draxl, Claudia

    2017-10-01

    In a first-principles study based on many-body perturbation theory, we analyze the optical excitations of azobenzene-functionalized self-assembled monolayers (SAMs) with increasing packing density and different terminations, considering for comparison the corresponding gas-phase molecules and dimers. Intermolecular coupling increases with the density of the chromophores independently of the functional groups. The intense π → π* resonance that triggers photo-isomerization is present in the spectra of isolated dimers and diluted SAMs, but it is almost completely washed out in tightly packed architectures. Intermolecular coupling is partially inhibited by mixing differently functionalized azobenzene derivatives, in particular when large groups are involved. In this way, the excitation band inducing the photo-isomerization process is partially preserved and the effects of dense packing partly counterbalanced. Our results suggest that a tailored design of azobenzene-functionalized SAMs which optimizes the interplay between the packing density of the chromophores and their termination can lead to significant improvements in the photo-switching efficiency of these systems.

  10. A yeast glycolipid biosurfactant, mannosylerythritol lipid, shows high binding affinity towards lectins on a self-assembled monolayer system.

    Science.gov (United States)

    Konishi, Masaaki; Imura, Tomohiro; Fukuoka, Tokuma; Morita, Tomotake; Kitamoto, Dai

    2007-03-01

    Mannosylerythritol lipids (MEL), which are glycolipid biosurfactants secreted by the Pseudozyma yeasts, show not only excellent surface-active properties but also versatile biochemical actions including antitumor and cell-differentiation activities. In order to address the biochemical actions, interactions between MEL-A, the major component of MEL, and different lectins were investigated using the surface plasmon resonance spectroscopy. The monolayer of MEL-A showed high binding affinity to concanavalin A (ConA) and Maackia amurensis lectin-I (MAL-I). The observed affinity constants for ConA and MAL-I were estimated to be 9.48 +/- 1.31 x 10(6) and 3.13 +/- 0.274 x 10(6) M(-1), respectively; the value was comparable to that of Manalpha1-6(Manalpha1-3)Man, which is one of the most specific probe to ConA. Significantly, alpha-methyl-D-mannopyranoside (1 mM) exhibited no binding inhibition between MEL-A and ConA. MEL-A is thus likely to self-assemble to give a high affinity surface, where ConA binds to the hydrophilic headgroup in a different manner from that generally observed in lectin-saccharide interactions. The binding manner should be related with the biochemical actions of MEL toward mammalian cells via protein-carbohydrate interactions.

  11. Partial ion yield and NEXAFS of 2-(perfluorooctyl)ethanethiol self-assembled monolayer: Comparison with PTFE results

    CERN Document Server

    Setoyama, H; Murase, T; Imamura, M; Mase, K; Okudaira, K K; Hara, M; Ueno, N

    2003-01-01

    Partial-ion-yield (PIY) spectra using ion time-of-flight (TOF) method and near-edge absorption fine structure (NEXAFS) spectra were measured for 2-(perfluorooctyl)ethanethiol [CF sub 3 (CF sub 2) sub 7 (CH sub 2) sub 2 SH] self-assembled monolayer (F8-SAM) on Au(1 1 1) near carbon K-edge. The PIY spectra of the F8-SAM at the magic angle, where -CF sub 3 groups exist at the surface were compared with those of the rubbed polytetrafluoroethylene (PTFE) thin film. The F sup + intensity from the F8-SAM at the photon energy of the sharp peak of the NEXAFS, which originates from the excitation of C1s electron to sigma sup * (C-F) states at -CF sub 2 - chain, was extremely smaller than that from the rubbed PTFE film. This result clearly indicates that the ions observed by PIY do not originate from the film inside but from the surface. This was confirmed by changes in ion-TOF mass spectra during soft X-ray induced etching of the F8-SAM. The NEXAFS peaks of the F8-SAM were also assigned by considering PIY results.

  12. Near-field photochemical and radiation-induced chemical fabrication of nanopatterns of a self-assembled silane monolayer

    Directory of Open Access Journals (Sweden)

    Ulrich C. Fischer

    2014-09-01

    Full Text Available A general concept for parallel near-field photochemical and radiation-induced chemical processes for the fabrication of nanopatterns of a self-assembled monolayer (SAM of (3-aminopropyltriethoxysilane (APTES is explored with three different processes: 1 a near-field photochemical process by photochemical bleaching of a monomolecular layer of dye molecules chemically bound to an APTES SAM, 2 a chemical process induced by oxygen plasma etching as well as 3 a combined near-field UV-photochemical and ozone-induced chemical process, which is applied directly to an APTES SAM. All approaches employ a sandwich configuration of the surface-supported SAM, and a lithographic mask in form of gold nanostructures fabricated through colloidal sphere lithography (CL, which is either exposed to visible light, oxygen plasma or an UV–ozone atmosphere. The gold mask has the function to inhibit the photochemical reactions by highly localized near-field interactions between metal mask and SAM and to inhibit the radiation-induced chemical reactions by casting a highly localized shadow. The removal of the gold mask reveals the SAM nanopattern.

  13. Microcontact printing technology as a method of fabrication of patterned self-assembled monolayers for application in nanometrology

    Science.gov (United States)

    Pałetko, Piotr; Moczała, Magdalena; Janus, Paweł; Grabiec, Piotr; Gotszalk, Teodor

    2013-07-01

    This paper is focused on manufacture technology of molecular self-assembled monolayers (SAM) using microcontact printing (μCP) techniqe. This technique, due to its low-cost and simplicity, is a very attractive one for further development of molecular electronics and nanotechnology. The SAM can be produced on gold or silicon oxide using thiol and silane based chemistry respectively[1]. The μCP techniques allow the imposition of molecular structures in specific areas. The chemical properties of the fabricated layers depend on the functional groups of tail molecules. Such structures can be used as chemical receptors or as interface between the substrate and the biosensor receptors [2]. Architecture of the tail molecule determines the chemical reactivity and hydrophilic or hydrophobic properties. In addition it modifies the tribological properties [4] and electrical structure parameters, such as contact potential diference (CPD) [5]. The height of the SAM structure containing carbon chain is highly dependent on the length and type of binding molecules to the substrate, which enables application of the μCP SAM structures in height metrology. The results of these studies will be presented in the work.

  14. Self-assembled monolayers with different chemical group substrates for the study of MCF-7 breast cancer cell line behavior

    International Nuclear Information System (INIS)

    Yan, Hongji; Yin, Yanbin; Li, Yu; Tian, Weiming; Zhang, Song; Nie, Yongzhan; He, Jin; Wang, Xiumei; Cui, Fuzhai; Chen, Xiongbiao

    2013-01-01

    The interactions between cancer cells and the extracellular matrix (ECM) are important with respect to a number of cell behavoirs, yet remain unclear. In this study, self-assembled monolayers with different terminal chemical groups (hydroxyl (-OH), carboxyl (-COOH), animo (-NH 2 ), mercapto (-SH), and methyl (-CH 3 )) were employed as substrates for the culture of MCF-7 cells to examine effects on cell behavior. Cell spreading was investigated by scanning electron microscopy, tallin expression by immunofluorescence, proliferation rate by counting cell numbers, cell cycle by flow cytometry, metabolism by high-performance liquid chromatography and cell migration by live cell imaging. Annexin V-FITC (fluorescein isothiocyanate) and JC-1 assays were performed to determine cell apoptosis and mitochondrial membrane potential, respectively. Our results demonstrate the varied behaviors of MCF-7 cells in response to different chemical groups. Specifically, NH 2 and COOH terminal functional groups promote proliferation, the production of lactic acid and mobility of MCF-7 cells; SH and OH terminal groups enhance the expression and distribution of tallin but result in weak cell proliferation, metabolism, spreading and mobility. These results are meaningful for uncovering the interactions between the ECM and cancer cells; they are potentially useful for designing novel cancer treatment strategies. (paper)

  15. Self-Assembly, Guest Capture, and NMR Spectroscopy of a Metal-Organic Cage in Water

    Science.gov (United States)

    Go, Eun Bin; Srisuknimit, Veerasak; Cheng, Stephanie L.; Vosburg, David A.

    2016-01-01

    A green organic-inorganic laboratory experiment has been developed in which students prepare a self-assembling iron cage in D[subscript 2]O at room temperature. The tetrahedral cage captures a small, neutral molecule such as cyclohexane or tetrahydrofuran. [Superscript 1]H NMR analysis distinguishes captured and free guests through diagnostic…

  16. On the influence of the aliphatic linker on fabrication of highly ordered and orientated self-assembled monolayers of aromatic selenols on AU(111)

    KAUST Repository

    Azzam, Waleed

    2014-03-06

    Self-assembled monolayers (SAMs) formed by adsorption of 1,2-dibenzyldiselenide (DPMSe) and 1,2-diphenyldiselenide (DBSe) on Au(111) substrates at room temperature have been characterized using scanning tunnelling microscopy, X-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and low-energy electron diffraction. Upon adsorption, the Se-Se bonds in DPMSe and DBSe were cleaved on the gold surface to form phenylmethaneselenolate (PMSe) and benzeneselenolate (BSe) species, respectively. Although both PMSe and BSe molecular entities only differ in their structure (an additional methyl group in PMSe), the resulting monolayer films revealed noteworthy dissimilarities regarding their adlayer SAM structure and surface morphology. The molecular adlayer structure and orientation of PMSe and BSe species were found to vary significantly with the immersion time (IT). The resulting PMSe films were poorly organized, and the structure was described by a (4√3 × 2) rectangular unit cell for the SAMs prepared with 24 h of IT. Moreover, the PMSe-SAMs were found to be unstable upon exposure to air for a long time. Our results showed that exposure to air for 48 h results in the formation of small bright ad-islands, which have a height corresponding to that of a single atomic step on the Au(111). Contrary, BSe-SAMs exhibited densely packed and well-ordered monolayers, and two different structural phases were resolved at short and long ITs. The most densely packed structure was obtained for SAMs prepared with very short ITs (10 min). Upon increasing the IT, the SAMs exhibited structural changes to a lower density of molecular packing structure. The spectroscopic data also confirmed this structural transformation by suggesting an upright orientation for BSe-SAMs prepared after short ITs and strongly inclined adsorption geometry for SAMs prepared after long ITs. © 2014 American Chemical Society.

  17. Self-assembled thiol monolayers with carboxylic acid functionality: Measuring pH-dependent phase transitions with the quartz crystal microbalance

    International Nuclear Information System (INIS)

    Wang, J.; Frostman, L.M.; Ward, M.D.

    1992-01-01

    The resonant frequency of the quartz crystal microbalance (QCM) coated with self-assembled thiol monolayers with carboxylic acid functionality is measured while the pH of the aqueous solvent is changed in this paper. Increased tensile stress with increasing pH activity partially contributed to the QCM response, but the major contribution was due to changes in the viscoelastic properties of the hydrodynamic layer in contact with the QCM. 28 refs., 3 figs

  18. Improving Light Extraction of Organic Light-Emitting Devices by Attaching Nanostructures with Self-Assembled Photonic Crystal Patterns

    Directory of Open Access Journals (Sweden)

    Kai-Yu Peng

    2014-01-01

    Full Text Available A single-monolayered hexagonal self-assembled photonic crystal (PC pattern fabricated onto polyethylene terephthalate (PET films by using simple nanosphere lithography (NSL method has been demonstrated in this research work. The patterned nanostructures acted as a scattering medium to extract the trapped photons from substrate mode of optical-electronic device for improving the overall external quantum efficiency of the organic light-emitting diodes (OLEDs. With an optimum latex concentration, the distribution of self-assembled polystyrene (PS nanosphere patterns on PET films can be easily controlled by adjusting the rotation speed of spin-coater. After attaching the PS nanosphere array brightness enhancement film (BEF sheet as a photonic crystal pattern onto the device, the luminous intensity of OLEDs in the normal viewing direction is 161% higher than the one without any BEF attachment. The electroluminescent (EL spectrum of OLEDs with PS patterned BEF attachment also showed minor color offset and superior color stabilization characteristics, and thus it possessed the potential applications in all kinds of display technology and solid-state optical-electronic devices.

  19. Dithiocarbamate Self-Assembled Monolayers as Efficient Surface Modifiers for Low Work Function Noble Metals

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Dominik; Schäfer, Tobias; Schulz, Philip; Jung, Sebastian; Rittich, Julia; Mokros, Daniel; Segger, Ingolf; Maercks, Franziska; Effertz, Christian; Mazzarello, Riccardo; Wuttig, Matthias

    2016-09-06

    Tuning the work function of the electrode is one of the crucial steps to improve charge extraction in organic electronic devices. Here, we show that N,N-dialkyl dithiocarbamates (DTC) can be effectively employed to produce low work function noble metal electrodes. Work functions between 3.1 and 3.5 eV are observed for all metals investigated (Cu, Ag, and Au). Ultraviolet photoemission spectroscopy (UPS) reveals a maximum decrease in work function by 2.1 eV as compared to the bare metal surface. Electronic structure calculations elucidate how the complex interplay between intrinsic dipoles and dipoles induced by bond formation generates such large work function shifts. Subsequently, we quantify the improvement in contact resistance of organic thin film transistor devices with DTC coated source and drain electrodes. These findings demonstrate that DTC molecules can be employed as universal surface modifiers to produce stable electrodes for electron injection in high performance hybrid organic optoelectronics.

  20. Experimental Investigation Of Microbially Induced Corrosion Of Test Samples And Effect Of Self-assembled Hydrophobic Monolayers. Exposure Of Test Samples To Continuous Microbial Cultures, Chemical Analysis, And Biochemical Studies

    CERN Document Server

    Laurinavichius, K S

    1998-01-01

    Experimental Investigation Of Microbially Induced Corrosion Of Test Samples And Effect Of Self-assembled Hydrophobic Monolayers. Exposure Of Test Samples To Continuous Microbial Cultures, Chemical Analysis, And Biochemical Studies

  1. Enhancement of seeding for electroless Cu plating of metallic barrier layers by using alkyl self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Sung-Te [Department of Electronic Engineering, Hsiuping University of Science and Technology, Dali 412, Taichung, Taiwan (China); Chung, Yu-Cheng [Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China); Fang, Jau-Shiung [Department of Materials Science and Engineering, National Formosa University, Huwei 632, Taiwan (China); Cheng, Yi-Lung [Department of Electrical Engineering, National Chi-Nan University, Puli, Nantou 545, Taiwan (China); Chen, Giin-Shan, E-mail: gschen@fcu.edu.tw [Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China)

    2017-05-31

    Highlights: • Ta barrier layers are used as model substrates for seeding of electroless plating. • Ta layers seeded with Ta-OH yield seeds with limited density and large size (>10 nm). • Substantial improvement of seeding is obtained with functionalized SAMs. • The mechanism of seeding improvement by functionalized SAMs is clearly clarified. - Abstract: Tethering a self-assembled monolayer (SAM) on ultralow-k (porous) dielectric materials as a seed-trapping layer for electroless Cu plating has been extensively studied. By contrast, literature on direct electroless Cu plating of metallic barrier layers assisted by SAMs is scarce. Therefore, Ta, a crucial component of barrier materials for Cu interconnect metallization, was investigated as a model substrate for a new seeding (Ni catalyst formation) process of electroless Cu plating. Transmission and scanning electron microscopies indicated that catalytic particles formed on Ta films through Ta−OH groups tend to become aggregates with an average size of 14 nm and density of 2 × 10{sup 15} m{sup −2}. By contrast, Ta films with a plasma-functionalized SAM tightly bound catalytic particles without agglomeration, thus yielding a markedly smaller size (3 nm) and higher density (3 × 10{sup 16} m{sup −2}; one order greater than those formed by other novel methods). X-ray photoelectron spectroscopy clearly identified the types of material species and functional groups induced at each step of the seeding process. Moreover, the phase of the catalytic particles, either nickel alkoxide, Ni(OH){sub 2}, or metallic Ni, along with the seed-bonding mechanism, was also unambiguously distinguished. The enhancement of film-formation quality of Cu by the new seeding process was thus demonstrated.

  2. Influence of molecular distortion on the exciton quenching for quaterthiophene-terminated self-assembled monolayers on Au(111)

    Science.gov (United States)

    Kato, Hiroyuki S.; Murakami, Yoshinari; Saitoh, Riyo; Osumi, Yuji; Okaue, Daijiro; Kiriyama, Yoshiaki; Ueba, Takahiro; Yamada, Takashi; Ie, Yutaka; Aso, Yoshio; Munakata, Toshiaki

    2018-03-01

    We have studied the dynamics of photoexcited electronic states for structure-specific alkanethiolate-based self-assembled monolayers (SAMs) on Au(111). At the even numbers of methylene units (n) in the alkylene chain, a molecular distortion due to strong interference between the end substituents is expected. Focused on this geometrical perturbation, here, we examine the influence of the molecular distortion on the quenching process of photoexcited quaterthiophene (4T)-terminated alkanethiolate SAMs (4TCnS-SAMs) for even n (= 6 and 8). The occupied and unoccupied electronic levels of 4TCnS-SAMs are specified by ultraviolet photoelectron spectroscopy (UPS) and two-photon photoemission (2PPE) spectroscopy, respectively. The quenching rate, i.e., lifetime (τn), of the photoexcited state for 4TCnS-SAMs is evaluated by the time-resolved 2PPE measurements. In comparison to the previously reported results for odd n [J. Phys. Chem. C 119 (2015) 7400-7407], we find that τn for even n is not in the middle of those for n ± 1 but close to that for n - 1, i.e., τ6 ≈ τ5 and τ8 ≈ τ7, in contrast to the negligible difference in the electronic levels for all n. By the examination of molecular configurations using scanning tunneling microscopy (STM) and infrared reflection absorption spectroscopy (IRAS), we elucidate the weak n dependence of the 4T group orientation and the n-parity-dependent conformation change of alkylene chain. We conclude that the n parity dependence of τn results from a structural distortion of the aliphatic alkylene chain, in which a skewed alkylene chain appears for even n, rather than the electronic modification of the aromatic 4T groups.

  3. Redox-induced ion pairing of anionic surfactants with ferrocene-terminated self-assembled monolayers: Faradaic electrochemistry and surfactant aggregation at the monolayer/liquid interface.

    Science.gov (United States)

    Dionne, Eric R; Sultana, Tania; Norman, Lana L; Toader, Violeta; Badia, Antonella

    2013-11-20

    Oxidoreduction of self-assembled monolayers (SAMs) of ferrocenyldodecanethiolate on gold in aqueous solutions of surface-active sodium n-alkyl sulfates (NaCnSO4) of 6, 8, 10, and 12 carbons is investigated by cyclic voltammetry and surface plasmon resonance. The effects of surfactant micellization and alkyl chain length on the redox response of the surface-tethered ferrocenes are examined. The SAM redox electrochemistry is sensitive to the surfactant aggregation state in solution. The nonideal behavior of the sodium alkyl sulfates at concentrations above the critical micelle concentration leads to a non-Nernstian variation of the SAM redox potential with concentration. The presence of micelles in solution results in decreased anodic-to-cathodic peak separations and anodic peak full widths at half-maximum. A longer alkyl chain length results in an increased ability of the alkyl sulfate anion to ion pair with the SAM-bound ferrocenium, resulting in oxidation of the ferrocene at lower potential. A comparison of the SAM redox potential at a fixed surfactant concentration of ideal behavior suggests a 4.5 × 10(4) difference in the ion-pairing abilities of the shorter-chain C6SO4(-) and longer-chain C12SO4(-). One-half of the available SAM-bound ferrocenes are oxidized in the NaCnSO4 electrolyte. Surfactant anions adsorb and assemble onto the SAM surface by specific ion-pairing interactions between the sulfate headgroups and oxidized ferrocenium species, forming an interdigitated monolayer in which the surfactant anions alternate between a heads-down and heads-up orientation with respect to the SAM. The work presented points to applications of ferrocenylalkanethiolate SAMs as anion-selective membranes, probes of micelle formation, and surfaces for the electrochemically switchable assembly of organosulfates.

  4. Damage-free surface treatment of carbon nanotubes and self-assembled monolayer devices using a neutral beam process for fusing top-down and bottom-up processes

    International Nuclear Information System (INIS)

    Samukawa, Seiji; Ishikawa, Yasushi; Okumura, Keiji; Sato, Yoshinori; Tohji, Kazuyuki; Ishida, Takao

    2008-01-01

    Plasma etching processes have been used for the past 30 years to shrink the pattern size of integrated devices. However, the inherent problems of plasma processes, such as ultraviolet photon radiation damage, limit the effectiveness of etching and surface treatments of nanoscale devices. To overcome these problems, we developed a neutral beam surface treatment process. The process uses neutral beams and a defect-free surface process to fabricate carbon nanotubes and self-assemble mono-layer devices. We found that neutral beams can be used to produce atomically defect-free surfaces in carbon nanotubes and organic molecules. This technique has potential for fabricating nanodevices

  5. Effect of fluorocarbon self-assembled monolayer films on sidewall adhesion and friction of surface micromachines with impacting and sliding contact interfaces

    International Nuclear Information System (INIS)

    Xiang, H.; Komvopoulos, K.

    2013-01-01

    A self-assembled monolayer film consisting of fluoro-octyltrichlorosilane (FOTS) was vapor-phase deposited on Si(100) substrates and polycrystalline silicon (polysilicon) surface micromachines. The hydrophobic behavior and structural composition of the FOTS film deposited on Si(100) were investigated by goniometry and X-ray photoelectron spectroscopy, respectively. The effects of contact pressure, relative humidity, temperature, and impact/sliding cycles on the adhesive and friction behavior of uncoated and FOTS-coated polysilicon micromachines (referred to as the Si and FOTS/Si micromachines, respectively) were investigated under controlled loading and environmental conditions. FOTS/Si micromachines demonstrated much lower and stable adhesion than Si micromachines due to the highly hydrophobic and conformal FOTS film. Contrary to Si micromachines, sidewall adhesion of FOTS/Si micromachines demonstrated a weak dependence on relative humidity, temperature, and impact cycles. In addition, FOTS/Si micromachines showed low and stable adhesion and low static friction for significantly more sliding cycles than Si micromachines. The adhesive and static friction characteristics of Si and FOTS/Si micromachines are interpreted in the context of physicochemical surface changes, resulting in the increase of the real area of contact and a hydrophobic-to-hydrophilic transition of the surface chemical characteristics caused by nanoscale surface smoothening and the removal of the organic residue (Si micromachines) or the FOTS film (FOTS/Si micromachines) during repetitive impact and oscillatory sliding of the sidewall surfaces.

  6. Characterization of Functionalized Self-Assembled Monolayers and Surface-Attached Interlocking Molecules Using Near-Edge X-ray Absorption Fine Structure Spectroscopy

    International Nuclear Information System (INIS)

    Willey, T; Willey, T

    2004-01-01

    Quantitative knowledge of the fundamental structure and substrate binding, as well as the direct measurement of conformational changes, are essential to the development of self-assembled monolayers (SAMs) and surface-attached interlocking molecules, catenanes and rotaxanes. These monolayers are vital to development of nano-mechanical, molecular electronic, and biological/chemical sensor applications. This dissertation investigates properties of functionalized SAMs in sulfur-gold based adsorbed molecular monolayers using quantitative spectroscopic techniques including near-edge x-ray absorption fine structure spectroscopy (NEXAFS) and x-ray photoelectron spectroscopy (XPS). The stability of the gold-thiolate interface is addressed. A simple model SAM consisting of dodecanethiol adsorbed on Au(111) degrades significantly in less than 24 hours under ambient laboratory air. S 2p and O 1s XPS show the gold-bound thiolates oxidize to sulfinates and sulfonates. A reduction of organic material on the surface and a decrease in order are observed as the layer degrades. The effect of the carboxyl vs. carboxylate functionalization on SAM structure is investigated. Carboxyl-terminated layers consisting of long alkyl-chain thiols vs. thioctic acid with short, sterically separated, alkyl groups are compared and contrasted. NEXAFS shows a conformational change, or chemical switchability, with carboxyl groups tilted over and carboxylate endgroups more upright. Surface-attached loops and simple surface-attached rotaxanes are quantitatively characterized, and preparation conditions that lead to desired films are outlined. A dithiol is often insufficient to form a molecular species bound at each end to the substrate, while a structurally related disulfide-containing polymer yields surface-attached loops. Similarly, spectroscopic techniques show the successful production of a simple, surface-attached rotaxane that requires a ''molecular riveting'' step to hold the mechanically attached

  7. Electrochemical and surface plasmon resonance characterization of β-cyclodextrin-based self-assembled monolayers and evaluation of their inclusion complexes with glucocorticoids

    Science.gov (United States)

    Frasconi, Marco; Mazzei, Franco

    2009-07-01

    This paper describes the characterization of a self-assembled β-cyclodextrin (β-CD)-derivative monolayer (β-CD-SAM) on a gold surface and the study of their inclusion complexes with glucocorticoids. To this aim the arrangement of a self-assembled β-cyclodextrin-derivative monolayer on a gold surface was monitored in situ by means of surface plasmon resonance (SPR) spectroscopy and double-layer capacitance measurements. Film thickness and dielectric constant were evaluated for a monolayer of β-CD using one-color-approach SPR. The selectivity of the β-CD host surface was verified by using electroactive species permeable and impermeable in the β-CD cavity. The redox probe was selected according to its capacity to permeate the β-CD monolayer and its electrochemical behavior. In order to evaluate the feasibility of an inclusion complex between β-CD-SAM with some steroids such as cortisol and cortisone, voltammetric experiments in the presence of the redox probes as molecules competitive with the steroids have been performed. The formation constant of the surface host-guest by β-CD-SAM and the steroids under study was calculated.

  8. Whispering-gallery-mode microlaser based on self-assembled organic single-crystalline hexagonal microdisks.

    Science.gov (United States)

    Wang, Xuedong; Liao, Qing; Kong, Qinghua; Zhang, Yi; Xu, Zhenzhen; Lu, Xiaomei; Fu, Hongbing

    2014-06-02

    Whispering-gallery-mode (WGM) resonators of semiconductor microdisks have been applied for achieving low-threshold and narrow-linewidth microlasers, but require sophisticated top-down processing technology. Organic single-crystalline hexagonal microdisks (HMDs) of p-distyrylbenzene (DSB) self-assembled from solution can function as WGM microresonators with a cavity quality factor (Q) of 210. Both multiple- and single-mode lasing had been achieved using DSB HMDs with an edge length of 4.3 and 1.2 μm, respectively. These organic microdisks fabricated by bottom-up self-assembly approach may offer potential applications as low-threshold microlaser sources for photonic circuit integration. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Self-assembly and Self-organization in Computer Science and Biology (Dagstuhl Seminar 15402)

    OpenAIRE

    Danos, Vincent; Koeppl, Heinz

    2016-01-01

    This report documents the program and the outcomes of Dagstuhl Seminar 15402 "Self-assembly and Self-organization in Computer Science and Biology". With the trend of technological systems to become more distributed they tend to resemble closer biological systems. Biological systems on all scale are distributed and most often operate without central coordination. Taking the morphogenesis as an example, it is clear that the complexity and precision of distributed mechanisms in biology supersede...

  10. Self Assembled Monolayers

    Indian Academy of Sciences (India)

    , the film formed dampens surface waves and ripples. The holiness of water has been attributed to this phenomena rather than to the oiliness of oil! Aristotle explained. T Padeep is at the. DepartDaeJ)! of Chemistry and Regional. Sophisticated.

  11. Self Assembled Monolayers

    Indian Academy of Sciences (India)

    one paper he discussed the effect of olive oil films on the surface tension of water and concluded that the films of olive oil are. 10-20 A in thickness. Rayleigh appeared to have the belief that oil spreads on the water surface to such an extent that the film thickness approaches molecular dimensions. Direct measure- ments of ...

  12. Nanoscale Structure of Self-Assembling Hybrid Materials of Inorganic and Electronically Active Organic Phases

    Energy Technology Data Exchange (ETDEWEB)

    Sofos, M.; Goswami, D.A. Stone D.K.; Okasinski, J.S.; Jin, H.; Bedzyk, M.J.; Stupp, S.I. (NWU)

    2008-10-06

    Hybrid materials with nanoscale structure that incorporates inorganic and organic phases with electronic properties offer potential in an extensive functional space that includes photovoltaics, light emission, and sensing. This work describes the nanoscale structure of model hybrid materials with phases of silica and electronically active bola-amphiphile assemblies containing either oligo(p-phenylene vinylene) or oligo(thiophene) segments. The hybrid materials studied here were synthesized by evaporation-induced self-assembly and characterized by X-ray scattering techniques. Grazing-incidence X-ray scattering studies of these materials revealed the formation of two-dimensional hexagonally packed cylindrical micelles of the organic molecules with diameters between 3.1 and 3.6 nm and cylindrical axes parallel to the surface. During the self-assembly process at low pH, the cylindrical aggregates of conjugated molecules become surrounded by silica giving rise to a hybrid structure with long-range order. Specular X-ray reflectivity confirmed the long-range periodicity of the hybrid films within a specific range of molar ratios of tetraethyl orthosilicate to cationic amphiphile. We did not observe any long-range ordering in fully organic analogues unless quaternary ammonium groups were replaced by tertiary amines. These observations suggest that charge screening in these biscationic conjugated molecules by the mineral phase is a key factor in the evolution of long range order in the self-assembling hybrids.

  13. Determination of low levels of cadmium ions by the under potential deposition on a self-assembled monolayer on gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Noyhouzer, Tomer [Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Mandler, Daniel, E-mail: mandler@vms.huji.ac.il [Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

    2011-01-17

    The electrochemical determination of low levels of Cd using a self-assembled monolayer (SAM) modified Au electrode is reported. Determination was based on the stripping of Cd, which was deposited by under potential deposition (UPD). A series of short alkanethiol SAMs bearing different end groups, i.e., sulfonate, carboxylate and ammonium, were examined. Lowest level of detection (ca. 50 ng L{sup -1}) was achieved with a 3-mercaptopropionic acid (MPA) monolayer using subtractive anodic square wave voltammetry (SASV). Additional surface methods, namely, reductive desorption and X-ray photoelectron spectroscopy, were applied to determine the interfacial structure of the electrodeposited Cd on the modified electrodes. We conclude that the deposited Cd forms a monoatomic layer, which bridges between the gold surface and the alkanethiol monolayer associating with both the gold and the sulfur atoms.

  14. Determination of low levels of cadmium ions by the under potential deposition on a self-assembled monolayer on gold electrode.

    Science.gov (United States)

    Noyhouzer, Tomer; Mandler, Daniel

    2011-01-17

    The electrochemical determination of low levels of Cd using a self-assembled monolayer (SAM) modified Au electrode is reported. Determination was based on the stripping of Cd, which was deposited by under potential deposition (UPD). A series of short alkanethiol SAMs bearing different end groups, i.e., sulfonate, carboxylate and ammonium, were examined. Lowest level of detection (ca. 50 ngL(-1)) was achieved with a 3-mercaptopropionic acid (MPA) monolayer using subtractive anodic square wave voltammetry (SASV). Additional surface methods, namely, reductive desorption and X-ray photoelectron spectroscopy, were applied to determine the interfacial structure of the electrodeposited Cd on the modified electrodes. We conclude that the deposited Cd forms a monoatomic layer, which bridges between the gold surface and the alkanethiol monolayer associating with both the gold and the sulfur atoms. Copyright © 2010 Elsevier B.V. All rights reserved.

  15. Synthesis of organic-inorganic hybrid compounds and their self-assembled behavior in different solvents.

    Science.gov (United States)

    Zhuang, Xuewen; Wang, Wenguang; Hao, Jingcheng

    2018-06-01

    Self-assembly behavior of polyoxometalates (POMs) is influenced by the functional group linked with polyoxometalates structure. We modified the POMs with organic molecule terpyridine to endow POMs the ability to assemble into nanostructure and control the properties of POMs. An amphiphilic organic-inorganic hybrid compound was prepared through combining the 4'-para-phenylcarboxyl-2,2':6',2''-terpyridine (PPCT) with POM to form the (TBA) 3 POM-PPCT. After cationic exchange, tetrabutylammonium cation (TBA + ) can be turned into H + to produce H 3 POM-PPCT. H 3 POM-PPCT showed excellent self-assembly behavior in different solvents. By adjusting the proportion of solvents, different fibers and leaf-like aggregates were obtained, which were determined by SEM and TEM observations. According to the experimental observations, mechanism of the formation of nanostructures was established. The redox properties of POMs can be maintained after the modification with PPCT, which were demonstrated by cyclic voltammetry (CV) measurements. The successful synthesis of these POMs may provide us an opportunity to find more functionalized ramifications of POMs, with self-assembled structures controlled in different solvent, but the interesting properties of these novel POMs can also provide motivation and guidance for the further development of novel functionalized POMs. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Molecular simulations of self-assembly processes in metal-organic frameworks: Model dependence

    Science.gov (United States)

    Biswal, Debasmita; Kusalik, Peter G.

    2017-07-01

    Molecular simulation is a powerful tool for investigating microscopic behavior in various chemical systems, where the use of suitable models is critical to successfully reproduce the structural and dynamic properties of the real systems of interest. In this context, molecular dynamics simulation studies of self-assembly processes in metal-organic frameworks (MOFs), a well-known class of porous materials with interesting chemical and physical properties, are relatively challenging, where a reasonably accurate representation of metal-ligand interactions is anticipated to play an important role. In the current study, we both investigate the performance of some existing models and introduce and test new models to help explore the self-assembly in an archetypal Zn-carboxylate MOF system. To this end, the behavior of six different Zn-ion models, three solvent models, and two ligand models was examined and validated against key experimental structural parameters. To explore longer time scale ordering events during MOF self-assembly via explicit solvent simulations, it is necessary to identify a suitable combination of simplified model components representing metal ions, organic ligands, and solvent molecules. It was observed that an extended cationic dummy atom (ECDA) Zn-ion model combined with an all-atom carboxylate ligand model and a simple dipolar solvent model can reproduce characteristic experimental structures for the archetypal MOF system. The successful use of these models in extensive sets of molecular simulations, which provide key insights into the self-assembly mechanism of this archetypal MOF system occurring during the early stages of this process, has been very recently reported.

  17. Work function shifts of a zinc oxide surface upon deposition of self-assembled monolayers: a theoretical insight.

    Science.gov (United States)

    Cornil, D; Van Regemorter, T; Beljonne, D; Cornil, J

    2014-10-14

    We have investigated at the theoretical Density Functional Theory level the way the work function of zinc oxide layers is affected upon deposition of self-assembled monolayers (SAMs). 4-tert-Butylpyridine (4TBP) and various benzoic acids (BA) were adsorbed on the apolar (101[combining macron]0) ZnO and used as probe systems to assess the influence of several molecular parameters. For the benzoid acids, we have investigated the impact of changing the nature of the terminal group (H, CN, OCH3) and the binding mode of the carboxylic acid (monodentate versus bidentate) on the apolar (101[combining macron]0) surface. For each system, we have quantified the contribution from the molecular core and the anchoring group as well as of the degree of surface reconstruction on the work function shift. For the benzoic acids, the structural reorganization of the surface induces a negative shift of the work function by about 0.3 ± 0.15 eV depending on the nature of the binding mode, irrespective of the nature of the terminal function. The bond-dipole potential strongly contributes to the modification of the work function, with values in the range +1.2 to +2.0 eV. In the case of 4TBP, we further characterized the influence of the degree of coverage and of co-adsorbed species (H, OH, and water molecules) on the ZnO/SAM electronic properties as well as the influence of the ZnO surface polarity by considering several models of the polar (0001) ZnO surface. The introduction of water molecules in the (un)dissociated form at full coverage on the non-polar surface only reduces the work function by 0.3-0.4 eV compared to a reference system without co-adsorbed species. Regarding the polar surface, the work function is also significantly reduced upon deposition of a single 4BTP molecule (from -1.44 eV to -1.73 eV for our model structures), with a shift similar in direction and magnitude compared to the non-polar surfaces.

  18. Hierarchised luminescent organic architectures: design, synthesis, self-assembly, self-organisation and functions.

    Science.gov (United States)

    Maggini, Laura; Bonifazi, Davide

    2012-01-07

    This critical review aims at highlighting the prevailing supramolecular approaches employed nowadays in the preparation of luminescent hierarchised materials. Specifically, it has the ambition to illustrate how progresses in the control of the supramolecular interaction toolbox ultimately led to the development of spectacular luminescent nano- and micro-architectures, through a combination of molecular self-assembly and self-organisation processes involving organic π-conjugated molecules. The reader will be guided through a systematic exploration of the most common avenues to prepare and characterise luminescent self-assembled/self-organised materials embedded into one-, two- or three-dimensional networks, accompanied by a critical discussion of their main advantages and limitations. Key representative examples of this research field will be thoroughly described, with a particular focus on those systems displaying potential on the device application scene. Particular attention will be devoted to the design and synthetic approaches aimed at the preparation of the primary π-conjugated molecular modules, the chemical, structural and electronic properties of which dramatically influence the fate and the features of the self-assembled/self-organised material (215 references). This journal is © The Royal Society of Chemistry 2012

  19. Equilibrium and non-equilibrium kinetics of self-assembled surfactant monolayers: a vibrational sum-frequency study of dodecanoate at the fluorite-water interface.

    Science.gov (United States)

    Schrödle, Simon; Richmond, Geraldine L

    2008-04-16

    The adsorption, desorption, and equilibrium monomer exchange processes of sodium dodecanoate at the fluorite(CaF 2)-water interface have been studied. For the first time, we use in situ vibrational sum-frequency spectroscopy (VSFS) to gain insights into the mechanism and kinetics of monolayer self-assembly at the mineral-water interface. By exploiting the nonlinear optical response of the adsorbate, the temporal correlation of headgroup adsorption and alignment of the surfactant's alkyl chain was monitored. Because of the unique surface-specificity of VSFS, changes in the interfacial water structure were also tracked experimentally. The spectra clearly reveal that the structure of interfacial water molecules is severely disturbed at the start of the adsorption process. With the formation of a well-ordered adsorbate layer, it is partially reestablished; however, the molecular orientation and state of coordination is significantly altered. Even at very low surfactant concentrations, overcharging of the mineral surface (i.e., the adsorption of adsorbates past the point of electrostatic equilibrium) was observed. This points out the importance of effects other than electrostatic interactions and it is proposed that cooperative effects of both water structure and surfactant hemimicelle formation at the interface are key factors. The present study also investigates desorption kinetics of partially and fully established monolayers and a statistical model for data analysis is proposed. Additional experiments were performed in the presence of electrolytes and showed that uni- and divalent anions affect the nonequilibrium kinetics of self-assembled monolayers in strikingly different ways.

  20. Scanning tunneling microscopy studies of corrosion passivation and nanometer-scale lithography with self-assembled monolayers

    Science.gov (United States)

    Zamborini, Francis Patrick

    The research in this dissertation examines the possible applications of organomercaptan self-assembled monolayers (SAMs) for corrosion passivation and nanometer-scale lithography. We examined linear-chain n-alkanethiol and aromatic SAMs in these studies and used scanning tunneling microscopy (STM) as the main tool for surface characterization. The corrosion passivation properties of n-alkanethiol SAMs were studied on Au in aqueous CN- and Br - solutions and on underpotentially deposited Cu on Au (Au/Cu-UPD) in aqueous HClO4. All SAMs suppress corrosion and shift the potential for corrosion to more positive potentials compared to that on the unmodified metals. We found that corrosion of n-alkanethiol SAM-modified Au begins at defects in the monolayer and the surface morphology depends on the functional end group of the SAM. Corrosion on the unpassivated metal surface begins at high energy sites such as step edges and pits. The chain length and functional end group of SAMs were varied to determine which factors were most important for the best protection against corrosion. We found that corrosion passivation improves with increasing chain length and more hydrophilic functional end groups like OH and COOH protect better than hydrophobic end groups like CH3. The passivation properties of linear-chain SAMs was compared with aromatic SAMs and we found that if they are equally thick and contain the same functional end group, the aromatic SAMs are superior. One goal of this research was to improve the barrier properties of SAMs. We found that depositing a single layer of Cu onto Au before adsorbing the SAM improved its barrier properties dramatically compared to when the SAM was adsorbed directly to the Au. In summary, the corrosion-related studies in this dissertation discuss the corrosion mechanism of SAM-modified metal surfaces, the important factors that determine the passivation properties of SAMs, and a strategy for dramatically improving the barrier properties of

  1. Investigation of the geometrical arrangement and single molecule charge transport in self-assembled monolayers of molecular towers based on tetraphenylmethane tripod

    Czech Academy of Sciences Publication Activity Database

    Sebechlebská, T.; Šebera, Jakub; Kolivoška, Viliam; Lindner, M.; Gasior, Jindřich; Meszáros, G.; Valášek, M.; Mayor, M.; Hromadová, Magdaléna

    2017-01-01

    Roč. 258, DEC 20 (2017), s. 1191-1200 ISSN 0013-4686 R&D Projects: GA ČR GJ16-07460Y Grant - others:AV ČR(CZ) MTA-16-02 Program:Bilaterální spolupráce Institutional support: RVO:61388955 Keywords : molecular electronics * multipodal platforms * reductive desorption of self-assembled monolayers Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 4.798, year: 2016

  2. Interfacial engineering of self-assembled monolayer modified semi-roll-to-roll planar heterojunction perovskite solar cells on flexible substrates

    DEFF Research Database (Denmark)

    Gu, Zhuowei; Zuo, Lijian; Larsen-Olsen, Thue Trofod

    2015-01-01

    The morphologies of the perovskite (e.g. CH3NH3PbI3) layer are demonstrated to be critically important for highly efficient perovskite solar cells. This work applies 3-aminopropanoic acid as a self-assembled monolayer (C3-SAM) on a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT...... 3.7% to 5.1%. The successful application of the facile HTL modification indicates a common strategy for SAM material design and selection for efficiency enhancement in perovskite photovoltaic devices....

  3. An introduction to ultrathin organic films from Langmuir-Blodgett to self-assembly

    CERN Document Server

    Ulman, Abraham

    1991-01-01

    The development of oriented organic monomolecular layers by the Langmuir-Blodgett (LB) and self-assembly (SA) techniques has led researchers toward their goal of assembling individual molecules into highly ordered architectures. Thus the continually growing contribution of LB and SA systems to the chemistry and physics of thin organic films is widely recognized. Equally well-known is the difficulty in keeping up to date with the burgeoning multidisciplinary research in this area. Dr. Ulman provides a massive survey of the available literature. The book begins with a section on analytical tools

  4. Direct imaging by atomic force microscopy of surface-localized self-assembled monolayers on a cuprate superconductor and surface X-ray scattering analysis of analogous monolayers on the surface of water

    DEFF Research Database (Denmark)

    Schougaard, Steen B.; Reitzel, Niels; Bjørnholm, Thomas

    2007-01-01

    A self-assembled monolayer of CF3(CF2)(3)(CH2)(11)NH2 atop the (001) surface of the high-temperature superconductor YBa2Cu3O7-x was imaged by atomic force microscopy (AFM). The AFM images provide direct 2D-structural evidence for the epitaxial 5.5 angstrom square root 2 x root 2R45 degrees unit...... was studied by grazing-incidence X-ray diffraction and specular X-ray reflectivity. Structural differences and similarities between the water-supported and superconductor-localized monolayers are discussed....

  5. Submicro photopatterning of alkanethiolate self-assembled monolayer using a negative mask and its application in the fabrication of biomolecular photodiode

    International Nuclear Information System (INIS)

    Oh, Se Young; Choi, Hyung Seok; Jie, Hang Sok; Park, Je Kyun

    2004-01-01

    Alkanethiolate self-assembled monolayer (SAM) formed by the adsorption of 11-mercaptoundecanoic acid (11-MUDA) molecules on a gold substrate. The alkanethiolate was oxidized by the irradiation of deep UV light with a 700-nm negative mask and then developed with a deionized water. A uniform submicro-pattern of 11-MUDA SAM was obtained. In order to array cytochrome c molecules along the patterned substrate, the well-characterized cytochrome c was immobilized. Electrochemical properties and morphology of the cytochrome c monolayer were investigated through the measurements of cyclic voltammetry and AFM. In addition, current-voltage characteristics of biomolecular multilayers consisting of cytochrome c and green fluorescent protein (GFP) were studied with a scanning tunneling microscope (STM)

  6. Multi-technique Characterization of Self-assembled Carboxylic Acid Terminated Alkanethiol Monolayers on Nanoparticle and Flat Gold Surfaces.

    Science.gov (United States)

    Techane, Sirnegeda D; Gamble, Lara J; Castner, David G

    2011-04-21

    Gold nanoparticles (AuNPs) with 14, 25 and 40nm diameters were functionalized with different chain length (C6, C8, C11 and C16) carboxylic acid terminated alkanethiol self-assembled monolayers (COOH-SAMs). X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to examine the changes in surface chemistry as both AuNP diameter and SAM chain length were varied. COOH-SAMs on flat gold surfaces were also examined and compared to the COOH-SAM on AuNP results. For a given surface, as the COOH-SAM chain length increased the XPS C/Au atomic ratio increased due to an increased number of carbon atoms per molecule in the overlayer and an increased attenuation of the Au substrate signal. For the C16 COOH-SAMs, as the size of AuNPs decreased the XPS C/Au atomic ratio and the apparent SAM thickness increased due to the increased curvature of the smaller AuNPs. The C16 COOH-SAMs on the flat Au had the lowest XPS C/Au atomic ratio and apparent SAM thickness of any C16 COOH-SAM covered Au surface. The effective take-off angles of the COOH-SAMs were also calculated by comparing the apparent thickness of COOH-SAMs with literature values. The effective take-off angle for C16 COOH-SAM on 14nm, 25nm and 40nm diameter AuNPs and flat Au were found to be 57°, 53°, 51° and 39°, respectively, for data acquired in a mode that collects a wide range of photoelectron take-off angles. The effective take-off angle for C16 COOH-SAM on 14nm AuNP and flat Au decreased to 52° and 0°, respectively, for data acquired in a mode that collects a narrow range of photoelectron take-off angles. The ToF-SIMS results showed similar changes in surface chemistry with COOH-SAM chain length and AuNP size. For example, the ratio of the sum of the C(1-4)H(x)O(y) positive ion intensities to the sum of the Au-containing positive ions intensities increased with decreasing AuNP size and increasing COOH-SAM chain length. Fourier transform IR spectroscopy in the

  7. Photosensitive self-assembling materials as functional dopants for organic photovoltaic cells

    Czech Academy of Sciences Publication Activity Database

    Bubnov, Alexej; Iwan, A.; Cigl, Martin; Boharewicz, B.; Tazbir, I.; Wójcik, K.; Sikora, A.; Hamplová, Věra

    2016-01-01

    Roč. 6, č. 14 (2016), s. 11577-11590 ISSN 2046-2069 R&D Projects: GA MŠk 7AMB13PL041; GA MŠk(CZ) LD14007; GA ČR GA15-02843S Grant - others:EU - ICT(XE) COST Action IC1208 Institutional support: RVO:68378271 Keywords : self-assembling materials * functional dopants * organic photovoltaic cells * azo group * liquid crystal Subject RIV: JI - Composite Materials Impact factor: 3.108, year: 2016

  8. DNA biosensor for detection of Salmonella typhi from blood sample of typhoid fever patient using gold electrode modified by self-assembled monolayers of thiols

    Science.gov (United States)

    Suryapratiwi, Windha Novita; Paat, Vlagia Indira; Gaffar, Shabarni; Hartati, Yeni Wahyuni

    2017-05-01

    Electrochemical biosensors are currently being developed in order to handle various clinical problems in diagnosing infectious diseases caused by pathogenic bacteria, or viruses. On this research, voltammetric DNA biosensor using gold electrode modified by thiols with self-assembled monolayers had been developed to detect a certain sequence of Salmonella typhi DNA from blood sample of typhoid fever patient. Thiol groups of cysteamines (Cys) and aldehyde groups from glutaraldehydes (Glu) were used as a link to increase the performance of gold electrode in detecting guanine oxidation signal of hybridized S. typhi DNA and ssDNA probe. Standard calibration method was used to determine analytical parameters from the measurements. The result shown that, the detection of S. typhi DNA from blood sample of typhoid fever patient can be carried out by voltammetry using gold electrode modified by self-assembled monolayers of thiols. A characteristic oxidation potential of guanine using Au/Cys/Gluwas obtained at +0.17 until +0.20 V. Limit of detection and limit of quantification from this measurements were 1.91μg mL-1 and 6.35 μg mL-1. The concentration of complement DNA from sample was 6.96 μg mL-1.

  9. Moiré pattern induced by the electronic coupling between 1-octanol self-assembled monolayers and graphite surface

    International Nuclear Information System (INIS)

    Silly, Fabien

    2012-01-01

    Two-dimensional self-assembly of 1-octanol molecules on a graphite surface is investigated using scanning tunneling microscopy (STM) at the solid/liquid interface. STM images reveal that this molecule self-assembles into a compact hydrogen-bonded herringbone nanoarchitecture. Molecules are preferentially arranged in a head-to-head and tail-to-tail fashion. A Moiré pattern appears in the STM images when the 1-octanol layer is covering the graphite surface. The large Moiré stripes are perpendicular to the 1-octanol lamellae. Interpretation of the STM images suggests that the Moiré periodicity is governed by the electronic properties of the graphite surface and the 1-octanol layer periodicity. (paper)

  10. Electron transport through rectifying self-assembled monolayer diodes on silicon: Fermi-level pinning at the molecule-metal interface.

    Science.gov (United States)

    Lenfant, S; Guerin, D; Tran Van, F; Chevrot, C; Palacin, S; Bourgoin, J P; Bouloussa, O; Rondelez, F; Vuillaume, D

    2006-07-20

    We report the synthesis and characterization of molecular rectifying diodes on silicon using sequential grafting of self-assembled monolayers of alkyl chains bearing a pi group at their outer end (Si/sigma-pi/metal junctions). We investigate the structure-performance relationships of these molecular devices, and we examine the extent to which the nature of the pi end group (change in the energy position of their molecular orbitals) drives the properties of these molecular diodes. Self-assembled monolayers of alkyl chains (different chain lengths from 6 to 15 methylene groups) functionalized by phenyl, anthracene, pyrene, ethylene dioxythiophene, ethylene dioxyphenyl, thiophene, terthiophene, and quaterthiophene were synthesized and characterized by contact angle measurements, ellipsometry, Fourier transform infrared spectroscopy, and atomic force microscopy. We demonstrate that reasonably well-packed monolayers are obtained in all cases. Their electrical properties were assessed by dc current-voltage characteristics and high-frequency (1-MHz) capacitance measurements. For all of the pi groups investigated here, we observed rectification behavior. These results extend our preliminary work using phenyl and thiophene groups (Lenfant et al., Nano Lett. 2003, 3, 741). The experimental current-voltage curves were analyzed with a simple analytical model, from which we extracted the energy position of the molecular orbital of the pi group in resonance with the Fermi energy of the electrodes. We report experimental studies of the band lineup in these silicon/alkyl pi-conjugated molecule/metal junctions. We conclude that Fermi-level pinning at the pi group/metal interface is mainly responsible for the observed absence of a dependence of the rectification effect on the nature of the pi groups, even though the groups examined were selected to have significant variations in their electronic molecular orbitals.

  11. Self-assembly of polyhedral metal-organic framework particles into three-dimensional ordered superstructures

    Science.gov (United States)

    Avci, Civan; Imaz, Inhar; Carné-Sánchez, Arnau; Pariente, Jose Angel; Tasios, Nikos; Pérez-Carvajal, Javier; Alonso, Maria Isabel; Blanco, Alvaro; Dijkstra, Marjolein; López, Cefe; Maspoch, Daniel

    2018-01-01

    Self-assembly of particles into long-range, three-dimensional, ordered superstructures is crucial for the design of a variety of materials, including plasmonic sensing materials, energy or gas storage systems, catalysts and photonic crystals. Here, we have combined experimental and simulation data to show that truncated rhombic dodecahedral particles of the metal-organic framework (MOF) ZIF-8 can self-assemble into millimetre-sized superstructures with an underlying three-dimensional rhombohedral lattice that behave as photonic crystals. Those superstructures feature a photonic bandgap that can be tuned by controlling the size of the ZIF-8 particles and is also responsive to the adsorption of guest substances in the micropores of the ZIF-8 particles. In addition, superstructures with different lattices can also be assembled by tuning the truncation of ZIF-8 particles, or by using octahedral UiO-66 MOF particles instead. These well-ordered, sub-micrometre-sized superstructures might ultimately facilitate the design of three-dimensional photonic materials for applications in sensing.

  12. Fracton pairing mechanism for unconventional superconductors: Self-assembling organic polymers and copper-oxide compounds

    DEFF Research Database (Denmark)

    Milovanov, A.V.; Juul Rasmussen, J.

    2002-01-01

    Self-assembling organic polymers and copper-oxide compounds are two classes of unconventional superconductors, whose challenging behavior does not comply with the traditional picture of Bardeen-Cooper-Schrieffer (BCS) superconductivity in regular crystals. In this paper, we propose a theoretical...... or holes) exchange fracton excitations, quantum oscillations of fractal lattices that mimic the complex microscopic organization of the unconventional superconductors. For the copper oxides, the superconducting transition temperature T-c as predicted by the fracton mechanism is of the order of similar to......150 K. We suggest that the marginal ingredient of the high-temperature superconducting phase is provided by fracton coupled holes that condensate in the conducting copper-oxygen planes owing to the intrinsic field-effect-transistor configuration of the cuprate compounds. For the gate...

  13. Effect of Soil Organic Matter Self-Assembly on Carbon Biodegradability (Invited)

    Science.gov (United States)

    Rice, J. A.; Chilom, G.; Baglieri, A.

    2009-12-01

    Recent work has demonstrated that soil organic matter (SOM) has a self-organizing character that is a result of the interaction of its amphiphilic and lipid components. The solid-state structural organization was examined by directly comparing the organization of humic acid as isolated with a physical mixture of the same chemical composition composed of its amphiphilic and lipid fractions using differential scanning calorimetry. Comparative measurements of the specific heat capacity as a function of temperature of the original humic acid reveal differences when compared to a mixture of the components with the same chemical composition. These differences provide direct evidence that humic acid’s solid state structure is more than just a mixture of components and is determined by specific interactions between its components. The result is a hierarchical architecture where a lower-level structure is determined by the self-assembly of amphiphilic components with lipids into a nanostructured composite material. A higher-level structure is formed by the association of this composite material with the remainder of humic acid’s components. This model is extended to the humin fraction of NOM which is shown to consist of similar fractions though the amphiphilic components are present in smaller proportions but are stronger amphiphiles. When deposited on surfaces from the solution state, SOM components form structures resembling vesicles which in turn form mass-fractal aggregates. Preliminary results have indicated that the self-assembled materials exhibit different stabilities than “unassembled” mixtures when exposed to the same microbial consortium.

  14. Surface sealing using self-assembled monolayers and its effect on metal diffusion in porous low-k dielectrics studied using monoenergetic positron beams

    Energy Technology Data Exchange (ETDEWEB)

    Uedono, Akira, E-mail: uedono.akira.gb@u.tsukuba.ac.jp [Division of Applied Physics, Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Armini, Silvia; Zhang, Yu [IMEC, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); Kakizaki, Takeaki [Division of Applied Physics, Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Krause-Rehberg, Reinhard [Department of Physics, Martin Luther University Halle, 06099 Halle (Germany); Anwand, Wolfgang; Wagner, Andreas [Institute for Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden (Germany)

    2016-04-15

    Graphical abstract: - Highlights: • Pores with cubic pore side lengths of 1.1 and 3.1 nm coexisted in the low-k film. • For the sample without the SAM sealing process, metal atoms diffused from the top Cu/MnN layer into the OSG film and were trapped by the pores. Almost all pore interiors were covered by those metals. • For the sample damaged by a plasma etch treatment before the SAM sealing process, self-assembled molecules diffused into the OSG film, and they were preferentially trapped by larger pores. - Abstract: Surface sealing effects on the diffusion of metal atoms in porous organosilicate glass (OSG) films were studied by monoenergetic positron beams. For a Cu(5 nm)/MnN(3 nm)/OSG(130 nm) sample fabricated with pore stuffing, C{sub 4}F{sub 8} plasma etch, unstuffing, and a self-assembled monolayer (SAM) sealing process, it was found that pores with cubic pore side lengths of 1.1 and 3.1 nm coexisted in the OSG film. For the sample without the SAM sealing process, metal (Cu and Mn) atoms diffused from the top Cu/MnN layer into the OSG film and were trapped by the pores. As a result, almost all pore interiors were covered with those metals. For the sample damaged by an Ar/C{sub 4}F{sub 8} plasma etch treatment before the SAM sealing process, SAMs diffused into the OSG film, and they were preferentially trapped by larger pores. The cubic pore side length in these pores containing self-assembled molecules was estimated to be 0.7 nm. Through this work, we have demonstrated that monoenergetic positron beams are a powerful tool for characterizing capped porous films and the trapping of atoms and molecules by pores.

  15. Cyclic voltammetry and scanning electrochemical microscopy studies of methylene blue immobilized on the self-assembled monolayer of n-dodecanethiol

    International Nuclear Information System (INIS)

    Salamifar, Seyed Ehsan; Mehrgardi, Masoud Ayatollahi; Kazemi, Sayed Habib; Mousavi, Mir Fazllollah

    2010-01-01

    Electron transfer (ET) kinetics through n-dodecanethiol (C 12 SH) self-assembled monolayer on gold electrode was studied using cyclic voltammetry (CV), scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS). An SECM model for compensating pinhole contribution, was used to measure the ET kinetics of solution-phase probes of ferrocyanide/ferricyanide (Fe(CN) 6 4-/3- ) and ferrocenemethanol/ferrociniummethanol (FMC 0/+ ) through the C 12 SH monolayer yielding standard tunneling rate constant (k ET 0 ) of (4 ± 1) x 10 -11 and (3 ± 1) x 10 -10 cm s -1 for Fe(CN) 6 4-/3- and FMC 0/+ respectively. Decay tunneling constants (β) of 0.97 and 0.96 A -1 for saturated alkane thiol chains were obtained using Fe(CN) 6 4- and FMC respectively. Also, it was found that methylene blue (MB) molecules are effectively immobilized on the C 12 SH monolayer and can mediate the ET between the solution-phase probes and underlying gold substrate. SECM-mediated model was used to simultaneously measure the bimolecular ET between the solution-phase probes and the monolayer-immobilized MB molecules, as well as tunneling ET between the monolayer-immobilized MB molecules and the underlying gold electrode, allowing the measurement of k BI = (5 ± 1) x 10 6 and (4 ± 2) x 10 7 cm 3 mol -1 s -1 for the bimolecular ET and k ET/MB 0 =(1±0.3)x10 -3 and (7 ± 3) x 10 -2 s -1 for the standard tunneling rate constant of ET using Fe(CN) 6 4-/3- and FMC 0/+ probes respectively.

  16. Electrochemical characterization of self-assembled monolayers (SAMs) of silanes on indium tin oxide (ITO) electrodes--tuning electron transfer behaviour across electrode-electrolyte interface.

    Science.gov (United States)

    Muthurasu, A; Ganesh, V

    2012-05-15

    In this work, we have systematically investigated the formation and characterization of Self-assembled Monolayer (SAM) films of several silanes on indium tin oxide (ITO) surfaces. Silane molecules having different domains namely substrate binding domain (siloxanes), electron transport region (aliphatic and aromatic spacer) and terminal functional groups (-SH, -CH(3) groups) are employed for the study in order to tune the electron transfer (ET) behaviour across SAM modified electrode-electrolyte interface. Structural characterization of these monolayer films is carried out using X-ray photoelectron spectroscopy (XPS) studies. Wettability (hydrophilic and hydrophobic nature) of such modified electrodes is evaluated using contact angle measurements. ET behaviour of these modified electrodes is investigated by electrochemical techniques namely cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using K(4)Fe(II)(CN)(6)|K(3)Fe(III)(CN)(6) redox couple as a probe. Disappearance of redox peaks in the CV measurements and formation of semicircle having a higher charge transfer resistance (R(ct)) values during EIS studies suggest that the resultant monolayer films are compact, highly ordered with very low defects and posses good blocking property with less pinholes. The heterogeneous ET rate constant (k) values are determined from EIS by fitting them to an appropriate equivalent circuit model. Based on our results, we comment on tuning the ET behaviour across the interface by a proper choice of spacer region. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. FET immunosensor for hemoglobin A1c using a gold nanofilm grown by a seed-mediated technique and covered with mixed self-assembled monolayers

    International Nuclear Information System (INIS)

    Xue, Q.; Bian, C.; Tong, J.; Sun, J.; Zhang, H.; Xia, S.

    2012-01-01

    A micro FET-based immunosensor was developed for the determination of hemoglobin-A1c (HbA1c). The HbA1c/hemoglobin ratio is an important index in diabetes control. The sensor was fabricated by Complementary Metal-Oxide-Semiconductor Transistor (CMOS) and Micro Electronic Mechanical System (MEMS) techniques. The antibodies were immobilized via mixed self-assembled monolayers (SAMs) on a gold nanofilm. The nanofilm was deposited on a gold electrode by seed-mediated growth and gave a uniform and well distributed coverage. Nonspecific sites and interferences by noise were eliminated by covering the AuNPs with mixed SAMs. Compared to the immunosensor fabricated via the mixed SAMs method without gold nanofilm, the immunosensor displays a more than 2-fold sensitivity. The immunosensor is capable of detecting HbA1c and hemoglobin in hemolyzed and diluted whole blood, and results showed good agreement with the established clinical method. (author)

  18. Self-assembled monolayers of bimetallic Au/Ag nanospheres with superior surface-enhanced Raman scattering activity for ultra-sensitive triphenylmethane dyes detection.

    Science.gov (United States)

    Tian, Yue; Zhang, Hua; Xu, Linlin; Chen, Ming; Chen, Feng

    2018-02-15

    The bimetallic Au/Ag self-assembled monolayers (SAMs) were constructed by using mono-dispersed Au/Ag nanospheres (Ag: 4.07%-34.53%) via evaporation-based assembly strategy. The composition-dependent surface-enhanced Raman scattering (SERS) spectroscopy revealed that the Au/Ag (Ag: 16.83%) SAMs provide maximized activity for triphenylmethane dyes detection. With the inter-metallic synergy, the optimized SAMs enable the Raman intensity of crystal violet molecules to be about 223 times higher than that of monometallic Au SAMs. Moreover, the SERS signals with excellent uniformity (<5% variation) are sensitive down to 10 -13   M concentrations because of the optimal matching between bimetallic plasmon resonance and the incident laser wavelength.

  19. On the use of (3-trimethoxysilylpropyl)diethylenetriamine self-assembled monolayers as seed layers for the growth of Mn based copper diffusion barrier layers

    Science.gov (United States)

    Brady-Boyd, A.; O'Connor, R.; Armini, S.; Selvaraju, V.; Hughes, G.; Bogan, J.

    2018-01-01

    In this work x-ray photoelectron spectroscopy is used to investigate in-vacuo, the interaction of metallic manganese with a (3-trimethoxysilylpropyl)diethylenetriamine (DETA) self-assembled monolayer (SAM) on SiO2 and non-porous low-k dielectric materials. Subsequent deposition of a ∼0.5 nm thick Mn, followed by a 200 °C anneal results in the Mn diffusing through the SAM to interact with the underlying SiO2 layer to form a Mn-silicate layer. Furthermore, there is evidence that the Mn interacts with the carbon and nitrogen within the SAM to form Mn-carbide and Mn-nitride, respectively. When deposited on low-k materials the Mn is found to diffuse through to the SAM on deposition and interact both with the SAM and the underlying substrate in a similar fashion.

  20. Self-assembled monolayers (SAMs) of alkoxycyanobiphenyl thiols on gold--a study of electron transfer reaction using cyclic voltammetry and electrochemical impedance spectroscopy.

    Science.gov (United States)

    Ganesh, V; Pal, Santanu Kumar; Kumar, Sandeep; Lakshminarayanan, V

    2006-04-01

    Self-assembled monolayers (SAMs) of liquid crystalline thiol-terminated alkoxycyanobiphenyl molecules with different alkyl chain lengths on Au surface have been studied for the first time using electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The barrier property of the SAM-modified surfaces was evaluated using two different redox probes, namely potassium ferro/ferri cyanide and hexaammineruthenium(III) chloride. It was found that for short-length alkyl chain thiol (C5) the electron transfer reaction of hexaammineruthenium(III) chloride takes place through tunneling mechanism. In contrast, redox reaction of potassium ferro/ferri cyanide is almost completely blocked by the SAM-modified Au surface. From the impedance data, a surface coverage value of >99.9% was calculated for all the thiol molecules.

  1. Cu-Cu diffusion bonding enhancement at low temperature by surface passivation using self-assembled monolayer of alkane-thiol

    Science.gov (United States)

    Tan, C. S.; Lim, D. F.; Singh, S. G.; Goulet, S. K.; Bergkvist, M.

    2009-11-01

    Self-assembled monolayer (SAM) of 1-hexanethiol is applied on copper (Cu) surface to retard surface oxidation during exposure in the ambient. This SAM layer can be desorbed effectively with an annealing step in inert N2 ambient to provide a clean Cu surface. Using this passivation method with SAM, wafers covered with thin Cu layer are passivated, stored, desorbed, and bonded at 250 °C. The bonded Cu layer presents clear evidence of substantial interdiffusion and grain growth despite prolonged exposure in the ambient. This method of passivation is proven to be effective and can be further optimized to enable high quality Cu-Cu direct bonding at low temperature for application in three-dimensional integration.

  2. Molecular-scale observation of YD2-o-C8 self-assembled monolayer on TiO2 (1 1 0)

    Science.gov (United States)

    Li, Ya-Juan; Sun, Lei; Jiang, Lei; Zhou, Qin; Ma, Zhi-Bo; Yang, Xue-Ming; Deng, Wei-Qiao

    2017-11-01

    The self-assembled monolayer (SAM) on TiO2 nanocrystal surface plays an important role in the processes of photoelectric conversion in dye sensitized solar cells (DSSCs). The SAM of dye YD2-o-C8, which was the best dye for DSSCs, has been observed by scanning tunneling microscope (STM) at molecular scale for the first time. The observation results showed that different morphologies of YD2-o-C8 SAM can be formed with or without chenodeoxycholic acid (cheno), which determined their corresponding photovoltaic cell efficiencies. The density functional theory (DFT) calculations explored the reason that was caused by the reduced electron coupling between side-to-side dimers separated by cheno molecules.

  3. Water-COOH Composite Structure with Enhanced Hydrophobicity Formed by Water Molecules Embedded into Carboxyl-Terminated Self-Assembled Monolayers.

    Science.gov (United States)

    Guo, Pan; Tu, Yusong; Yang, Jinrong; Wang, Chunlei; Sheng, Nan; Fang, Haiping

    2015-10-30

    By combining molecular dynamics simulations and quantum mechanics calculations, we show the formation of a composite structure composed of embedded water molecules and the COOH matrix on carboxyl-terminated self-assembled monolayers (COOH SAMs) with appropriate packing densities. This composite structure with an integrated hydrogen bond network inside reduces the hydrogen bonds with the water above. This explains the seeming contradiction on the stability of the surface water on COOH SAMs observed in experiments. The existence of the composite structure at appropriate packing densities results in the two-step distribution of contact angles of water droplets on COOH SAMs, around 0° and 35°, which compares favorably to the experimental measurements of contact angles collected from forty research articles over the past 25 years. These findings provide a molecular-level understanding of water on surfaces (including surfaces on biomolecules) with hydrophilic functional groups.

  4. Protein nanorings organized by poly(styrene-block-ethylene oxide) self-assembled thin films

    Science.gov (United States)

    Malmström, Jenny; Wason, Akshita; Roache, Fergus; Yewdall, N. Amy; Radjainia, Mazdak; Wei, Shanghai; Higgins, Michael J.; Williams, David E.; Gerrard, Juliet A.; Travas-Sejdic, Jadranka

    2015-11-01

    This study explores the use of block copolymer self-assembly to organize Lsmα, a protein which forms stable doughnut-shaped heptameric structures. Here, we have explored the idea that 2-D crystalline arrays of protein filaments can be prepared by stacking doughnut shaped Lsmα protein into the poly(ethylene oxide) blocks of a hexagonal microphase-separated polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer. We were able to demonstrate the coordinated assembly of such a complex hierarchical nanostructure. The key to success was the choice of solvent systems and protein functionalization that achieved sufficient compatibility whilst still promoting assembly. Unambiguous characterisation of these structures is difficult; however AFM and TEM measurements confirmed that the protein was sequestered into the PEO blocks. The use of a protein that assembles into stackable doughnuts offers the possibility of assembling nanoscale optical, magnetic and electronic structures.This study explores the use of block copolymer self-assembly to organize Lsmα, a protein which forms stable doughnut-shaped heptameric structures. Here, we have explored the idea that 2-D crystalline arrays of protein filaments can be prepared by stacking doughnut shaped Lsmα protein into the poly(ethylene oxide) blocks of a hexagonal microphase-separated polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer. We were able to demonstrate the coordinated assembly of such a complex hierarchical nanostructure. The key to success was the choice of solvent systems and protein functionalization that achieved sufficient compatibility whilst still promoting assembly. Unambiguous characterisation of these structures is difficult; however AFM and TEM measurements confirmed that the protein was sequestered into the PEO blocks. The use of a protein that assembles into stackable doughnuts offers the possibility of assembling nanoscale optical, magnetic and electronic structures. Electronic supplementary

  5. Free-standing gold-nanoparticle monolayer film fabricated by protein self-assembly of α-synuclein.

    Science.gov (United States)

    Lee, Junghee; Bhak, Ghibom; Lee, Ji-Hye; Park, Woohyun; Lee, Minwoo; Lee, Daekyun; Jeon, Noo Li; Jeong, Dae H; Char, Kookheon; Paik, Seung R

    2015-04-07

    Free-standing nanoparticle films are of great importance for developing future nano-electronic devices. We introduce a protein-based fabrication strategy of free-standing nanoparticle monolayer films. α-Synuclein, an amyloidogenic protein, was utilized to yield a tightly packed gold-nanoparticle monolayer film interconnected by protein β-sheet interactions. Owing to the stable protein-protein interaction, the film was successfully expanded to a 4-inch diameter sheet, which has not been achieved with any other free-standing nanoparticle monolayers. The film was flexible in solution, so it formed a conformal contact, surrounding even microspheres. Additionally, the monolayer film was readily patterned at micrometer-scale and thus unprecedented double-component nanoparticle films were fabricated. Therefore, the free-floating gold-nanoparticle monolayer sheets with these properties could make the film useful for the development of bio-integrated nano-devices and high-performance sensors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Thermal Conductivity of a Monolayer of Exfoliated Graphite Nanoplatelets Prepared by Liquid-Liquid Interfacial Self-Assembly

    Directory of Open Access Journals (Sweden)

    Jinglei Xiang

    2010-01-01

    Full Text Available A monolayer film composed of exfoliated graphite nanoplatelets (xGnPs was extracted from a chloroform-water interface and supported on a glass substrate. The nanoplatelets are interconnected at the edges without overlapping forming a very densely packed structure with uniform thickness. Micro-Raman spectroscopy with a 50 mW 532 nm laser generating heat at the center of a xGnP sample was used to probe the thermal conductivity of the xGnP monolayer at different power levels. The Raman G peak shift of graphite was used to record the local temperature rise in the monolayer. The cross-sectional area of heat conduction is determined by the thickness of individual nanoplatelets. A UV-Vis spectrometer was used to measure the absorption of light by the monolayer. Depending on the interface density, the thermal conductivities are around 380 W/m K and 290 W/m K for monolayers with average particle size of 10 μm and 5 μm, respectively.

  7. Functionalisation of bolaamphiphiles with mononuclear bis(2,2 '-bipyridyl)ruthenium(II) complexes for application in self assembled monolayers

    NARCIS (Netherlands)

    Killeen, JS; Browne, WR; Skupin, M; Fuhrhop, JH; Vos, JG

    2003-01-01

    A novel ruthenium(II) polypyridyl complex connected covalently to a bolaamphiphile, containing amide linkages to provide rigidity via hydrogen bonding in the monolayer, has been prepared. The ruthenium( II) complexes of this ligand and of the intermediates in the synthesis were prepared by modi.

  8. Electric bistability induced by incorporating self-assembled monolayers/aggregated clusters of azobenzene derivatives in pentacene-based thin-film transistors.

    Science.gov (United States)

    Tseng, Chiao-Wei; Huang, Ding-Chi; Tao, Yu-Tai

    2012-10-24

    Composite films of pentacene and a series of azobenzene derivatives are prepared and used as the active channel material in top-contact, bottom-gate field-effect transistors. The transistors exhibit high field-effect mobility as well as large I-V hysteresis as a function of the gate bias history. The azobenzene moieties, incorporated either in the form of self-assembled monolayer or discrete multilayer clusters at the dielectric surface, result in electric bistability of the pentacene-based transistor either by photoexcitation or gate biasing. The direction of threshold voltage shifts, size of hysteresis, response time, and retention characteristics all strongly depend on the substituent on the benzene ring. The results show that introducing a monolayer of azobenzene moieties results in formation of charge carrier traps responsible for slower switching between the bistable states and longer retention time. With clusters of azobenzene moieties as the trap sites, the switching is faster but the retention is shorter. Detailed film structure analyses and correlation with the transistor/memory properties of these devices are provided.

  9. Highly Sensitive Aluminium(III) Ion Sensor Based on a Self-assembled Monolayer on a Gold Nanoparticles Modified Screen-printed Carbon Electrode.

    Science.gov (United States)

    See, Wong Pooi; Heng, Lee Yook; Nathan, Sheila

    2015-01-01

    A new approach for the development of a highly sensitive aluminium(III) ion sensor via the preconcentration of aluminium(III) ion with a self-assembled monolayer on a gold nanoparticles modified screen-printed carbon electrode and current mediation by potassium ferricyanide redox behavior during aluminium(III) ion binding has been attempted. A monolayer of mercaptosuccinic acid served as an effective complexation ligand for the preconcentration of trace aluminium; this led to an enhancement of aluminium(III) ion capture and thus improved the sensitivity of the sensor with a detection limit of down to the ppb level. Under the optimum experimental conditions, the sensor exhibited a wide linear dynamic range from 0.041 to 12.4 μM. The lower detection limit of the developed sensor was 0.037 μM (8.90 ppb) using a 10 min preconcentration time. The sensor showed excellent selectivity towards aluminium(III) ion over other interference ions.

  10. Use of self assembled monolayers at variable coverage to control interface bonding in a model study of interfacial fracture: Pure shear loading

    Energy Technology Data Exchange (ETDEWEB)

    KENT,MICHAEL S.; YIM,HYUN; MATHESON,AARON J.; COGDILL,C.; NELSON,GERALD C.; REEDY JR.,EARL DAVID

    2000-05-16

    The relationships between fundamental interfacial interactions, energy dissipation mechanisms, and fracture stress or fracture toughness in a glassy thermoset/inorganic solid joint are not well understood. This subject is addressed with a model system involving an epoxy adhesive on a polished silicon wafer containing its native oxide. The proportions of physical and chemical interactions at the interface, and the in-plane distribution, are varied using self-assembling monolayers of octadecyltrichlorosilane (ODTS). The epoxy interacts strongly with the bare silicon oxide surface, but forms only a very weak interface with the methylated tails of the ODTS monolayer. The fracture stress is examined as a function of ODTS coverage in the napkin-ring (pure shear) loading geometry. The relationship between fracture stress and ODTS coverage is catastrophic, with a large change in fracture stress occurring over a narrow range of ODTS coverage. This transition in fracture stress does not correspond to a wetting transition of the epoxy. Rather, the transition in fracture stress corresponds to the onset of deformation in the epoxy, or the transition from brittle to ductile fracture. The authors postulate that the transition in fracture stress occurs when the local stress that the interface can support becomes comparable to the yield stress of the epoxy. The fracture results are independent of whether the ODTS deposition occurs by island growth (T{sub dep} = 10 C) or by homogeneous growth (T{sub dep} = 24 C).

  11. Indirect amperometric sensing of dopamine using a redox-switchable naphthoquinone-terminated self-assembled monolayer on gold electrode

    International Nuclear Information System (INIS)

    Hammami, Asma; Raouafi, Noureddine; Sahli, Rihab

    2016-01-01

    We report on the design of a simple yet sensitive and selective electrode for amperometric determination of dopamine at a cathodic potential as low as −0.30 V vs. Ag/AgCl. The electrode was obtained by self-assembly of ω-mercaptopropyl naphthoquinone (NQ-SAM) on the surface of a polycrystalline gold electrode. The presence of dopamine induces an increase of the reduction current peak at −0.30 V corresponding to the reduction of naphthoquinone to hydronaphthoquinone. Dopamine and dopamine-quinone accumulate on the surface to form a 3D network linked by hydrogen bonds. Raman and infrared spectroscopy as well as atomic force microscopy confirmed the multilayer formation. The method allows dopamine to be indirectly detected at a working potential that is lower by 0.50 V than the standard oxidation potential at a bare gold electrode. The sensor shows distinct oxidation potentials for dopamine (120 mV), ascorbic acid (280 mV) and uric acid (520 mV) which makes the method fairly selective. The analytical range extends from 1 to 100 μM concentrations of dopamine, and the limits of detection and quantification are 0.040 and 0.134 μM, respectively. (author)

  12. Design and Synthesis of Self-Assembled Monolayers on Mesoporous Supports (SAMMS): The Importance of Ligand Posture in Functional Nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Fryxell, Glen E.; Mattigod, Shas V.; Lin, Yuehe; Wu, Hong; Fiskum, Sandra K.; Parker, Kent E.; Zheng, Feng; Yantasee, Wassana; Zemanian, Thomas S.; Addleman, Raymond S.; Liu, Jun; Xu, Jide; Kemner, Kenneth M.; Kelly, Shelley; Feng, Xiangdong

    2007-07-01

    Water, and water quality, are issues of critical importance to the future of humankind. The Earth’s water supplies have been contaminated by a wide variety of industrial, military and natural sources. The need exists for an efficient separation technology to remove heavy metal and radionuclide contamination from water. Surfactant templated synthesis of mesoporous ceramics provides a versatile foundation upon which to build high efficiency environmental sorbents. These nanoporous ceramics condense a huge amount of surface area into a very small volume. These mesoporous architectures can be subsequently functionalized through molecular self-assembly. These functional mesoporous materials offer significant capabilities in terms of removal of heavy metals and radionuclides from a variety of liquid media, including groundwater, contaminated oils and contaminated chemical weapons. They are highly efficient sorbents, whose rigid, open pore structure allows for rapid, efficient sorption kinetics. Their interfacial chemistry can be fine-tuned to selectively sequester a specific target species, such as heavy metals, tetrahedral oxometallate anions and radionuclides. This manuscript provides a review of the design, synthesis and performance of the sorbent materials. The role that ligand posture plays in the chemistry of these interfacial ligand fields is discussed.

  13. TOF-SIMS structural characterization of self-assembly monolayer of cytochrome b5 onto gold substrate.

    OpenAIRE

    Aoyagi, Satoka; Rouleau, Alain; Boireau, Wilfrid

    2008-01-01

    International audience; Orientation and three-dimensional structure of immobilized proteins on bio-devices are very important to assure their high performance. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is able to analyze upper surface of one layer of molecules. Orientation of immobilized proteins can be evaluated based on determination of a partial structure, representing ensemble of amino acids, on the surface part. In this study, a monolayer of cytochrome b5 was reconstitute...

  14. Self-assembly of monodisperse starburst carbon spheres into hierarchically organized nanostructured supercapacitor electrodes.

    Science.gov (United States)

    Kim, Sung-Kon; Jung, Euiyeon; Goodman, Matthew D; Schweizer, Kenneth S; Tatsuda, Narihito; Yano, Kazuhisa; Braun, Paul V

    2015-05-06

    We report a three-dimensional (3D) porous carbon electrode containing both nanoscale and microscale porosity, which has been hierarchically organized to provide efficient ion and electron transport. The electrode organization is provided via the colloidal self-assembly of monodisperse starburst carbon spheres (MSCSs). The periodic close-packing of the MSCSs provides continuous pores inside the 3D structure that facilitate ion and electron transport (electrode electrical conductivity ∼0.35 S m(-1)), and the internal meso- and micropores of the MSCS provide a good specific capacitance. The capacitance of the 3D-ordered porous MSCS electrode is ∼58 F g(-1) at 0.58 A g(-1), 48% larger than that of disordered MSCS electrode at the same rate. At 1 A g(-1) the capacitance of the ordered electrode is 57 F g(-1) (95% of the 0.24 A g(-1) value), which is 64% greater than the capacitance of the disordered electrode at the same rate. The ordered electrode preserves 95% of its initial capacitance after 4000 charging/discharging cycles.

  15. Silicon based near infrared photodetector using self-assembled organic crystalline nano-pillars

    Energy Technology Data Exchange (ETDEWEB)

    Ajiki, Yoshiharu, E-mail: yoshiharu-ajiki@ot.olympus.co.jp, E-mail: isao@i.u-tokyo.ac.jp [Micromachine Center, 67 Kanda Sakumagashi, Chiyoda-ku, Tokyo 100-0026 (Japan); Kan, Tetsuo [Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Yahiro, Masayuki; Hamada, Akiko; Adachi, Chihaya [Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Adachi, Junji [Office for Strategic Research Planning, Kyushu University, 6-10-1 Hakozaki, Higashi, Fukuoka 812-8581 (Japan); Matsumoto, Kiyoshi [IRT Research Initiative, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Shimoyama, Isao, E-mail: yoshiharu-ajiki@ot.olympus.co.jp, E-mail: isao@i.u-tokyo.ac.jp [Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); IRT Research Initiative, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan)

    2016-04-11

    We propose a silicon (Si) based near-infrared photodetector using self-assembled organic crystalline nano-pillars, which were formed on an n-type Si substrate and were covered with an Au thin-film. These structures act as antennas for near-infrared light, resulting in an enhancement of the light absorption on the Au film. Because the Schottky junction is formed between the Au/n-type Si, the electron excited by the absorbed light can be detected as photocurrent. The optical measurement revealed that the nano-pillar structures enhanced the responsivity for the near-infrared light by 89 (14.5 mA/W) and 16 (0.433 mA/W) times compared with those of the photodetector without nano-pillars at the wavelengths of 1.2 and 1.3 μm, respectively. Moreover, no polarization dependency of the responsivity was observed, and the acceptable incident angle ranged from 0° to 30°. These broad responses were likely to be due to the organic nano-pillar structures' having variation in their orientation, which is advantageous for near-infrared detector uses.

  16. Self-assembly of molecular dumbbells into organized bundles with tunable size.

    Science.gov (United States)

    Lee, Myongsoo; Jeong, Yang-Seung; Cho, Byoung-Ki; Oh, Nam-Keun; Zin, Wang-Cheol

    2002-02-15

    Dumbbell-shaped molecules consisting of three biphenyls connected through vinyl linkages as a conjugated rod segment and aliphatic polyether dendritic wedges with different cross-sections (i.e., dibranch (1), tetrabranch (2) and hexabranch (3)) were synthesized and characterized. The molecular dumbbells self-assemble into discrete bundles that organize into three-dimensional superlattices. Molecule 1, based on a dibranched dendritic wedge, organizes into primitive monoclinic-crystalline and body-centered, tetragonal liquid crystalline structures, while molecules 2 and 3, based on tetra- and hexabranched dendritic wedges, respectively, form only body-centered, tetragonal liquid crystalline structures. X-ray diffraction experiments and density measurements showed that the rod-bundle cross-sectional area decreases with increasing cross-section of the dendritic wedges. The influences of supramolecular structure on the bulk-state optical properties were investigated by measuring the UV/Vis absorption and steady state fluorescence spectroscopies. As the cross-section of the dendritic wedge of the molecule increases, the absorption and emission maxima shift to higher energy. This can be attributed to a quantum size effect of the three-dimensionally confined nanostructure.

  17. Self-assembly and sensing-group graft of pre-modified CNTs on resonant micro-cantilevers for specific detection of volatile organic compound vapors

    Science.gov (United States)

    Xu, Pengcheng; Li, Xinxin; Yu, Haitao; Liu, Min; Li, Jungang

    2010-11-01

    This paper reports MWCNT (multi-wall carbon nano-tube)-modified resonant micro-cantilever chemical sensors for detection of trinitrotoluene (TNT) vapor. The MWCNTs are pre-modified and then area-selectively self-assembled at the free-end gold pad of a micro-cantilever, in which a resonance-exciting heater and a signal-readout piezoresistive Wheatstone bridge are integrated. Featuring a high specific surface area, the MWCNTs are further functionalized with TNT-sensitive groups by grafting onto the sidewalls of the MWCNTs. To lower the non-specific absorption of water and other small organic molecules, the SiO2 surface of the micro-cantilever was also pre-treated for hydrophobicity and oleophobicity by self-assembling a monolayer of heptadecafluorodecyltrimethoxysilane. The results of our sensing experiments have shown a capability to rapidly detect ppb-level TNT vapor, and a high specificity of the functionalized groups to TNT molecules. The experiment has also confirmed a good long-term stability in detecting sensitivity.

  18. Multiscale active layer morphologies for organic photovoltaics through self-assembly of nanospheres.

    Science.gov (United States)

    Gehan, Timothy S; Bag, Monojit; Renna, Lawrence A; Shen, Xiaobo; Algaier, Dana D; Lahti, Paul M; Russell, Thomas P; Venkataraman, Dhandapani

    2014-09-10

    We address here the need for a general strategy to control molecular assembly over multiple length scales. Efficient organic photovoltaics require an active layer comprised of a mesoscale interconnected networks of nanoscale aggregates of semiconductors. We demonstrate a method, using principles of molecular self-assembly and geometric packing, for controlled assembly of semiconductors at the nanoscale and mesoscale. Nanoparticles of poly(3-hexylthiophene) (P3HT) or [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were fabricated with targeted sizes. Nanoparticles containing a blend of both P3HT and PCBM were also fabricated. The active layer morphology was tuned by the changing particle composition, particle radii, and the ratios of P3HT:PCBM particles. Photovoltaic devices were fabricated from these aqueous nanoparticle dispersions with comparable device performance to typical bulk-heterojunction devices. Our strategy opens a revolutionary pathway to study and tune the active layer morphology systematically while exercising control of the component assembly at multiple length scales.

  19. Reactions of BBr(n)(+) (n = 0--2) at fluorinated and hydrocarbon self-assembled monolayer surfaces: observations of chemical selectivity in ion--surface scattering.

    Science.gov (United States)

    Wade, N; Shen, J; Koskinen, J; Cooks, R G

    2001-07-01

    Ion-surface reactions involving BBr(n)(+) (n = 0--2) with a fluorinated self-assembled monolayer (F-SAM) surface were investigated using a multi-sector scattering mass spectrometer. Collisions of the B(+) ion yield BF(2)(+) at threshold energy with the simpler product ion BF(+)* appearing at higher collision energies and remaining of lower abundance than BF(2)(+) at all energies examined. In addition, the reactively sputtered ion CF(+) accompanies the formation of BF(2)(+) at low collision energies. These results stand in contrast with previous data on the ion-surface reactions of atomic ions with the F-SAM surface in that the threshold and most abundant reaction products in those cases involved the abstraction of a single fluorine atom. Gas-phase enthalpy data are consistent with BF(2)(+) being the thermodynamically favored product. The fact that the abundance of BF(2)(+) is relatively low and relatively insensitive to changes in collision energy suggests that this reaction proceeds through an entropically demanding intermediate at the vacuum--surface interface, one which involves interaction of the B(+) ion simultaneously with two fluorine atoms. By contrast with the reaction of B(+), the odd-electron species BBr(+)* reacts with the F-SAM surface to yield an abundant single-fluorine abstraction product, BBrF(+). Corresponding gas-phase ion--molecule experiments involving B(+) and BBr(+)* with C(6)F(14) also yield the products BF(+)* and BF(2)(+), but only in extremely low abundances and with no preference for double fluorine abstraction. Ion--surface reactions were also investigated for BBr(n)(+) (n = 0-2) with a hydrocarbon self-assembled monolayer (H-SAM) surface. Reaction of the B(+) ion and dissociative reactions of BBr(+)* result in the formation of BH(2)(+), while the thermodynamically less favorable product BH(+)* is not observed. Collisions of BBr(2)(+) with the H-SAM surface yield the dissociative ion-surface reaction products, BBrH(+) and BBrCH(3

  20. Self-assembled monolayer resists and nanoscale lithography of silicon dioxide thin films by chemically enhanced vapor etching (CEVE)

    Science.gov (United States)

    Pan, M.; Yun, M.; Kozicki, M. N.; Whidden, T. K.

    1996-10-01

    We report on the use of electron-beam exposed monolayers of undecylenic acid in the etch rate enhancement of silicon dioxide films in HF vapor for the formation of nanoscale features in the oxide. Variations of the etching characteristics with electron beam parameters are examined and the results analyzed in terms of proposed models of the etching mechanism. Apparent variations in the relative concentrations of etch initiator with the thermal history of the samples prior to etching provides support for the dominant etch initiator within this system as the carboxylic acid moiety bound at the oxide surface. Other variations in the etching characteristics are discussed in terms of differences in localized concentrations of hydrocarbon crosslinks and the effect that this has upon the etch initiation. The process has been employed in the production of features in silicon dioxide surface masks with sizes down to 50 nm.

  1. Formation of Merocyanine Self-Assembled Monolayer and Its Nonlinear Optical Properties Probed by Second-Harmonic Generation and Surface Plasmon Resonance

    Science.gov (United States)

    Tsuboi, Kazuma; Seki, Kazuhiko; Ouchi, Yukio; Fujita, Katsuhiko; Kajikawa, Kotaro

    2003-02-01

    Nonlinear optical responses of a self-assembled monolayer (SAM) containing merocyanine chromophore, 1-alkyl-4-(4-hydroxystyryl) pyridinium bromide (HSP), on gold in water and in ethanol were studied by second-harmonic generation (SHG). The pH dependence of the SHG response clearly showed a solvatochromic characteristic of the merocyanine from a protonated form to a zwitterionic form. A large second-order susceptibility χzzz=5.0× 10-7 esu (2.1× 102 pm/V) was found in a basic solution of ethanol where the merocyanine is in the zwitterionic form. Combination of the SHG and surface plasmon resonance (SPR) spectroscopy measurements also provides us with details of the formation process of the merocyanine SAMs in the ethanol solution of the HSP-terminated-alkyldisulfide, ω,ω\\prime-dithiodi[1-undecyl-4-(4-hydroxystyryl)pyridinium bromide](HSPC11SS). A considerable difference was found in the kinetics between SPR and SHG, because SHG probes the molecules in a noncentrosymmetric fashion on the gold surface while SPR probes the optical thickness of the film. The difference enabled us to separate the chemisorption from the physisorption in the adsorption process. Interestingly, both probes showed slower kinetics in the solution of higher concentration, suggesting association of the disulfide molecules in the solution of high concentration.

  2. Successive coordination of palladium(II)-ions and terpyridine-ligands to a pyridyl-terminated self-assembled monolayer on gold

    Science.gov (United States)

    Poppenberg, Johannes; Richter, Sebastian; Darlatt, Erik; Traulsen, Christoph H.-H.; Min, Hyegeun; Unger, Wolfgang E. S.; Schalley, Christoph A.

    2012-02-01

    The deposition of palladium on a novel, reversibly protonatable, pyridyl-terminated self-assembled monolayer on gold substrates has been studied by X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS spectroscopy) and time of flight-secondary ion mass spectrometry (ToF-SIMS). For this purpose, 12-(pyridin-4-yl)dodecane-1-thiol, consisting of a surface-active head group, an unfunctionalized hydrocarbon backbone and a terminal pyridyl group, has been synthesized and deposited on gold surfaces. Coordination of Pd(II) ions to the pyridyl group was examined. Furthermore, a reversible protonation/deprotonation cycle has been applied, and the relation between protonation and the amount of complexed palladium was studied. Investigation of the SAM by angle-resolved NEXAFS spectroscopy revealed the aliphatic backbone to be preferentially upright oriented with the aromatic head group being not preferentially oriented. The palladium layer was further coordinated with a CF3-labeled terpyridine ligand in order to prove the accessibility of the Pd(II) ions to further complexation and the platform useful for deposition of further layers toward a multi-layered system.

  3. Label-free impedimetric sensor for a ribonucleic acid oligomer specific to hepatitis C virus at a self-assembled monolayer-covered electrode.

    Science.gov (United States)

    Park, Jin-Young; Lee, Yoon-suk; Chang, Byoung-Yong; Kim, Byeang Hyean; Jeon, Sangmin; Park, Su-Moon

    2010-10-01

    A ribonucleic acid (RNA) sensor based on hybridization of its peptide nucleic acid (PNA) molecule with a target RNA oligomer of the internal ribosome entry site sequence specific to the hepatitis C virus (HCV) and the electrochemical impedance detection is described. This RNA is one of the most conservative molecules of the whole HCV RNA genome. The ammonium ion terminated PNA molecule was immobilized via its host-guest interactions with the diaza crown ring of 3-thiophene-acetamide-diaza-18-crown-6 synthesized by a simple two-step method, which forms a well-defined self-assembled monolayer (SAM) on gold. Hybridization events of the probe PNA with the target RNA were monitored by measuring charge-transfer resistances for the Fe(CN)(6)(3-/4-) redox probe using Fourier transform electrochemical impedance spectroscopy. The ratio of the resistances of the SAM-covered electrode measured before and after hybridization increased linearly with log[RNA] in the rat liver lysate with a detection limit of about 23 pM.

  4. Fabrication of hybrid self-assembled monolayer/hafnium oxide gate dielectric by radical oxidation for molybdenum disulfide field-effect transistors

    Science.gov (United States)

    Kawanago, Takamasa; Ikoma, Ryo; Oba, Tomoaki; Takagi, Hiroyuki

    2017-11-01

    In this study, radical oxidation is applied to the fabrication of a hybrid self-assembled monolayer (SAM)/hafnium oxide (HfOx) gate dielectric in molybdenum disulfide (MoS2) field-effect transistors. The fabrication process involves radical oxidation to form HfOx at the surface of metallic HfN, SAM formation by immersion, and the deterministic transfer of MoS2 flakes. A subthreshold slope of 75 mV/dec and small hysteresis were demonstrated, indicating superior interfacial properties. Cross-sectional transmission electron microscopy revealed the uniform formation of the HfOx layer at the surface of HfN. The SAM is indispensable for the superior interfacial properties in MoS2 field-effect transistors. The radical oxidation is not restricted to the oxidation of silicon and germanium substrates and was also found to be applicable to the fabrication of a high-k gate dielectric. This study opens up interesting possibilities of radical oxidation for research on functional electronic devices.

  5. First-Principles Surface Stress Calculations and Multiscale Deformation Analysis of a Self-Assembled Monolayer Adsorbed on a Micro-Cantilever

    Directory of Open Access Journals (Sweden)

    Yu-Ching Shih

    2014-04-01

    Full Text Available Micro-cantilever sensors are widely used to detect biomolecules, chemical gases, and ionic species. However, the theoretical descriptions and predictive modeling of these devices are not well developed, and lag behind advances in fabrication and applications. In this paper, we present a novel multiscale simulation framework for nanomechanical sensors. This framework, combining density functional theory (DFT calculations and finite element method (FEM analysis, is capable of analyzing molecular adsorption-induced deformation and stress fields in the sensors from the molecular scale to the device scale. Adsorption of alkanethiolate self-assembled monolayer (SAM on the Au(111 surface of the micro-cantilever sensor is studied in detail to demonstrate the applicability of this framework. DFT calculations are employed to investigate the molecular adsorption-induced surface stress upon the gold surface. The 3D shell elements with initial stresses obtained from the DFT calculations serve as SAM domains in the adsorption layer, while FEM is employed to analyze the deformation and stress of the sensor devices. We find that the micro-cantilever tip deflection has a linear relationship with the coverage of the SAM domains. With full coverage, the tip deflection decreases as the molecular chain length increases. The multiscale simulation framework provides a quantitative analysis of the displacement and stress fields, and can be used to predict the response of nanomechanical sensors subjected to complex molecular adsorption.

  6. Impact of self-assembled monolayer assisted surface dipole modulation of PET substrate on the quality of RF-sputtered AZO film

    Energy Technology Data Exchange (ETDEWEB)

    Vo, Thieu Thi Tien [Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Faculty of Chemical Engineering and Food Technology, Ba Ria-Vung Tau University, Vung Tau (Viet Nam); Mahesh, K.P.O. [Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Lin, Pao-Hung [Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Tai, Yian, E-mail: ytai@mail.ntust.edu.tw [Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China)

    2017-05-01

    Highlights: • We use SAMs functionalizing the PET substrates to generate different surface dipoles. • We deposited AZO film on pristine and SAMs-modified PET substrate. • The positive dipole moment of PET surface promotes the crystallinity of AZO film. • The negative dipole moment of PET surface deteriorates the crystallinity of AZO film. • The electrical properties of AZO/PET changes upon the variation of the crystallinity. - Abstract: In this study, we fabricated the electron donating/withdrawing group functionalized organosilane self-assembled monolayers (SAMs) on transparent polyethylene terephthalate (PET) flexible substrate followed by the deposition of aluminum doped zinc oxide (AZO) using RF magnetron sputtering at room temperature. The effect of different SAMs on transparent PET substrates and AZO films were studied by contact angle (CA), X-ray photoelectron spectroscopy (XPS), Atomic force microscopy (AFM), X-ray diffraction (XRD), Field-Emission scanning electron microscope (FE-SEM), Hall measurement and UV–vis spectroscopy (UV–vis). The results presented that the surface dipole (i.e. electron-donating/withdrawing) of different SAMs functionalized PET substrates affected the quality of the AZO films which deposited on top of them. The crystallinity, the charge mobility, and the carrier concentration of the AZO improved when the film was deposited on the PET functionalized with electron donating group, which was possibly due to favored interaction between electron donating group and Al ions.

  7. Fabrication and Characterization of a Stabilized Thin Film Ag/AgCl Reference Electrode Modified with Self-Assembled Monolayer of Alkane Thiol Chains for Rapid Biosensing Applications

    Directory of Open Access Journals (Sweden)

    Tanzilur Rahman

    2017-10-01

    Full Text Available The fabrication of miniaturized electrical biosensing devices can enable the rapid on-chip detection of biomarkers such as miRNA molecules, which is highly important in early-stage cancer detection. The challenge in realizing such devices remains in the miniaturization of the reference electrodes, which is an integral part of electrical detection. Here, we report on a novel thin film Ag/AgCl reference electrode (RE that has been fabricated on top of a Au-sputtered glass surface, which was coated with a self-assembled monolayer (SAM of 6-mercepto-1-hexanol (MCH. The electrode showed very little measurement deviation (−1.5 mv from a commercial Ag/AgCl reference electrode and exhibited a potential drift of only ± 0.2 mV/h. In addition, the integration of this SAM-modified microfabricated thin film RE enabled the rapid detection (<30 min of miRNA (let-7a. The electrode can be integrated seamlessly into a microfluidic device, allowing the highly stable and fast measurement of surface potential and is expected to be very useful for the development of miniature electrical biosensors.

  8. Use of a DNA film on a self-assembled monolayer for investigating the physical process of DNA damage induced by core electron ionization.

    Science.gov (United States)

    Narita, Ayumi; Fujii, Kentaro; Baba, Yuji; Shimoyama, Iwao

    2016-11-01

    A novel two-layer sample composed of a deoxyribonucleic acid (DNA) film and self-assembled monolayer (SAM) was prepared on an inorganic surface to mimic the processes in which DNA is damaged by soft X-ray irradiation. A mercaptopropyltrimethoxysilane (MPTS) SAM was formed on a sapphire surface, then oligonucleotide (OGN) molecules were adsorbed on the MPTS-SAM. The thicknesses and chemical states of the layers were determined by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray fine structure (NEXAFS) around the phosphorus (P) and sulfur (S) K-edges. To induce the damage to the OGN molecules, the sample was irradiated with synchrotron soft X-rays. The chemical state of the OGN molecules before and after irradiation was examined by NEXAFS around the nitrogen (N) K-edge region. The thickness of the MPTS-OGN layer was approximately 7.7 nm. The S atom of the OGN molecules was located at the bottom of the OGN layer. The peak shape of the N K-edge NEXAFS spectra of the MPTS-OGN layers clearly changed following irradiation. The MPTS-OGN layer formed on the sapphire surface. The chemical states and the structure of the interface were elucidated using synchrotron soft X-rays. The OGN molecules adsorbed on the MPTS films decomposed upon exposure to soft X-ray irradiation.

  9. The fabrication of thin films with nanopores and nanogrooves from block copolymer thin films on the neutral surface of self-assembled monolayers

    Science.gov (United States)

    Park, Dae-Ho

    2007-09-01

    A simple and well-ordered fabrication procedure for polymeric thin films with nanopores and nanogrooves is described. By utilizing the neutral surface of self-assembled monolayers (SAMs) of commercially available 3-(p-methoxyphenyl)propyltrichlorosilane (MPTS), the cylindrical microdomains of PMMA of the asymmetric polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) block copolymer were oriented perpendicular to the surface due to the balanced interfacial interactions of the blocks with the surface. Thin films with perpendicularly oriented lamellae without mixed lamellae could also be fabricated by simply using a binary blend of the same asymmetric PS-b-PMMA diblock copolymer and PMMA homopolymer in the wet-brush regime up to 50% of the total PMMA weight fraction on the same neutral surface. Nanotemplates with arrays of nanopores and nanogrooves were fabricated by selective removal of PMMA domains via ultraviolet (UV) irradiation and sequential washing. SAMs of MPTS on a substrate with aluminium oxide surface were also fabricated and were used to fabricate nanoporous thin film. A thin film of PS-b-PEO with perpendicularly oriented poly(ethylene oxide) (PEO) domains on the SAMs of MPTS is also demonstrated.

  10. The fabrication of thin films with nanopores and nanogrooves from block copolymer thin films on the neutral surface of self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Park, Dae-Ho [Department of Materials Science and Engineering, Polymer Research Institute, Pohang University of Science and Technology, San 31, Hyoja-Dong, Nam-Gu, Pohang 790-784 (Korea, Republic of)

    2007-09-05

    A simple and well-ordered fabrication procedure for polymeric thin films with nanopores and nanogrooves is described. By utilizing the neutral surface of self-assembled monolayers (SAMs) of commercially available 3-(p-methoxyphenyl)propyltrichlorosilane (MPTS), the cylindrical microdomains of PMMA of the asymmetric polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) block copolymer were oriented perpendicular to the surface due to the balanced interfacial interactions of the blocks with the surface. Thin films with perpendicularly oriented lamellae without mixed lamellae could also be fabricated by simply using a binary blend of the same asymmetric PS-b-PMMA diblock copolymer and PMMA homopolymer in the wet-brush regime up to 50% of the total PMMA weight fraction on the same neutral surface. Nanotemplates with arrays of nanopores and nanogrooves were fabricated by selective removal of PMMA domains via ultraviolet (UV) irradiation and sequential washing. SAMs of MPTS on a substrate with aluminium oxide surface were also fabricated and were used to fabricate nanoporous thin film. A thin film of PS-b-PEO with perpendicularly oriented poly(ethylene oxide) (PEO) domains on the SAMs of MPTS is also demonstrated.

  11. Crystal growth of barium nitrate on thiol-terminated self-assembled monolayers and a Raman spectroscopic investigation of the crystal facets

    Science.gov (United States)

    Lu, Fei; Zhao, Bing; Li, Ran; Ruan, Weidong

    2015-09-01

    Self-assembled monolayers (SAMs) of (3-mercaptopropyl)trimethoxysilane (MPTS) were used as templates to induce the nucleation and growth of Ba(NO3)2 microcrystals. X-ray diffraction (XRD) patterns and optical microscopy images were employed to investigate the crystallinity and morphology of the microcrystals. It is interesting that the soaking direction of the templates plays an important role in the crystal growth process. When the MPTS-modified substrates were soaked in a vertical manner, square-like microcrystals with the (100) orientation were synthesized; however, when the substrates were soaked in a horizontal manner, triangular-like microcrystals with the (111) orientation were obtained. These differences may be due to the different regulatory mechanisms involved in the modulation of the crystal growth by the SAMs. These mechanistic discoveries pave a new way to control and design new crystals. Another interesting phenomenon is that the Raman intensity of the (111) facet of the triangular Ba(NO3)2 microcrystals is five times that of the (100) facet. By using this difference, the crystal facet index can be rapidly determined.

  12. Rapid localized deactivation of self-assembled monolayers by propagation-controlled laser-induced plasma and its application to self-patterning of electronics and biosensors

    Science.gov (United States)

    Kim, Jongsu; Kwon, Seung-Gab; Back, Seunghyun; Kang, Bongchul

    2018-03-01

    We present a novel laser-induced surface treatment process to rapidly control the spatial wettabilities of various functional solutions with submicron to micron resolutions. Ultrathin hydrophobic self-assembled monolayers (SAMs) that little absorb typical laser lights due to short penetration depth were selectively deactivated by instantaneous interaction with laser-induced metallic plasmas. The spatial region of the deactivated SAM, which corresponds to process resolution, is adjustable by controlling the spatial propagation of the plasma. This method leads to the parallel formation of hydrophilic functional solutions on glass substrates with a minimum resolution on the submicron scale. To show its feasibility in device engineering fields, this method was applied to the cost-effective fabrication of electronics and biosensors. Rapid self-patterning of electronic and biological functional solutions (silver nanoparticle solution and streptavidin protein solution) was successfully realized by selective deactivation of two different SAMs (tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS) for electronics and the hetero-hybrid SAM (octadecyltrichlorosilane (OTS)/2-[methoxy(polyethyleneoxy)propyl] trichlorosilane (PEG)) for biosensors). As a result, this method can be exploited for the rapid and low-cost fabrication of various thin film devices such as electronics, biosensors, energy, displays, and photonics.

  13. First-principles surface stress calculations and multiscale deformation analysis of a self-assembled monolayer adsorbed on a micro-cantilever.

    Science.gov (United States)

    Shih, Yu-Ching; Chen, Chuin-Shan; Wu, Kuang-Chong

    2014-04-23

    Micro-cantilever sensors are widely used to detect biomolecules, chemical gases, and ionic species. However, the theoretical descriptions and predictive modeling of these devices are not well developed, and lag behind advances in fabrication and applications. In this paper, we present a novel multiscale simulation framework for nanomechanical sensors. This framework, combining density functional theory (DFT) calculations and finite element method (FEM) analysis, is capable of analyzing molecular adsorption-induced deformation and stress fields in the sensors from the molecular scale to the device scale. Adsorption of alkanethiolate self-assembled monolayer (SAM) on the Au(111) surface of the micro-cantilever sensor is studied in detail to demonstrate the applicability of this framework. DFT calculations are employed to investigate the molecular adsorption-induced surface stress upon the gold surface. The 3D shell elements with initial stresses obtained from the DFT calculations serve as SAM domains in the adsorption layer, while FEM is employed to analyze the deformation and stress of the sensor devices. We find that the micro-cantilever tip deflection has a linear relationship with the coverage of the SAM domains. With full coverage, the tip deflection decreases as the molecular chain length increases. The multiscale simulation framework provides a quantitative analysis of the displacement and stress fields, and can be used to predict the response of nanomechanical sensors subjected to complex molecular adsorption.

  14. Direct electrochemistry and electrocatalysis of hemoglobin at three-dimensional gold film electrode modified with self-assembled monolayers of 3-mercaptopropylphosphonic acid

    International Nuclear Information System (INIS)

    Chen Yu; Yang Xiaojing; Guo Lirong; Li Jing; Xia Xinghua; Zheng Limin

    2009-01-01

    Multilayered hemoglobin (Hb) molecules were successfully immobilized on three-dimensional gold film electrode modified with self-assembled monolayers (SAMs) of 3-mercaptopropylphosphonic acid. Direct electrochemistry of the immobilized multilayered Hb occurs with high thermal stability and electrochemical stability. In the multilayered Hb film, the most inner Hb molecules can directly transfer electron with the electrode, while the Hb protein beyond this layer communicates electron with the electrode via protein-protein electron exchange. In addition, the proposed functional interface can greatly enhance electron transfer rate of the immobilized Hb protein (k s = 15.8 ± 2.0 s -1 ) due to the increase of roughness of the gold substrate. Under optimized experimental conditions, the multilayered Hb film displays good bioelectrocatalytic activity toward the reduction of hydrogen peroxide. This electrochemical sensor shows fast response (less than 1 s), wide linear range (7.8 x 10 -8 to 9.1 x 10 -5 M) and low detection limit (2.5 x 10 -8 M), which can be attributed to good mass transport, large Hb proteins loading per unit area and fast electron transfer rate of Hb protein.

  15. Impact of self-assembled monolayer assisted surface dipole modulation of PET substrate on the quality of RF-sputtered AZO film

    International Nuclear Information System (INIS)

    Vo, Thieu Thi Tien; Mahesh, K.P.O.; Lin, Pao-Hung; Tai, Yian

    2017-01-01

    Highlights: • We use SAMs functionalizing the PET substrates to generate different surface dipoles. • We deposited AZO film on pristine and SAMs-modified PET substrate. • The positive dipole moment of PET surface promotes the crystallinity of AZO film. • The negative dipole moment of PET surface deteriorates the crystallinity of AZO film. • The electrical properties of AZO/PET changes upon the variation of the crystallinity. - Abstract: In this study, we fabricated the electron donating/withdrawing group functionalized organosilane self-assembled monolayers (SAMs) on transparent polyethylene terephthalate (PET) flexible substrate followed by the deposition of aluminum doped zinc oxide (AZO) using RF magnetron sputtering at room temperature. The effect of different SAMs on transparent PET substrates and AZO films were studied by contact angle (CA), X-ray photoelectron spectroscopy (XPS), Atomic force microscopy (AFM), X-ray diffraction (XRD), Field-Emission scanning electron microscope (FE-SEM), Hall measurement and UV–vis spectroscopy (UV–vis). The results presented that the surface dipole (i.e. electron-donating/withdrawing) of different SAMs functionalized PET substrates affected the quality of the AZO films which deposited on top of them. The crystallinity, the charge mobility, and the carrier concentration of the AZO improved when the film was deposited on the PET functionalized with electron donating group, which was possibly due to favored interaction between electron donating group and Al ions.

  16. Adsorption and Fibrillization of Islet Amyloid Polypeptide at Self-Assembled Monolayers Studied by QCM-D, AFM, and PM-IRRAS.

    Science.gov (United States)

    Hajiraissi, Roozbeh; Hanke, Marcel; Yang, Yu; Duderija, Belma; Gonzalez Orive, Alejandro; Grundmeier, Guido; Keller, Adrian

    2018-03-20

    Aggregation and fibrillization of human islet amyloid polypeptide (hIAPP) plays an important role in the development of type 2 diabetes mellitus. Understanding the interaction of hIAPP with interfaces such as cell membranes at a molecular level therefore represents an important step toward new therapies. Here, we investigate the fibrillization of hIAPP at different self-assembled alkanethiol monolayers (SAMs) by quartz crystal microbalance with dissipation monitoring (QCM-D), atomic force microscopy (AFM), and polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). We find that hydrophobic interactions with the CH 3 -terminated SAM tend to retard hIAPP fibrillization compared to the carboxylic acid-terminated SAM where attractive electrostatic interactions lead to the formation of a three-dimensional network of interwoven fibrils. At the hydroxyl- and amino-terminated SAMs, fibrillization appears to be governed by hydrogen bonding between the peptide and the terminating groups which may even overcome electrostatic repulsion. These results thus provide fundamental insights into the molecular mechanisms governing amyloid assembly at interfaces.

  17. Investigation of Bovine Serum Albumin (BSA) Attachment onto Self-Assembled Monolayers (SAMs) Using Combinatorial Quartz Crystal Microbalance with Dissipation (QCM-D) and Spectroscopic Ellipsometry (SE)

    Science.gov (United States)

    Phan, Hanh T. M.; Bartelt-Hunt, Shannon; Rodenhausen, Keith B.; Schubert, Mathias; Bartz, Jason C.

    2015-01-01

    Understanding protein adsorption kinetics to surfaces is of importance for various environmental and biomedical applications. Adsorption of bovine serum albumin to various self-assembled monolayer surfaces including neutral and charged hydrophilic and hydrophobic surfaces was investigated using in-situ combinatorial quartz crystal microbalance with dissipation and spectroscopic ellipsometry. Adsorption of bovine serum albumin varied as a function of surface properties, bovine serum albumin concentration and pH value. Charged surfaces exhibited a greater quantity of bovine serum albumin adsorption, a larger bovine serum albumin layer thickness, and increased density of bovine serum albumin protein compared to neutral surfaces at neutral pH value. The quantity of adsorbed bovine serum albumin protein increased with increasing bovine serum albumin concentration. After equilibrium sorption was reached at pH 7.0, desorption of bovine serum albumin occurred when pH was lowered to 2.0, which is below the isoelectric point of bovine serum albumin. Our data provide further evidence that combinatorial quartz crystal microbalance with dissipation and spectroscopic ellipsometry is a sensitive analytical tool to evaluate attachment and detachment of adsorbed proteins in systems with environmental implications. PMID:26505481

  18. Investigation of Bovine Serum Albumin (BSA Attachment onto Self-Assembled Monolayers (SAMs Using Combinatorial Quartz Crystal Microbalance with Dissipation (QCM-D and Spectroscopic Ellipsometry (SE.

    Directory of Open Access Journals (Sweden)

    Hanh T M Phan

    Full Text Available Understanding protein adsorption kinetics to surfaces is of importance for various environmental and biomedical applications. Adsorption of bovine serum albumin to various self-assembled monolayer surfaces including neutral and charged hydrophilic and hydrophobic surfaces was investigated using in-situ combinatorial quartz crystal microbalance with dissipation and spectroscopic ellipsometry. Adsorption of bovine serum albumin varied as a function of surface properties, bovine serum albumin concentration and pH value. Charged surfaces exhibited a greater quantity of bovine serum albumin adsorption, a larger bovine serum albumin layer thickness, and increased density of bovine serum albumin protein compared to neutral surfaces at neutral pH value. The quantity of adsorbed bovine serum albumin protein increased with increasing bovine serum albumin concentration. After equilibrium sorption was reached at pH 7.0, desorption of bovine serum albumin occurred when pH was lowered to 2.0, which is below the isoelectric point of bovine serum albumin. Our data provide further evidence that combinatorial quartz crystal microbalance with dissipation and spectroscopic ellipsometry is a sensitive analytical tool to evaluate attachment and detachment of adsorbed proteins in systems with environmental implications.

  19. Synchrotron radiation stimulated etching of SiO sub 2 thin films with a Co contact mask for the area-selective deposition of self-assembled monolayer

    CERN Document Server

    Wang, C

    2003-01-01

    The area-selective deposition of a self-assembled monolayer (SAM) was demonstrated on a pattern structure fabricated by synchrotron radiation (SR) stimulated etching of a SiO sub 2 thin film on the Si substrate. The etching was conducted by irradiating the SiO sub 2 thin film with SR through a Co contact mask and using a mixture of SF sub 6 + O sub 2 as the reaction gas. The SR etching stopped completely at the SiO sub 2 /Si interface. After the SR etching, the Si surface and the SiO sub 2 surface beneath the Co mask were evaluated by an atomic force microscope (AFM). A dodecene SAM was deposited on the Si surface, and trichlorosilane-derived SAMs (octadecyltrichlorosilane, and octenyltrichlorosilane) were deposited on the SiO sub 2 surface beneath the Co mask. The structure of the deposited SAMs showed a densely packed and well-ordered molecular architecture, which was characterized by infrared spectroscopy, ellipsometry, and water contact angle (WCA) measurements. (author)

  20. Self-assembly of a highly organized, hexameric supramolecular architecture: formation, structure and properties.

    Science.gov (United States)

    Schaeffer, Gaël; Fuhr, Olaf; Fenske, Dieter; Lehn, Jean-Marie

    2014-01-03

    Two derivatives, (3)L and (9)L, of a ditopic, multiply hydrogen-bonding molecule, known for more than a decade, have been found, in the solid state as well as in solvents of low polarity at room temperature, to exist not as monomers, but to undergo a remarkable self-assembly into a complex supramolecular species. The solid-state molecular structure of (3)L, determined by single-crystal X-ray crystallography, revealed that it forms a highly organized hexameric entity (3)L6 with a capsular shape, resulting from the interlocking of two sets of three monomolecular components, linked through hydrogen-bonding interactions. The complicated (1)H NMR spectra observed in o-dichlorobenzene (o-DCB) for (3)L and (9)L are consistent with the presence of a hexamer of D3 symmetry in both cases. DOSY measurements confirm the hexameric constitution in solution. In contrast, in a hydrogen-bond-disrupting solvent, such as DMSO, the (1)H NMR spectra are very simple and consistent with the presence of isolated monomers only. Extensive temperature-dependent (1)H NMR studies in o-DCB showed that the L6 species dissociated progressively into the monomeric unit on increasing th temperature, up to complete dissociation at about 90 °C. The coexistence of the hexamer and the monomer indicated that exchange was slow on the NMR timescale. Remarkably, no species other than hexamer and monomer were detected in the equilibrating mixtures. The relative amounts of each entity showed a reversible sigmoidal variation with temperature, indicating that the assembly proceeded with positive cooperativity. A full thermodynamic analysis has been applied to the data. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Spectroscopic imaging studies of nanoscale polarity and mass transport phenomena in self-assembled organic nanotubes.

    Science.gov (United States)

    Xu, Hao; Nagasaka, Shinobu; Kameta, Naohiro; Masuda, Mitsutoshi; Ito, Takashi; Higgins, Daniel A

    2017-08-02

    Synthetic organic nanotubes self-assembled from bolaamphiphile surfactants are now being explored for use as drug delivery vehicles. In this work, several factors important to their implementation in drug delivery are explored. All experiments are performed with the nanotubes immersed in ethanol. First, Nile Red (NR) and a hydroxylated Nile Red derivative (NR-OH) are loaded into the nanotubes and spectroscopic fluorescence imaging methods are used to determine the apparent dielectric constant of their local environment. Both are found in relatively nonpolar environments, with the NR-OH molecules preferring regions of relatively higher dielectric constant compared to NR. Unique two-color imaging fluorescence correlation spectroscopy (imaging FCS) measurements are then used along with the spectroscopic imaging results to deduce the dielectric properties of the environments sensed by mobile and immobile populations of probe molecules. The results reveal that mobile NR molecules pass through less polar regions, likely within the nanotube walls, while immobile NR molecules are found in more polar regions, possibly near the nanotube surfaces. In contrast, mobile and immobile NR-OH molecules are found to locate in environments of similar polarity. The imaging FCS results also provide quantitative data on the apparent diffusion coefficient for each dye. The mean diffusion coefficient for the NR dye was approximately two-fold larger than that of NR-OH. Slower diffusion by the latter could result from its additional hydrogen bonding interactions with polar triglycine, amine, and glucose moieties near the nanotube surfaces. The knowledge gained in these studies will allow for the development of nanotubes that are better engineered for applications in the controlled transport and release of uncharged, dipolar drug molecules.

  2. Photoelectron spectroscopy of self-assembled monolayers of molecular switches on noble metal surfaces; Photoelektronenspektroskopie selbstorganisierter Adsorbatschichten aus molekularen Schaltern auf Edelmetalloberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Heinemann, Nils

    2012-09-12

    Self-assembled monolayers (SAMs) of butanethiolate (C4) on single crystalline Au(111) surfaces were prepared by adsorption from solution. The thermally activated desorption behaviour of the C4 molecules from the gold substrate was examined by qualitative thermal desorption measurements (TDM), through this a desorption temperature T{sub Des}=473 K could be determined. With this knowledge, it was possible to produce samples of very good surface quality, by thermal treatment T{sub Sample}self-assembly from solution on Au(111), was examined using laser-based photoelectron spectroscopy. Differences in the molecular dipole moment characteristic for the trans and the cis isomer of ABT were observed via changes in the sample work function, accessible by detection of the threshold energy for photoemission. A quantitative

  3. Interactions of gaseous HNO3 and water with individual and mixed alkyl self-assembled monolayers at room temperature

    Czech Academy of Sciences Publication Activity Database

    Nishino, N.; Hollingsworth, S. A.; Stern, A. C.; Roeselová, Martina; Tobias, D. J.; Finlayson-Pitts, B. J.

    2014-01-01

    Roč. 16, č. 6 (2014), s. 2358-2367 ISSN 1463-9076 R&D Projects: GA MŠk ME09064 Institutional support: RVO:61388963 Keywords : organic surface * molecular dynamics * nitric acid deprotonation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.493, year: 2014

  4. Quantitative self-assembly of a purely organic three-dimensional catenane in water

    Science.gov (United States)

    Li, Hao; Zhang, Huacheng; Lammer, Aaron D.; Wang, Ming; Li, Xiaopeng; Lynch, Vincent M.; Sessler, Jonathan L.

    2015-12-01

    Self-assembly by means of coordinative bond formation has opened up opportunities for the high-yield synthesis of molecules with complex topologies. However, the preparation of purely covalent molecular architectures in aqueous media has remained a challenging task. Here, we present the preparation of a three-dimensional catenane through a self-assembly process that relies on the formation of dynamic hydrazone linkages in an acidic aqueous medium. The quantitative synthesis process and the mechanically interlocked structure of the resulting catenane were established by NMR spectroscopy, mass spectrometry, X-ray crystallography and HPLC studies. In addition, the labile hydrazone linkages of the individual [2]catenane components may be ‘locked’ by increasing the pH of the solution, yielding a relatively kinetically stable molecule. The present study thus details a simple approach to the creation and control of complex molecular architectures under reaction conditions that mimic biological milieux.

  5. Characterization and reactivity of organic monolayers on gold and platinum surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chien-Ching [Iowa State Univ., Ames, IA (United States)

    1995-12-06

    Purpose is to understand how the mobilization, dielectric, orientation, composition, coverage, and structure of self-assembled organic monolayers on metal surfaces affects the surface reactivities and properties of these films in order to facilitate the construction of desired films. Two model systems were used: tiols at Au and aromatic acids at Pt. Surface analysis methods, including contact angle, electrochemistry, ellipsometry, infrared reflection absorption spectroscopy (IRRAS), and x-ray photospectroscopy, were used to study the self-assembled organic monolayers on Au and Pt. IRRAS, contact angle, and electrochemistry were used to determine the surface pKa of phenylcarboxylic acids and pyridylcarboxylic acids monolayers on Pt. These techniques were also used to determine the orientation of polymethylene chain axis and the carboxylic follow the structural evolution of the chains and end group of the thiolate monolayers during formation. IRRAS was also used to assess the carboxylic acid group in terms of its possible existence as the non-hydrogen-bonded species, the hydrogen-bonded dimeric group, and the hydrogen-bonded polymeric group. These different forms of the end group were also followed vs coverage, as well as the reactivity vs solution pH. IRRAS and contact angle were used to calculate the rate constant of the esterification of carboxylic acid-terminated monolayers on Au.

  6. Self-Assembly of Block and Graft Copolymers in Organic Solvents: An Overview of Recent Advances

    Directory of Open Access Journals (Sweden)

    Leonard Ionut Atanase

    2018-01-01

    Full Text Available This review is an attempt to update the recent advances in the self-assembly of amphiphilic block and graft copolymers. Their micellization behavior is highlighted for linear AB, ABC triblock terpolymers, and graft structures in non-aqueous selective polar and non-polar solvents, including solvent mixtures and ionic liquids. The micellar characteristics, such as particle size, aggregation number, and morphology, are examined as a function of the copolymers’ architecture and molecular characteristics.

  7. Organic molecules deposited on graphene: A computational investigation of self-assembly and electronic structure

    International Nuclear Information System (INIS)

    Oliveira, I. S. S. de; Miwa, R. H.

    2015-01-01

    We use ab initio simulations to investigate the adsorption and the self-assembly processes of tetracyanoquinodimethane (TCNQ), tetrafluoro-tetracyanoquinodimethane (F4-TCNQ), and tetrasodium 1,3,6,8-pyrenetetrasulfonic acid (TPA) on the graphene surface. We find that there are no chemical bonds at the molecule–graphene interface, even at the presence of grain boundaries on the graphene surface. The molecules bond to graphene through van der Waals interactions. In addition to the molecule–graphene interaction, we performed a detailed study of the role played by the (lateral) molecule–molecule interaction in the formation of the, experimentally verified, self-assembled layers of TCNQ and TPA on graphene. Regarding the electronic properties, we calculate the electronic charge transfer from the graphene sheet to the TCNQ and F4-TCNQ molecules, leading to a p-doping of graphene. Meanwhile, such charge transfer is reduced by an order of magnitude for TPA molecules on graphene. In this case, it is not expected a significant doping process upon the formation of self-assembled layer of TPA molecules on the graphene sheet

  8. A hybrid biocatalyst consisting of silver nanoparticle and naphthalenethiol self-assembled monolayer prepared for anchoring glucose oxidase and its use for an enzymatic biofuel cell

    Science.gov (United States)

    Christwardana, Marcelinus; Kim, Do-Heyoung; Chung, Yongjin; Kwon, Yongchai

    2018-01-01

    A novel hybrid biocatalyst is synthesized by the enzyme composite consisting of silver nanoparticle (AgNP), naphthalene-thiol based couplers (Naph-SH) and glucose oxidase (GOx), which is then bonded with the supporter consisting of polyethyleneimine (PEI) and carbon nanotube (CNT) (CNT/PEI/AgNPs/Naph-SH/GOx) to facilitate glucose oxidation reaction (GOR). Here, the AgNPs play a role in obstructing denaturation of the GOx molecules from the supporter because of Ag-thiol bond, while the PEIs have the AgNPs keep their states without getting ionized by hydrogen peroxide produced during anodic reaction. The Naph-SHs also prevent ionization of the AgNP by forming self-assembled monolayer on their surface. Such roles of each component enable the catalyst to form (i) hydrophobic interaction between the GOx molecules and supporter and (ii) π-conjugated electron pathway between the GOx molecules and AgNP, promoting electron transfer. Catalytic nature of the catalyst is characterized by measuring catalytic activity and performance of enzymatic biofuel cell (EBC) using the catalyst. Regarding the catalytic activity, the catalyst leads to high electron transfer rate constant (9.6 ± 0.4 s-1), low Michaelis-Menten constant (0.51 ± 0.04 mM), and low charge transfer resistance (7.3 Ω cm2) and high amount of immobilized GOx (54.6%), while regarding the EBC performance, high maximum power density (1.46 ± 0.07 mW cm-2) with superior long-term stability result are observed.

  9. Controlling noncovalent interactions between a lysine-rich α-helical peptide and self-assembled monolayers of alkanethiols on Au through functional group diversity

    Science.gov (United States)

    Raigoza, Annette F.; Onyirioha, Kristeen; Webb, Lauren J.

    2017-02-01

    Reliably attaching a structured biomolecule to an inorganic substrate would enable the preparation of surfaces that incorporate both biological and inorganic functions and structures. To this end, we have previously developed a procedure using the copper(I)-catalyzed click reaction to tether synthetic α-helical peptides carrying two alkyne groups to well-ordered alkanethiol self-assembled monolayers (SAM) on a Au(111) surface, in which the SAM is composed of a mixture of methyl and azide termination. Proteins, however, are composed of many diverse functional groups, and this composition directly effects protein structure, interactions, and reactivity. Here, we explore the utility of mixed SAMs with alternative terminating functional groups to tune and direct the reactivity of the surface through noncovalent peptide-surface interactions. We study both polar surfaces (OH-terminated) and charged surfaces (COOH- and NH3-terminated, which are negatively and positively charged, respectively, under our reaction conditions). Surfaces were functionalized with a bipolar peptide composed of Lys and Leu residues that could express different interactions through either hydrophilic and/or charge (Lys) or hydrophobic (Leu) influences. X-ray photoelectron spectroscopy (XPS) and surface infrared spectroscopy were used to characterize surfaces at all stages of the peptide functionalization procedure. This strategy resulted in a high density of surface-bound α-helices without aggregation. Mixed SAMs that included a positively charged alkanethiol along with the azide-terminated thiol resulted in a more efficient reaction and better alignment of the peptide with the azide on the surface. Negatively charged surfaces increased physisorption of the peptide, which was then removed during sample rinsing. This work demonstrates that varying easily controlled chemical inputs during the functionalization steps allows the reaction conditions to be balanced for the chemical needs of a

  10. Correction: An unsymmetrical non-fullerene acceptor: synthesis via direct heteroarylation, self-assembly, and utility as a low energy absorber in organic photovoltaic cells.

    Science.gov (United States)

    Payne, Abby-Jo; Li, Shi; Dayneko, Sergey V; Risko, Chad; Welch, Gregory C

    2017-09-21

    Correction for 'An unsymmetrical non-fullerene acceptor: synthesis via direct heteroarylation, self-assembly, and utility as a low energy absorber in organic photovoltaic cells' by Abby-Jo Payne et al., Chem. Commun., 2017, 53, 10168-10171.

  11. Self-assembled monolayers of Lewis bases: effects on surface and interfacial electronic properties in III-V optical semiconductors

    Science.gov (United States)

    Dorsten, J. F.; Maslar, James E.; Zhang, Ying; Rauchfuss, T. B.; Bohn, Paul W.; Agarwala, S.; Adesida, Ilesanmi; Caneau, Catherine; Bhat, Rajaram J.

    1994-07-01

    The nature and disposition of surface states can have a dramatic effect on the near-surface electronic properties in semiconductor heterostructures. In particular the lack of a well-defined surface oxide in III-V materials means that surface band bending can cause surface recombination velocities to be up to 103 larger than in Si-based materials. Raman scattering by coupled longitudinal optic phonons and 2D electron gas electrons in In0.52Al0.48AsIn0.53Ga0.47As (delta) -doped heterostructures is used to demonstrate the extreme sensitivity to surface states. The two highest frequency modes, of the three coupled electron-phonon modes expected in this system, were observed, with the L+ mode being identified for the first time in InGaAs-based systems. The large dispersion of this mode makes it a particularly sensitive probe for changes in such properties as carrier concentration and subband energy. For structures with higher carrier concentrations coupling of the longitudinal optic phonon to multiple electron intersubband transitions is resolved. In order to passivate native surface states organic thiols are being investigated. Measurements on bulk GaAs indicate a change in the surface depletion region thickness, within the abrupt junction model, of up to 50 angstrom (ca. 30%). Changes in carrier scattering times up to 50% have also been observed.

  12. Improved characteristics of conventional and inverted polymer photodetectors using phosphonic acid-based self-assembled monolayer treatment for interfacial engineering of Ga-doped ZnO electrodes

    Science.gov (United States)

    Kajii, Hirotake; Mohri, Yoshinori; Okui, Hiyuto; Kondow, Masahiko; Ohmori, Yutaka

    2018-03-01

    The characteristics of conventional and inverted polymer photodetectors based on a blend of a donor, poly(3-hexylthiophene) (P3HT), and an acceptor, fullerene derivative [6,6]phenyl-C61-butyric acid methyl ester (PCBM) using Ga-doped ZnO (GZO) electrodes modified by phosphonic acid-based self-assembled monolayer (SAM) treatment in a short time are investigated. Fluoroalkyl SAM, 1H,1H,2H,2H-perfluorooctane phosphonic acid (FOPA) treatment leads to efficient hole extraction from the active layer. The characteristics of the conventional device with GZO modified by FOPA treatment are almost the same as those with indium tin oxide modified by FOPA. Cs2CO3 and aminoalkyl SAM, 11-aminoundecylphosphonic acid (11-AUPA) treatments suppress the hole injection from GZO to the organic layer. For the inverted devices with GZO cathodes using Cs2CO3 and 11-AUPA, the dark current decreases, which results in the improved photodetector detectivity. An inverted device with both Cs2CO3 and 11-AUPA exhibits incident-photon-to-current conversion efficiency (IPCE) of approximately 65% (80%) at 0 V (-6 V) under light irradiation (λ = 500 nm), high on/off ratio, and improved durability. Improved open-circuit voltage and IPCE at low voltages are achieved by these treatments, which are related with the improved internal built-in field, the reduction of recombination probability in the vicinity of GZO, and the modified charge collection efficiency.

  13. Charge trapping at organic/self-assembly molecule interfaces studied by electrical switching behaviour in a crosspoint structure

    International Nuclear Information System (INIS)

    Li Yun; Pan Lijia; Pu Lin; Shi Yi; Liu Chuan; Tsukagoshi, Kazuhito

    2012-01-01

    Charge trapping at organic/self-assembly molecule (SAM) interfaces is studied by the electrical switching behaviour in a crosspoint structure, where interfacial charge trapping tunes the potential barrier of the SAM layer. The sample with rubrene exhibits the write-once read-many-times memory effect, which is due to the interfacial charges trapped at deep states. On the other hand, the sample with 2-amino-4,5-dicyanoimidazole presents recyclable conduction transition, which results from the trapped charges distributed at shallow states. Moreover, the percentage of the charges trapped at shallow states can be estimated from electrical transition levels. (paper)

  14. Charge trapping at organic/self-assembly molecule interfaces studied by electrical switching behaviour in a crosspoint structure

    Science.gov (United States)

    Li, Yun; Liu, Chuan; Pan, Lijia; Pu, Lin; Tsukagoshi, Kazuhito; Shi, Yi

    2012-01-01

    Charge trapping at organic/self-assembly molecule (SAM) interfaces is studied by the electrical switching behaviour in a crosspoint structure, where interfacial charge trapping tunes the potential barrier of the SAM layer. The sample with rubrene exhibits the write-once read-many-times memory effect, which is due to the interfacial charges trapped at deep states. On the other hand, the sample with 2-amino-4,5-dicyanoimidazole presents recyclable conduction transition, which results from the trapped charges distributed at shallow states. Moreover, the percentage of the charges trapped at shallow states can be estimated from electrical transition levels.

  15. Multi-Chlorine-Substituted Self-Assembled Molecules As Anode Interlayers: Tuning Surface Properties and Humidity Stability for Organic Photovoltaics.

    Science.gov (United States)

    Cheng, Xiaofang; Huang, Liqiang; Zhang, Lifu; Ai, Qingyun; Chen, Lie; Chen, Yiwang

    2017-03-15

    Self-assembled small molecules (SASMs) are effective materials to improve the interfacial properties between a metal/metal oxide and the overlying organic layer. In this work, surface modification of indium tin oxide (ITO) electrode by a series of Cl-containing SASMs has been exploited to control the surface properties of ITO and device performance for organic photovoltaics. Depending on the position and degrees of chlorination for SASMs, we could precisely manipulate the work function of the ITO electrode, and chemisorption of SASMs on ITO as well. Consequently, a power conversion efficiency (PCE) of 9.1% was achieved with tetrachlorobenzoic acid (2,3,4,5-CBA) SASM by a simple solution-processed method based on PTB7-Th-PC 71 BM heterojunction. More intriguingly, we discover that device performance is closely associated with the humidity of ambient conditions. When the humidity increases from 35-55% to 80-95%, device performance with 2,3,4,5-CBA has negligible reduction, in contrast with other SASMs that show a sharp reduction in PCEs. The increased device performance is primarily attributed to a matched work function, stable chemisorption, and beneficial wettability with overlying active layer. These findings suggest an available approach for manufacturing inexpensive, stable, efficient, and environmentally friendly organic photovoltaics by appropriate self-assembled small molecules.

  16. Preparation and characterization of ZrO{sub 2} thin film on sulfonated self-assembled monolayer of 3-mercaptopropyl trimethoxysilane

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jinqing; Yang Shengrong; Liu Xiaohong; Ren Sili; Guan Fei; Chen Miao

    2004-01-15

    Silane coupling reagent (3-mercaptopropyl trimethoxysilane (MPTS)) was prepared on single-crystal Si substrate to form two-dimensional self-assembled monolayer (SAM) and the terminal -SH group in the film was in situ oxidized to -SO{sub 3}H group to endow the film with good chemisorption ability. Thus, ZrO{sub 2} thin film were deposited on the oxidized MPTS-SAM, by enhanced hydrolysis of zirconium sulfate (Zr(SO{sub 4}){sub 2}{center_dot}4H{sub 2}O) solution in the presence of HCl at 70 deg. C, making use of the chemisorption ability of the -SO{sub 3}H group. The thickness of the films was determined with an ellipsometer, while the chemical feature, phase composition, thermal stability, and morphology of the films were analyzed by means of Fourier transformation infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction analysis, thermogravimetric analysis, and atomic force microscopy. As the results, the as-deposited ZrO{sub 2} film was composed of nanocrystalline tetragonal ZrO{sub 2} (t-ZrO{sub 2}) and an amorphous basic zirconium sulfate. The annealing of the films at 500 deg. C led to crystallization to t-ZrO{sub 2}, while further heating to 800 deg. C eliminated S in the film, and the ZrO{sub 2} film consisted of nanocrystalline tetragonal ZrO{sub 2} and monoclinic ZrO{sub 2} in this case. The as-deposited ZrO{sub 2} thin films were compact and crack-free, showing quadratically-looking features which were not observed previously, while the thickness of the ZrO{sub 2} films decreased with increasing annealing temperature. Since the ZrO{sub 2} film was well adhered to the MPTS-SAM, it might find promising application in the surface-modification of single-crystal Si and SiC in microelectromechanical systems (MEMS)

  17. Controlling noncovalent interactions between a lysine-rich α-helical peptide and self-assembled monolayers of alkanethiols on Au through functional group diversity

    Energy Technology Data Exchange (ETDEWEB)

    Raigoza, Annette F.; Onyirioha, Kristeen; Webb, Lauren J., E-mail: lwebb@cm.utexas.edu

    2017-02-28

    Highlights: • Functional variety in SAMs control covalent binding of proteins to surfaces. • Peptide density on Au(111) surfaces controlled by SAM functional groups. • Affinity between biomolecule and SAM surface follows a Langmuir isotherm. • Surface chemistry can mimic functional group diversity in proteins and peptides. - Abstract: Reliably attaching a structured biomolecule to an inorganic substrate would enable the preparation of surfaces that incorporate both biological and inorganic functions and structures. To this end, we have previously developed a procedure using the copper(I)-catalyzed click reaction to tether synthetic α-helical peptides carrying two alkyne groups to well-ordered alkanethiol self-assembled monolayers (SAM) on a Au(111) surface, in which the SAM is composed of a mixture of methyl and azide termination. Proteins, however, are composed of many diverse functional groups, and this composition directly effects protein structure, interactions, and reactivity. Here, we explore the utility of mixed SAMs with alternative terminating functional groups to tune and direct the reactivity of the surface through noncovalent peptide-surface interactions. We study both polar surfaces (OH-terminated) and charged surfaces (COOH- and NH{sub 3}-terminated, which are negatively and positively charged, respectively, under our reaction conditions). Surfaces were functionalized with a bipolar peptide composed of Lys and Leu residues that could express different interactions through either hydrophilic and/or charge (Lys) or hydrophobic (Leu) influences. X-ray photoelectron spectroscopy (XPS) and surface infrared spectroscopy were used to characterize surfaces at all stages of the peptide functionalization procedure. This strategy resulted in a high density of surface-bound α-helices without aggregation. Mixed SAMs that included a positively charged alkanethiol along with the azide-terminated thiol resulted in a more efficient reaction and better

  18. Novel nonlinear optical material with poly(3-hexylthiophene) thin film prepared on quartz glass surface modified by self-assembled monolayer

    Science.gov (United States)

    Ochiai, Shizuyasu; Mototani, Suguru; Ramajothi, Jayaraman; Kojima, Kenzo; Mizutani, Teruyoshi

    2008-08-01

    The third-order nonlinear optical properties of regioregular poly(3-hexylthiophene) (RR-P3HT) thin films prepared on fused glass substrate were evaluated. The surface modification by hexamethyldisilazane (HMDS) and octadecyltrichlorosilane (ODTS) was performed on the glass substrate to form self-assembled monolayer (SAM) layers. The formation of SAM layers on the glass substrate increase the contact angle of the solution and the optical property of the RR-P3HT thin films is enhanced due to the excellent orientation and alignment of the thin film. The π-conjugated macromolecule thin films can be prepared by spin-coating and drop-casting methods and the structure and orientation alignment of thin films can be controlled by the solution processing and deposition techniques. The nonlinear optical property, third-harmonic generation of RR-P3HT thin films has been evaluated by Maker-fringe method. The third-order nonlinear optical susceptibilities χ(3) (-3ω ω, ω, ω) of drop-cast RR-P3HT thin films on quartz glass substrate were estimated from optical third-harmonics (TH) intensity measurement. An Nd:YAG laser with a wavelength of 1064 nm, pulse width of 5 ns and a repetition frequency of 10 Hz was used to evaluate the TH intensity. The effect of surface modification of quartz glass substrate by HMDS and ODTS on the RR-P3HT film structure was also investigated. The orientation alignment and crystallinity of the RR-P3HT thin films were evaluated using X-ray diffraction (XRD) and UV-vis absorption spectra. The UV-vis and XRD profile reveals the better orientation and crystallinity of the RR-P3HT thin film after surface modification by HMDS and ODTS. Moreover the incident angle dependences of third harmonic (TH) intensity was measured and the TH intensity of RR-P3HT thin film prepared on glass substrate with SAM layer was found to higher than that of non-treated substrate. The SAM layers significantly enhances the optical property of the material and the third

  19. High-performance organic complementary inverters using monolayer graphene electrodes.

    Science.gov (United States)

    Jeong, Yong Jin; Jang, Jaeyoung; Nam, Sooji; Kim, Kyunghun; Kim, Lae Ho; Park, Seonuk; An, Tae Kyu; Park, Chan Eon

    2014-05-14

    Chemical vapor deposition-grown graphene has been an attractive electrode material for organic electronic devices, such as organic field-effect transistors (OFETs), because it is highly conductive and provides good oxidation and thermal stability properties. However, it still remains a challenge to demonstrate organic complementary circuits using graphene electrodes because of the relatively poor performance of n-type OFETs. Here, we report the development of high-performance organic complementary inverters using graphene as source/drain electrodes and N, N'-ditridecyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C13) and pentacene as n- and p-type organic semiconductors, respectively. Graphene electrodes were n-doped via the formation of NH2-terminated self-assembled monolayers that lowered the work function and the electron injection barrier between the graphene and PTCDI-C13. Thermal annealing improved the molecular packing among PTCDI-C13 groups on the graphene surface, thereby increasing the crystallinity and grain size. The thermally annealed PTCDI-C13 OFETs prepared using n-doped graphene electrodes exhibited a good field-effect mobility of up to 0.43 cm2/(V s), which was comparable to the values obtained from other p-type pentacene OFETs. By integrating p- and n-type OFETs, we successfully fabricated organic complementary inverters that exhibited highly symmetric operation with an excellent voltage gain of up to 124 and good noise margin.

  20. Self-assembled organic radicals on Au(111) surfaces: a combined ToF-SIMS, STM, and ESR study.

    Science.gov (United States)

    Mannini, Matteo; Sorace, Lorenzo; Gorini, Lapo; Piras, Federica M; Caneschi, Andrea; Magnani, Agnese; Menichetti, Stefano; Gatteschi, Dante

    2007-02-27

    Electron spin resonance (ESR), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and scanning tunneling microscopy (STM) have been used in parallel to characterize the deposition on gold surface of a series of nitronyl nitroxide radicals. These compounds have been specifically synthesized with methyl-thio linking groups suitable to interact with the gold surface to form self-assembled monolayers (SAMs), which can be considered relevant in the research for molecular-based spintronics devices, as suggested in recent papers. The degree of the expected ordering on the surface of these SAMs has been tuned by varying the chemical structure of synthesized radicals. ToF-SIMS has been used to support the evidence of the occurrence of the deposition process. STM has shown the different qualities of the obtained SAMs, with the degree of local order increasing as the degree of freedom of the molecules on the surface is decreased. Finally, ESR has confirmed that the deposition process does not affect the paramagnetic characteristics of radicals and that it affords a complete single-layered coverage of the surface. Further, the absence of angular dependence in the spectra indicates that the small regions of local ordering do not give rise to a long-range order and suggests a quite large mobility of the radical on the surface, probably due to the weak interaction with gold provided by the methyl-thio linking group.

  1. Improved efficiency of organic light-emitting diodes with self-assembled molybdenum oxide hole injection layers

    Science.gov (United States)

    Liu, Chia-Wei; Tsai, Ming-Chih; Cheng, Tsung-Chin; Ho, Yu-Hsuan; You, Huang-kuo; Li, Chia-Shuo; Chen, Chin-Ti; Wu, Chih-I.

    2017-05-01

    In this paper, we demonstrate the use of self-assembly to fabricate solution-processed molybdenum oxide (MoO3) films by simply casting a metal oxide solution onto an indium tin oxide substrate. The self-assembled MoO3 (SA-MoO3) films were used as hole injection layers (HILs) in green phosphorescent organic light-emitting diodes. The devices with SA-MoO3 HILs exhibited nearly double the efficiency of the one made with commonly used evaporated MoO3 (e-MoO3) HILs. This improvement was attributed to the much smoother surface and smaller grains of the SA-MoO3 films to reduce the leakage currents, as shown by monitoring the surface morphology via atomic force microscopy and scanning electron microscopy. The work function and Mo 3d core level characteristics were determined via ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy. The e-MoO3 film offered better conductivity and hole injection ability; however, the increased device current may not enhance electroluminance proportionally. As a result, the efficiencies of SA-MoO3 devices were better than those of e-MoO3 devices.

  2. Self-Assembled Nanocomposite Organic Polymers with Aluminum and Scandium as Heterogeneous Water-Compatible Lewis Acid Catalysts.

    Science.gov (United States)

    Miyamura, Hiroyuki; Sonoyama, Arisa; Hayrapetyan, Davit; Kobayashi, Shū

    2015-09-01

    While water-compatible Lewis acids have great potential as accessible and environmentally benign catalysts for various organic transformations, efficient immobilization of such Lewis acids while keeping high activity and without leaching of metals even under aqueous conditions is a challenging task. Self-assembled nanocomposite catalysts of organic polymers, carbon black, aluminum reductants, and scandium salts as heterogeneous water-compatible Lewis acid catalysts are described. These catalysts could be successfully applied to various C-C bond-forming reactions without leaching of metals. Scanning transmission electron microscopy analyses revealed that the nanocomposite structure of Al and Sc was fabricated in these heterogeneous catalysts. It is noted that Al species, which are usually decomposed rapidly in the presence of water, are stabilized under aqueous conditions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Self-Assembling Organic Nanopores as Synthetic Transmembrane Channels with Tunable Functions

    Science.gov (United States)

    Wei, Xiaoxi

    A long-standing goal in the area of supramolecular self-assembly involves the development of synthetic ion/water channels capable of mimicking the mass-transport characteristics of biological channels and pores. Few examples of artificial transmembrane channels with large lumen, high conductivity and selectivity are known. A review of pronounced biological transmembrane protein channels and some representative synthetic models have been provided in Chapter 1, followed by our discovery and initial investigation of shape-persistent oligoamide and phenylene ethynylene macrocycles as synthetic ion/water channels. In Chapter 2, the systematic structural modification of oligoamide macrocycles 1, the so-called first-generation of these shape-persistent macrocycles, has led to third-generation macrocycles 3. The third generation was found to exhibit unprecedented, strong intermolecular association in both the solid state and solution via multiple techniques including X-ray diffraction (XRD), SEM, and 1H NMR. Fluorescence spectroscopy paired with dynamic light scattering (DLS) revealed that macrocycles 3 can assemble into a singly dispersed nanotubular structure in solution. The resultant self-assembling pores consisting of 3 were examined by HPTS-LUVs assays and BLM studies (Chapter 3) and found to form cation-selective (PK+/PCl- = 69:1) transmembrane ion channels with large conductance (200 ˜ 2000 pS for alkali cations) and high stability with open times reaching to 103 seconds. Tuning the aggregation state of macrocycles by choosing an appropriate polar solvent mixture (i.e., 3:1, THF:DMF, v/v) and concentration led to the formation of ion channels with well-defined square top behavior. A parallel study using DLS to examine the size of aggregates was used in conjunction with channel activity assays (LUVs/BLM) to reveal the effects of the aggregation state on channel activity. Empirical evidence now clearly indicates that a preassembled state, perhaps that of a

  4. Nonlinear optical studies of organic monolayers

    International Nuclear Information System (INIS)

    Shen, Y.R.

    1988-02-01

    Second-order nonlinear optical effects are forbidden in a medium with inversion symmetry, but are necessarily allowed at a surface where the inversion summary is broken. They are often sufficiently strong so that a submonolayer perturbation of the surface can be readily detected. They can therefore be used as effective tools to study monolayers adsorbed at various interfaces. We discuss here a number of recent experiments in which optical second harmonic generation (SHG) and sum-frequency generation (SFG) are employed to probe and characterize organic monolayers. 15 refs., 5 figs

  5. Peptide amphiphile self-assembly

    Science.gov (United States)

    Iscen, Aysenur; Schatz, George C.

    2017-08-01

    Self-assembly is a process whereby molecules organize into structures with hierarchical order and complexity, often leading to functional materials. Biomolecules such as peptides, lipids and DNA are frequently involved in self-assembly, and this leads to materials of interest for a wide variety of applications in biomedicine, photonics, electronics, mechanics, etc. The diversity of structures and functions that can be produced provides motivation for developing theoretical models that can be used for a molecular-level description of these materials. Here we overview recently developed computational methods for modeling the self-assembly of peptide amphiphiles (PA) into supramolecular structures that form cylindrical nanoscale fibers using molecular-dynamics simulations. Both all-atom and coarse-grained force field methods are described, and we emphasize how these calculations contribute insight into fiber structure, including the importance of β-sheet formation. We show that the temperature at which self-assembly takes place affects the conformations of PA chains, resulting in cylindrical nanofibers with higher β-sheet content as temperature increases. We also present a new high-density PA model that shows long network formation of β-sheets along the long axis of the fiber, a result that correlates with some experiments. The β-sheet network is mostly helical in nature which helps to maintain strong interactions between the PAs both radially and longitudinally. Contribution to Focus Issue Self-assemblies of Inorganic and Organic Nanomaterials edited by Marie-Paule Pileni.

  6. Self-assembly of organocyanide dianions and metal–organic macrocycles into polymeric architectures including an unprecedented quadruple helical aperiodic structure\

    Czech Academy of Sciences Publication Activity Database

    Zhang, X.; Zhao, H.; Palatinus, Lukáš; Gagnon, K.J.; Bacsa, J.; Dunbar, K.R.

    2016-01-01

    Roč. 16, č. 4 (2016), s. 1805-1811 ISSN 1528-7483 Institutional support: RVO:68378271 Keywords : crystal engineering * self-assembled polymer * modulated structure * helical chain Subject RIV: CC - Organic Chemistry Impact factor: 4.055, year: 2016

  7. Ionic self-assembly of surface functionalized metal-organic polyhedra nanocages and their ordered honeycomb architecture at the air/water interface.

    Science.gov (United States)

    Li, Yantao; Zhang, Daojun; Gai, Fangyuan; Zhu, Xingqi; Guo, Ya-nan; Ma, Tianliang; Liu, Yunling; Huo, Qisheng

    2012-08-18

    Metal-organic polyhedra (MOP) nanocages were successfully surface functionalized via ionic self-assembly and the ordered honeycomb architecture of the encapsulated MOP nanocages was also fabricated at the air/water surface. The results provide a novel synthetic method and membrane processing technique of amphiphilic MOP nanocages for various applications.

  8. Supersaturated Self-Assembled Charge-Selective Interfacial Layers for Organic Solar Cells

    Science.gov (United States)

    2014-11-24

    layers (IFLs) on the tin-doped indium oxide (ITO) anodes of organic photovoltaic (OPV) cells , a series of Ar2N-(CH2)n-SiCl3 precursors with Ar = 3,4...applications such as organic photovoltaics ,1−6 thin-film transistors ,7−9 and organic/ polymer light-emitting diodes.10−13 Using SAM surface mod- ification...oxide (ITO) anodes of organic photovoltaic (OPV) cells , a series of Ar2N-(CH2)n-SiCl3 precursors with Ar = 3,4-difluorophenyl, n = 3, 6, 10, and 18, was

  9. Semifluorinated Alkylphosphonic Acids Form High-Quality Self-Assembled Monolayers on Ag-Coated Yttrium Barium Copper Oxide Tapes and Enable Filamentization of the Tapes by Microcontact Printing.

    Science.gov (United States)

    Park, Chul Soon; Lee, Han Ju; Lee, Dahye; Jamison, Andrew C; Galstyan, Eduard; Zagozdzon-Wosik, Wanda; Freyhardt, Herbert C; Jacobson, Allan J; Lee, T Randall

    2016-08-30

    A custom-designed semifluorinated phosphonic acid, (9,9,10,10,11,11,12,12,13,13,14,14,15,15,16,16,16-heptadecafluorohexadecyl)phosphonic acid (F8H8PA), and a normal hexadecylphosphonic acid (H16PA) were synthesized and used to generate self-assembled monolayers (SAMs) on commercially available yttrium barium copper oxide (YBCO) tapes. In this study, we wished to evaluate the effectiveness of these monolayer films as coatings for selectively etching YBCO. Initial films formed by solution deposition and manual stamping using a non-patterned polydimethylsiloxane stamp allowed for a comparison of the film-formation characteristics. The resulting monolayers were characterized by X-ray photoelectron spectroscopy (XPS), contact angle goniometry, and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS). To prepare line-patterned (filamentized) YBCO tapes, standard microcontact printing (μ-CP) procedures were used. The stamped patterns on the YBCO tapes were characterized by scanning electron microscopy (SEM) before and after etching to confirm the effectiveness of the patterning process on the YBCO surface and energy-dispersive X-ray spectroscopy (EDX) to obtain the atomic composition of the exposed interface.

  10. Improving performance, stability, and processability of OFETs with printed Ag electrodes by means of a novel, multipurpose self-assembled monolayer (Conference Presentation)

    Science.gov (United States)

    Alt, Milan; Jesper, Malte; Schinke, Janusz; Hillebrandt, Sabina; Reiser, Patrick; Rödlmeier, Tobias; Angelova, Iva; Hamburger, Manuel; Lemmer, Ulrich; Hernandez-Sosa, Gerardo; Lovrincic, Robert

    2016-11-01

    We present a novel SAM-forming molecule bisjulolidyldisulfide that reduces the WF of metal surfaces by 1.2 eV and can lower the barrier for electron injection to organic semiconductors. Applied to Au and Ag surfaces, including inkjet-printed Ag on PET, we characterized bisjulolidyldisulfide monolayers by means of photoelectron spectroscopy (PES) and sessile drop technique, as well as their influence on the performance of n-type OFETs. Next a strong reduction of the contact resistance by two orders of magnitude, we found that this SAM treatment extends the shelf lifetime of ambient-stored OFET devices. Also, it improves the wettability and thereby facilitates solution processing of a subsequent layer with respect to the untreated surface. The full electrical functionality of bisjulolidyldisulfide SAMs was found to become manifest with only one minute of immersion in ethanol solution. PES measurements suggests that the surface coverage is thorough on Au, but only fractional on Ag, especially on printed Ag. However, the quality of SAM-treated bottom contacts in n-type OFETs is very similar for all three investigated metal surfaces (Au and Ag evaporated and printed Ag). This is especially important for printed Ag-electrodes, as their surface was found to be significantly worse for device performance in comparison to their evaporated Ag counterpart. Using this surface treatment we realized integrated unipolar n-type ring oscillators with inkjet printed Ag electrodes.

  11. Scanning tunneling microscopy, Fourier transform infrared spectroscopy, and electrochemical characterization of 2-naphthalenethiol self-assembled monolayers on the Au surface: a study of bridge-mediated electron transfer in Ru(NH3)6(2+)/Ru(NH3)6(3+) redox reactions.

    Science.gov (United States)

    Ganesh, V; Lakshminarayanan, V

    2005-09-01

    We have studied the structure, adsorption kinetics, and barrier properties of self-assembled monolayers of 2-naphthalenethiol on Au using electrochemical techniques, grazing-angle Fourier transform infrared (FTIR) spectroscopy, and scanning tunneling microscopy (STM). The results of cyclic voltammetric and impedance measurements using redox probes show that 2-naphthalenethiol on Au forms a stable and reproducible, but moderately blocking, monolayer. Annealing of the self-assembled monolayer (SAM)-modified surface at 72 +/- 2 degrees C remarkably improves the blocking property of the monolayer of 2-naphthalenethiol on Au. From the study of kinetics of SAM formation, we find that the self-assembly follows Langmuir adsorption isotherm. Our STM and FTIR results show that the molecules are adsorbed with the naphthalene ring tilted from the surface normal by forming a square root 3 x 3 R30 degrees overlayer structure. From our studies, we conclude that the electron-transfer reaction of ferro/ferricyanide in the freshly formed monolayer occurs predominantly through the pinholes and defects present in the monolayer. However, in the case of thermally annealed specimen, although the ferro/ferricyanide reaction is almost completely blocked, the electron-transfer reaction of hexaammineruthenium(III) chloride is not significantly inhibited. It is proposed that the electron-transfer reaction in the case of the ruthenium redox couple takes place by a tunneling mechanism through the high-electron-density aromatic naphthalene ring acting as a bridge between the monolayer-modified electrode and the ruthenium complex.

  12. Self-assembly of ferromagnetic organic-inorganic perovskite-like films.

    Science.gov (United States)

    Akhtar, Naureen; Polyakov, Alexey O; Aqeel, Aisha; Gordiichuk, Pavlo; Blake, Graeme R; Baas, Jacob; Amenitsch, Heinz; Herrmann, Andreas; Rudolf, Petra; Palstra, Thomas T M

    2014-12-10

    Perovskite-based organic-inorganic hybrids hold great potential as active layers in electronics or optoelectronics or as components of biosensors. However, many of these applications require thin films grown with good control over structure and thickness--a major challenge that needs to be addressed. The work presented here is an effort towards this goal and concerns the layer-by-layer deposition at ambient conditions of ferromagnetic organic-inorganic hybrids consisting of alternating CuCl4-octahedra and organic layers. The Langmuir-Blodgett technique used to assemble these structures provides intrinsic control over the molecular organization and film thickness down to the molecular level. Magnetic characterization reveals that the coercive field for these thin films is larger than that for solution-grown layered bulk crystals. The strategy presented here suggests a promising cost effective route to facilitate the excellently controlled growth of sophisticated materials on a wide variety of substrates that have properties relevant for the high density storage media and spintronic devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Integrative self-assembly of functional hybrid nanoconstructs by inorganic wrapping of single biomolecules, biomolecule arrays and organic supramolecular assemblies.

    Science.gov (United States)

    Patil, Avinash J; Li, Mei; Mann, Stephen

    2013-08-21

    Synthesis of functional hybrid nanoscale objects has been a core focus of the rapidly progressing field of nanomaterials science. In particular, there has been significant interest in the integration of evolutionally optimized biological systems such as proteins, DNA, virus particles and cells with functional inorganic building blocks to construct mesoscopic architectures and nanostructured materials. However, in many cases the fragile nature of the biomolecules seriously constrains their potential applications. As a consequence, there is an on-going quest for the development of novel strategies to modulate the thermal and chemical stabilities, and performance of biomolecules under adverse conditions. This feature article highlights new methods of "inorganic molecular wrapping" of single or multiple protein molecules, individual double-stranded DNA helices, lipid bilayer vesicles and self-assembled organic dye superstructures using inorganic building blocks to produce bio-inorganic nanoconstructs with core-shell type structures. We show that spatial isolation of the functional biological nanostructures as "armour-plated" enzyme molecules or polynucleotide strands not only maintains their intact structure and biochemical properties, but also enables the fabrication of novel hybrid nanomaterials for potential applications in diverse areas of bionanotechnology.

  14. Integrative self-assembly of functional hybrid nanoconstructs by inorganic wrapping of single biomolecules, biomolecule arrays and organic supramolecular assemblies

    Science.gov (United States)

    Patil, Avinash J.; Li, Mei; Mann, Stephen

    2013-07-01

    Synthesis of functional hybrid nanoscale objects has been a core focus of the rapidly progressing field of nanomaterials science. In particular, there has been significant interest in the integration of evolutionally optimized biological systems such as proteins, DNA, virus particles and cells with functional inorganic building blocks to construct mesoscopic architectures and nanostructured materials. However, in many cases the fragile nature of the biomolecules seriously constrains their potential applications. As a consequence, there is an on-going quest for the development of novel strategies to modulate the thermal and chemical stabilities, and performance of biomolecules under adverse conditions. This feature article highlights new methods of ``inorganic molecular wrapping'' of single or multiple protein molecules, individual double-stranded DNA helices, lipid bilayer vesicles and self-assembled organic dye superstructures using inorganic building blocks to produce bio-inorganic nanoconstructs with core-shell type structures. We show that spatial isolation of the functional biological nanostructures as ``armour-plated'' enzyme molecules or polynucleotide strands not only maintains their intact structure and biochemical properties, but also enables the fabrication of novel hybrid nanomaterials for potential applications in diverse areas of bionanotechnology.

  15. A self-assembled fluorescent organic nanoprobe and its application for sulfite detection in food samples and living systems.

    Science.gov (United States)

    Gao, Tang; Cao, Xiaozheng; Ge, Peng; Dong, Jie; Yang, Shuqi; Xu, Huan; Wu, Yong; Gao, Feng; Zeng, Wenbin

    2017-05-23

    Sulfur dioxide (SO 2 ) is a widely distributed air pollutant, and humans can easily be exposed to sulfite by inhaling SO 2 , thus inducing respiratory responses and diseases. Hence, to develop a rapid, sensitive and selective method for detection of sulfites is of great importance. Herein, we designed and synthesized a novel tetraphenyl imidazole compound TIBM with aggregation-induced emission enhancement (AIEE). TIBM can self-assemble into well-organized nanoparticles and is reported as an excellent probe for detection of sulfite with high selectivity and sensitivity. The nanoprobe performed very well for the detection of sulfite with an ultrafast detection time (15 s) and an ultralow detection limit (7.4 nM), which is superior to most of the reported probes. Moreover, the nanoprobe was successfully used to detect sulfite in food samples with a favorable accuracy. In addition, we developed paper-based devices for point-of-care detection of sulfite with naked eyes. Furthermore, due to its high water solubility, cell membrane permeability and good biocompatibility, the nanoproboe was further applied to detect sulfite in living systems. This study may offer some helpful insights for designing other AIE-based fluorescent nanosensors for various analytes.

  16. Magnetic field effects and self-assembled n-type nanostructures to increase charge collection in organic photovoltaics

    Science.gov (United States)

    Carter, Austin Roberts

    -accepting fullerenes reduce the population of loosely bound electron-hole pairs, thereby quenching the magnetic field effects. The second approach to increase charge collection in organic photovoltaics uses self-assembled perylene diimide nanostructures in a nanofabric heterojunction. Cyclic voltammetry, photoluminescence quenching and bilayer device measurement shows that perylene diimides are good electron acceptors and potential alternatives to fullerene-based acceptors. Perylene diimides are also excellent n-type conductors; the field-effect transistor mobility of bis(octyl)-perylenediimide (PDI-C8) was measured to be mue =0.05+/-0.01 cm2 V-1 s-1 . In addition, flat perylene diimide molecules tend to pi-pi stack to form nanofibers and nanofabrics using a simple solvent mixture self-assembly procedure. PDI-C8 nanofibers were incorporated into a novel device architecture---the nanofabric hetero junction---to increase collection of electrons. Devices incorporating PDI-C8 nanofibers exhibited a 110% increase in the short circuit current density compared to devices without the nanofibers. This increase is attributed to the fibers increasing the donor-acceptor interfacial area, transporting electrons out of the device along dedicated conduction pathways and reducing the build up of space-charge.

  17. Self-Assembled Fibers Containing Stable Organic Radical Moieties: Alignment and Magnetic Properties in Liquid Crystals.

    Science.gov (United States)

    Eimura, Hiroki; Umeta, Yoshikazu; Tokoro, Hiroko; Yoshio, Masafumi; Ohkoshi, Shin-Ichi; Kato, Takashi

    2016-06-20

    Macroscopically oriented stable organic radicals have been obtained by using a liquid-crystalline (LC) gel composed of an l-isoleucine-based low molecular weight gelator containing a 2,2,6,6-tetramethylpiperidine 1-oxyl moiety. The LC gel has allowed magnetic measurements of the oriented organic radical. The gelator has formed fibrous aggregates in liquid crystals via intermolecular hydrogen bonds. The fibrous aggregates of the radical gelator are formed and oriented on cooling by applying a magnetic field to the mixture of liquid crystals and the gelator. Superconducting quantum interference device (SQUID) measurements have revealed that both oriented and nonoriented fibrous aggregates exhibited antiferromagnetic interactions, in which super-exchange interaction constant J is estimated as -0.89 cm(-1) . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Crystalline self-assembly of organic molecules with metal ions at the air-aqueous solution interface. A grazing incidence X-ray scattering study

    DEFF Research Database (Denmark)

    Weissbuch, I.; Buller, R.; Kjær, K.

    2002-01-01

    The advent of intense X-rays from synchrotron sources made possible to probe, at the molecular level, the structural aspects of self-assemblies generated at interfaces. Here we present the two-dimensional (2-D) packing arrangements of two-, three- and multi-component organo-metallic self-assembli......The advent of intense X-rays from synchrotron sources made possible to probe, at the molecular level, the structural aspects of self-assemblies generated at interfaces. Here we present the two-dimensional (2-D) packing arrangements of two-, three- and multi-component organo-metallic self......-assemblies formed via interfacial reaction at the air-aqueous solution interface, as determined by grazing incidence X-ray diffraction (GIRD) and X-ray specular reflectivity techniques. GIXD yields structural information on the crystalline part of the Langmuir film, including the ions and counterions lateral order...... of metal ions bound to the polar head groups of amphipilic molecules; use of bolaamphiphiles to generate oriented thin films with metal ions arranged in periodic layers; delineation of differences in the lateral organization of metal ions at interfaces as induced by racemates and enantiomerically pure...

  19. Molecular self-assembly advances and applications

    CERN Document Server

    Dequan, Alex Li

    2012-01-01

    In the past several decades, molecular self-assembly has emerged as one of the main themes in chemistry, biology, and materials science. This book compiles and details cutting-edge research in molecular assemblies ranging from self-organized peptide nanostructures and DNA-chromophore foldamers to supramolecular systems and metal-directed assemblies, even to nanocrystal superparticles and self-assembled microdevices

  20. A Facile Method for Detection of Substituted Salicylic Acids Using Pyrenesulfonamide-Terminated Self-Assembled Monolayers on Silicon Oxide Surfaces

    International Nuclear Information System (INIS)

    Han, Gyeongyeop; Choi, Jaehyuck; Lee, Jungkyu; Kumar, Ashwani; Lee, Ju-Young; Kim, Hong-Seok

    2016-01-01

    We have developed a method for sensing substituted salicylic acids on silicon oxide surfaces. The receptor molecule was successfully immobilized onto the surface by self-assembly, and, as a demonstration, micropatterns of substituted salicylic acids were generated by soft lithography techniques. We believe that this approach used herein will not only widen the understanding of the specific interactions between salicylic acids and pyrenesulfonamide derivatives, but also be applicable to practical devices such as chemo/bio analytical sensors. We have successfully demonstrated the molecular recognition between salicylic acids and pyrene derivatives in solution by fluorescence measurement. Briefly, selective recognition was achieved using intermolecular interactions, including π-π interactions and multi-hydrogen bonds, and intramolecular hydrogen bonding between the phenolic O-H group and the adjacent C=O group

  1. Easily processable highly ordered Langmuir-Blodgett films of quaterthiophene disiloxane dimer for monolayer organic field-effect transistors.

    Science.gov (United States)

    Sizov, Alexey S; Anisimov, Daniil S; Agina, Elena V; Borshchev, Oleg V; Bakirov, Artem V; Shcherbina, Maxim A; Grigorian, Souren; Bruevich, Vladimir V; Chvalun, Sergei N; Paraschuk, Dmitry Yu; Ponomarenko, Sergei A

    2014-12-23

    Self-assembly of highly soluble water-stable tetramethyldisiloxane-based dimer of α,α'-dialkylquaterthiophene on the water-air interface was investigated by Langmuir, grazing incidence X-ray diffraction, and X-ray reflectivity techniques. The conditions for formation of very homogeneous crystalline monolayer Langmuir-Blodgett (LB) films of the oligomer were found. Monolayer organic field-effect transistors (OFETs) based on these LB films as a semiconducting layer showed hole mobilities up to 3 × 10(-3) cm(2)/(V s), on-off ratio of 10(5), small hysteresis, and high long-term stability. The electrical performance of the LB films studied is close to that for the same material in the bulk or in the monolayer OFETs prepared from water vapor sensitive chlorosilyl derivatives of quaterthiophene by self-assembling from solution. These findings show high potential of disiloxane-based LB films in monolayer OFETs for large-area organic electronics.

  2. Monolayer Films Prepared by the Spontaneous Self-Assembly of Symmetrical and Unsymmetrical Dialkyl Sulfides from Solution Onto Gold Substrates: Structure, Properties, and Reactivity of Constituent Functional Groups.

    Science.gov (United States)

    1987-10-01

    this time.41 X-Ray Photoelectron Spectroscopy. Obtaining reliable *XPS data for the monolayer films proved consistently troublesome, until it became...of argon for 5-15 seconds. The properties of the films were measured immediately by ellipsometry and contact angle goniometry . Gold substrates were

  3. Self-assembled, aligned ZnO nanorod buffer layers for high-current-density, inverted organic photovoltaics.

    Science.gov (United States)

    Rao, Arun D; Karalatti, Suresh; Thomas, Tiju; Ramamurthy, Praveen C

    2014-10-08

    Two different soft-chemical, self-assembly-based solution approaches are employed to grow zinc oxide (ZnO) nanorods with controlled texture. The methods used involve seeding and growth on a substrate. Nanorods with various aspect ratios (1-5) and diameters (15-65 nm) are grown. Obtaining highly oriented rods is determined by the way the substrate is mounted within the chemical bath. Furthermore, a preheat and centrifugation step is essential for the optimization of the growth solution. In the best samples, we obtain ZnO nanorods that are almost entirely oriented in the (002) direction; this is desirable since electron mobility of ZnO is highest along this crystallographic axis. When used as the buffer layer of inverted organic photovoltaics (I-OPVs), these one-dimensional (1D) nanostructures offer: (a) direct paths for charge transport and (b) high interfacial area for electron collection. The morphological, structural, and optical properties of ZnO nanorods are studied using scanning electron microscopy, X-ray diffraction, and ultraviolet-visible light (UV-vis) absorption spectroscopy. Furthermore, the surface chemical features of ZnO films are studied using X-ray photoelectron spectroscopy and contact angle measurements. Using as-grown ZnO, inverted OPVs are fabricated and characterized. For improving device performance, the ZnO nanorods are subjected to UV-ozone irradiation. UV-ozone treated ZnO nanorods show: (i) improvement in optical transmission, (ii) increased wetting of active organic components, and (iii) increased concentration of Zn-O surface bonds. These observations correlate well with improved device performance. The devices fabricated using these optimized buffer layers have an efficiency of ∼3.2% and a fill factor of 0.50; this is comparable to the best I-OPVs reported that use a P3HT-PCBM active layer.

  4. Design, Synthesis, and Use of Peptides Derived from Human Papillomavirus L1 Protein for the Modification of Gold Electrode Surfaces by Self-Assembled Monolayers.

    Science.gov (United States)

    Lara Carrillo, John Alejandro; Fierro Medina, Ricardo; Manríquez Rocha, Juan; Bustos Bustos, Erika; Insuasty Cepeda, Diego Sebastián; García Castañeda, Javier Eduardo; Rivera Monroy, Zuly Jenny

    2017-11-14

    In order to obtain gold electrode surfaces modified with Human Papillomavirus L1 protein (HPV L1)-derived peptides, two sequences, SPINNTKPHEAR and YIK, were chosen. Both have been recognized by means of sera from patients infected with HPV. The molecules, Fc-Ahx-SPINNTKPHEAR, Ac-C- Ahx -(Fc)KSPINNTKPHEAR, Ac-C- Ahx -SPINNTKPHEAR(Fc)K, C- Ahx -SPINNTKPHEAR, and (YIK)₂- Ahx -C, were designed, synthesized, and characterized. Our results suggest that peptides derived from the SPINNTKPHEAR sequence, containing ferrocene and cysteine residues, are not stable and not adequate for electrode surface modification. The surface of polycrystalline gold electrodes was modified with the peptides C-Ahx-SPINNTKPHEAR or (YIK)₂-Ahx-C through self-assembly. The modified polycrystalline gold electrodes were characterized via infrared spectroscopy and electrochemical measurements. The thermodynamic parameters, surface coverage factor, and medium pH effect were determined for these surfaces. The results indicate that surface modification depends on the peptide sequence (length, amino acid composition, polyvalence, etc.). The influence of antipeptide antibodies on the voltammetric response of the modified electrode was evaluated by comparing results obtained with pre-immune and post-immune serum samples.

  5. Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

    International Nuclear Information System (INIS)

    Yuan, Yi; Liu, Zheming; Liu, Zhenyang; Peng, Lan; Li, Yongjie; Tang, Aiwei

    2017-01-01

    Highlights: • CsPbBr 3 perovskite nanocrystals have been synthesized in the presence of organic amines with different hydrocarbon length. • The photoluminescence of the CsPbBr 3 nanocrystals is affected by the varying the carbon length of the organic amines. • The lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr 3 nanocrystals. - Abstract: All-inorganic halide perovskites have become one of the most prospective materials for lightening and display technology due to their color-tunable and narrow-band emission. Herein, we have systematically studied the effects of organic amines with different hydrocarbon chain length on the optical properties and morphology as well as the crystal structure of colloidal CsPbBr 3 nanocrystals (NCs), which were synthesized in the presence of oleic acid (OA) and organic amines by using a simple hot-injection approach. The hydrocarbon chain length has shown an independent correlation to the morphology and crystal structure of the as-obtained CsPbBr 3 NCs at 160 °C, but their optical properties can be affected to some extent. The photoluminescence quantum yields (PLQYs) of the CsPbBr 3 NCs synthesized in the presence of organic amines with long carbon chain length are generally in the range of 55–80% for different reaction time, but the PLQYs of less than 20% are obtained for the products synthesized in the presence of octylamine (OTAm) with short carbon chain length. The effects of the reaction temperature on the optical properties, size and crystal structure of the CsPbBr 3 NCs synthesized in the presence of cetylamine (CTAm) are studied. Interestingly, some nanoplates also appear in these CsPbBr 3 NCs obtained at relatively low temperatures (120 and 140 °C), which have a strong tendency to self-assemble into face-to-face nanostructures. Such a similar self-assembly behavior is also observed in the product synthesized in the presence of

  6. Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Yi; Liu, Zheming; Liu, Zhenyang; Peng, Lan; Li, Yongjie; Tang, Aiwei, E-mail: awtang@bjtu.edu.cn

    2017-05-31

    Highlights: • CsPbBr{sub 3} perovskite nanocrystals have been synthesized in the presence of organic amines with different hydrocarbon length. • The photoluminescence of the CsPbBr{sub 3} nanocrystals is affected by the varying the carbon length of the organic amines. • The lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr{sub 3} nanocrystals. - Abstract: All-inorganic halide perovskites have become one of the most prospective materials for lightening and display technology due to their color-tunable and narrow-band emission. Herein, we have systematically studied the effects of organic amines with different hydrocarbon chain length on the optical properties and morphology as well as the crystal structure of colloidal CsPbBr{sub 3} nanocrystals (NCs), which were synthesized in the presence of oleic acid (OA) and organic amines by using a simple hot-injection approach. The hydrocarbon chain length has shown an independent correlation to the morphology and crystal structure of the as-obtained CsPbBr{sub 3} NCs at 160 °C, but their optical properties can be affected to some extent. The photoluminescence quantum yields (PLQYs) of the CsPbBr{sub 3} NCs synthesized in the presence of organic amines with long carbon chain length are generally in the range of 55–80% for different reaction time, but the PLQYs of less than 20% are obtained for the products synthesized in the presence of octylamine (OTAm) with short carbon chain length. The effects of the reaction temperature on the optical properties, size and crystal structure of the CsPbBr{sub 3} NCs synthesized in the presence of cetylamine (CTAm) are studied. Interestingly, some nanoplates also appear in these CsPbBr{sub 3} NCs obtained at relatively low temperatures (120 and 140 °C), which have a strong tendency to self-assemble into face-to-face nanostructures. Such a similar self-assembly behavior is also observed in the

  7. Directed self-assembled crystalline oligomer domains on graphene and graphite

    DEFF Research Database (Denmark)

    Balzer, Frank; Henrichsen, Henrik Hartmann; Klarskov, Mikkel Buster

    2014-01-01

    We observe the formation of thin films of fibre-like aggregates from the prototypical organic semiconductor molecule para-hexaphenylene (p-6P) on graphite thin flakes and on monolayer graphene. Using atomic force microscopy, scanning electron microscopy, x-ray diffraction, polarized fluorescence...... show that the graphene surface can be used as a growth substrate to direct the self-assembly of organic molecular thin films and nanofibres, both with and without lithographical processing....

  8. Self-assembly of semiconductor/insulator interfaces in one-step spin-coating: a versatile approach for organic field-effect transistors.

    Science.gov (United States)

    Liu, Chuan; Li, Yun; Lee, Michael V; Kumatani, Akichika; Tsukagoshi, Kazuhito

    2013-06-07

    Self-assembly of interfaces is of great interest in physical and chemical domains. One of the most challenging targets is to obtain an optimal interface structure showing good electronic properties by solution-processing. Interfaces of semiconductor/semiconductor, semiconductor/insulator and insulator/insulator have been successfully manipulated to obtain high-performance devices. In this review we discuss a special class of interface, semiconductor/insulator interface, formed by vertical phase separation during spin-coating and focus on the versatile applications in organic field-effect transistors (OFETs). The formation of such an interface can be finished within tens of seconds and its mechanism is related to the materials, surfaces and dynamics. Fascinatingly, such self-assembly could be used to simplify the fabrication procedure, improve film spreading, change interfacial properties, modify semiconductor morphology, and encapsulate thin films. These merits lead to OFETs with high performance and good reliability. Also, the method is very suitable for combining with other solution-processed techniques such as patterning and post-annealing, which leads to facile paper electronics, in situ purification and single crystal formation. Research on this topic not only provides an in-depth understanding of self-assembly in solution processing, but also opens new paths towards flexible organic electronics.

  9. Supramolecular Langmuir monolayers and multilayered vesicles of self-assembling DNA–lipid surface structures and their further implications in polyelectrolyte-based cell transfections

    Energy Technology Data Exchange (ETDEWEB)

    Demirsoy, Fatma Funda Kaya [Ankara University, The Central Laboratory of The Institute of Biotechnology (Turkey); Eruygur, Nuraniye [Gazi University, Department of Pharmacognosy, Faculty of Pharmacy (Turkey); Süleymanoğlu, Erhan, E-mail: erhans@mail.ru [Gazi University, Department of Pharmaceutical Chemistry, Faculty of Pharmacy (Turkey)

    2015-01-15

    The basic interfacial characteristics of DNA–lipid recognitions have been studied. The complex structures of individual unbound DNA molecules and their binary and ternary complexes with zwitterionic lipids and divalent cations were followed by employing lipid monolayers at the air–liquid interfaces, as well as by performing various microscopic, spectroscopic, and thermodynamic measurements with multilayered vesicles. The pressure-area isotherms depicted that Mg{sup 2+}-ions increase the surface pressure of lipid films and thus give rise to electrostatic and hydrophobic lipid–DNA interactions in terms of DNA adsorption, adhesion, and compaction. These features were further approached by using multilamellar vesicles with a mean diameter of 850 nm, where a metal ion-directed nucleic acid compaction and condensation effects were shown. The data obtained show the effectiveness of Langmuir monolayers and lipid multilayers in studying nucleic acid–lipid recognitions. The data provide with further details and support previous reports on mainly structural features of these recognitions. Biomolecular surface recognition events were presented in direct link with spectral and thermodynamic features of lipid vesicle–polynucleotide complex formations. The results serve to build a theoretical model considering the use of neutral lipids in lipoplex designs as a polyelectrolyte alternatives to the currently employed cytotoxic cationic liposomes. The supramolecular structures formed and their possible roles in interfacial electrostatic and hydrophobic mechanisms of endosomal escape in relevant cell transfection assays are particularly emphasized.

  10. Combined atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and quartz crystal microbalance (QCM) studies of glucose oxidase (GOx) immobilised onto self-assembled monolayer on the gold film

    International Nuclear Information System (INIS)

    Losic, D.; Shapter, J.; Gooding, J.; Erokin, P.; Short, K.

    1999-01-01

    In fabrication of biosensors, self-assembled monolayers (SAM) are an attractive method of immobilising enzymes at electrode surface since it allows precise control over the amount and spatial distribution of the immobilized enzyme. The covalent attachment of glucose oxidase (GOx) to a carboxylic terminated SAM chemisorbed onto gold films was achieved via carbodiimide activation of the carboxylic acids to a reactive intermediate susceptible to nucleophilic attack by amines on free lysine chains of the enzyme. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and quartz crystal microbalance (QCM) measurements were used for characterisation of GOx modified gold surfaces. Tapping mode AFM studies have revealed that GOx molecules form slightly disordered arrays of pentagonal or hexagonal clusters. Observed features of immobilised GOx are distributed as a submonolayer on the SAM surface which has allowed visualisation of native and unfolded enzyme structure. The presence of the SAM and enzyme on the gold surface was detected by XPS spectroscopy. Spectra show typical peaks for the C 1s, O 1s and N 1s regions. A kinetic study of the adsorption of GOx onto activated SAM using in-situ QCM allowed determination the amount of immobilised GOx on the layer and consequently the optimal immobilisation conditions. Performance parameters of the biosensor such as sensitivity to glucose concentration as a function of enzyme loading were evaluated amperometrically using the redox mediator p-benzoquinone

  11. Tracing the 4000 year history of organic thin films: From monolayers on liquids to multilayers on solidsa)

    Science.gov (United States)

    Greene, J. E.

    2015-03-01

    The recorded history of organic monolayer and multilayer thin films spans approximately 4000 years. Fatty-acid-based monolayers were deposited on water by the ancients for applications ranging from fortune telling in King Hammurabi's time (˜1800 BC, Mesopotamia) to stilling choppy waters for sailors and divers as reported by the Roman philosopher Pliny the Elder in ˜78 AD, and then much later (1774) by the peripatetic American statesman and natural philosopher Benjamin Franklin, to Japanese "floating-ink" art (suminagashi) developed ˜1000 years ago. The modern science of organic monolayers began in the late-1800s/early-1900s with experiments by Lord Rayleigh and the important development by Agnes Pockels, followed two decades later by Irving Langmuir, of the tools and technology to measure the surface tension of liquids, the surface pressure of organic monolayers deposited on water, interfacial properties, molecular conformation of the organic layers, and phase transitions which occur upon compressing the monolayers. In 1935, Katherine Blodgett published a landmark paper showing that multilayers can be synthesized on solid substrates, with controlled thickness and composition, using an apparatus now known as the Langmuir-Blodgett (L-B) trough. A disadvantage of LB films for some applications is that they form weak physisorbed bonds to the substrate. In 1946, Bigelow, Pickett, and Zisman demonstrated, in another seminal paper, the growth of organic self-assembled monolayers (SAMs) via spontaneous adsorption from solution, rather than from the water/air interface, onto SiO2 and metal substrates. SAMs are close-packed two-dimensional organic crystals which exhibit strong covalent bonding to the substrate. The first multicomponent adsorbed monolayers and multilayer SAMs were produced in the early 1980s. Langmuir monolayers, L-B multilayers, and self-assembled mono- and multilayers have found an extraordinarily broad range of applications including controlled wetting

  12. Tracing the 4000 year history of organic thin films: From monolayers on liquids to multilayers on solids

    Energy Technology Data Exchange (ETDEWEB)

    Greene, J. E. [University of Illinois, Urbana, Illinois 61801 (United States); Linköping University, 581 83 Linköping (Sweden); National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China)

    2015-03-15

    The recorded history of organic monolayer and multilayer thin films spans approximately 4000 years. Fatty-acid-based monolayers were deposited on water by the ancients for applications ranging from fortune telling in King Hammurabi's time (∼1800 BC, Mesopotamia) to stilling choppy waters for sailors and divers as reported by the Roman philosopher Pliny the Elder in ∼78 AD, and then much later (1774) by the peripatetic American statesman and natural philosopher Benjamin Franklin, to Japanese “floating-ink” art (suminagashi) developed ∼1000 years ago. The modern science of organic monolayers began in the late-1800s/early-1900s with experiments by Lord Rayleigh and the important development by Agnes Pockels, followed two decades later by Irving Langmuir, of the tools and technology to measure the surface tension of liquids, the surface pressure of organic monolayers deposited on water, interfacial properties, molecular conformation of the organic layers, and phase transitions which occur upon compressing the monolayers. In 1935, Katherine Blodgett published a landmark paper showing that multilayers can be synthesized on solid substrates, with controlled thickness and composition, using an apparatus now known as the Langmuir-Blodgett (L-B) trough. A disadvantage of LB films for some applications is that they form weak physisorbed bonds to the substrate. In 1946, Bigelow, Pickett, and Zisman demonstrated, in another seminal paper, the growth of organic self-assembled monolayers (SAMs) via spontaneous adsorption from solution, rather than from the water/air interface, onto SiO{sub 2} and metal substrates. SAMs are close-packed two-dimensional organic crystals which exhibit strong covalent bonding to the substrate. The first multicomponent adsorbed monolayers and multilayer SAMs were produced in the early 1980s. Langmuir monolayers, L-B multilayers, and self-assembled mono- and multilayers have found an extraordinarily broad range of applications including

  13. Self-assembled nanostructures

    CERN Document Server

    Zhang, Jin Z; Liu, Jun; Chen, Shaowei; Liu, Gang-yu

    2003-01-01

    Nanostructures refer to materials that have relevant dimensions on the nanometer length scales and reside in the mesoscopic regime between isolated atoms and molecules in bulk matter. These materials have unique physical properties that are distinctly different from bulk materials. Self-Assembled Nanostructures provides systematic coverage of basic nanomaterials science including materials assembly and synthesis, characterization, and application. Suitable for both beginners and experts, it balances the chemistry aspects of nanomaterials with physical principles. It also highlights nanomaterial-based architectures including assembled or self-assembled systems. Filled with in-depth discussion of important applications of nano-architectures as well as potential applications ranging from physical to chemical and biological systems, Self-Assembled Nanostructures is the essential reference or text for scientists involved with nanostructures.

  14. A new amperometric method for rapid detection of Escherichia coli density using a self-assembled monolayer-based bienzyme biosensor

    International Nuclear Information System (INIS)

    Tang Hui; Zhang Wen; Geng Ping; Wang Qingjiang; Jin Litong; Wu Zirong; Lou Min

    2006-01-01

    A new amperometric method was developed for rapid detection of Escherichia coli (E. coli) density using a bienzyme biosensor. The bienzyme biosensor was fabricated based on the covalent immobilization of laccase and horseradish peroxidase (HRP) at indium tin oxide (ITO) electrode by (3-aminopropyl) triethoxysilane (APTES) monolayer. The bienzyme biosensor showed a high sensitivity in determination of the polyphenolic compounds, which was microbially generated from the salicylic acid (SA) added into the culture medium during the course of E. coli metabolism. Since the amount of polyphenolic compounds depends on E. coli density, the bienzyme biosensor was applied for the rapid and high sensitive detection of E. coli density after the E. coli solution was incubated in culture medium with salicylic acid for 2.5 h at 37 deg. C. By chronoamperometry, the amplified response current was obtained at the bienzyme biosensor, due to the substrate recycling of the polyphenolic compounds driven by bienzyme-catalyzed oxidation and electrochemical reduction. The amplified response current at the biosensor was linear with the E. coli density ranging from 1.6 x 10 3 to 1.0 x 10 7 cells/mL. The bienzyme biosensor could detect the E. coli density with a detection limit of 9.7 x 10 2 cells/mL within 3 h

  15. Effects of Self-Assembled Monolayer Modification of Nickel Oxide Nanoparticles Layer on the Performance and Application of Inverted Perovskite Solar Cells.

    Science.gov (United States)

    Wang, Qin; Chueh, Chu-Chen; Zhao, Ting; Cheng, Jiaqi; Eslamian, Morteza; Choy, Wallace C H; Jen, Alex K-Y

    2017-10-09

    Entirely low-temperature solution-processed (≤100 °C) planar p-i-n perovskite solar cells (PSCs) offer great potential for commercialization of roll-to-roll fabricated photovoltaic devices. However, the stable inorganic hole-transporting layer (HTL) in PSCs is usually processed at high temperature (200-500 °C), which is far beyond the tolerant temperature (≤150 °C) of roll-to-roll fabrication. In this context, inorganic NiO x nanoparticles (NPs) are an excellent candidate to serve as the HTL in PSCs, owing to their excellent solution processability at room temperature. However, the low-temperature processing condition is usually accompanied with defect formation, which deteriorates the film quality and device efficiency to a large extent. To suppress this setback, we used a series of benzoic acid selfassembled monolayers (SAMs) to passivate the surface defects of the NiO x NPs and found that 4-bromobenzoic acid could effectively play the role of the surface passivation. This SAM layer reduces the trap-assisted recombination, minimizes the energy offset between the NiO x NPs and perovskite, and changes the HTL surface wettability, thus enhancing the perovskite crystallization, resulting in more stable PSCs with enhanced power conversion efficiency (PCE) of 18.4 %, exceeding the control device PCE (15.5 %). Also, we incorporated the above-mentioned SAMs into flexible PSCs (F-PSCs) and achieved one of the highest PCE of 16.2 % on a polyethylene terephthalate (PET) substrate with a remarkable power-per-weight of 26.9 W g -1 . This facile interfacial engineering method offers great potential for the large-scale manufacturing and commercialization of PSCs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

    Science.gov (United States)

    Yuan, Yi; Liu, Zheming; Liu, Zhenyang; Peng, Lan; Li, Yongjie; Tang, Aiwei

    2017-05-01

    All-inorganic halide perovskites have become one of the most prospective materials for lightening and display technology due to their color-tunable and narrow-band emission. Herein, we have systematically studied the effects of organic amines with different hydrocarbon chain length on the optical properties and morphology as well as the crystal structure of colloidal CsPbBr3 nanocrystals (NCs), which were synthesized in the presence of oleic acid (OA) and organic amines by using a simple hot-injection approach. The hydrocarbon chain length has shown an independent correlation to the morphology and crystal structure of the as-obtained CsPbBr3 NCs at 160 °C, but their optical properties can be affected to some extent. The photoluminescence quantum yields (PLQYs) of the CsPbBr3 NCs synthesized in the presence of organic amines with long carbon chain length are generally in the range of 55-80% for different reaction time, but the PLQYs of less than 20% are obtained for the products synthesized in the presence of octylamine (OTAm) with short carbon chain length. The effects of the reaction temperature on the optical properties, size and crystal structure of the CsPbBr3 NCs synthesized in the presence of cetylamine (CTAm) are studied. Interestingly, some nanoplates also appear in these CsPbBr3 NCs obtained at relatively low temperatures (120 and 140 °C), which have a strong tendency to self-assemble into face-to-face nanostructures. Such a similar self-assembly behavior is also observed in the product synthesized in the presence of oleylamine (OLAm), but only flat nanoplates are observed in the products in the presence of OTAm at 120 °C. The results indicate that the lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr3 NCs. This work opens up an alternative approach to controllable-synthesis of perovskite NCs through varying the carbon chain length of organic surfactants, and enlightens

  17. Polymorphism of lipid self-assembly systems

    International Nuclear Information System (INIS)

    Takahashi, Hiroshi

    2002-01-01

    When lipid molecules are dispersed into an aqueous medium, various self-organized structures are formed, depending on conditions (temperature, concentration, etc), in consequence of the amphipathic nature of the molecules. In addition, lipid self-assembly systems exhibit polymorphic phase transition behavior. Since lipids are one of main components of biomembranes, studies on the structure and thermodynamic properties of lipid self-assembly systems are fundamentally important for the consideration of the stability of biomembranes. (author)

  18. Self-assembly: a minimalist route to the fabrication of nanomaterials.

    Science.gov (United States)

    Lazzari, Massimo; Rodríguez-Abreu, Carlos; Rivas, José; López-Quintela, M Arturo

    2006-04-01

    Self-assembly of molecular or nonmolecular components by non-covalent interactions offers an invaluable tool for the preparation of discrete nanostructures and extended 2D and 3D materials, which are often not accessible by any other fabrication process. In this article we summarize the most recent advances in the generation of nanomaterials such as self-assembled monolayers (SAMs) and structures formed from amphiphilic molecules, colloids, peptides, and polymers by nontemplated self-assembly either at the solid state or in solution. The current status of templated self-assembly and the use of self-assembled structures as template and for patterning other materials is also covered. A special emphasis is placed on strategies presenting either original and somehow exploratory approaches, eventually combining bottom-up and top-down methods, or that concern methods for the production of materials with potential application, e.g., in photonics, as sensors, for drug delivery and electric and magnetic devices. In all the sections, we outline self-organization and applications enabled with self-separated block copolymers.

  19. Self-assembled biomimetic nanoreactors I: Polymeric template

    Science.gov (United States)

    McTaggart, Matt; Malardier-Jugroot, Cecile; Jugroot, Manish

    2015-09-01

    The variety of nanoarchitectures made feasible by the self-assembly of alternating copolymers opens new avenues for biomimicry. Indeed, self-assembled structures allow the development of nanoreactors which combine the efficiency of high surface area metal active centres to the effect of confinement due to the very small cavities generated by the self-assembly process. A novel self-assembly of high molecular weight alternating copolymers is characterized in the present study. The self-assembly is shown to organize into nanosheets, providing a 2 nm hydrophobic cavity with a 1D confinement.

  20. Facile preparation of surface-exchangeable core@shell iron oxide@gold nanoparticles for magnetic solid-phase extraction: Use of gold shell as the intermediate platform for versatile adsorbents with varying self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yaping [Beijing National Laboratory of Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Graduate School, University of Chinese Academy of Sciences, Beijing 100049 (China); Qi, Li, E-mail: qili@iccas.ac.cn [Beijing National Laboratory of Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Shen, Ying [Beijing National Laboratory of Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Graduate School, University of Chinese Academy of Sciences, Beijing 100049 (China); Ma, Huimin [Beijing National Laboratory of Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-02-06

    Graphical abstract: -- Highlights: •The core@shell Fe{sub 3}O{sub 4}@Au nanoparticles functionalized with SAMs were successfully constructed. •The SAMs could be transformed from one kind to another via thiol exchange process. •The developed nanomaterials could be applied in mode switching MSPE. -- Abstract: The core@shell Fe{sub 3}O{sub 4}@Au nanoparticles (NPs) functionalized with exchangeable self-assembled monolayers have been developed for mode switching magnetic solid-phase extraction (MSPE) using high performance liquid chromatography with ultraviolet detection. The adsorbents were synthesized by chemical coprecipitation to prepare magnetic cores followed by sonolysis to produce gold shells. Functionalization of Fe{sub 3}O{sub 4}@Au NPs surface was realized through self-assembly of commercially available low molecular weight thiol-containing ligands using gold shells as intermediate platform and the dynamic nature of Au–S chemistry allowed substituent of one thiol-containing ligand with another simply by thiol exchange process. The resultant adsorbents were characterized by transmission electronic microscopy, Fourier transform infrared spectroscopy, elemental analysis, contact angle measurement, and vibrating sample magnetometry. To evaluate the versatile performance of the developed MSPE adsorbents, they were applied for normal-phase SPE followed by reversed-phase SPE. A few kinds of diphenols and polycyclic aromatic hydrocarbons (PAHs) were employed as model analytes, respectively. The predominant parameters affecting extraction efficiency were investigated and optimized. Under the optimum experimental conditions, wide dynamic linear range (6.25–1600 μg L{sup −1} for diphenols and 1.56–100 μg L{sup −1} for PAHs) with good linearity (r{sup 2} ≥ 0.989) and low detection limits (0.34–16.67 μg L{sup −1} for diphenols and 0.26–0.52 μg L{sup −1} for PAHs) were achieved. The advantage of the developed method is that the Fe{sub 3}O

  1. SYNTHESIS AND CHARACTERIZATION OF NOVEL INORGANIC AND ORGANIC HYBRID POLY[CYCLOTRIPHOSPHAZENE-co-(4,4'-DIAMINODIPHENYLMETHANE] MICROSPHERES via ONE-POT SELF-ASSEMBLY POLYCONDENSATION APPROACH

    Directory of Open Access Journals (Sweden)

    Yasemin Süzen

    2016-06-01

    Full Text Available Abstract: Cross-linked cyclomatrix polyphosphazene microspheres have been successfully synthesized via self-assembly polycondensation reaction between hexachlorocyclotriphosphazene (HCCP and 4,4¢-diaminodiphenylmethane (DADPM in acetonitrile. The absence of any stabilizing agent or surfactant and usage of only an ultrasonic bath have been the advantages for this reaction. HCCP and DADPM ratios have been attempted to obtain the best morphology by SEM-EDX. The size of microspheres were ranging from 4.46 to 4.74 μm. The inorganic-organic hybrid microspheres were characterized by FTIR, TGA, UV, Fluorescence and XRD.

  2. Rational design of BINOL-based diimidazolyl ligands: homochiral channel-like mono-component organic frameworks by hydrogen-bond-directed self-assembly.

    Science.gov (United States)

    Yang, Li; Yang, Fei; Lan, Jingbo; Gao, Ge; You, Jingsong; Su, Xiaoyu

    2011-04-21

    We have developed a synthetic strategy to selectively incorporate the imidazole ring into the 1,1'-bi-2-naphthol (BINOL) skeleton at the different position. The resulting conformationally rigid BINOL-based diimidazolyl ligands bearing both hydrogen-bond-acceptors and -donators can self-assemble into homochiral channel-like mono-component organic frameworks via intermolecular O-H···N hydrogen bonds between the phenolic hydroxyl group and the N2 or N4 atom of the imidazole ring.

  3. Photovoltaic self-assembly.

    Energy Technology Data Exchange (ETDEWEB)

    Lavin, Judith; Kemp, Richard Alan; Stewart, Constantine A.

    2010-10-01

    This late-start LDRD was focused on the application of chemical principles of self-assembly on the ordering and placement of photovoltaic cells in a module. The drive for this chemical-based self-assembly stems from the escalating prices in the 'pick-and-place' technology currently used in the MEMS industries as the size of chips decreases. The chemical self-assembly principles are well-known on a molecular scale in other material science systems but to date had not been applied to the assembly of cells in a photovoltaic array or module. We explored several types of chemical-based self-assembly techniques, including gold-thiol interactions, liquid polymer binding, and hydrophobic-hydrophilic interactions designed to array both Si and GaAs PV chips onto a substrate. Additional research was focused on the modification of PV cells in an effort to gain control over the facial directionality of the cells in a solvent-based environment. Despite being a small footprint research project worked on for only a short time, the technical results and scientific accomplishments were significant and could prove to be enabling technology in the disruptive advancement of the microelectronic photovoltaics industry.

  4. Macroscopic magnetic Self assembly

    NARCIS (Netherlands)

    Löthman, Per Arvid

    2018-01-01

    Exploring the macroscopic scale's similarities to the microscale is part and parcel of this thesis as reflected in the research question: what can we learn about the microscopic scale by studying the macroscale? Investigations of the environment in which the self-assembly takes place, and the

  5. Protection of iron against corrosion by coverage with ultrathin two-dimensional polymer films of a hydroxymethylbenzene self-assembled monolayer anchored by the formation of a covalent bond

    International Nuclear Information System (INIS)

    Shimura, Tadashi; Aramaki, Kunitsugu

    2008-01-01

    Ultrathin films of two-dimensional polymers were prepared on an iron electrode by modification of a p-hydroxymethylbenzene p-HOCH 2 C 6 H 4 (HOMB) self-assembled monolayer (SAM) with 1,2-bis(triethoxysilyl)ethane (C 2 H 5 O) 3 Si(CH 2 ) 2 Si(OC 2 H 5 ) 3 (BTESE) and alkyltriethoxysilanes C n H 2n+1 Si(OC 2 H 5 ) 3 (C n TES, n = 8 and 18). The electrode was derivatized by cathodic reduction of p-hydroxymethylbenzenediazonium tetrafluoroborate HOCH 2 C 6 H 4 N 2 BF 4 in an electrolytic acetonitrile solution below 10deg. C for 1 h to form the SAM via a covalent bond between carbon and iron atoms. The protective ability of the polymer film against iron corrosion was determined by polarization measurement of the coated electrode in an oxygenated 0.5 M NaCl solution. The protective efficiencies of the polymer films prepared by modification with BTESE plus C 8 TES and C 18 TES were 63.9% and 68.5% after immersion in 0.5 M NaCl for 1.5 h, respectively. These values were higher than those of the one-dimensional polymer films prepared with the respective C n TES. The film of the HOMB SAM modified with BTESE plus C 8 TES was characterized by contact angle measurement using a drop of water and X-ray photoelectron and FTIR reflection spectroscopies. The films of the HOMB SAM modified with BTESE plus C 8 TES and C 18 TES were persistent during immersion of the coated electrodes in 0.5 M NaCl for many hours by far as compared with the alkanethiol SAM anchored on iron by the formation of a coordinate bond

  6. Photocatalytic oxidation of the organic monolayers on TiO2 surface investigated by in-situ sum frequency generation spectroscopy

    Directory of Open Access Journals (Sweden)

    Yujin Tong

    2015-10-01

    Full Text Available In-situ vibrational sum frequency generation (SFG spectroscopy has been employed to investigate the photocatalytic oxidation of two types of well-ordered organic monolayers, namely, an arachidic acid (AA monolayer prepared by the Langmuir-Blodgett method and an octadecyltrichlorosilane (OTS monolayer prepared by the self-assembling method, on a TiO2 surface under ultraviolet (UV irradiation. The extremely high sensitivity and unique selectivity of the SFG spectroscopy enabled us to directly probe the structural changes in these monolayers during the surface photocatalytic oxidation and further elucidate their reaction mechanisms at a molecular level. It was revealed that the ordering of the monolayers during the photocatalytic reaction is strongly dependent on their interaction with the substrate; the AA monolayer maintains its ordered conformation until the final oxidation stage, while the OTS monolayer shows a large increase in disordering during the initial oxidation stage, indicating a different photocatalytic reaction mechanism of the two monolayers on the TiO2 surface.

  7. Photocatalytic oxidation of the organic monolayers on TiO{sub 2} surface investigated by in-situ sum frequency generation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Yujin; Peng, Qiling; Ma, Tongsen; Nishida, Takuma; Ye, Shen, E-mail: ye@cat.hokudai.ac.jp [Catalysis Research Center, Hokkaido University, Sapporo 060-0811 (Japan)

    2015-10-01

    In-situ vibrational sum frequency generation (SFG) spectroscopy has been employed to investigate the photocatalytic oxidation of two types of well-ordered organic monolayers, namely, an arachidic acid (AA) monolayer prepared by the Langmuir-Blodgett method and an octadecyltrichlorosilane (OTS) monolayer prepared by the self-assembling method, on a TiO{sub 2} surface under ultraviolet (UV) irradiation. The extremely high sensitivity and unique selectivity of the SFG spectroscopy enabled us to directly probe the structural changes in these monolayers during the surface photocatalytic oxidation and further elucidate their reaction mechanisms at a molecular level. It was revealed that the ordering of the monolayers during the photocatalytic reaction is strongly dependent on their interaction with the substrate; the AA monolayer maintains its ordered conformation until the final oxidation stage, while the OTS monolayer shows a large increase in disordering during the initial oxidation stage, indicating a different photocatalytic reaction mechanism of the two monolayers on the TiO{sub 2} surface.

  8. Molecular Electronics of Self-Assembled Monolayers

    DEFF Research Database (Denmark)

    Wang, Xintai

    This thesis deals withmolecular electronic investigations on self-assembledmonolayers. The thesis is divided into seven chapters, as outlined below.Chapter 1 is a general introduction of the history of molecular electronics and its current state.Chapter 2 is separated into three parts. Part I...... providesa brief introduction toself-assembledmonolayers(SAMs), includingits structure, formation, and its role in molecular electronic investigations. Part II is an introduction of different molecular functions, which are interesting for designing real devices. Part III is an introduction of a novel carbon...... material: graphene, and how such material can be incorporated intothe field of molecular electronics.Chapter 3 is a brief introduction of important instruments used in this thesis.Chapter 4, 5 and 6 describe the major experimental work in this thesis. Chapter 4 introduces two novel anchoring...

  9. Cooperative effects of fibronectin matrix assembly and initial cell-substrate adhesion strength in cellular self-assembly.

    Science.gov (United States)

    Brennan, James R; Hocking, Denise C

    2016-03-01

    organize cells into modular building blocks for artificial tissue fabrication. Fibronectin is an ECM protein that plays a key role in tissue formation during embryonic development. Additionally, the cell-mediated process of converting soluble fibronectin into insoluble, ECM-associated fibrils has been shown to initiate cellular self-assembly in vitro. In this study, we examine the relationship between the strength of cell-substrate adhesions and the ability of fibronectin fibril assembly to induce cellular self-assembly. Our results indicate that substrate composition and density play cooperative roles with cell-mediated fibronectin matrix assembly to control the transition of cells from 2D monolayers into 3D multicellular aggregates. Results of this study provide a quantitative approach to build predictive models of cellular self-assembly, as well as a simple cell-culture platform to produce biomimetic units for modular tissue engineering. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  10. Self-assembled nanostructured metamaterials

    Science.gov (United States)

    Ponsinet, Virginie; Baron, Alexandre; Pouget, Emilie; Okazaki, Yutaka; Oda, Reiko; Barois, Philippe

    2017-07-01

    The concept of metamaterials emerged in the years 2000 with the achievement of artificial structures enabling nonconventional propagation of electromagnetic waves, such as negative phase velocity or negative refraction. The electromagnetic response of metamaterials is generally based on the presence of optically resonant elements —or meta-atoms— of sub-wavelength size and well-designed morphology so as to provide the desired electric and magnetic optical properties. Top-down technologies based on lithography techniques have been intensively used to fabricate a variety of efficient electric and magnetic resonators operating from microwave to visible light frequencies. However, the technological limits of the top-down approach are reached in visible light where a huge number of nanometre-sized elements is required. We show here that the bottom-up fabrication route based on the combination of nanochemistry and the self-assembly methods of colloidal physics provide an excellent alternative for the large-scale synthesis of complex meta-atoms, as well as for the fabrication of 2D and 3D samples exhibiting meta-properties in visible light. Contribution to the Focus Issue Self-assemblies of Inorganic and Organic Nanomaterials edited by Marie-Paule Pileni.

  11. Photo-switchable Donor-Acceptor (D-A) Dyad Interfacial Self-Assembled Monolayers for Organic Photovoltaic Cells

    Science.gov (United States)

    2015-11-05

    Dye-Sensitized Solar Cells," Dyes and Pigments , 107, 9-14, 2014 (DOI: 10.1016/j.dyepig.2014.03.010). Here we report the synthesis and...electron acceptor and anchoring unit for Dye-Sensitized Solar Cells,\\" Dyes and Pigments , 107, 9-14, 2014 (DOI: 10.1016/j.dyepig.2014.03.010). 4. Danny...linked by vinyl-fluorene or vinyl-thiophene spacers for dye-sensitized solar cells,” Dyes and Pigments , 112, 127-137, 2014 (DOI: 10.1016/j.dyepig

  12. Metal-organic and supramolecular networks driven by 5-chloronicotinic acid: Hydrothermal self-assembly synthesis, structural diversity, luminescent and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhu-Qing, E-mail: zqgao2008@163.com [School of Chemical and Biological Engineering, Taiyuan University of Science and Technology, Taiyuan 030021 (China); Li, Hong-Jin [School of Chemical and Biological Engineering, Taiyuan University of Science and Technology, Taiyuan 030021 (China); Gu, Jin-Zhong, E-mail: gujzh@lzu.edu.cn [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Zhang, Qing-Hua [School of Chemical and Biological Engineering, Taiyuan University of Science and Technology, Taiyuan 030021 (China); Kirillov, Alexander M. [Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049–001 Lisbon (Portugal)

    2016-09-15

    Four new crystalline solids, namely [Co{sub 2}(µ{sub 2}-5-Clnic){sub 2}(µ{sub 3}-5-Clnic){sub 2}(µ{sub 2}-H{sub 2}O)]{sub n} (1), [Co(5-Clnic){sub 2}(H{sub 2}O){sub 4}]·2(5-ClnicH) (2), [Pb(µ{sub 2}-5-Clnic){sub 2}(phen)]{sub n} (3), and [Cd(5-Clnic){sub 2}(phen){sub 2}]·3H{sub 2}O (4) were generated by hydrothermal self-assembly methods from the corresponding metal(II) chlorides, 5-chloronicotinic acid (5-ClnicH) as a principal building block, and 1,10-phenanthroline (phen) as an ancillary ligand (optional). All the products 1–4 were characterized by IR spectroscopy, elemental analysis, thermogravimetric (TGA), powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. Their structures range from an intricate 3D metal-organic network 1 with the 3,6T7 topology to a ladder-like 1D coordination polymer 3 with the 2C1 topology, whereas compounds 2 and 4 are the discrete 0D monomers. The structures of 2 and 4 are further extended (0D→2D or 0D→3D) by hydrogen bonds, generating supramolecular networks with the 3,8L18 and ins topologies, respectively. Synthetic aspects, structural features, thermal stability, magnetic (for 1) and luminescent (for 3 and 4) properties were also investigated and discussed. - Graphical abstract: A new series of crystalline solids was self-assembled and fully characterized; their structural, topological, luminescent and magnetic features were investigated. Display Omitted.

  13. Self-assembly of self-assembled molecular triangles

    Indian Academy of Sciences (India)

    While the solution state structure of 1 can be best described as a trinuclear complex, in the solidstate well-fashioned intermolecular - and CH- interactions are observed. Thus, in the solid-state further self-assembly of already self-assembled molecular triangle is witnessed. The triangular panels are arranged in a linear ...

  14. Self-Assembly on Gold and Graphene for Molecular Electronics

    DEFF Research Database (Denmark)

    Reeler, Nini Elisabeth Abildgaard

    to take place before full coverage of the AuNPs. After full coverage the negatively charged dithiocarbamate end groups tended to repel each other leading to a stabilization of the AuNPs and clusters in the solution. An additional project concerned the fabrication of various self-assembled monolayers (SAMs...

  15. Heterogeneous electron transfer kinetics and electrocatalytic behaviour of mixed self-assembled ferrocenes and SWCNT layers

    CSIR Research Space (South Africa)

    Nkosi, D

    2010-01-01

    Full Text Available The electron transfer dynamics and electrocatalytic behaviour of ferrocene-terminated self-assembled monolayers (SAMs), co-adsorbed with single-walled carbon nanotubes (SWCNTs) on a gold electrode, have been interrogated for the first time...

  16. Self-assembly of cobalt-centered metal organic framework and multiwalled carbon nanotubes hybrids as a highly active and corrosion-resistant bifunctional oxygen catalyst

    Science.gov (United States)

    Fang, Yiyun; Li, Xinzhe; Li, Feng; Lin, Xiaoqing; Tian, Min; Long, Xuefeng; An, Xingcai; Fu, Yan; Jin, Jun; Ma, Jiantai

    2016-09-01

    Metal organic frameworks (MOF) derived carbonaceous materials have emerged as promising bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts for electrochemical energy conversion and storage. But previous attempts to overcome the poor electrical conductivity of MOFs hybrids involve a harsh high-template pyrolytic process to in situ form carbon, which suffer from extremely complex operation and inevitable carbon corrosion at high positive potentials when OER is operated. Herein, a self-assembly approach is presented to synthesize a non-precious metal-based, high active and strong durable Co-MOF@CNTs bifunctional catalyst for OER and ORR. CNTs not only improve the transportation of the electrons but also can sustain the harsh oxidative environment of OER without carbon corrosion. Meanwhile, the unique 3D hierarchical structure offers a large surface area and stable anchoring sites for active centers and CNTs, which enables the superior durability of hybrid. Moreover, a synergistic catalysis of Co(II), organic ligands and CNTs will enhance the bifunctional electrocatalytic performance. Impressively, the hybrid exhibits comparable OER and ORR catalytic activity to RuO2 and 20 wt% Pt/C catalysts and superior stability. This facile and versatile strategy to fabricating MOF-based hybrids may be extended to other electrode materials for fuel cell and water splitting applications.

  17. Halogen bonding between an isoindoline nitroxide and 1,4-diiodotetrafluorobenzene: new tools and tectons for self-assembling organic spin systems.

    Science.gov (United States)

    Hanson, Graeme R; Jensen, Paul; McMurtrie, John; Rintoul, Llew; Micallef, Aaron S

    2009-01-01

    Radical assembly: Halogen bonding has been observed for the first time between an isoindoline nitroxide and an iodoperfluorocarbon (see figure), which cocrystallize to form a discrete 2:1 supramolecular compound in which N--O(.)I halogen bonding is the dominant intermolecular interaction. This illustrates the potential use of halogen bonding and isoindoline nitroxide tectons for the assembly of organic spin systems.The isoindoline nitroxide 1,1,3,3-tetramethylisoindolin-2-yloxyl (TMIO) and 1,4-diiodotetrafluorobenzene readily form a discrete 2:1 complex that shows evidence of relatively strong N--O(.)I halogen bonding. This interaction was characterized in the solid state by single-crystal X-ray analysis, thermal analysis, and vibrational spectroscopy (IR and Raman), backed by density functional theory calculations. EPR spectroscopy performed on a solution of TMIO in pentafluoroiodobenzene, a halogen-bonding donor, indicates that halogen bonding induces an increase in electron density at the nitroxide nitrogen nucleus and an increase in the nitroxide rotational correlation time. Our findings demonstrate the potential of utilizing halogen-bonding interactions to promote the self-assembly of new isoindoline nitroxide tectons for the preparation of organic spin systems.

  18. Self-assembly and hierarchical patterning of aligned organic nanowire arrays by solvent evaporation on substrates with patterned wettability.

    Science.gov (United States)

    Bao, Rong-Rong; Zhang, Cheng-Yi; Zhang, Xiu-Juan; Ou, Xue-Mei; Lee, Chun-Sing; Jie, Jian-Sheng; Zhang, Xiao-Hong

    2013-06-26

    The controlled growth and alignment of one-dimensional organic nanostructures at well-defined locations considerably hinders the integration of nanostructures for electronic and optoelectronic applications. Here, we demonstrate a simple process to achieve the growth, alignment, and hierarchical patterning of organic nanowires on substrates with controlled patterns of surface wettability. The first-level pattern is confined by the substrate patterns of wettability. Organic nanostructures are preferentially grown on solvent wettable regions. The second-level pattern is the patterning of aligned organic nanowires deposited by controlling the shape and movement of the solution contact lines during evaporation on the wettable regions. This process is controlled by the cover-hat-controlled method or vertical evaportation method. Therefore, various new patterns of organic nanostructures can be obtained by combing these two levels of patterns. This simple method proves to be a general approach that can be applied to other organic nanostructure systems. Using the as-prepared patterned nanowire arrays, an optoelectronic device (photodetector) is easily fabricated. Hence, the proposed simple, large-scale, low-cost method of preparing patterns of highly ordered organic nanostructures has high potential applications in various electronic and optoelectronic devices.

  19. Metal-organic coordination-enabled layer-by-layer self-assembly to prepare hybrid microcapsules for efficient enzyme immobilization.

    Science.gov (United States)

    Wang, Xiaoli; Jiang, Zhongyi; Shi, Jiafu; Liang, Yanpeng; Zhang, Chunhong; Wu, Hong

    2012-07-25

    A novel layer-by-layer self-assembly approach enabled by metal-organic coordination was developed to prepare polymer-inorganic hybrid microcapsules. Alginate was first activated via N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) coupling chemistry, and subsequently reacted with dopamine. Afterward, the dopamine modified alginate (Alg-DA) and titanium(IV) bis(ammonium lactato) dihydroxide (Ti(IV)) were alternatively deposited onto CaCO3 templates. The coordination reaction between the catechol groups of Alg-DA and the Ti(IV) allowed the alternative assembly to form a series of multilayers. After removing the templates, the alginate-titanium hybrid microcapsules were obtained. The high mechanical stability of hybrid microcapsules was demonstrated by osmotic pressure experiment. Furthermore, the hybrid microcapsules displayed superior thermal stability due to Ti(IV) coordination. Catalase (CAT) was used as model enzyme, either encapsulated inside or covalently attached on the surface of the resultant microcapsules. No CAT leakage from the microcapsules was detected after incubation for 48 h. The encapsulated CAT, with a loading capacity of 450-500 mg g(-1) microcapsules, exhibited desirable long-term storage stability, whereas the covalently attached CAT, with a loading capacity of 100-150 mg g(-1) microcapsules, showed desirable operational stability.

  20. Enhancing Cooperativity in Bifunctional Acid–Pd Catalysts with Carboxylic Acid-Functionalized Organic Monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Coan, Patrick D. [Department of Chemical and Biological Engineering, University of Colorado—Boulder, Boulder, Colorado 80309, United States; Ellis, Lucas D. [Department of Chemical and Biological Engineering, University of Colorado—Boulder, Boulder, Colorado 80309, United States; Griffin, Michael B. [National Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States; Schwartz, Daniel K. [Department of Chemical and Biological Engineering, University of Colorado—Boulder, Boulder, Colorado 80309, United States; Medlin, J. Will [Department of Chemical and Biological Engineering, University of Colorado—Boulder, Boulder, Colorado 80309, United States

    2018-03-01

    Cooperative catalysts containing a combination of noble metal hydrogenation sites and Bronsted acid sites are critical for many reactions, including the deoxygenation (DO) of biomass-derived oxygenates in the upgrading of pyrolysis oil. One route toward the design of cooperative catalysts is to tether two different catalytically active functions so that they are in close proximity while avoiding undesirable interactions that can block active sites. Here, we deposited carboxylic acid (CA)-functionalized organophosphonate monolayers onto Al2O3-supported Pd nanoparticle catalysts to prepare bifunctional catalysts containing both Bronsted acid and metal sites. Modification with phosphonic acids (PAs) improved activity and selectivity for gas-phase DO reactions, but the degree of improvement was highly sensitive to both the presence and positioning of the CA group, suggesting a significant contribution from both the PA and CA sites. Short spacer lengths of 1-2 methylene groups between the phosphonate head and CA tail were found to yield the best DO rates and selectivities, whereas longer chains performed similarly to self-assembled monolayers having alkyl tails. Results from a combination of density functional theory and Fourier transform infrared spectroscopy suggested that the enhanced catalyst performance on the optimally positioned CAs was due to the generation of strong acid sites on the Al2O3 support adjacent to the metal. Furthermore, the high activity of these sites was found to result from a hydrogen-bonded cyclic structure involving cooperativity between the phosphonate head group and CA tail function. More broadly, these results indicate that functional groups tethered to supports via organic ligands can influence catalytic chemistry on metal nanoparticles.

  1. Synthesis and Self-Assembly of Triangulenium Salts

    DEFF Research Database (Denmark)

    Shi, Dong

    . The formed vesicles showed excellent stability standing over for 7 month at ambient lab conditions or upon heated up to 70 °C as monitored by dynamic light scattering (DLS) method. Chapter 4 reportes the dynamic air–water interfaces catalyzed self-assembly of insoluble aminotriangulenium salts into Stable......–water interfaces and lateral compression of the monolayer results in the collapsing toward the formation of bilayer nanosheets. The nanosheets showed excellent stability after standing over 10 months stocked in a close vial at ambient conditions due to the ionic atmosphere surrounding its charged surfaces...... in the self-assembly of the synthetic amphiphilic triangulenium salt in aqueous media. In this chapter, self-assembled nanotubes, nanorribbons and nanorods are presented and collusions II are made based on the experimental observations. The following chapter 6 repots the chain length effect on the self...

  2. Synthesis, electrochemistry, STM investigation of oligothiophene self-assemblies with superior structural order and electronic properties

    Science.gov (United States)

    Kuo, Cheng-Yu; Liu, Yinghao; Yarotski, Dmitry; Li, Hao; Xu, Ping; Yen, Hung-Ju; Tretiak, Sergei; Wang, Hsing-Lin

    2016-12-01

    Three oligothiophene (terthiophene, tetrathiophene and pentathiophene) derivatives are synthesized and their monolayer self-assemblies on gold (Au) are prepared via Au-S covalent bond. Our UV-Vis experimental characterization of solution reveals the dependence of the optical properties on the conjugation length of the oligothiophenes, which compares well with Time-Dependent Density Functional Theory (TDDFT) simulations of spectra of individual chromophores. Photoluminescent spectra of thin films show pronounced red shifts compared to that of solutions, suggesting strong inter-oligomer interactions. The comparative studies of cyclic voltammograms of tetrathiophene from solution, cast film and self-assembled monolayer (SAM) indicate presence of one, two, and three oxidized species in these samples, respectively, suggesting a very strong electronic coupling between tetrathiophene molecules in the SAM. Scanning tunneling microscopy (STM) imaging of SAMs of the tetrathiophene on an atomically flat Au surface exhibits formation of monolayer assemblies with molecular order, and the molecular packing appears to show an overlay of oligothiophene molecules on top of another one. In contrast, the trimer and pentamer images show only aggregated species lacking long-range order on the molecular level. Such trends in going from disordered-ordered-disordered monolayer assemblies are mainly due to a delicate balance between inter-chromophore π-π couplings, hydrophobic interaction and the propensity to form Au-S covalent bond. Such hypothesis has been validated by our computational results suggesting different interaction patterns of oligothiophenes with odd numbered and even numbered thiophene repeat units placed in a dimer configuration. Observed correlations between oligomer geometry and structural order of monolayer assembly elucidate important structure-property relationships and have implications for these molecular structures in organic optoelectronic devices and energy

  3. Self-assembly between biomacromolecules and lipids

    Science.gov (United States)

    Liang, Hongjun

    Anionic DNA and cationic lipsomes can self-assemble into a multi-lamellar structure where two-dimensional (2-D) lipid sheets confine a periodic one-dimensional (1-D) lattice of parallel DNA chains, between which Cd2+ ions can condense, and be subsequently reacted with H 2S to template CdS nanorods with crystallographic control analogous to biomineralization. The strong electrostatic interactions align the templated CdS (002) polar planes parallel to the negatively charged sugar-phosphate DNA backbone, which indicates that molecular details of the DNA molecule are imprinted onto the inorganic crystal structure. The resultant nanorods have (002) planes tilted by ˜60° with respect to the rod axis, in contrast to all known II-VI semiconductor nanorods. Rational design of the biopolymer-membrane templates is possible, as demonstrated by the self-assembly between anionic M13 virus and cationic membrane. The filamentous virus has diameter ˜3x larger but similar surface charge density as DNA, the self-assembled complexes maintain the multi-lamellar structure, but pore sizes are ˜10x larger in area, which can be used to package and organize large functional molecules. Not only the counter-charged objects can self-assemble, the like-charged biopolymer and membrane can also self-assemble with the help of multivalent ions. We have investigated anionic lipid-DNA complexes induced by a range of divalent ions to show how different ion-mediated interactions are expressed in the self-assembled structures, which include two distinct lamellar phases and an inverted hexagonal phase. DNA can be selectively organized into or expelled out of the lamellar phases depending on membrane charge density and counterion concentration. For a subset of ion (Zn2+ etc.) at high enough concentration, 2-D inverted hexagonal phase can be formed where DNA strands are coated with anionic lipid tubes via interaction with Zn2+ ions. We suggest that the effect of ion binding on lipid's spontaneous

  4. Self-Assembly of Nanoparticle Surfactants

    Science.gov (United States)

    Lombardo, Michael T.

    Self-assembly utilizes non-covalent forces to organize smaller building blocks into larger, organized structures. Nanoparticles are one type of building block and have gained interest recently due to their unique optical and electrical properties which have proved useful in fields such as energy, catalysis, and advanced materials. There are several techniques currently used to self-assemble nanoparticles, each with its own set of benefits and drawbacks. Here, we address the limited number of techniques in non-polar solvents by introducing a method utilizing amphiphilic gold nanoparticles. Grafted polymer chains provide steric stabilization while small hydrophilic molecules induce assembly through short range attractive forces. The properties of these self-assembled structures are found to be dependent on the polymer and small molecules surface concentrations and chemistries. These particles act as nanoparticle surfactants and can effectively stabilize oil-water interfaces, such as in an emulsion. In addition to the work in organic solvent, similar amphiphilic particles in aqueous media are shown to effectively stabilize oil-in-water emulsions that show promise as photoacoustic/ultrasound theranostic agents.

  5. Electron Injection to Control Self-Assembly and Disassembly of Phenylacetylene on Gold

    Science.gov (United States)

    Baddorf, Arthur P.; Li, Qing; Han, Chengbo; Bernholc, J.; Terrones, Humberto; Sumpter, Bobby; Fuentes-Cabrera, Miguel; Yi, Jieyu; Gai, Zheng; Maksymovych, Peter; Pan, Minghu

    2013-03-01

    The power of two-dimensional organic molecular systems for applications including electronics, functionalization and nanolithography is enabled by our ability to produce structures through self-assembly on a surface. Unfortunately, relying on thermal fluctuations to drive the surface attachment reactions has limited self-assembled molecules (SAMs) to little beyond alkanethiols on gold. We demonstrate a seminal example of non-thermal control over molecular self-assembly, where hot-electron injection rather than thermal fluctuations transform a disordered layer of weakly bonded hydrocarbon molecules into an ordered, dense monolayer. The process is reversible, in that injection of holes reverts to a disordered state. Since electron and hole injection is accomplished with a STM, unprecedented local control over ordered and disordered domains is achieved. STM imaging and correlated density functional calculations reveal that ordered domains consist of molecules vertically aligned and more strongly attached to the gold substrate through the acetylene tail, while disordered domains contain weakly bound molecules lying flat. Research was conducted at the CNMS, sponsored by the Division of Scientific User Facilities, U.S. Department of Energy.

  6. Heterointerface Screening Effects between Organic Monolayers and Monolayer Transition Metal Dichalcogenides

    KAUST Repository

    Zheng, Yu Jie

    2016-01-21

    © 2016 American Chemical Society. The nature and extent of electronic screening at heterointerfaces and their consequences on energy level alignment are of profound importance in numerous applications, such as solar cells, electronics etc. The increasing availability of two-dimensional (2D) transition metal dichalcogenides (TMDs) brings additional opportunities for them to be used as interlayers in "van der Waals (vdW) heterostructures" and organic/inorganic flexible devices. These innovations raise the question of the extent to which the 2D TMDs participate actively in dielectric screening at the interface. Here we study perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) monolayers adsorbed on single-layer tungsten diselenide (WSe2), bare graphite, and Au(111) surfaces, revealing a strong dependence of the PTCDA HOMO-LUMO gap on the electronic screening effects from the substrate. The monolayer WSe2 interlayer provides substantial, but not complete, screening at the organic/inorganic interface. Our results lay a foundation for the exploitation of the complex interfacial properties of hybrid systems based on TMD materials.

  7. Self-assembly of self-assembled molecular triangles

    Indian Academy of Sciences (India)

    (tmeda), 2,2 -bipyridine (bpy), and 1,10-phenanthroline. (phen), etc. The synthesis and dynamic studies of a vari- ety of designed Pd(II) cages are well studied1a−d but the crystal engineering of Pd(II)-based self-assembled coordination cages has been less explored.4 Recently we have been investigating the significance of ...

  8. Self-assembled Nanomaterials for Chemotherapeutic Applications

    Science.gov (United States)

    Shieh, Aileen

    The self-assembly of short designed peptides into functional nanostructures is becoming a growing interest in a wide range of fields from optoelectronic devices to nanobiotechnology. In the medical field, self-assembled peptides have especially attracted attention with several of its attractive features for applications in drug delivery, tissue regeneration, biological engineering as well as cosmetic industry and also the antibiotics field. We here describe the self-assembly of peptide conjugated with organic chromophore to successfully deliver sequence independent micro RNAs into human non-small cell lung cancer cell lines. The nanofiber used as the delivery vehicle is completely non-toxic and biodegradable, and exhibit enhanced permeability effect for targeting malignant tumors. The transfection efficiency with nanofiber as the delivery vehicle is comparable to that of the commercially available RNAiMAX lipofectamine while the toxicity is significantly lower. We also conjugated the peptide sequence with camptothecin (CPT) and observed the self-assembly of nanotubes for chemotherapeutic applications. The peptide scaffold is non-toxic and biodegradable, and drug loading of CPT is high, which minimizes the issue of systemic toxicity caused by extensive burden from the elimination of drug carriers. In addition, the peptide assembly drastically increases the solubility and stability of CPT under physiological conditions in vitro, while active CPT is gradually released from the peptide chain under the slight acidic tumor cell environment. Cytotoxicity results on human colorectal cancer cells and non-small cell lung cancer cell lines display promising anti-cancer properties compared to the parental CPT drug, which cannot be used clinically due to its poor solubility and lack of stability in physiological conditions. Moreover, the peptide sequence conjugated with 5-fluorouracil formed a hydrogel with promising topical chemotherapeutic applications that also display

  9. Silk nanofibril self-assembly versus electrospinning.

    Science.gov (United States)

    Humenik, Martin; Lang, Gregor; Scheibel, Thomas

    2018-02-02

    Natural silk fibers represent one of the most advanced blueprints for (bio)polymer scientists, displaying highly optimized mechanical properties due to their hierarchical structures. Biotechnological production of silk proteins and implementation of advanced processing methods enabled harnessing the potential of these biopolymer not just based on the mechanical properties. In addition to fibers, diverse morphologies can be produced, such as nonwoven meshes, films, hydrogels, foams, capsules and particles. Among them, nanoscale fibrils and fibers are particularly interesting concerning medical and technical applications due to their biocompatibility, environmental and mechanical robustness as well as high surface-to-volume ratio. Therefore, we introduce here self-assembly of silk proteins into hierarchically organized structures such as supramolecular nanofibrils and fabricated materials based thereon. As an alternative to self-assembly, we also present electrospinning a technique to produce nanofibers and nanofibrous mats. Accordingly, we introduce a broad range of silk-based dopes, used in self-assembly and electrospinning: natural silk proteins originating from natural spinning glands, natural silk protein solutions reconstituted from fibers, engineered recombinant silk proteins designed from natural blueprints, genetic fusions of recombinant silk proteins with other structural or functional peptides and moieties, as well as hybrids of recombinant silk proteins chemically conjugated with nonproteinaceous biotic or abiotic molecules. We highlight the advantages but also point out drawbacks of each particular production route. The scope includes studies of the natural self-assembly mechanism during natural silk spinning, production of silk fibrils as new nanostructured non-native scaffolds allowing dynamic morphological switches, as well as studying potential applications. This article is categorized under:  Biology-Inspired Nanomaterials

  10. Characterization and Application of DNA-templated Silver Nanoclusters and Polarized Spectroscopy of Self-Assembled Nanostructures

    DEFF Research Database (Denmark)

    Carro-Temboury, Miguel R.

    In this thesis two different systems are investigated envisioning their potential applications: DNA-templated silver nanoclusters (DNA-AgNCs) and ionic self-assembled (ISA) nanostructures based on azo-dyes. Mainly Visible-NIR spectroscopy was used to probe electronic transitions with absorbance...... other applications are possible such as detection of analytes, pH detection or their use as active layer of Organic Light Emitting Diodes (OLEDs). The fluorophores studied here, DNAAgNCs, are few nanometer sized and formed by a few to ca. 20 silver atoms templated by one or two single stranded DNA (ss...... fluorescence decay time as a function of emission wavelength (Average decay time spectra). This proved to be a robust method to characterize the complexity of the system due to the multi-exponential decay of the emitters. In order to study the electroluminescence from the C24-AgNCs in Self-Assembled Monolayer...

  11. Self-Assembly of "Chalcone" Type Push-Pull Dye Molecules into Organic Single Crystalline Microribbons and Rigid Microrods for Vis/NIR Range Photonic Cavity Applications.

    Science.gov (United States)

    Vattikunta, Radhika; Venkatakrishnarao, Dasari; Mohiddon, Mahamad Ahamad; Chandrasekar, Rajadurai

    2016-11-04

    A novel supramolecular fluorescent donor-acceptor type dye molecule, (2E,4E)-1-(2-hydroxyphenyl)-5-(pyren-1-yl)penta-2,4-dien-1-one (HPPD) self-assembles in a mixture of ethanol/chloroform through intermolecular π-π stacking (distance ca. 3.384 Å) to form J-aggregated single-crystalline microribbons displaying Fabry-Pèrot (F-P) type visible-range optical resonance. The corresponding borondifluoride dye (HPPD-BF), with a reduced HOMO-LUMO gap, self-assembles into crystalline microrods acting as an F-P type resonator in the near-infrared (NIR) range. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Self-assembly of cyclodextrins

    DEFF Research Database (Denmark)

    Fülöp, Z.; Kurkov, S.V.; Nielsen, T.T.

    2012-01-01

    that increases upon formation of inclusion complexes with lipophilic drugs. However, the stability of such aggregates is not sufficient for parenteral administration. In this review CD polymers and CD containing nanoparticles are categorized, with focus on self-assembled CD nanoparticles. It is described how...

  13. Low-Temperature PM IRRAS of a Monolayer on Au: Spectra of C18D37SH

    Czech Academy of Sciences Publication Activity Database

    Mašát, Milan; Wen, Jin; Sofer, Z.; Michl, Josef

    2017-01-01

    Roč. 33, č. 23 (2017), s. 5613-5616 ISSN 0743-7463 R&D Projects: GA ČR GA14-02337S Institutional support: RVO:61388963 Keywords : self-assembled monolayers * gold surface * electrodes Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 3.833, year: 2016

  14. Self-Assembly in Biosilicification and Biotemplated Silica Materials

    Directory of Open Access Journals (Sweden)

    Francisco M. Fernandes

    2014-09-01

    Full Text Available During evolution, living organisms have learned to design biomolecules exhibiting self-assembly properties to build-up materials with complex organizations. This is particularly evidenced by the delicate siliceous structures of diatoms and sponges. These structures have been considered as inspiration sources for the preparation of nanoscale and nanostructured silica-based materials templated by the self-assembled natural or biomimetic molecules. These templates range from short peptides to large viruses, leading to biohybrid objects with a wide variety of dimensions, shapes and organization. A more recent strategy based on the integration of biological self-assembly as the driving force of silica nanoparticles organization offers new perspectives to elaborate highly-tunable, biofunctional nanocomposites.

  15. Self-Assembly in Biosilicification and Biotemplated Silica Materials.

    Science.gov (United States)

    Fernandes, Francisco M; Coradin, Thibaud; Aimé, Carole

    2014-09-04

    During evolution, living organisms have learned to design biomolecules exhibiting self-assembly properties to build-up materials with complex organizations. This is particularly evidenced by the delicate siliceous structures of diatoms and sponges. These structures have been considered as inspiration sources for the preparation of nanoscale and nanostructured silica-based materials templated by the self-assembled natural or biomimetic molecules. These templates range from short peptides to large viruses, leading to biohybrid objects with a wide variety of dimensions, shapes and organization. A more recent strategy based on the integration of biological self-assembly as the driving force of silica nanoparticles organization offers new perspectives to elaborate highly-tunable, biofunctional nanocomposites.

  16. Synthesis and Self-Assembly of Chiral Cylindrical Molecular Complexes: Functional Heterogeneous Liquid-Solid Materials Formed by Helicene Oligomers

    Directory of Open Access Journals (Sweden)

    Nozomi Saito

    2018-01-01

    Full Text Available Chiral cylindrical molecular complexes of homo- and hetero-double-helices derived from helicene oligomers self-assemble in solution, providing functional heterogeneous liquid-solid materials. Gels and liotropic liquid crystals are formed by fibril self-assembly in solution; molecular monolayers and fibril films are formed by self-assembly on solid surfaces; gels containing gold nanoparticles emit light; silica nanoparticles aggregate and adsorb double-helices. Notable dynamics appears during self-assembly, including multistep self-assembly, solid surface catalyzed double-helix formation, sigmoidal and stairwise kinetics, molecular recognition of nanoparticles, discontinuous self-assembly, materials clocking, chiral symmetry breaking and homogeneous-heterogeneous transitions. These phenomena are derived from strong intercomplex interactions of chiral cylindrical molecular complexes.

  17. Thermomechanical Response of Self-Assembled Nanoparticle Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yifan [Department; James; Chan, Henry [Center; Narayanan, Badri [Center; McBride, Sean P. [Department; Sankaranarayanan, Subramanian K. R. S. [Center; Lin, Xiao-Min [Center; Jaeger, Heinrich M. [Department; James

    2017-07-21

    Monolayers composed of colloidal nanoparticles, with a thickness of less than 10 nm, have remarkable mechanical moduli and can suspend over micrometer-sized holes to form free-standing membranes. In this paper, we discuss experiment's and coarse-grained molecular dynamics simulations characterizing the thermomechanical properties of these self-assembled nanoparticle membranes. These membranes remain strong and resilient up to temperatures much higher than previous simulation predictions and exhibit an unexpected hysteretic behavior during the first heating cooling cycle. We show this hysteretic behavior can be explained by an asymmetric ligand configuration from the self assembly process and can be controlled by changing the ligand coverage or cross-linking the ligand molecules. Finally, we show the screening effect of water molecules on the ligand interactions can strongly affect the moduli and thermomechanical behavior.

  18. Reducing leakage currents in n-channel organic field-effect transistors using molecular dipole monolayers on nanoscale oxides.

    Science.gov (United States)

    Martínez Hardigree, Josué F; Dawidczyk, Thomas J; Ireland, Robert M; Johns, Gary L; Jung, Byung-Jun; Nyman, Mathias; Osterbacka, Ronald; Marković, Nina; Katz, Howard E

    2013-08-14

    Leakage currents through the gate dielectric of thin film transistors remain a roadblock to the fabrication of organic field-effect transistors (OFETs) on ultrathin dielectrics. We report the first investigation of a self-assembled monolayer (SAM) dipole as an electrostatic barrier to reduce leakage currents in n-channel OFETs fabricated on a minimal, leaky ∼10 nm SiO2 dielectric on highly doped Si. The electric field associated with 1H,1H,2H,2H-perfluoro-octyltriethoxysilane (FOTS) and octyltriethoxysilane (OTS) dipolar chains affixed to the oxide surface of n-Si gave an order of magnitude decrease in gate leakage current and subthreshold leakage and a two order-of-magnitude increase in ON/OFF ratio for a naphthalenetetracarboxylic diimide (NTCDI) transistor. Identically fabricated devices on p-Si showed similarly reduced leakage and improved performance for oxides treated with the larger dipole FOTS monolayer, while OTS devices showed poorer transfer characteristics than those on bare oxide. Comparison of OFETs on both substrates revealed that relative device performance from OTS and FOTS treatments was dictated primarily by the organosilane chain and not the underlying siloxane-substrate bond. This conclusion is supported by the similar threshold voltages (VT) extrapolated for SAM-treated devices, which display positive relative VT shifts for FOTS on either substrate but opposite VT shifts for OTS treatment on n-Si and p-Si. Our results highlight the potential of dipolar SAMs as performance-enhancing layers for marginal quality dielectrics, broadening the material spectrum for low power, ultrathin organic electronics.

  19. Self-assembled nanocomposite organic-inorganic proton conducting sulfonated poly-ether-ether-ketone (SPEEK)-based membranes: Optimized mechanical, thermal and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Sgreccia, E. [Dip. Scienze e Tecnologie Chimiche, Universita di Roma Tor Vergata, 00133 Roma (Italy); Universite de Provence-CNRS: Laboratoire Chimie Provence (UMR 6264), Centre St Jerome, Marseille (France); Di Vona, M.L.; Licoccia, S. [Dip. Scienze e Tecnologie Chimiche, Universita di Roma Tor Vergata, 00133 Roma (Italy); Sganappa, M.; Casciola, M. [Dip. Chimica, Universita di Perugia, Via Elce di Sotto 8, Perugia (Italy); Chailan, J.F. [MAPIEM (EA 4323), Universite Sud Toulon-Var, Toulon (France); Knauth, P. [Universite de Provence-CNRS: Laboratoire Chimie Provence (UMR 6264), Centre St Jerome, Marseille (France)

    2009-07-15

    Mechanical, thermal and electrical properties of polymer blends of SPEEK with 7% SiPPSU are reported. Presence of silicon stabilizes the polymer morphology. The glass transition temperature, determined by dynamic mechanical analysis, depends more on blend formation than on degree of sulfonation. The water uptake coefficients, determined in liquid water and water vapour, are strongly reduced by the presence of the secondary silylated phase, so that blend membranes do not dissolve in water even at 140 C. The electrical conductivity is of the order of pure SPEEK and does not degrade even at high relative humidity. The sum of these properties make these self-assembled nanocomposite membranes most attractive for use in intermediate temperature PEMFC. (author)

  20. Characterization of heterojunctions via x-ray and uv photoemission spectroscopy: energy level implications for single and mixed monolayer SAMs, cadmium selenide nanoparticle films, and organic semiconductor depositions

    Science.gov (United States)

    Graham, Amy L.

    This work has centered on the interface dipoles arising at heterojunctions between metals, semiconductor nanoparticles, self-assembled monolayers, and organic semiconductor materials. Alkanethiol self-assembled monolayers, CdSe nanocrystals, and the organic semiconductors zinc phthalocyanine (ZnPc) and Buckminster fullerene (C60) were the basis of these investigations. UV photoemission spectroscopy has proven to be an invaluable tool to observe the vacuum level shifts for these analyses while using XPS to corroborate surface structure. With a full evaluation of these surfaces, the shifts in the vacuum level, valence ionizations, and core ionizations, the impact of these interfaces, as well as their influence on the subsequent deposition of organic semiconductor layers is established. Alkanethiols possessing varying dipole moments were examined on gold and silver substrates. The viability of these alkanethiols was demonstrated to predictively adjust the work function of these metals as a function of their intrinsic dipole moments projected to surface normal, and established differences between Ag---S and Au---S bonds. The capability of the SAMs to modify the work function of gold provided an opportunity for mixed monolayers of the alkanethiols to produce a precise range of work functions by minimal adjustments of solution concentration, which were examined with a simple point dipole model. Photoemission spectroscopy offers a thorough analysis of CdSe nanoparticle films. Despite a plethora of research on these nanocrystals, there still is controversy on the magnitude of the shift in the valence band with diameter. In our research we found the majority of the valence band shift could be attributed to the interface dipole, ignored previously. Meanwhile, the valence band tethered films was obscured by the sulfur of the thiol tether. Finally, organic semiconductor layers deposited on SAMs on gold exhibited various interface dipole effects at these heterojunctions. Charge

  1. Self-assembling holographic biosensors and biocomputers.

    Energy Technology Data Exchange (ETDEWEB)

    Light, Yooli Kim; Bachand, George David (Sandia National Laboratories, Albuquerque, NM); Schoeniger, Joseph S.; Trent, Amanda M. (Sandia National Laboratories, Albuquerque, NM)

    2006-05-01

    We present concepts for self-assembly of diffractive optics with potential uses in biosensors and biocomputers. The simplest such optics, diffraction gratings, can potentially be made from chemically-stabilized microtubules migrating on nanopatterned tracks of the motor protein kinesin. We discuss the fabrication challenges involved in patterning sub-micron-scale structures with proteins that must be maintained in aqueous buffers to preserve their activity. A novel strategy is presented that employs dry contact printing onto glass-supported amino-silane monolayers of heterobifunctional crosslinkers, followed by solid-state reactions of these cross-linkers, to graft patterns of reactive groups onto the surface. Successive solution-phase addition of cysteine-mutant proteins and amine-reactive polyethylene glycol allows assembly of features onto the printed patterns. We present data from initial experiments showing successful micro- and nanopatterning of lines of single-cysteine mutants of kinesin interleaved with lines of polyethylene, indicating that this strategy can be employed to arrays of features with resolutions suitable for gratings.

  2. Self-assembly of microcapsules via colloidal bond hybridization and anisotropy

    Science.gov (United States)

    Evers, Chris H. J.; Luiken, Jurriaan A.; Bolhuis, Peter G.; Kegel, Willem K.

    2016-06-01

    Particles with directional interactions are promising building blocks for new functional materials and may serve as models for biological structures. Mutually attractive nanoparticles that are deformable owing to flexible surface groups, for example, may spontaneously order themselves into strings, sheets and large vesicles. Furthermore, anisotropic colloids with attractive patches can self-assemble into open lattices and the colloidal equivalents of molecules and micelles. However, model systems that combine mutual attraction, anisotropy and deformability have not yet been realized. Here we synthesize colloidal particles that combine these three characteristics and obtain self-assembled microcapsules. We propose that mutual attraction and deformability induce directional interactions via colloidal bond hybridization. Our particles contain both mutually attractive and repulsive surface groups that are flexible. Analogously to the simplest chemical bond—in which two isotropic orbitals hybridize into the molecular orbital of H2—these flexible groups redistribute on binding. Via colloidal bond hybridization, isotropic spheres self-assemble into planar monolayers, whereas anisotropic snowman-shaped particles self-assemble into hollow monolayer microcapsules. A modest change in the building blocks thus results in much greater complexity of the self-assembled structures. In other words, these relatively simple building blocks self-assemble into markedly more complex structures than do similar particles that are isotropic or non-deformable.

  3. Chemical reactions directed Peptide self-assembly.

    Science.gov (United States)

    Rasale, Dnyaneshwar B; Das, Apurba K

    2015-05-13

    Fabrication of self-assembled nanostructures is one of the important aspects in nanoscience and nanotechnology. The study of self-assembled soft materials remains an area of interest due to their potential applications in biomedicine. The versatile properties of soft materials can be tuned using a bottom up approach of small molecules. Peptide based self-assembly has significant impact in biology because of its unique features such as biocompatibility, straight peptide chain and the presence of different side chain functionality. These unique features explore peptides in various self-assembly process. In this review, we briefly introduce chemical reaction-mediated peptide self-assembly. Herein, we have emphasised enzymes, native chemical ligation and photochemical reactions in the exploration of peptide self-assembly.

  4. Chemical Reactions Directed Peptide Self-Assembly

    Directory of Open Access Journals (Sweden)

    Dnyaneshwar B. Rasale

    2015-05-01

    Full Text Available Fabrication of self-assembled nanostructures is one of the important aspects in nanoscience and nanotechnology. The study of self-assembled soft materials remains an area of interest due to their potential applications in biomedicine. The versatile properties of soft materials can be tuned using a bottom up approach of small molecules. Peptide based self-assembly has significant impact in biology because of its unique features such as biocompatibility, straight peptide chain and the presence of different side chain functionality. These unique features explore peptides in various self-assembly process. In this review, we briefly introduce chemical reaction-mediated peptide self-assembly. Herein, we have emphasised enzymes, native chemical ligation and photochemical reactions in the exploration of peptide self-assembly.

  5. Understanding the self-assembly of TCNQ on Cu(111)

    DEFF Research Database (Denmark)

    Stradi, Daniele; Borca, Bogdana; Barja, Sara

    2016-01-01

    The structure of self-assembled monolayers of 7,7',8,8'-tetracyano-p-quinodimethane (TCNQ) adsorbed on Cu(111) has been studied using a combination of scanning tunnelling microscopy (STM) experiments and density functional theory (DFT) calculations. We show that the polymorphism of the self...... perpendicular to the other. Conversely, when the substrate is held at room temperature during deposition and slightly annealed afterwards, a more complex structure with five molecules per unit cell is formed. DFT calculations complement the experimental results by revealing that the building blocks of the two...

  6. Directed self-assembly of DNA tiles into complex nanocages.

    Science.gov (United States)

    Tian, Cheng; Li, Xiang; Liu, Zhiyu; Jiang, Wen; Wang, Guansong; Mao, Chengde

    2014-07-28

    Tile-based self-assembly is a powerful method in DNA nanotechnology and has produced a wide range of well-defined nanostructures. But the resulting structures are relatively simple. Increasing the structural complexity and the scope of the accessible structures is an outstanding challenge in molecular self-assembly. A strategy to partially address this problem by introducing flexibility into assembling DNA tiles and employing directing agents to control the self-assembly process is presented. To demonstrate this strategy, a range of DNA nanocages have been rationally designed and constructed. Many of them can not be assembled otherwise. All of the resulting structures have been thoroughly characterized by gel electrophoresis and cryogenic electron microscopy. This strategy greatly expands the scope of accessible DNA nanostructures and would facilitate technological applications such as nanoguest encapsulation, drug delivery, and nanoparticle organization. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Hydrodynamic Self-Assembly of Topographical Patterns on Soft Materials

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Satish [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-01-06

    The objective of this project is to use theoretical tools to explore fundamentally new ways of creating and controlling surface topography on soft materials (e.g., polymeric liquids, gels, colloidal suspensions) that make use of principles from hydrodynamics and self-assembly. Surface topography is known to have a significant impact on the optical, adhesive, and wetting properties of materials, so improved fundamental understanding of how to create and control it will help enable the tailoring of these properties to desired specifications. Self-assembly is the spontaneous organization of an ordered structure, and hydrodynamics often plays an important role in the self-assembly of soft materials. This research supported through this project has led to the discovery of a number of novel phenomena that are described in published journal articles. In this way, the research significantly adds to the fundamental understanding of the topics investigated.

  8. Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates

    KAUST Repository

    Zhao, Kui

    2016-07-13

    We demonstrate that local and long range orders of poly(3-hexylthiophene) (P3HT) semicrystalline films can be synergistically improved by combining chemical functionalization of the dielectric surface with solution-state disentanglement and pre-aggregation of P3HT in a theta solvent, leading to a very significant enhancement of the field effect carrier mobility. The pre-aggregation and surface functionalization effects combine to enhance the carrier mobility nearly 100-fold as compared with standard film preparation by spin-coating, and nearly 10-fold increase over the benefits of pre-aggregation alone. In situ quartz crystal microbalance with dissipation (QCM-D) experiments reveal enhanced deposition of pre-aggregates on surfaces modified with an alkyl-terminated self-assembled monolayer (SAM) in comparison to un-aggregated polymer chains. Additional investigations reveal the combined pre-aggregation and surface functionalization significantly enhances local order of the conjugated polymer through planarization and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining complementary routes, such as well-known pre-aggregation with substrate chemical functionalization, to enhance the polymer self-assembly and improve its interfacial order with benefits for transport properties.

  9. Crystalline mono- and multilayer self-assemblies of oligothiophenes at the air-water interface

    DEFF Research Database (Denmark)

    Isz, S.; Weissbuch, I.; Kjær, K.

    1997-01-01

    The formation of Langmuir monolayers at the air-water interface has long been believed to be limited to amphiphilic molecules containing a hydrophobic chain and a hydrophilic headgroup. Here we report the formation of crystalline mono- and multilayer self-assemblies of oligothiophenes, a class...

  10. Controlling water evaporation through self-assembly.

    Science.gov (United States)

    Roger, Kevin; Liebi, Marianne; Heimdal, Jimmy; Pham, Quoc Dat; Sparr, Emma

    2016-09-13

    Water evaporation concerns all land-living organisms, as ambient air is dryer than their corresponding equilibrium humidity. Contrarily to plants, mammals are covered with a skin that not only hinders evaporation but also maintains its rate at a nearly constant value, independently of air humidity. Here, we show that simple amphiphiles/water systems reproduce this behavior, which suggests a common underlying mechanism originating from responding self-assembly structures. The composition and structure gradients arising from the evaporation process were characterized using optical microscopy, infrared microscopy, and small-angle X-ray scattering. We observed a thin and dry outer phase that responds to changes in air humidity by increasing its thickness as the air becomes dryer, which decreases its permeability to water, thus counterbalancing the increase in the evaporation driving force. This thin and dry outer phase therefore shields the systems from humidity variations. Such a feedback loop achieves a homeostatic regulation of water evaporation.

  11. Self-Assembly of Infinite Structures

    Directory of Open Access Journals (Sweden)

    Scott M. Summers

    2009-06-01

    Full Text Available We review some recent results related to the self-assembly of infinite structures in the Tile Assembly Model. These results include impossibility results, as well as novel tile assembly systems in which shapes and patterns that represent various notions of computation self-assemble. Several open questions are also presented and motivated.

  12. Self-assembled nanomaterials for photoacoustic imaging.

    Science.gov (United States)

    Wang, Lei; Yang, Pei-Pei; Zhao, Xiao-Xiao; Wang, Hao

    2016-02-07

    In recent years, extensive endeavors have been paid to construct functional self-assembled nanomaterials for various applications such as catalysis, separation, energy and biomedicines. To date, different strategies have been developed for preparing nanomaterials with diversified structures and functionalities via fine tuning of self-assembled building blocks. In terms of biomedical applications, bioimaging technologies are urgently calling for high-efficient probes/contrast agents for high-performance bioimaging. Photoacoustic (PA) imaging is an emerging whole-body imaging modality offering high spatial resolution, deep penetration and high contrast in vivo. The self-assembled nanomaterials show high stability in vivo, specific tolerance to sterilization and prolonged half-life stability and desirable targeting properties, which is a kind of promising PA contrast agents for biomedical imaging. Herein, we focus on summarizing recent advances in smart self-assembled nanomaterials with NIR absorption as PA contrast agents for biomedical imaging. According to the preparation strategy of the contrast agents, the self-assembled nanomaterials are categorized into two groups, i.e., the ex situ and in situ self-assembled nanomaterials. The driving forces, assembly modes and regulation of PA properties of self-assembled nanomaterials and their applications for long-term imaging, enzyme activity detection and aggregation-induced retention (AIR) effect for diagnosis and therapy are emphasized. Finally, we conclude with an outlook towards future developments of self-assembled nanomaterials for PA imaging.

  13. Controlled doping by self-assembled dendrimer-like macromolecules

    Science.gov (United States)

    Wu, Haigang; Guan, Bin; Sun, Yingri; Zhu, Yiping; Dan, Yaping

    2017-02-01

    Doping via self-assembled macromolecules might offer a solution for developing single atom electronics by precisely placing individual dopants at arbitrary location to meet the requirement for circuit design. Here we synthesize dendrimer-like polyglycerol macromolecules with each carrying one phosphorus atom in the core. The macromolecules are immobilized by the coupling reagent onto silicon surfaces that are pre-modified with a monolayer of undecylenic acid. Nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) are employed to characterize the synthesized macromolecules and the modified silicon surfaces, respectively. After rapid thermal annealing, the phosphorus atoms carried by the macromolecules diffuse into the silicon substrate, forming dopants at a concentration of 1017 cm-3. Low-temperature Hall effect measurements reveal that the ionization process is rather complicated. Unlike the widely reported simple ionization of phosphorus dopants, nitrogen and carbon are also involved in the electronic activities in the monolayer doped silicon.

  14. Shape Restoration by Active Self-Assembly

    Directory of Open Access Journals (Sweden)

    D. Arbuckle

    2005-01-01

    Full Text Available Shape restoration is defined as the problem of constructing a desired, or goal, solid shape Sg by growing an initial solid Si, which is a subset of the goal but is otherwise unknown. This definition attempts to capture abstractly a situation that often arises in the physical world when a solid object loses its desired shape due to wear and tear, corrosion or other phenomena. For example, if the top of the femur becomes distorted, the hip joint no longer functions properly and may have to be replaced surgically. Growing it in place back to its original shape would be an attractive alternative to replacement. This paper presents a solution to the shape restoration problem by using autonomous assembly agents (robots that self-assemble to fill the volume between Sg and Si. If the robots have very small dimension (micro or nano, the desired shape is approximated with high accuracy. The assembly agents initially execute a random walk. When two robots meet, they may exchange a small number of messages. The robot behavior is controlled by a finite state machine with a small number of states. Communication contact models chemical communication, which is likely to be the medium of choice for robots at the nanoscale, while small state and small messages are limitations that also are expected of nanorobots. Simulations presented here show that swarms of such robots organize themselves to achieve shape restoration by using distributed algorithms. This is one more example of an interesting geometric problem that can be solved by the Active Self-Assembly paradigm introduced in previous papers by the authors.

  15. Micro- and Nanopatterning of Functional Organic Monolayers on Oxide-Free Silicon by Laser-Induced Photothermal Desorption

    NARCIS (Netherlands)

    Scheres, L.; Klingebiel, B.; Maat, ter J.; Giesbers, M.; Jong, de J.H.S.G.M.; Hartmann, N.; Zuilhof, H.

    2010-01-01

    The photothermal laser patterning of functional organic monolayers, prepared on oxide-free hydrogen-terminated silicon, and subsequent backfilling of the laser-written lines with a second organic monolayer that differs in its terminal functionality, is described. Since the thermal monolayer

  16. Controllable two-stage droplet evaporation method and its nanoparticle self-assembly mechanism.

    Science.gov (United States)

    Xie, Yong; Guo, Shengming; Guo, Chuanfei; He, Meng; Chen, Dongxue; Ji, Yinglu; Chen, Ziyu; Wu, Xiaochun; Liu, Qian; Xie, Sishen

    2013-05-28

    Bottom-up self-assembly is able to constitute a variety of structures and has been thought to be a promising way for advanced nanofabrication. Droplet evaporation, as the simplest method, has been used in various self-assemblies. However, the assembled area is not large enough and the order is still not well controlled. Here we show a facile and controllable two-stage droplet evaporation method by adjusting the humidity and temperature of the evaporating droplet. Taking the highly monodispersed gold nanorods (GNRs) as an example, large-area, self-assembly monolayer arrays are reproducibly achieved. To understand the self-assembly mechanism, we adopted simplified models to analyze the interactions between the nanorods. The results show that a metastable state of secondary-energy-minimum exists, especially in the latter stage of the assembly process, leading to the ordered arrays. A large electrostatic barrier between the assembled arrays prevents the formation of the multilayer structures and thereby leads to the preferential monolayers. Moreover, we predict possibilities of different types of assemblies of the nanorods, and a schematic phase diagram is finally given. The results here may offer a way toward high-quality self-assembled nanoparticles superlattices for use in enhanced spectroscopy, sensors, or nanodevices.

  17. Functional organic thin films

    OpenAIRE

    Scharnberg, Michael

    2007-01-01

    Organic thin films are used in many technological and engineering applications nowadays. They find use as coatings, sensors, detectors, as matrix materials in nanocomposites, as self-assembled monolayers for surface functionalization, as low-k dielectrics in integrated circuits and in advanced organic electronic applications like organic light emitting diodes, organic field effect transistors and organic photovoltaics (esp. organic solar cells) and many other applications. OLED displays are n...

  18. Controlled Self-Assembly of Photofunctional Supramolecular Nanotubes.

    Science.gov (United States)

    Cohen, Erez; Weissman, Haim; Pinkas, Iddo; Shimoni, Eyal; Rehak, Pavel; Král, Petr; Rybtchinski, Boris

    2018-01-23

    Designing supramolecular nanotubes (SNTs) with distinct dimensions and properties is highly desirable, yet challenging, since structural control strategies are lacking. Furthermore, relatively complex building blocks are often employed in SNT self-assembly. Here, we demonstrate that symmetric bolaamphiphiles having a hydrophobic core comprised of two perylene diimide moieties connected via a bipyridine linker and bearing polyethylene glycol (PEG) side chains can self-assemble into diverse molecular nanotubes. The structure of the nanotubes can be controlled by assembly conditions (solvent composition and temperature) and a PEG chain length. The resulting nanotubes differ both in diameter and cross section geometry, having widths of 3 nm (triangular-like cross-section), 4 nm (rectangular), and 5 nm (hexagonal). Molecular dynamics simulations provide insights into the stability of the tubular superstructures and their initial stages of self-assembly, revealing a key role of oligomerization via side-by-side aromatic interactions between bis-aromatic cores. Probing electronic and photonic properties of the nanotubes revealed extended electron delocalization and photoinduced charge separation that proceeds via symmetry breaking, a photofunction distinctly different from that of the fibers assembled from the same molecules. A high degree of structural control and insights into SNT self-assembly advance design approaches toward functional organic nanomaterials.

  19. Biocompatible and Biomimetic Self-Assembly of Functional Nanostructures

    Science.gov (United States)

    2017-03-15

    ability to combat antibiotic resistance and fungal infections. In a related way, we assessed encapsulation of bacterial cells in silica based...AFRL-AFOSR-VA-TR-2017-0047 Biocompatible and Biomimetic Self-Assembly of Functional Nanostructures Jeffrey Brinker UNIVERSITY OF NEW MEXICO Final...ORGANIZATION NAME(S) AND ADDRESS(ES) UNIVERSITY OF NEW MEXICO 1700 LOMAS BLVD NE ALBUQUERQUE, NM 87106 US 8. PERFORMING ORGANIZATION REPORT NUMBER 9

  20. Solvent mediated self-assembly of solids

    Energy Technology Data Exchange (ETDEWEB)

    De Yoreo, J.; Wilson, W.D.; Palmore, T.

    1997-12-12

    Solvent-mediated crystallization represents a robust approach to self-assembly of nanostructures and microstructures. In organic systems, the relative ease with which the structure of hydrogen- bonded molecules can be manipulated allows for generation of a wide variety of nanoscale crystal structures. In living organisms, control over the micron-to-millimeter form of inorganic crystals is achieved through introduction of bio-organic molecules. The purpose of this proposal is to understand the interplay between solution chemistry, molecular structure, surface chemistry, and the processes of nucleation and crystal growth in solvent-mediated systems, with the goal of developing the atomic and molecular basis of a solvent-mediated self-assembly technology. We will achieve this purpose by: (1) utilizing an atomic force microscopy (AFM) approach that provides in situ, real time imaging during growth from solutions, (2) by modifying kinetic Monte Carlo (KMC) models to include solution-surface kinetics, (3) by introducing quantum chemistry (QC) calculations of the potentials of the relevant chemical species and the near-surface structure of the solution, and (4) by utilizing molecular dynamics (MD) simulations to identify the minimum energy pathways to the solid state. Our work will focus on two systems chosen to address both the manometer and micron-to-millimeter length scales of assembly, the family of 2,5- diketopiperazines (X-DKPs) and the system of CaCO{sub 3} with amino acids. Using AFM, we will record the evolution of surface morphology, critical lengths, step speeds, and step-step interactions as a function of supersaturation and temperature. In the case of the X-DKPs, these measurements will be repeated as the molecular structure of the growth unit is varied. In the case of CaCO{sub 3}, they will be performed as a function of solution chemistry including pH, ionic strength, and amino acid content. In addition, we will measure nucleation rates and orientations of

  1. Self-assembled electrical materials from contorted aromatics

    Science.gov (United States)

    Xiao, Shengxiong

    This thesis describes the design, synthesis, self-assembly and electrical properties of new types of contorted polycyclic aromatic hydrocarbons. These topologically interesting contorted aromatics show promising transistor characteristics as new building blocks for organic field-effect transistors (OFETs) at different length scales. In chapter 2, a class of pentacenes that are substituted along their long edges with aromatic rings were synthesized. Their solid-state assemblies were studied by X-ray crystallography. Their performance as thin film transistors (TFTs) and single crystal field effect transistors (SCFETs) were systematically evaluated. A structure-property relationship between these highly phenylated pentacenes was found. Chapter 3 explores the new concept of whether a non-planar aromatic core could yield efficacious electronic materials, as the ultimate success in the organic electronics will require a holistic approach to creating new building blocks. Synthesis, functionalization and assembly of a new type of contorted hexabenzocoronene (HBC) whose aromatic core is heavily distorted away from planarity due to the steric congestion around its proximal carbons were discussed. Structural studies by X-ray crystallography showed that these HBC molecules stack into columnar structures in the solid state, which are ideal for conduction. Chapter 4 describes that microscale liquid crystalline thin film OFETs of tetradodecyloxy HBC showed the best transistor properties of all discotic columnar materials. Chapter 5 details the fabrication and characterization of nanoscale single crystalline fiber OFETs of octadodecyloxyl HBC. In Chapter 6 we show that a molecular scale monolayer of HBC acid chlorides could be self-assembled on SiO2 insulating layer and could be organized laterally between the ends of 2 nm carbon nanotube gaps to form high quality FETs that act as environmental and chemical sensors. Chapter 7 details the enforced one-dimensional photoconductivity

  2. Directed Self-Assembly of Nanodispersions

    Energy Technology Data Exchange (ETDEWEB)

    Furst, Eric M [University of Delaware

    2013-11-15

    Directed self-assembly promises to be the technologically and economically optimal approach to industrial-scale nanotechnology, and will enable the realization of inexpensive, reproducible and active nanostructured materials with tailored photonic, transport and mechanical properties. These new nanomaterials will play a critical role in meeting the 21st century grand challenges of the US, including energy diversity and sustainability, national security and economic competitiveness. The goal of this work was to develop and fundamentally validate methods of directed selfassembly of nanomaterials and nanodispersion processing. The specific aims were: 1. Nanocolloid self-assembly and interactions in AC electric fields. In an effort to reduce the particle sizes used in AC electric field self-assembly to lengthscales, we propose detailed characterizations of field-driven structures and studies of the fundamental underlying particle interactions. We will utilize microscopy and light scattering to assess order-disorder transitions and self-assembled structures under a variety of field and physicochemical conditions. Optical trapping will be used to measure particle interactions. These experiments will be synergetic with calculations of the particle polarizability, enabling us to both validate interactions and predict the order-disorder transition for nanocolloids. 2. Assembly of anisotropic nanocolloids. Particle shape has profound effects on structure and flow behavior of dispersions, and greatly complicates their processing and self-assembly. The methods developed to study the self-assembled structures and underlying particle interactions for dispersions of isotropic nanocolloids will be extended to systems composed of anisotropic particles. This report reviews several key advances that have been made during this project, including, (1) advances in the measurement of particle polarization mechanisms underlying field-directed self-assembly, and (2) progress in the

  3. Hyperthermal Carbon Dioxide Interactions with Self-Assembled Monolayer Surfaces

    Science.gov (United States)

    2013-09-08

    They measured two populations of rotational distributions, one corresponding to the surface temperature and the other corresponding to a much higher...involved in the collision. This is the first application of the soft-sphere model to the scattering of molecules, which have internal structure, as...temperature. Scattering dynamics on these fluorinated liquid and SAM surfaces were compared directly. It was found that the scattering dynamics were very

  4. Self-assembly of inorganic nanoparticles: Ab ovo

    Science.gov (United States)

    Kotov, Nicholas A.

    2017-09-01

    There are numerous remarkable studies related to the self-organization of polymers, coordination compounds, microscale particles, biomolecules, macroscale particles, surfactants, and reactive molecules on surfaces. The focus of this paper is on the self-organization of nanoscale inorganic particles or simply nanoparticles (NPs). Although there are fascinating and profound discoveries made with other self-assembling structures, the ones involving NPs deserve particular attention because they (a) are omnipresent in Nature; (b) have relevance to numerous disciplines (physics, chemistry, biology, astronomy, Earth sciences, and others); (c) embrace most of the features, geometries, and intricacies observed for the self-organization of other chemical species; (d) offer new tools for studies of self-organization phenomena; and (e) have a large economic impact, extending from energy and construction industries, to optoelectronics, biomedical technologies, and food safety. Despite the overall success of the field it is necessary to step back from its multiple ongoing research venues and consider two questions: What is self-assembly of nanoparticles? and Why do we need to study it? The reason to bring them up is to achieve greater scientific depth in the understanding of these omnipresent phenomena and, perhaps, deepen their multifaceted impact. Contribution to the Focus Issue Self-assemblies of Inorganic and Organic Nanomaterials edited by Marie-Paule Pileni.

  5. Organosilicon derivatives of BTBT for monolayer organic field effect transistors

    Science.gov (United States)

    Agina, Elena V.; Polinskaya, Marina S.; Trul, Askold A.; Chekusova, Viktoria P.; Sizov, Alexey S.; Borshchev, Oleg V.; Ponomarenko, Sergey A.

    2017-08-01

    Synthesis of novel organosilicon derivatives of [1]benzothieno[3,2-b][1]-benzothiophene (BTBT) linked though flexible aliphatic spacers to a disiloxane anchor group is reported. They were successfully used in monolayer OFETs with the charge carrier mobilities up to 0.02 cm2 /Vs, threshold voltage close to 0 V and On/Off ratio up to 10,000. Influence of the chemical structure of the molecules synthesized on the morphology, molecular 2D ordering in the monolayers and their semiconducting properties is considered. The effect of different methods of the ultrathin semiconducting layer preparation, such as Langmuir-Blodgett, Langmuir-Schaefer, spin coating or doctor blade, on the OFET performance is discussed.

  6. The self-assembling process and applications in tissue engineering

    Science.gov (United States)

    Lee, Jennifer K.; Link, Jarrett M.; Hu, Jerry C. Y.; Athanasiou, Kyriacos A.

    2018-01-01

    Tissue engineering strives to create neotissues capable of restoring function. Scaffold-free technologies have emerged that can recapitulate native tissue function without the use of an exogenous scaffold. This chapter will survey, in particular, the self-assembling and self-organization processes as scaffold-free techniques. Characteristics and benefits of each process are described, and key examples of tissues created using these scaffold-free processes are examined to provide guidance for future tissue engineering developments. This chapter aims to explore the potential of self-assembly and self-organization scaffold-free approaches, detailing the recent progress in the in vitro tissue engineering of biomimetic tissues with these methods, toward generating functional tissue replacements. PMID:28348174

  7. An unsymmetrical non-fullerene acceptor: synthesis via direct heteroarylation, self-assembly, and utility as a low energy absorber in organic photovoltaic cells.

    Science.gov (United States)

    Payne, Abby-Jo; Li, Shi; Dayneko, Sergey V; Risko, Chad; Welch, Gregory C

    2017-09-12

    This study reports on the design and synthesis of an unsymmetrical π-conjugated organic molecule composed of perylene diimide, thienyl diketopyrrolopyrrole, and indoloquinoxaline pieced together using direct heteroarylation. This material demonstrates unprecedented response in the thin-film upon post-deposition solvent vapor annealing, resulting in dramatic red-shifts in optical absorption. Such changes were utilized to enhance photocurrent generation in P3HT based organic solar cells.

  8. Forces that Drive Nanoscale Self-assembly on Solid Surfaces

    International Nuclear Information System (INIS)

    Suo, Z.; Lu, W.

    2000-01-01

    Experimental evidence has accumulated in the recent decade that nanoscale patterns can self-assemble on solid surfaces. A two-component monolayer grown on a solid surface may separate into distinct phases. Sometimes the phases select sizes about 10 nm, and order into an array of stripes or disks. This paper reviews a model that accounts for these behaviors. Attention is focused on thermodynamic forces that drive the self-assembly. A double-welled, composition-dependent free energy drives phase separation. The phase boundary energy drives phase coarsening. The concentration-dependent surface stress drives phase refining. It is the competition between the coarsening and the refining that leads to size selection and spatial ordering. These thermodynamic forces are embodied in a nonlinear diffusion equation. Numerical simulations reveal rich dynamics of the pattern formation process. It is relatively fast for the phases to separate and select a uniform size, but exceedingly slow to order over a long distance, unless the symmetry is suitably broken

  9. DNA–melamine hybrid molecules: from self-assembly to nanostructures

    Directory of Open Access Journals (Sweden)

    Rina Kumari

    2015-06-01

    Full Text Available Single-stranded DNA–melamine hybrid molecular building blocks were synthesized using a phosphoramidation cross-coupling reaction with a zero linker approach. The self-assembly of the DNA–organic hybrid molecules was achieved by DNA hybridization. Following self-assembly, two distinct types of nanostructures in the form of linear chains and network arrays were observed. The morphology of the self-assembled nanostructures was found to depend on the number of DNA strands that were attached to a single melamine molecule.

  10. Temperature dependent coordinating self-assembly.

    Science.gov (United States)

    Wang, Yijie; Gao, Xuedong; Xiao, Yunlong; Zhao, Qiang; Yang, Jiang; Yan, Yun; Huang, Jianbin

    2015-04-14

    Self-assemblies dominated by coordination interaction are hardly responsive to thermal stimuli. We show that in case the coordinating mode changes with temperature, the resultant assemblies also exhibit temperature dependence. The self-assemblies are constructed with perylene tetracarboxylate and metal ions. Compounds containing a perylene skeleton often self-assemble into micro-belts, which is also true for the combination of perylene tetracarboxylate and metal ions. However, a unique pinecone structure was observed upon increasing the temperature of the coordinating system. The structural transition is triggered by the change of coordinating mode between the carboxylate group and the metal ion. At low temperature, intermolecular coordination occurs which favours the growth of the coordinating self-assembly along the long axis of the perylene. However, upon the elevation of temperature, the coordination is overwhelmed by intra-molecular mode. This is against the extension of the coordinating assembly due to the loss of connection between neighbouring perylenes. As a result, the pinecone structure is observed. We expect that the cases introduced in this work may inspire the design of structurally controllable temperature-dependent soft materials based on coordinating self-assembly.

  11. Self-assembled tunable photonic hyper-crystals.

    Science.gov (United States)

    Smolyaninova, Vera N; Yost, Bradley; Lahneman, David; Narimanov, Evgenii E; Smolyaninov, Igor I

    2014-07-16

    We demonstrate a novel artificial optical material, the "photonic hyper-crystal", which combines the most interesting features of hyperbolic metamaterials and photonic crystals. Similar to hyperbolic metamaterials, photonic hyper-crystals exhibit broadband divergence in their photonic density of states due to the lack of usual diffraction limit on the photon wave vector. On the other hand, similar to photonic crystals, hyperbolic dispersion law of extraordinary photons is modulated by forbidden gaps near the boundaries of photonic Brillouin zones. Three dimensional self-assembly of photonic hyper-crystals has been achieved by application of external magnetic field to a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing.

  12. Controllable self-assembly of NaREF4 upconversion nanoparticles and their distinctive fluorescence properties

    Science.gov (United States)

    Liu, Xiaoxia; Ni, Yaru; Zhu, Cheng; Fang, Liang; Kou, Jiahui; Lu, Chunhua; Xu, Zhongzi

    2016-07-01

    The paper presents the growth of hexagonal NaYF4:Yb3+, Tm3+ nanocrystals with tunable sizes induced by different contents of doped Yb3+ ions (10%-99.5%) using the thermal decomposition method. These nanoparticles, which have different sizes, are then self-assembled at the interface of cyclohexane and ethylene and transferred onto a normal glass slide. It is found that the size of nanoparticles directs their self-assembly. Due to the appropriate size of 40.5 nm, 15% Yb3+ ions doped nanoparticles are able to be self-assembled into an ordered inorganic monolayer membrane with a large area of about 10 × 10 μm2. More importantly, the obvious short-wave (300-500 nm) fluorescence improvement of the ordered 2D self-assembly structure is observed to be relative to disordered nanoparticles, which is because intrinsic absorption and scattering of upconversion nanoparticles leads to the self-loss of fluorescence, especially the short-wave fluorescence inside the disordered structure, and the relative emission of short-wave fluorescence is reduced. The construction of a 2D self-assembly structure can effectively avoid this and improve the radiated short-wave fluorescence, especially UV photons, and is able to direct the design of new types of solid-state optical materials in many fields.

  13. Self-assembling enzymes and the origins of the cytoskeleton

    Science.gov (United States)

    Barry, Rachael; Gitai, Zemer

    2011-01-01

    The bacterial cytoskeleton is composed of a complex and diverse group of proteins that self-assemble into linear filaments. These filaments support and organize cellular architecture and provide a dynamic network controlling transport and localization within the cell. Here, we review recent discoveries related to a newly appreciated class of self-assembling proteins that expand our view of the bacterial cytoskeleton and provide potential explanations for its evolutionary origins. Specifically, several types of metabolic enzymes can form structures similar to established cytoskeletal filaments and, in some cases, these structures have been repurposed for structural uses independent of their normal role. The behaviors of these enzymes suggest that some modern cytoskeletal proteins may have evolved from dual-role proteins with catalytic and structural functions. PMID:22014508

  14. Numerical approach on dynamic self-assembly of colloidal particles

    Science.gov (United States)

    Ibrahimi, Muhamet; Ilday, Serim; Makey, Ghaith; Pavlov, Ihor; Yavuz, Özgàn; Gulseren, Oguz; Ilday, Fatih Omer

    Far from equilibrium systems of artificial ensembles are crucial for understanding many intelligent features in self-organized natural systems. However, the lack of established theory underlies a need for numerical implementations. Inspired by a novel work, we simulate a solution-suspended colloidal system that dynamically self assembles due to convective forces generated in the solvent when heated by a laser. In order to incorporate with random fluctuations of particles and continuously changing flow, we exploit a random-walk based Brownian motion model and a fluid dynamics solver prepared for games, respectively. Simulation results manage to fit to experiments and show many quantitative features of a non equilibrium dynamic self assembly, including phase space compression and an ensemble-energy input feedback loop.

  15. Lipid Self-Assemblies and Nanostructured Emulsions for Cosmetic Formulations

    Directory of Open Access Journals (Sweden)

    Chandrashekhar V. Kulkarni

    2016-10-01

    Full Text Available A majority of cosmetic products that we encounter on daily basis contain lipid constituents in solubilized or insolubilized forms. Due to their amphiphilic nature, the lipid molecules spontaneously self-assemble into a remarkable range of nanostructures when mixed with water. This review illustrates the formation and finely tunable properties of self-assembled lipid nanostructures and their hierarchically organized derivatives, as well as their relevance to the development of cosmetic formulations. These lipid systems can be modulated into various physical forms suitable for topical administration including fluids, gels, creams, pastes and dehydrated films. Moreover, they are capable of encapsulating hydrophilic, hydrophobic as well as amphiphilic active ingredients owing to their special morphological characters. Nano-hybrid materials with more elegant properties can be designed by combining nanostructured lipid systems with other nanomaterials including a hydrogelator, silica nanoparticles, clays and carbon nanomaterials. The smart materials reviewed here may well be the future of innovative cosmetic applications.

  16. Unprecedented Self-Organized Monolayer of a Ru(II) Complex by Diazonium Electroreduction.

    Science.gov (United States)

    Nguyen, Van Quynh; Sun, Xiaonan; Lafolet, Frédéric; Audibert, Jean-Frédéric; Miomandre, Fabien; Lemercier, Gilles; Loiseau, Frédérique; Lacroix, Jean-Christophe

    2016-08-03

    A new heteroleptic polypyridyle Ru(II) complex was synthesized and deposited on surface by the diazonium electroreduction process. It yields to the covalent grafting of a monolayer. The functionalized surface was characterized by XPS, electrochemistry, AFM, and STM. A precise organization of the molecules within the monolayer is observed with parallel linear stripes separated by a distance of 3.8 nm corresponding to the lateral size of the molecule. Such organization suggests a strong cooperative process in the deposition process. This strategy is an original way to obtain well-controlled and stable functionalized surfaces for potential applications related to the photophysical properties of the grafted chromophore. As an exciting result, it is the first example of a self-organized monolayer (SOM) obtained using diazonium electroreduction.

  17. Self-Assembly of Gold Nanoparticles at the Liquid/Liquid Interface

    International Nuclear Information System (INIS)

    Lee, Kang Yeol; Han, Sang Woo

    2005-01-01

    We have shown that the crown ether derivative can mediate the transfer of gold nanoparticles in water solution to water/oil interface, results in directing the self-assembly of nanoparticles in the form of a novel nanocomposite film. The interfacial film of nanoparticles could be transferred to various solid substrates. The experimental results indicate the formation of nanoparticles monolayers at water/oil interfaces. Our work is an important step towards interfacial entrapment and self-assembly of nanoparticles for efficient creation of 2D nanostructures. These types of materials may be used in developing catalysts, sensors, and nanoelectronic devices. Currently, we are attempting to synthesize other composite films by using specific interactions between suitable organic or inorganic ligands and various nanoparticles. The intense research activity in the field of nanoparticles is motivated by the search for new materials in order to further miniaturize electronic devices, as well as by the fundamental question of how molecular electronic properties evolve with increasing size in this intermediate region between molecular and solid-state physics. In this respect, molecularly bridged nanoparticle aggregates have been attracting growing interest. The properties of two-dimensional assemblies of metal nanoparticles are controlled by the composition, geometry, and spatial arrangement of the nanoparticle building blocks. Such structures have been used for a variety of important applications in catalysis, photonics, electronics, and biological sensing. The 2D/3D control over the spatial arrangement of nanoparticles is primarily based on the thiolamphilic nature of metal nanoparticles, hydrogenbonding interactions, the highly specific recognition interaction of antigens/antibodies, and specific base-pairing interactions between DNA and its complementary strand

  18. Advanced Photoemission Spectroscopy Investigations Correlated with DFT Calculations on the Self-Assembly of 2D Metal Organic Frameworks Nano Thin Films.

    Science.gov (United States)

    Elzein, Radwan; Chang, Chun-Min; Ponomareva, Inna; Gao, Wen-Yang; Ma, Shengqian; Schlaf, Rudy

    2016-11-16

    Metal-organic frameworks (MOFs) deposited from solution have the potential to form 2-dimensional supramolecular thin films suitable for molecular electronic applications. However, the main challenges lie in achieving selective attachment to the substrate surface, and the integration of organic conductive ligands into the MOF structure to achieve conductivity. The presented results demonstrate that photoemission spectroscopy combined with preparation in a system-attached glovebox can be used to characterize the electronic structure of such systems. The presented results demonstrate that porphyrin-based 2D MOF structures can be produced and that they exhibit similar electronic structure to that of corresponding conventional porphyrin thin films. Porphyrin MOF multilayer thin films were grown on Au substrates prefunctionalized with 4-mercaptopyridine (MP) via incubation in a glovebox, which was connected to an ultrahigh vacuum system outfitted with photoelectron spectroscopy. The thin film growth process was carried out in several sequential steps. In between individual steps the surface was characterized by photoemission spectroscopy to determine the valence bands and evaluate the growth mode of the film. A comprehensive evaluation of X-ray photoemission spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and inverse photoemission spectroscopy (IPES) data was performed and correlated with density functional theory (DFT) calculations of the density of states (DOS) of the films involved to yield the molecular-level insights into the growth and the electronic properties of MOF-based 2D thin films.

  19. Formation of n-Alkyl Monolayers by Organomercury Deposition on Gold

    Czech Academy of Sciences Publication Activity Database

    Scholz, F.; Kaletová, Eva; Stensrud, Elizabeth; Ford, W. E.; Kohutová, Anna; Mucha, Malgorzata; Stibor, Ivan; Michl, Josef; Wrochem von, F.

    2013-01-01

    Roč. 4, č. 16 (2013), s. 2624-2629 ISSN 1948-7185 R&D Projects: GA ČR GA203/07/1619; GA ČR GA203/09/0705 EU Projects: European Commission(XE) 213382 - FUNMOL; European Commission(XE) 227756 - DIPOLAR ROTOR ARRAY Institutional support: RVO:61388963 Keywords : self-assembled monolayers * ray photoelectron-spectroscopy * altitudinal molecular rotors Subject RIV: CC - Organic Chemistry Impact factor: 6.687, year: 2013

  20. Self-assembly of tetracyanonaphtho-quinodimethane (TNAP) based metal-organic networks on Pb(1 1 1): Structural, electronic, and magnetic properties

    Science.gov (United States)

    Ahmadi, Gelavizh; Franke, Katharina J.

    2016-06-01

    We use scanning tunneling microscopy and spectroscopy to investigate structural and electronic properties of tetracyanonaphtho-quinodimethane (TNAP) based metal-organic networks on a superconducting Pb(1 1 1) surface. At low temperatures, the TNAP molecules form densely packed islands. When deposited at room temperature, Pb adatoms are incorporated into fourfold bonding nodes with the TNAP molecules leading to long-range ordered porous structures. Co-deposition of NaCl with TNAP yields a Na source for an ionically bonded Na-TNAP structure. Fourfold bonding motifs are also created by Fe atoms with the cyano terminations of TNAP. However, the structures are irregular and do not sustain the formation of long-range ordered networks. Some Fe centers with molecules surrounded in a local C2 symmetry exhibit Shiba states as a fingerprint of a magnetic interaction with the superconducting surface.

  1. Adsorption and self-assembly of M13 phage into directionally organized structures on C and SiO2 films.

    Science.gov (United States)

    Moghimian, Pouya; Srot, Vesna; Rothenstein, Dirk; Facey, Sandra J; Harnau, Ludger; Hauer, Bernhard; Bill, Joachim; van Aken, Peter A

    2014-09-30

    A versatile method for the directional assembly of M13 phage using amorphous carbon and SiO2 thin films was demonstrated. A high affinity of the M13 phage macromolecules for incorporation into aligned structures on an amorphous carbon surface was observed at the concentration range, in which the viral nanofibers tend to disorder. In contrast, the viral particles showed less freedom to adopt an aligned orientation on SiO2 films when deposited in close vicinity. Here an interpretation of the role of the carbon surface in significant enhancement of adsorption and generation of viral arrays with a high orientational order was proposed in terms of surface chemistry and competitive electrostatic interactions. This study suggests the use of amorphous carbon substrates as a template for directional organization of a closely-packed and two-dimensional M13 viral film, which can be a promising route to mineralize a variety of smooth and homogeneous inorganic nanostructure layers.

  2. Self-assembled bilayers based on organothiol and organotrimethoxysilane on zinc platform

    International Nuclear Information System (INIS)

    Berger, Francois; Delhalle, Joseph; Mekhalif, Zineb

    2010-01-01

    This study describes the formation of a bilayer system developed on electrodeposited zinc. In a first step, a monolayer of 11-mercapto-1-undecanol is grafted on zinc, optimization of the conditions of elaboration have been performed. In a second step, organotrimethoxysilane have been grafted on the zinc modified with the hydroxyl terminated self-assembled monolayer (SAM) to finalize the bilayer system. X-ray photoelectron spectroscopy (XPS), polarization modulation-infrared reflection absorption spectroscopy (PM-IRRAS) and contact angle measurements are used to characterize each step of modification. An electrochemical evaluation of the different created systems is carried out by linear sweep voltammetry (LSV), cyclic voltammetry (CV) and scanning vibrating electrode technique (SVET). The impact of the modification of zinc using SAM and self-assembled bilayer (SAB) on the electrochemical activity of the surface is highlighted.

  3. Remote control of self-assembled microswimmers

    Science.gov (United States)

    Grosjean, G.; Lagubeau, G.; Darras, A.; Hubert, M.; Lumay, G.; Vandewalle, N.

    2015-11-01

    Physics governing the locomotion of microorganisms and other microsystems is dominated by viscous damping. An effective swimming strategy involves the non-reciprocal and periodic deformations of the considered body. Here, we show that a magnetocapillary-driven self-assembly, composed of three soft ferromagnetic beads, is able to swim along a liquid-air interface when powered by an external magnetic field. More importantly, we demonstrate that trajectories can be fully controlled, opening ways to explore low Reynolds number swimming. This magnetocapillary system spontaneously forms by self-assembly, allowing miniaturization and other possible applications such as cargo transport or solvent flows.

  4. Self-assembling segmented coiled tubing

    Science.gov (United States)

    Raymond, David W.

    2016-09-27

    Self-assembling segmented coiled tubing is a concept that allows the strength of thick-wall rigid pipe, and the flexibility of thin-wall tubing, to be realized in a single design. The primary use is for a drillstring tubular, but it has potential for other applications requiring transmission of mechanical loads (forces and torques) through an initially coiled tubular. The concept uses a spring-loaded spherical `ball-and-socket` type joint to interconnect two or more short, rigid segments of pipe. Use of an optional snap ring allows the joint to be permanently made, in a `self-assembling` manner.

  5. Nanoparticle induced wetting of polymer films and self-assembled multilayers of nanocomponents

    Science.gov (United States)

    Krishnan, R. S.

    The control of dewetting for thin polymer films is a technical challenge and of significant academic interest. Although studies have been published on the wetting of polymer films in the presence of nanoparticles, the underlying physics is still a matter of debate. In this work, we report a systematic study of improved wetting behavior of thin polymer films containing nanoparticles, as a function of nanoparticle size and concentration. An enthalpy matched system consisting of polystyrene nanoparticles in linear polystyrene is used to show that nanoparticles are uniformly distributed in the film after spin coating and drying, however on annealing the film above its bulk glass transition temperature the nanoparticles segregate strongly to the solid substrate. We find that for a wide range of film thicknesses and nanoparticle sizes, approximately monolayer substrate coverage of nanoparticles is required for strong dewetting inhibition. We also show that cadmium selenide quantum dots inhibit dewetting of both polystyrene and PMMA thin films. Moreover, TEM microscopy images indicate that CdSe quantum dots segregate primarily to the air surface. Gain of configuration entropy of the melt linear chains promotes segregation of nanoparticles to the substrate, as occurs for polystyrene nanoparticles. However, for CdSe nanoparticles this is offset by surface energy terms which promote segregation of the nanoparticles to the air surface. We argue that this is due to the inert low-energy Oleic acid brush introduced to promote organic compatibility of the quantum dot surfaces. Finally, we use the nanoparticle induced wetting of a polymer film due to the self-assembly of nanoparticles at the interface to construct the layered assembly of polymer-nanoparticle sandwich films. We report an alternative route to multilayer nanostructures where the layered self-assembly of the constituents is driven by the interplay between entropy, due to architectural differences, and surface energy

  6. Modulating the electronic and optical properties of monolayer arsenene phases by organic molecular doping

    Science.gov (United States)

    Singh, Deobrat; Gupta, Sanjeev K.; Sonvane, Yogesh; Sahoo, Satyaprakash

    2017-12-01

    Recently, arsenene monolayer structure of the arsenic with two phases has displayed semiconducting behavior. We have systematically investigated the electronic and optical properties of single-layer arsenene with two types of functionalized organic molecules; an electrophilic molecule [tetracyanoquinodimethane (TCNQ)] and a nucleophilic molecule [tetrathiafulvalene (TTF)], as an electron acceptor and electron donor, respectively. The interfacial charge transfer between the arsenene monolayer and TCNQ/TTF molecules extensively reduces the band gap of arsenene and accordingly resulted in a p- or n-type semiconducting behavior, respectively. We have also performed the interfacial charge transfer from organic molecules to monolayer arsenene and vice versa. The interfacial surface molecular modification has established an efficient way to develop the light harvesting of arsenene in different polarization directions. Our theoretical investigation suggests that such n- and p-type arsenene semiconductors would broaden the applications in the field of nanoelectronic and optoelectronic devices such as photodiodes and it is also useful for constructing functional electronic systems.

  7. Self-assembly of metal-organic coordination polymers constructed from a bent dicarboxylate ligand: diversity of coordination modes, structures, and gas adsorption.

    Science.gov (United States)

    Yang, Wenbin; Lin, Xiang; Blake, Alexander J; Wilson, Claire; Hubberstey, Peter; Champness, Neil R; Schröder, Martin

    2009-12-07

    We have synthesized five new metal-organic coordination polymers incorporating the bent ligand H(2)hfipbb [4,4'-(hexafluoroisopropylidene)bis(benzoic acid)] with different transition metal ions and co-ligands via solvothermal reactions to give [Zn(2)(hfipbb)(2)(py)(2)] x DMF (1), [Zn(2)(hfipbb)(2)(4,4'-bipy)(H(2)O)] (2), [Zn(2)(hfipbb)(2)(bpdab)].2DMF (3), [Cd(2)(hfipbb)(2)(DMF)(2)] x 2 DMF (4), and [Co(hfipbb)(dpp)] x MeOH (5) (py = pyridine, 4,4'-bipy = 4,4'-bipyridine, bpdab = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, dpp = 1,3-di(4-pyridyl)propane). Compound 1 displays a 2-fold 2D-->2D parallel interpenetrated layer network with one-dimensional (1D) helical channels, while 3 exhibits a three-dimensional pillared helical-layer open framework of alpha-Po topology based upon binuclear paddlewheel units. In compounds 2 and 5, binuclear motifs with double carboxylate bridges are linked by hfipbb(2-) ligands into a 1D ribbon, which are further assembled into two-dimensional non-interpenetrated (4,4) layers via bipyridyl co-ligands. However, the different bridging modes of hfipbb(2-) ligands and the different disposition of the coordinated co-ligands around metal ions result in subtle differences in the final architecture. Thus, 2 is based on a binuclear cluster node, double-stranded hfipbb(2-) linkers, and single-stranded 4,4'-bipy linkers, while 5 is based on a binuclear cluster node and hfipbb(2-) and dpp linkers which are both double-stranded. Among these compounds, the Cd(II) complex 4 is possibly the most interesting because it represents a rare example in which metal centers are linked by carboxylate groups into infinite chains further joined together by hfipbb(2-) spacers to form a 2D network with tubular helical channels. All these coordination polymers exhibit low solvent-accessible volumes. Both 3 and 4 retain structural integrity and permanent microporosity upon evacuation of guest molecules, with hydrogen uptakes of 0.57 and 0.78 wt %, respectively, at

  8. A three-layer model of self-assembly induced surface-energy variation experimentally extracted by using nanomechanically sensitive cantilevers

    International Nuclear Information System (INIS)

    Zuo Guomin; Li Xinxin

    2011-01-01

    This research is aimed at elucidating surface-energy (or interfacial energy) variation during the process of molecule-layer self-assembly on a solid surface. A quasi-quantitative plotting model is proposed and established to distinguish the surface-energy variation contributed by the three characteristic layers of a thiol-on-gold self-assembled monolayer (SAM), namely the assembly-medium correlative gold/head-group layer, the chain/chain interaction layer and the tail/medium layer, respectively. The data for building the model are experimentally extracted from a set of correlative thiol self-assemblies in different media. The variation in surface-energy during self-assembly is obtained by in situ recording of the self-assembly induced nanomechanical surface-stress using integrated micro-cantilever sensors. Based on the correlative self-assembly experiment, and by using the nanomechanically sensitive self-sensing cantilevers to monitor the self-assembly induced surface-stressin situ, the experimentally extracted separate contributions of the three layers to the overall surface-energy change aid a comprehensive understanding of the self-assembly mechanism. Moreover, the quasi-quantitative modeling method is helpful for optimal design, molecule synthesis and performance evaluation of molecule self-assembly for application-specific surface functionalization.

  9. Bola-amphiphile self-assembly

    DEFF Research Database (Denmark)

    Svaneborg, Carsten

    2012-01-01

    Bola-amphiphiles are rod-like molecules where both ends of the molecule likes contact with water, while the central part of the molecule dislikes contact with water. What do such molecules do when they are dissolved in water? They self-assemble into micelles. This is a Dissipartive particle...

  10. Stabilization of Self-Assembled Alumina Mesophases

    NARCIS (Netherlands)

    Perez, Lidia Lopez; Perdriau, Sebastien; ten Brink, Gert; Kooi, Bart J.; Heeres, Hero Jan; Melian-Cabrera, Ignacio

    2013-01-01

    An efficient route to stabilize alumina mesophases derived from evaporation-induced self-assembly is reported after investigating various aspects in-depth: influence of the solvent (EtOH, s-BuOH, and t-BuOH) on the textural and structural properties of the mesophases based on aluminum

  11. Self-assembled nanogaps for molecular electronics

    International Nuclear Information System (INIS)

    Tang Qingxin; Tong Yanhong; Jain, Titoo; Hassenkam, Tue; Moth-Poulsen, Kasper; Bjoernholm, Thomas; Wan Qing

    2009-01-01

    A nanogap for molecular devices was realized using solution-based self-assembly. Gold nanorods were assembled to gold nanoparticle-coated conducting SnO 2 :Sb nanowires via thiol end-capped oligo(phenylenevinylene)s (OPVs). The molecular gap was easily created by the rigid molecule itself during self-assembly and the gap length was determined by the molecule length. The gold nanorods and gold nanoparticles, respectively covalently bonded at the two ends of the molecule, had very small dimensions, e.g. a width of ∼20 nm, and hence were expected to minimize the screening effect. The ultra-long conducting SnO 2 :Sb nanowires provided the bridge to connect one of the electrodes of the molecular device (gold nanoparticle) to the external circuit. The tip of the atomic force microscope (AFM) was contacted onto the other electrode (gold nanorod) for the electrical measurement of the OPV device. The conductance measurement confirmed that the self-assembly of the molecules and the subsequent self-assembly of the gold nanorods was a feasible method for the fabrication of the nanogap of the molecular devices.

  12. Self-assembly of patchy colloidal dumbbells

    NARCIS (Netherlands)

    Avvisati, Guido; Vissers, Teun; Dijkstra, Marjolein

    2015-01-01

    We employ Monte Carlo simulations to investigate the self-assembly of patchy colloidal dumbbells interacting via a modified Kern-Frenkel potential by probing the system concentration and dumbbell shape. We consider dumbbells consisting of one attractive sphere with diameter sigma(1) and one

  13. Self-assembled nanogaps for molecular electronics

    DEFF Research Database (Denmark)

    Tang, Qingxin; Tong, Yanhong; Jain, Titoo

    2009-01-01

    A nanogap for molecular devices was realized using solution-based self-assembly. Gold nanorods were assembled to gold nanoparticle-coated conducting SnO2:Sb nanowires via thiol end-capped oligo(phenylenevinylene)s (OPVs). The molecular gap was easily created by the rigid molecule itself during self...

  14. Coded nanoscale self-assembly

    Indian Academy of Sciences (India)

    teristics. In an effort to sustain and further such innovative developments, it is necessary to investigate the organization and growth of nanomaterials. In general, any rational approach towards designing materials are essentially of two kinds: In one method a big structure is cut down in size until the desired shape is achieved.

  15. Self-assembled nanolaminate coatings (SV)

    Energy Technology Data Exchange (ETDEWEB)

    Fan, H.

    2012-03-01

    Sandia National Laboratories (Sandia) and Lockheed Martin Aeronautics (LM Aero) are collaborating to develop affordable, self-assembled, nanocomposite coatings and associated fabrication processes that will be tailored to Lockheed Martin product requirements. The purpose of this project is to develop a family of self-assembled coatings with properties tailored to specific performance requirements, such as antireflective (AR) optics, using Sandia-developed self-assembled techniques. The project met its objectives by development of a simple and economic self-assembly processes to fabricate multifunctional coatings. Specifically, materials, functionalization methods, and associated coating processes for single layer and multiple layers coatings have been developed to accomplish high reflective coatings, hydrophobic coatings, and anti-reflective coatings. Associated modeling and simulations have been developed to guide the coating designs for optimum optical performance. The accomplishments result in significant advantages of reduced costs, increased manufacturing freedom/producibility, improved logistics, and the incorporation of new technology solutions not possible with conventional technologies. These self-assembled coatings with tailored properties will significantly address LMC's needs and give LMC a significant competitive lead in new engineered materials. This work complements SNL's LDRD and BES programs aimed at developing multifunctional nanomaterials for microelectronics and optics as well as structure/property investigations of self-assembled nanomaterials. In addition, this project will provide SNL with new opportunities to develop and apply self-assembled nanocomposite optical coatings for use in the wavelength ranges of 3-5 and 8-12 micrometers, ranges of vital importance to military-based sensors and weapons. The SANC technologies will be applied to multiple programs within the LM Company including the F-35, F-22, ADP (Future Strike Bomber

  16. Logical NAND and NOR Operations Using Algorithmic Self-assembly of DNA Molecules

    Science.gov (United States)

    Wang, Yanfeng; Cui, Guangzhao; Zhang, Xuncai; Zheng, Yan

    DNA self-assembly is the most advanced and versatile system that has been experimentally demonstrated for programmable construction of patterned systems on the molecular scale. It has been demonstrated that the simple binary arithmetic and logical operations can be computed by the process of self assembly of DNA tiles. Here we report a one-dimensional algorithmic self-assembly of DNA triple-crossover molecules that can be used to execute five steps of a logical NAND and NOR operations on a string of binary bits. To achieve this, abstract tiles were translated into DNA tiles based on triple-crossover motifs. Serving as input for the computation, long single stranded DNA molecules were used to nucleate growth of tiles into algorithmic crystals. Our method shows that engineered DNA self-assembly can be treated as a bottom-up design techniques, and can be capable of designing DNA computer organization and architecture.

  17. Integrating DNA strand-displacement circuitry with DNA tile self-assembly

    Science.gov (United States)

    Zhang, David Yu; Hariadi, Rizal F.; Choi, Harry M.T.; Winfree, Erik

    2013-01-01

    DNA nanotechnology has emerged as a reliable and programmable way of controlling matter at the nanoscale through the specificity of Watson–Crick base pairing, allowing both complex self-assembled structures with nanometer precision and complex reaction networks implementing digital and analog behaviors. Here we show how two well-developed frameworks, DNA tile self-assembly and DNA strand-displacement circuits, can be systematically integrated to provide programmable kinetic control of self-assembly. We demonstrate the triggered and catalytic isothermal self-assembly of DNA nanotubes over 10 μm long from precursor DNA double-crossover tiles activated by an upstream DNA catalyst network. Integrating more sophisticated control circuits and tile systems could enable precise spatial and temporal organization of dynamic molecular structures. PMID:23756381

  18. Self-assembly and headgroup effect in nanostructured organogels via cationic amphiphile-graphene oxide composites.

    Directory of Open Access Journals (Sweden)

    Tifeng Jiao

    Full Text Available Self-assembly of hierarchical graphene oxide (GO-based nanomaterials with novel functions has received a great deal of attentions. In this study, nanostructured organogels based on cationic amphiphile-GO composites were prepared. The gelation behaviors of amphiphile-GO composites in organic solvents can be regulated by changing the headgroups of amphiphiles. Ammonium substituted headgroup in molecular structures in present self-assembled composites is more favorable for the gelation in comparison to pyridinium headgroup. A possible mechanism for headgroup effects on self-assembly and as-prepared nanostructures is proposed. It is believed that the present amphiphile-GO self-assembled system will provide an alternative platform for the design of new GO nanomaterials and soft matters.

  19. Triptycene-terminated thiolate and selenolate monolayers on Au(111

    Directory of Open Access Journals (Sweden)

    Jinxuan Liu

    2017-04-01

    Full Text Available To study the implications of highly space-demanding organic moieties on the properties of self-assembled monolayers (SAMs, triptycyl thiolates and selenolates with and without methylene spacers on Au(111 surfaces were comprehensively studied using ultra-high vacuum infrared reflection absorption spectroscopy, X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy and thermal desorption spectroscopy. Due to packing effects, the molecules in all monolayers are substantially tilted. In the presence of a methylene spacer the tilt is slightly less pronounced. The selenolate monolayers exhibit smaller defect densities and therefore are more densely packed than their thiolate analogues. The Se–Au binding energy in the investigated SAMs was found to be higher than the S–Au binding energy.

  20. Ambient Surface Analysis of Organic Monolayers using Direct Analysis in Real Time Orbitrap Mass Spectrometry

    NARCIS (Netherlands)

    Manova, R.K.; Joshi, S.; Debrassi, A.; Bhairamadgi, N.S.; Roeven, E.; Gagnon, J.; Tahir, M.N.; Claassen, F.W.; Scheres, L.M.W.; Wennekes, T.; Schroën, C.G.P.H.; Beek, van T.A.; Zuilhof, H.; Nielen, M.W.F.

    2014-01-01

    A better characterization of nanometer-thick organic layers (monolayers) as used for engineering surface properties, biosensing, nanomedicine, and smart materials will widen their application. The aim of this study was to develop direct analysis in real time high-resolution mass spectrometry

  1. Visible-light attachment of Si-C linked functionalized organic monolayers on silicon surfaces

    NARCIS (Netherlands)

    Smet, de L.C.P.M.; Pukin, A.V.; Sun, Q.Y.; Eves, B.J.; Lopinski, G.P.; Visser, G.M.; Zuilhof, H.; Sudhölter, E.J.R.

    2005-01-01

    Organic monolayers on hydrogen-terminated silicon surfaces were prepared under extremely mild conditions using visible light and analyzed by a variety of surface-sensitive techniques: (angle-resolved) X-ray photoelectron spectroscopy (ARXPS), scanning tunneling microscopy (STM), high-resolution

  2. Selective Binding, Self-Assembly and Nanopatterning of the Creutz-Taube Ion on Surfaces

    Directory of Open Access Journals (Sweden)

    Qingling Hang

    2009-02-01

    Full Text Available The surface attachment properties of the Creutz-Taube ion, i.e., [(NH35Ru(pyrazineRu(NH35]5+, on both hydrophilic and hydrophobic types of surfaces were investigated using X-ray photoelectron spectroscopy (XPS. The results indicated that the Creutz-Taube ions only bound to hydrophilic surfaces, such as SiO2 and –OH terminated organic SAMs on gold substrates. No attachment of the ions on hydrophobic surfaces such as –CH3 terminated organic SAMs and poly(methylmethacrylate (PMMA thin films covered gold or SiO2 substrates was observed. Further ellipsometric, atomic force microscopy (AFM and time-dependent XPS studies suggested that the attached cations could form an inorganic analog of the self-assembled monolayer on SiO2 substrate with a “lying-down” orientation. The strong electrostatic interaction between the highly charged cations and the anionic SiO2 surface was believed to account for these observations. Based on its selective binding property, patterning of wide (~200 nm and narrow (~35 nm lines of the Creutz-Taube ions on SiO2 surface were demonstrated through PMMA electron resist masks written by electron beam lithography (EBL.

  3. Molecular self-assembly for biological investigations and nanoscale lithography

    Science.gov (United States)

    Cheunkar, Sarawut

    Small, diffusible molecules when recognized by their binding partners, such as proteins and antibodies, trigger enzymatic activity, cell communication, and immune response. Progress in analytical methods enabling detection, characterization, and visualization of biological dynamics at the molecular level will advance our exploration of complex biological systems. In this dissertation, analytical platforms were fabricated to capture membrane-associated receptors, which are essential proteins in cell signaling pathways. The neurotransmitter serotonin and its biological precursor were immobilized on gold substrates coated with self-assembled monolayers (SAMs) of oligo(ethylene glycol)alkanethiols and their reactive derivatives. The SAM-coated substrates present the biologically selective affinity of immobilized molecules to target native membrane-associated receptors. These substrates were also tested for biospecificity using antibodies. In addition, small-molecule-functionalized platforms, expressing neurotransmitter pharmacophores, were employed to examine kinetic interactions between G-protein-coupled receptors and their associated neurotransmitters. The binding interactions were monitored using a quartz crystal microbalance equipped with liquid-flow injection. The interaction kinetics of G-protein-coupled serotonin 1A receptor and 5-hydroxytyptophan-functionalized surfaces were studied in a real-time, label-free environment. Key binding parameters, such as equilibrium dissociation constants, binding rate constants, and dissociative half-life, were extracted. These parameters are critical for understanding and comparing biomolecular interactions in modern biomedical research. By integrating self-assembly, surface functionalization, and nanofabrication, small-molecule microarrays were created for high-throughput screening. A hybrid soft-lithography, called microcontact insertion printing, was used to pattern small molecules at the dilute scales necessary for highly

  4. Combustion and self-assembly of nanoenergetic materials

    Science.gov (United States)

    Malchi, Jonathan Yaniv

    The recent worldwide interest in nanotechnology spans a wide variety of scientific fields such as electronics, biology, materials science and medicine. Because of their extremely small dimensions, nanoparticles demonstrate properties different from matter at larger scales. Understanding these unusual properties and utilizing them for macroscale devices is an overall goal for nanotechnology. Moreover, manipulating these small particles into organized structures is crucial for taking full advantage of what nanotechnology has to offer, however it has proven to be a difficult task. Recent work utilizing electrostatic forces shows great potential for the self-assembly of nanoparticles into organized two-dimensional and three-dimensional structures. Overall, this work examines how nanotechnology and self-assembly can benefit the field of energetic materials. Because of aluminum's high energy density and low cost, it has been used in the field of energetic materials for several decades. In order to achieve sufficient energy release rates, aluminum is typically manufactured as a powder having spherical particles with diameters on the micron scale. It is well-known that decreasing the original particle diameter of a fuel particle will increase the burning time and, thus, energy release rate. Therefore, aluminum particles have recently been made to have diameters on the nanoscale, and shown to be advantageous for several applications. The combustion of nanoaluminum (nAl) in various systems is the primary focus of this study. A progression of experiments is used to analyze the combustion of nAl: (1) a fully heterogeneous flame spread system, (2) a semi-homogeneous sonicated thermite system and (3) a quasi-homogeneous self-assembled thermite system. The flame spread experiment physically separates the nAl from the gaseous oxidizer allowing for a well-understood convective, diffusive, reactive system to be analyzed. Because of the simplicity of the experimental setup, variables

  5. A Novel Strategy for Synthesis of Gold Nanoparticle Self Assemblies

    NARCIS (Netherlands)

    Verma, Jyoti; Lal, Sumit; van Veen, Henk A.; van Noorden, Cornelis J. F.

    2014-01-01

    Gold nanoparticle self assemblies are one-dimensional structures of gold nanoparticles. Gold nanoparticle self assemblies exhibit unique physical properties and find applications in the development of biosensors. Methodologies currently available for lab-scale and commercial synthesis of gold

  6. Dominant effects of first monolayer energetics at donor/acceptor interfaces on organic photovoltaics.

    Science.gov (United States)

    Izawa, Seiichiro; Nakano, Kyohei; Suzuki, Kaori; Hashimoto, Kazuhito; Tajima, Keisuke

    2015-05-20

    Energy levels of the first monolayer are manipulated at donor/acceptor interfaces in planar heterojunction organic photovoltaics by using molecular self-organization. A "cascade" energy landscape allows thermal-activation-free charge generation by photoirradiation, destabilizes the energy of the interfacial charge-transfer state, and suppresses bimolecular charge recombination, resulting in a higher open-circuit voltage and fill factor. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Amphiphilic building blocks for self-assembly: from amphiphiles to supra-amphiphiles.

    Science.gov (United States)

    Wang, Chao; Wang, Zhiqiang; Zhang, Xi

    2012-04-17

    The process of self-assembly spontaneously creates well-defined structures from various chemical building blocks. Self-assembly can include different levels of complexity: it can be as simple as the dimerization of two small building blocks driven by hydrogen bonding or as complicated as a cell membrane, a remarkable supramolecular architecture created by a bilayer of phospholipids embedded with functional proteins. The study of self-assembly in simple systems provides a fundamental understanding of the driving forces and cooperativity behind these processes. Once the rules are understood, these guidelines can facilitate the research of highly complex self-assembly processes. Among the various components for self-assembly, an amphiphilic molecule, which contains both hydrophilic and hydrophobic parts, forms one of the most powerful building blocks. When amphiphiles are dispersed in water, the hydrophilic component of the amphiphile preferentially interacts with the aqueous phase while the hydrophobic portion tends to reside in the air or in the nonpolar solvent. Therefore, the amphiphiles aggregate to form different molecular assemblies based on the repelling and coordinating forces between the hydrophilic and hydrophobic parts of the component molecules and the surrounding medium. In contrast to conventional amphiphiles, supra-amphiphiles are constructed on the basis of noncovalent interactions or dynamic covalent bonds. In supra-amphiphiles, the functional groups can be attached to the amphiphiles by noncovalent synthesis, greatly speeding their construction. The building blocks for supra-amphiphiles can be either small organic molecules or polymers. Advances in the development of supra-amphiphiles will not only enrich the family of conventional amphiphiles that are based on covalent bonds but will also provide a new kind of building block for the preparation of complex self-assemblies. When polymers are used to construct supra-amphiphiles, the resulting

  8. Programming protein self assembly with coiled coils

    Science.gov (United States)

    Dietz, Hendrik; Bornschlögl, Thomas; Heym, Roland; König, Frauke; Rief, Matthias

    2007-11-01

    The controlled assembly of protein domains into supramolecular structures will be an important prerequisite for the use of functional proteins in future nanotechnology applications. Coiled coils are multimerization motifs whose dimerization properties can be programmed by amino acid sequence. Here, we report programmed supramolecular self-assembly of protein molecules using coiled coils and directly demonstrate its potential on the single molecule level by AFM force spectroscopy. We flanked two different model proteins, Ig27 from human cardiac titin and green fluorescent protein (GFP), by coiled coil binding partners and studied the capability of these elementary building blocks to self-assemble into linear chains. Simple sterical constraints are shown to control the assembly process, providing evidence that many proteins can be assembled with this method. An application for this technique is the design of polyproteins for single molecule force spectroscopy with an integrated force-calibration standard.

  9. Ternary self-assemblies in water

    DEFF Research Database (Denmark)

    Hill, Leila R.; Blackburn, Octavia A.; Jones, Michael W.

    2013-01-01

    The self-assembly of higher order structures in water is realised by using the association of 1,3-biscarboxylates to binuclear meta-xylyl bridged DO3A complexes. Two dinicotinate binding sites are placed at a right-angle in a rhenium complex, which is shown to form a 1 : 2 complex with α,α'-bis(E......The self-assembly of higher order structures in water is realised by using the association of 1,3-biscarboxylates to binuclear meta-xylyl bridged DO3A complexes. Two dinicotinate binding sites are placed at a right-angle in a rhenium complex, which is shown to form a 1 : 2 complex with α...

  10. Self-assembling membranes and related methods thereof

    Science.gov (United States)

    Capito, Ramille M; Azevedo, Helena S; Stupp, Samuel L

    2013-08-20

    The present invention relates to self-assembling membranes. In particular, the present invention provides self-assembling membranes configured for securing and/or delivering bioactive agents. In some embodiments, the self-assembling membranes are used in the treatment of diseases, and related methods (e.g., diagnostic methods, research methods, drug screening).

  11. SUPPORTING INFORMATION Gold nanodots self-assembled ...

    Indian Academy of Sciences (India)

    VICHU

    Figure S1. Catalytic test reactions carried out for different AuNDs catalysts. Figure S2. Catalytic test reactions carried out for AuNDs prepared using different Au concentrations. Figure S3. AFM images of self-assembled AuNDs and bare PADA films. Figure S4. Recycle study of catalytic plate. Figure S5-S16. 1H and 13C NMR ...

  12. Preface: special topic on supramolecular self-assembly at surfaces.

    Science.gov (United States)

    Bartels, Ludwig; Ernst, Karl-Heinz; Gao, Hong-Jun; Thiel, Patricia A

    2015-03-14

    Supramolecular self-assembly at surfaces is one of the most exciting and active fields in Surface Science today. Applications can take advantage of two key properties: (i) versatile pattern formation over a broad length scale and (ii) tunability of electronic structure and transport properties, as well as frontier orbital alignment. It provides a new frontier for Chemical Physics as it uniquely combines the versatility of Organic Synthesis and the Physics of Interfaces. The Journal of Chemical Physics is pleased to publish this Special Topic Issue, showcasing recent advances and new directions.

  13. Biomimetic self-assembly of a functional asymmetrical electronic device.

    Science.gov (United States)

    Boncheva, Mila; Gracias, David H; Jacobs, Heiko O; Whitesides, George M

    2002-04-16

    This paper introduces a biomimetic strategy for the fabrication of asymmetrical, three-dimensional electronic devices modeled on the folding of a chain of polypeptide structural motifs into a globular protein. Millimeter-size polyhedra-patterned with logic devices, wires, and solder dots-were connected in a linear string by using flexible wire. On self-assembly, the string folded spontaneously into two domains: one functioned as a ring oscillator, and the other one as a shift register. This example demonstrates that biomimetic principles of design and self-organization can be applied to generate multifunctional electronic systems of complex, three-dimensional architecture.

  14. Self-assembly of polar food lipids.

    Science.gov (United States)

    Leser, Martin E; Sagalowicz, Laurent; Michel, Martin; Watzke, Heribert J

    2006-11-16

    Polar lipids, such as monoglycerides and phospholipids, are amphiphilic molecules commonly used as processing and stabilization aids in the manufacturing of food products. As all amphiphilic molecules (surfactants, emulsifiers) they show self-assembly phenomena when added into water above a certain concentration (the critical aggregation concentration). The variety of self-assembly structures that can be formed by polar food lipids is as rich as it is for synthetic surfactants: micelles (normal and reverse micelles), microemulsions, and liquid crystalline phases can be formulated using food-grade ingredients. In the present work we will first discuss microemulsion and liquid crystalline phase formation from ingredients commonly used in food industry. In the last section we will focus on three different potential application fields, namely (i) solubilization of poorly water soluble ingredients, (ii) controlled release, and (iii) chemical reactivity. We will show how the interfacial area present in self-assembly structures can be used for (i) the delivery of functional molecules, (ii) controlling the release of functional molecules, and (iii) modulating the chemical reactivity between reactive molecules, such as aromas.

  15. A self-assembled nanocarrier loading teniposide improves the oral delivery and drug concentration in tumor.

    Science.gov (United States)

    Zhang, Zhiwen; Ma, Li; Jiang, Shijun; Liu, Zeying; Huang, Jian; Chen, Lingli; Yu, Haijun; Li, Yaping

    2013-02-28

    We attempted to improve the oral delivery of lipophilic teniposide to achieve higher drug concentration in tumor by self-assembled nanocarrier for further oral chemotherapy. The teniposide loaded self-assembled nanocarrier (TSN) was spherical nanometric particles with narrow size distribution. The intestinal absorption of teniposide from TSN was obviously improved 4.09- and 6.35-fold in duodenum and jejunum at 0.5h after oral administration, then significantly decreased with the prolongation of time. The cellular uptake of TSN in Caco-2 cell monolayer was significantly enhanced over 3 folds and increased with incubation time. Moreover, TSN could be internalized into Caco-2 cell monolayer through clathrin-mediated endocytosis pathway, and then mainly transported into the systemic circulation via portal vein and intestinal lymphatic pathway. The pharmacokinetic results indicated that the AUC(0-t) value of TSN in rats was significantly improved 5.41-fold than that of teniposide solution, moreover, the teniposide concentration in tumor from TSN was obviously improved over 7-fold in tumor bearing mice. The captured image indicated that the oral administered TSN could specifically accumulate in tumor in the xenograft model. Therefore, the self-assembled nanocarrier was promising to enhance the oral delivery of lipophilic teniposide and its concentration in tumor for oral chemotherapy. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. A facile and general preparation of high-performance noble-metal-based free-standing nanomembranes by a reagentless interfacial self-assembly strategy

    Science.gov (United States)

    Wu, Haoxi; He, Haili; Zhai, Yujuan; Li, Haijuan; Lai, Jianping; Jin, Yongdong

    2012-10-01

    As a simple and flexible 2D platform, the water-air interface is envisioned as an environmentally-friendly approach to prepare ultrathin free-standing nanomembranes (FNMs) of monolayered nanoparticles of interest via interfacial self-assembly. However, attempts so far have been rather rare due to the lack of efficient methods. In this article, we report on a facile and general strategy for fabrication of a family of noble metal-based FNMs by a simple and reagentless interfacial self-assembly tactics to prepare functional (plasmonic or catalytic) FNMs, such as Au, Ag, Pd, Pt-FNMs and their bimetallic hybrids, Ag/Au-FNMs and Pd/Pt-FNMs. The organic solvent-free process, varying somewhat from metal to metal only in precursors, reducing agents and dosage of reagents used, is found to be a general phenomenon and ligand-independent (irrespective of the monolayer quality of the resulting FNMs), allowing the growth of high-quality noble metal-based FNMs with well-defined nanoparticulate and monolayer morphology as large as several square centimeters. Heat treatment (boiling) is performed to accelerate the formation of FNMs within 15 min. More significantly, the as-prepared plasmonic Au-FNMs acting as a SERS substrate show a superior activity; whereas the resulting catalytic Pd-FNMs, except for their excellent ethanol electrooxidation performance, exhibit higher electrocatalytic activity for formic acid oxidation than commercial catalysts.As a simple and flexible 2D platform, the water-air interface is envisioned as an environmentally-friendly approach to prepare ultrathin free-standing nanomembranes (FNMs) of monolayered nanoparticles of interest via interfacial self-assembly. However, attempts so far have been rather rare due to the lack of efficient methods. In this article, we report on a facile and general strategy for fabrication of a family of noble metal-based FNMs by a simple and reagentless interfacial self-assembly tactics to prepare functional (plasmonic or

  17. Electrochemically controlled self-assembly of block copolymer nanostructures

    Science.gov (United States)

    Eitouni, Hany Basam

    Organometallic block copolymers, wherein one block is composed of alternating ferrocene and dialkylsilane units in the main chain, undergo self-assembly to form microphase-separated ordered structures similarly to typical organic block copolymers. The 1,1'-dimethylsilylferrocenophane monomer was synthesized and polymerized anionically with other monomers to make a variety of different organometallic block copolymers. The phase behavior and thermodynamic interactions of anionically synthesized poly(styrene-block-ferrocenyldimethylsilane) (SF) and poly(isoprene-block-ferrocenyldimethylsilane) (IF) copolymers were examined using depolarized light scattering, small angle x-ray and neutron scattering (SAXS and SANS), and transmission electron microscopy. The temperature-dependence of the Flory-Huggins parameter, chi, and the statistical segment lengths of SF and IF copolymers were determined by SAXS and SANS using the random phase approximation. The thermodynamic interactions in poly(ferrocenyldimethylsilane) diblock copolymers were systematically adjusted by oxidizing the ferrocene moieties with silver salts and examined using SAXS and depolarized light scattering. The polymers retained microphase separated ordered structures upon oxidation and showed systematic changes in the location of the order-disorder transition as a function of extent of oxidation. By controlling the redox properties of the ferrocene moiety in the backbone of the polymer, we present a method for controlling the self-assembled microstructure and hence bulk material properties. Using electrochemical techniques, a novel means of controlling the order-disorder transition of block copolymers was discovered. By applying very small electrical potentials to disordered solutions of organometallic block copolymers, oriented ordered grains were formed near one electrode, the result of electrochemical reactions. After reversing the electrical bias on the system, the ordered grains disappeared and new

  18. DNA self-assembly-driven positioning of molecular components on nanopatterned surfaces

    Science.gov (United States)

    Szymonik, M.; Davies, A. G.; Wälti, C.

    2016-09-01

    We present a method for the specific, spatially targeted attachment of DNA molecules to lithographically patterned gold surfaces—demonstrated by bridging DNA strands across nanogap electrode structures. An alkanethiol self-assembled monolayer was employed as a molecular resist, which could be selectively removed via electrochemical desorption, allowing the binding of thiolated DNA anchoring oligonucleotides to each electrode. After introducing a bridging DNA molecule with single-stranded ends complementary to the electrode-tethered anchoring oligonucleotides, the positioning of the DNA molecule across the electrode gap, driven by self-assembly, occurred autonomously. This demonstrates control of molecule positioning with resolution limited only by the underlying patterned structure, does not require any alignment, is carried out entirely under biologically compatible conditions, and is scalable.

  19. Products and Kinetics of the Reactions of an Alkane Monolayer and a Terminal Alkene Monolayer with NO₃ Radicals

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Simone; Bertram, Allan K.

    2009-01-27

    The reactions of an alkanethiol and a terminal alkenethiol self-assembled monolayer with NO₃ radicals (in the presence of NO₂ and O₂) were studied. For the alkane monolayer, infrared (IR) spectroscopy and time-of-flight secondary ion mass spectrometry (ToF-SIMS) confirmed the formation of organonitrates (RONO₂). The observation of organonitrates is in contrast to the recent X-ray photoelectron spectroscopy (XPS) data, which showed very little nitrogen-containing surface species. The identification of organonitrates may help explain why significant volatilization of the organic chain was not observed in recent studies of alkane monolayer oxidation by NO₃ radicals. The reactive uptake coefficient (g) of NO₃ on alkene monolayers determined in our study is higher than the values obtained in a recent study using liquid and solid alkene bulk films. A possible reason for this difference may be the location of the double bond at the interface. Using the g value determined in our studies, we show that under conditions where NO₃ is high the lifetime of an alkene monolayer in the atmosphere may be short (approximately 20 min). XPS, IR, and ToF-SIMS were used to identify surface functional groups after the oxidation of the alkene monolayers by NO₃. The results are consistent with the formation of C-O, aldehyde/ketone, carboxylic groups, and nitrogen containing species.

  20. Designing self-assembling 3D structures of microcapsules

    Science.gov (United States)

    Li, Like; Shum, Henry; Shklyaev, Oleg; Yashin, Victor; Balazs, Anna

    Self-assembly of complex, three-dimensional structures is commonly achieved by biological cells but difficult to realize in synthetic systems with micron-scale or larger components. Some previous modeling studies have considered only the planar self-assembly of microcapsules on a substrate. In this work, nanoparticles released from the capsules bind to the substrate and to the shells of nearby capsules. The non-uniform nanoparticle deposition on a capsule's surface leads to adhesion gradients, which drive the capsules to effectively ``climb'' on top of one another and self-organize in the vertical direction. We determine conditions that favor this structural organization. In particular, we study how the vertical structuring depends on the background fluid flow, the topography of the microcapsules and the underlying surface, the capsule-capsule interaction and that between the capsules and the substrate. The findings can provide design rules for the autonomous creation of novel nanocomposites, where the layers are formed from nanoparticle-containing and nanoparticle-decorated microcapsules.