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electron transfer

Thomas P Senftle, Emily A Carter
Knowledge of a semiconductor electrode's band edge alignment is essential for optimizing processes that occur at the semiconductor/electrolyte interface. Photocatalytic processes are particularly sensitive to such alignments, as they govern the transfer of photo-excited electrons or holes from the surface to reactants in the electrolyte solution. Reconstructions of a semiconductor surface during operation, as well as its interaction with the electrolyte solution, must be considered when determining band edge alignment...
May 25, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Soonjae Pyo, Wondo Kim, Han-Il Jung, Jungwook Choi, Jongbaeg Kim
Low-dimensional carbon materials, such as semiconducting carbon nanotubes (CNTs), conducting graphene, and their hybrids, are of great interest as promising candidates for flexible, foldable, and transparent electronics. However, the development of highly photoresponsive, flexible, and transparent optoelectronics still remains limited due to their low absorbance and fast recombination rate of photoexcited charges, despite the considerable potential of photodetectors for future wearable and foldable devices...
May 24, 2017: Small
Li Chen, Wei-Lin Chen, Jian-Ping Li, Jia-Bo Wang, En-Bo Wang
The serious electron recombination occurring in TiO2/quantum dot sensitizer/electrolyte interface is the key reason for hindering the further efficiency improvement of QDSCs. Polyoxometalate(POM) can be as electron transfer media to decreasing electron recombination of photoelectric device, which is due to the excellent oxidation reduction properties and thermostability. So in this paper, POM/TiO2 electronic interface layer prepared by a simple layer-by-layer self-assembly method is added between FTO and mesoporous TiO2 in the photoanode of the QDSCs, and their effects on the photovoltaic performance are systematically investigated...
May 23, 2017: ChemSusChem
Yusuke Chiba, Maning Liu, Yasuhiro Tachibana, Tetsuaki Fujihara, Yasushi Tsuji, Jun Terao
We successfully synthesized a hetero face-to-face porphyrin array composed of ZnTPP and RuTPP(DABCO)₂ (TPP: 5,10,15,20-tetraphenylporphyrin, DABCO: 1,4-diazabi-cyclo[2.2.2]octane) in 2:1 molar ratio. A cyclic Zn porphyrin dimer (ZnCP) was also used as the host molecule for the Ru porphyrin. In the latter, the Ru-DABCO bonding in RuTPP(DABCO)₂ was stabilized by the host-guest complexation. Reaction progress kinetic analysis of the ligand substitution reaction of RuTPP(DABCO)₂ and that in ZnCP revealed the stabilization mechanism of the Ru-DABCO bonding...
May 22, 2017: Chemistry, An Asian Journal
Laurent Bouffier, Stéphane Reculusa, Valérie Ravaine, Alexander Kuhn
A new simple and versatile method for the preparation of surface wetting gradients is proposed. It is based on the combination of electrode surface structuration introduced by a sacrificial template approach and the formation of a tuneable molecular gradient by bipolar electrochemistry. The gradient involves the formation of a self-assembled monolayer on gold surface by selecting an appropriate thiol molecule and the subsequent reductive desorption by means of bipolar electrochemistry. Under these conditions, the completion of the reductive desorption process evolves along the bipolar surface with a maximum strength localized at the cathodic edge and a decreasing driving force toward the middle of the surface...
May 22, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Indrajit Ghosh, Rizwan S Shaikh, Burkhard König
Photosynthetic organisms exploit antenna chromophores to absorb light and transfer excitation energy to the reaction center where redox reactions occur. In contrast, in visible-light chemical photoredox catalysis, a single species (i.e., the photoredox catalyst) absorbs light and performs the redox chemistry. Mimicking the energy flow of the biological model, we report a two-center photoredox catalytic approach in which the tasks of light energy collection and electron transfer (i.e., redox reactions) are assigned to two different molecules...
May 24, 2017: Angewandte Chemie
Jinqiang Zhang, Bing Sun, Yufei Zhao, Katja Kretschmer, Guoxiu Wang
Large over-potentials owing to the sluggish kinetics of battery reactions have always been the drawbacks of Li-O2 batteries, which lead to short cycle life. Although redox mediators have been intensively investigated to overcome this issue, side-reactions are generally induced by the solvated nature of redox mediators. Herein, we report an alternative method to achieve more efficient utilization of tetrathiafulvalene (TTF) in Li-O2 batteries. By coordinating TTF(+) with LiCl during charging, an organic conductor TTF(+) Clx(-) precipitate covers Li2 O2 to provide an additional electron-transfer pathway on the surface, which can significantly reduce the charge over-potential, improve the energy efficiency of Li-O2 batteries, and eliminate side-reactions between the lithium metal anode and TTF(+) ...
May 23, 2017: Angewandte Chemie
Andrea Mulas, Xiaoyan He, Yves-Marie Hervault, Lucie Norel, Stéphane Rigaut, Corinne Lagrost
Two carbon-rich ruthenium complexes bearing a dithienylethene (DTE) unit and a hexylthiol spacer were designed to be attached on gold surfaces. Both compounds display photochemically-driven switching properties, allowing reversible conversion from open to closed forms of the DTE units upon irradiation in solution. In contrast, only the bimetallic complex undergoes an efficient electrochemical ring closure at low potential, (0.5 V vs SCE), whereas the monometallic complex show a simple one electron reversible redox event...
May 22, 2017: Chemistry: a European Journal
Sahng Ha Lee, Da Som Choi, Milja Pesic, Yang Woo, Caroline Paul, Frank Hollmann, Chan Beum Park
Enoate reductases from the family of Old Yellow Enzymes (OYEs) can catalyze stereoselective trans-hydrogenation of activated C=C bonds. Here, we report visible light-driven activation of OYEs through NAD(P)H-free, direct transfer of photoexcited electrons from xanthene dyes to the prosthetic flavin moiety. Our spectroscopic and electrochemical analyses verified spontaneous association of rose bengal and its derivatives with OYEs. Illumination of a white light-emitting-diode triggered photoreduction of OYEs by xanthene dyes, which facilitated the enantioselective reduction of C=C bonds in the absence of NADH...
May 23, 2017: Angewandte Chemie
Ariel R Levy, Meital Turgeman, Lada Gevorkyan-Aiapetov, Sharon Ruthstein
Metallochaperones are responsible for shuttling metal ions to target proteins. Thus, a metallochaperone's structure must be sufficiently flexible both to hold onto its ion while traversing the cytoplasm and to transfer the ion to or from a partner protein. Here, we sought to shed light on the structure of Atox1, a metallochaperone involved in the human copper regulation system. Atox1 shuttles copper ions from the main copper transporter, Ctr1, to the ATP7b transporter in the Golgi apparatus. Conventional biophysical tools such as X-ray or NMR cannot always target the various conformational states of metallochaperones, owing to a requirement for crystallography or low sensitivity and resolution...
May 20, 2017: Protein Science: a Publication of the Protein Society
John M Kelly, Paraic Keane, James Hall, Fergus Poynton, Bjorn Poulsen, Sarah Gurung, Ian Clark, Igor Sazanovich, Michael Towrie, Thorfinnur Gunnlaugsson, Susan Quinn, Christine Cardin
Key to the development of DNA-targeting phototherapeutic drugs is determining the interplay between the photoactivity of the drug and its binding preference for a target sequence. For the photo-oxidising lambda-[Ru(TAP)2(dppz)]2+ (Ʌ-1) complex bound to either d{T1C2G3G4C5G6C7C8G9A10}2 (G9) or d{TCGGCGCCIA}2 (I9), the X-ray crystal structures shows the dppz intercalated at the terminal T1C2;G9A10 step or T1C2;I9A10 step. Thus substitution of the G9 nucleobase by inosine does not affect intercalation in the solid state although with I9 the dppz is more deeply inserted...
May 25, 2017: Chemistry: a European Journal
Anne-Catherine Heuskin, Bernard Gallez, Olivier Feron, Philippe Martinive, Carine Michiels, Stéphane Lucas
PURPOSE: To identify which physical properties of nanoparticles are correlated to the survival fraction of cells exposed in vitro to low energy protons in combination with nanoparticles. METHODS: The Geant4 simulation toolkit (version 10.3) was used to model nanoparticles of different sizes (5 to 50 nm) and materials (Ti, Zr, Hf, Ta, Au, Pt), with or without an organic capping ensuring biocompatibility and to irradiate them with 1.3 or 4 MeV protons and 5.3 MeV alpha particles...
May 23, 2017: Medical Physics
Hiraku Ohno, Kazuki Takeda, Satomi Niwa, Tomotaka Tsujinaka, Yuya Hanazono, Yu Hirano, Kunio Miki
High-potential iron-sulfur protein (HiPIP) is a soluble electron carrier protein of photosynthetic bacteria with an Fe4S4 cluster. Although structural changes accompanying the electron transfer are important for understanding of the functional mechanism, the changes have not been clarified in sufficient detail. We previously reported the high-resolution crystal structures of HiPIP from a thermophilic purple bacterium Thermochromatium tepidum in the reduced state. In order to perform a detailed comparison between the structures in different redox states, the oxidized structure should also be revealed at high resolution...
2017: PloS One
Jorge Dagnino-Leone, Maximiliano Figueroa, Claudia Mella, María Alejandra Vorphal, Frédéric Kerff, Aleikar José Vásquez, Marta Bunster, José Martínez-Oyanedel
Phycobilisomes (PBS) are accessory light harvesting protein complexes that directionally transfer energy towards photosystems. Phycobilisomes are organized in a central core and rods radiating from it. Components of phycobilisomes in Gracilaria chilensis (Gch) are Phycobiliproteins (PBPs), Phycoerythrin (PE), and Phycocyanin (PC) in the rods, while Allophycocyanin (APC) is found in the core, and linker proteins (L). The function of such complexes depends on the structure of each component and their interaction...
2017: PloS One
Manuel P Luitz, Anders Barth, Alvaro H Crevenna, Rainer Bomblies, Don C Lamb, Martin Zacharias
Fluorescence spectroscopy techniques like Förster resonance energy transfer (FRET) and fluorescence correlation spectroscopy (FCS) have become important tools for the in vitro and in vivo investigation of conformational dynamics in biomolecules. These methods rely on the distance-dependent quenching of the fluorescence signal of a donor fluorophore either by a fluorescent acceptor fluorophore (FRET) or a non-fluorescent quencher, as used in FCS with photoinduced electron transfer (PET). The attachment of fluorophores to the molecule of interest can potentially alter the molecular properties and may affect the relevant conformational states and dynamics especially of flexible biomolecules like intrinsically disordered proteins (IDP)...
2017: PloS One
Ying Liu, Yinlian Zhu, Yunlong Tang, Yujia Wang, Yixiao Jiang, Yaobin Xu, Bin Zhang, Xiuliang Ma
Ferroelectrics hold promise for sensors, transducers, and telecommunications. With the demand of electronic devices scaling down, they take the form of nanoscale films. However, the polarizations in ultrathin ferroelectric films are usually reduced dramatically due to the depolarization field caused by incomplete charge screening at interfaces, hampering the integrations of ferroelectrics into electric devices. Here, we design and fabricate a ferroelectric/multiferroic BiFeO3/PbTiO3 system, which exhibits discontinuities in both chemical valence and ferroelectric polarization across the interface...
May 25, 2017: Nano Letters
Junlin Jiang, Amani A Alsam, Shanshan Wang, Shawkat M Aly, Zhenxing Pan, Omar F Mohammed, Kirk S Schanze
A series of -conjugated oligomer-acceptor dyads were synthesized that feature oligo(phenylene ethynylene) (OPE) conjugated backbones end-capped with a naphthalene diimide (NDI) acceptor. The OPE segments vary in length from 4 to 8 phenylene ethynene units (PEn-NDI, where n = 4, 6 and 8). Fluorescence and transient absorption spectroscopy reveals that intramolecular OPE NDI charge transfer dominates the deactivation of excited states of the PEn-NDI oligomers. Both charge separation (CS) and charge recombination (CR) are strongly exothermic (G0CS ~ -1...
May 25, 2017: Journal of Physical Chemistry. A
Michael Hollerer, Daniel Lüftner, Philipp Hurdax, Thomas Ules, Serguei Soubatch, Frank Stefan Tautz, Georg Koller, Peter Puschnig, Martin Sterrer, Michael G Ramsey
It is becoming accepted that ultra-thin dielectric layers on metals are not merely passive decoupling layers, but can actively influence orbital energy level alignment and charge transfer at interfaces. As such, they can be important in applications ranging from catalysis to organic electronics. However, the details at the molecular level are still under debate. In this study, we present a comprehensive analysis of the phenomenon of charge transfer promoted by a dielectric interlayer with a comparative study of pentacene adsorbed on Ag(001) with and without an ultra-thin MgO interlayer...
May 25, 2017: ACS Nano
Seungjin Park, Jun Hui Park, Seongpil Hwang, Juhyoun Kwak
A programmable electrochemical rectifier based on thin-layer electrochemistry is described here. Both the rectification ratio and the response time of the device are programmable by controlling the gap distance of the thin-layer electrochemical cell, which is easily controlled using commercially available beads. One of the electrodes was modified using a ferrocene-terminated self-assembled monolayer (SAM) to offer unidirectional charge transfers via soluble redox species. The thin-layer configuration provided enhanced mass transport, which was determined by the gap thickness...
May 25, 2017: ACS Applied Materials & Interfaces
S A Khan, B Amin, Li-Yong Gan, Iftikhar Ahmad
The structural, electronic, and photocatalytic properties of two-dimensional Ti2CO2, Zr2CO2, and Hf2CO2 MXenes were investigated by first-principles (PBE and hybrid) calculations. Transition from an indirect to a direct band gap was achieved for the biaxial tensile strain of 3% for Ti2CO2, 8% for Zr2CO2, and 13% for Hf2CO2 while the nature of the band gap remained indirect in the case of the compressive strain. The size of the band gap passed through a maximum under tensile strain and decreased monotonically under compressive strain...
May 25, 2017: Physical Chemistry Chemical Physics: PCCP
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