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1.
Sebastian Preiß Ayla Päpcke Lukas Burkhardt Luca Großmann Prof. Dr. Stefan Lochbrunner Prof. Dr. Matthias Bauer Prof. Dr. Till Opatz Prof. Dr. Katja Heinze 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(23):5940-5949
In the context of solar-to-chemical energy conversion, inspired by natural photosynthesis, the synthesis, electrochemical properties and photoinduced electron-transfer processes of three novel zinc(II)-gold(III) bis(porphyrin) dyads [ZnII(P)–AuIII(P)]+ are presented (P: tetraaryl porphyrin). Time-resolved spectroscopic studies indicated ultrafast dynamics (k >1010 s−1) after visible-light excitation, which finally yielded a charge-shifted state [ZnII(P ⋅ +)–AuII(P)]+ featuring a gold(II) center. The lifetime of this excited state is quite long due to a comparably slow charge recombination (k ≈3×108 s−1). The [ZnII(P ⋅ +)–AuII(P)]+ charge-shifted state is reductively quenched by amines in bimolecular reactions, yielding the neutral zinc(II)–gold(II) bis(porphyrin) ZnII(P)–AuII(P). The electronic nature of this key gold(II) intermediate, prepared by chemical or photochemical reduction, is elucidated by UV/Vis, X-band EPR, gold L3-edge X-ray absorption near edge structure (XANES) and paramagnetic 1H NMR spectroscopy as well as by quantum chemical calculations. Finally, the gold(II) site in ZnII(P)–AuII(P) is thermodynamically and kinetically competent to reduce an aryl azide to the corresponding aryl amine, paving the way to catalytic applications of gold(III) porphyrins in photoredox catalysis involving the gold(III/II) redox couple. 相似文献
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Shannon J. Lee Juyeon Won Dr. Lin-Lin Wang Dr. Dapeng Jing Colin P. Harmer Dr. Justin Mark Dr. Georgiy Akopov Prof. Kirill Kovnir 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(26):7383-7390
Three novel isostructural equiatomic gold tetrel pnictides, AuSiAs, AuGeP, and AuGeAs, were synthesized and characterized. These phases crystallize in the noncentrosymmetric (NCS) monoclinic space group Cc (no. 9), featuring square-planar Au within cis-[AuTt2Pn2] units (Tt=tetrel, Si, Ge; Pn=pnictogen, P, As). This is in drastic contrast to the structure of previously reported AuSiP, which exhibits typical linear coordination of Au with Si and P. Chemical bonding analysis through the electron localization function suggests covalent two-center two-electron Tt−Pn bonds, and three-center Au−Tt−Au and Au−Pn−Au bonds with 1.6 e− per bond. X-ray photoelectron spectroscopy studies support the covalent and nonionic nature of Au−Pn and Au−Tt bonds. The title materials were found to be n-type narrow-gap semiconductors or semimetals, with nearly temperature-independent electrical resistivities and low thermal conductivities. A combination of the semimetallic properties with tunable NCS structure provides opportunities for the development of materials based on gold tetrel pnictides. 相似文献
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Timothy R. Corkish Christian T. Haakansson Peter D. Watson Prof. Allan J. McKinley Dr. Duncan A. Wild 《Chemphyschem》2021,22(1):69-75
A combined experimental and theoretical approach has been used to investigate X−⋅⋅⋅CH2O (X=F, Cl, Br, I) complexes in the gas phase. Photoelectron spectroscopy, in tandem with time-of-flight mass spectrometry, has been used to determine electron binding energies for the Cl−⋅⋅⋅CH2O, Br−⋅⋅⋅CH2O, and I−⋅⋅⋅CH2O species. Additionally, high-level CCSD(T) calculations found a C2v minimum for these three anion complexes, with predicted electron detachment energies in excellent agreement with the experimental photoelectron spectra. F−⋅⋅⋅CH2O was also studied theoretically, with a Cs hydrogen-bonded complex found to be the global minimum. Calculations extended to neutral X⋅⋅⋅CH2O complexes, with the results of potential interest to atmospheric CH2O chemistry. 相似文献
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Jaya Mehara Adarsh Koovakattil Surendran Teun van Wieringen Deeksha Setia Dr. Cina Foroutan-Nejad Dr. Michal Straka Prof. Dr. Lubomír Rulíšek Prof. Dr. Jana Roithová 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(60):e202201794
Gold(II) complexes are rare, and their application to the catalysis of chemical transformations is underexplored. The reason is their easy oxidation or reduction to more stable gold(III) or gold(I) complexes, respectively. We explored the thermodynamics of the formation of [AuII(L)(X)]+ complexes (L=ligand, X=halogen) from the corresponding gold(III) precursors and investigated their stability and spectral properties in the IR and visible range in the gas phase. The results show that the best ancillary ligands L for stabilizing gaseous [AuII(L)(X)]+ complexes are bidentate and tridentate ligands with nitrogen donor atoms. The electronic structure and spectral properties of the investigated gold(II) complexes were correlated with quantum chemical calculations. The results show that the molecular and electronic structure of the gold(II) complexes as well as their spectroscopic properties are very similar to those of analogous stable copper(II) complexes. 相似文献
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Rapid one-step synthesis, characterization and functionalization of silica coated gold nanoparticles
Newaz Mohammed Bahadur Shun WatanabeTakeshi Furusawa Masahide Sato Fumio KurayamaIqbal Ahmed Siddiquey Yoshio KobayashiNoboru Suzuki 《Colloids and surfaces. A, Physicochemical and engineering aspects》2011,392(1):137-144
This paper describes a rapid, simple and one-step method for preparing silica coated gold (Au@SiO2) nanoparticles with fine tunable silica shell thickness and surface functionalization of the prepared particles with different groups. Monodispersed Au nanoparticles with a mean particle size of 16 nm were prepared by citrate reduction method. Silica coating was carried out by mixing the as prepared Au solution, tetraethoxysilane (TEOS) and ammonia followed by microwave (MW) irradiation. Although there are several ways of coating Au nanoparticles with silica in the literature, each of these needs pre-coating step as well as long reaction duration. The present method is especially useful for giving the opportunity to cover the colloidal Au particles with uniform silica shell within very short time and forgoes the use of a silane coupling agent or pre-coating step before silica coating. Au@SiO2 nanoparticles with wide range of silica shell thickness (5-105 nm) were prepared within 5 min of MW irradiation by changing the concentration of TEOS only. The size uniformity and monodispersity were found to be better compared to the particles prepared by conventional methods, which were confirmed by dynamic light scattering and transmission electron microscopic techniques. The prepared Au@SiO2 nanoparticles were further functionalized with amino, carboxylate, alkyl groups to facilitate the rapid translation of the nanoparticles to a wide range of end applications. The functional groups were identified by XPS, and zeta potential measurements. 相似文献
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Felix Duensing Elisabeth Gruber Paul Martini Marcelo Goulart Michael Gatchell Bilal Rasul Olof Echt Fabio Zappa Masoomeh Mahmoodi-Darian Paul Scheier 《Molecules (Basel, Switzerland)》2021,26(12)
Complexes of atomic gold with a variety of ligands have been formed by passing helium nanodroplets (HNDs) through two pickup cells containing gold vapor and the vapor of another dopant, namely a rare gas, a diatomic molecule (H2, N2, O2, I2, P2), or various polyatomic molecules (H2O, CO2, SF6, C6H6, adamantane, imidazole, dicyclopentadiene, and fullerene). The doped HNDs were irradiated by electrons; ensuing cations were identified in a high-resolution mass spectrometer. Anions were detected for benzene, dicyclopentadiene, and fullerene. For most ligands L, the abundance distribution of AuLn+ versus size n displays a remarkable enhancement at n = 2. The propensity towards bis-ligand formation is attributed to the formation of covalent bonds in Au+L2 which adopt a dumbbell structure, L-Au+-L, as previously found for L = Xe and C60. Another interesting observation is the effect of gold on the degree of ionization-induced intramolecular fragmentation. For most systems gold enhances the fragmentation, i.e., intramolecular fragmentation in AuLn+ is larger than in pure Ln+. Hydrogen, on the other hand, behaves differently, as intramolecular fragmentation in Au(H2)n+ is weaker than in pure (H2)n+ by an order of magnitude. 相似文献
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Organic Semiconductor/Gold Interface Interactions: From Physisorption on Planar Surfaces to Chemical Reactions with Metal Nanoparticles 下载免费PDF全文
Giovanni Ligorio Dr. Marco Vittorio Nardi Christos Christodoulou Prof. Dr. Norbert Koch 《Chemphyschem》2015,16(12):2602-2608
The interaction of gold nanoparticles (AuNPs) with prototypical organic semiconductors used in optoelectronics, namely, tris(8‐hydroxyquinoline)aluminium (Alq3) and 4,4‐bis[N‐(1‐naphthyl)‐N‐phenylamino]diphenyl (α‐NPD), is investigated in situ by X‐ray photoelectron spectroscopy (XPS). These AuNPs‐on‐molecule experiments are compared with the reversed molecule‐on‐Au cases. The molecules‐on‐Au systems show only weak interactions, and the evolution of the XP spectra is dominated by final‐state effects. In contrast, in the AuNPs‐on‐molecules cases, both initial‐state effects and final‐state effects occur. Spectral features arising for both molecules and metal indicate charge transfer and the formation of organometallic complexes (initial‐state effects). The energy shift in the metal emission underlines the size‐induced nanometric nature of the molecule/Au interaction (final‐state effects). Consequently, the chemical interaction between metals and organic semiconductors likely depends strongly on the deposition sequence in general. 相似文献
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Prof. Dr. Han Myoung Lee Prof. Dr. Kwang S. Kim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(41):13203-13207
Since gold clusters have mostly been studied theoretically by using DFT calculations, more accurate studies are of importance. Thus, small neutral and anionic gold clusters (Aun and Aun?, n=4–7) were investigated by means of coupled cluster with singles, doubles, and perturbative triple excitations [CCSD(T)] calculations with large basis sets, and some differences between DFT and CCSD(T) results are discussed. Interesting isomeric structures that have dangling atoms were obtained. Structures having dangling atoms appear to be stable up to n=4 for neutral gold clusters and up to n=7 for anionic clusters. The relative stabilities and electronic properties of some isomers and major structures are discussed on the basis of the CCSD(T) calculations. This accurate structure prediction of small gold clusters corresponding to experimental photoelectron spectral peaks is valuable in the field of atom‐scale materials science including nanocatalysts. 相似文献
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《Surface and interface analysis : SIA》2004,36(7):640-644
The chemical composition variation of silicon under 4 keV O2+ ion beam bombardment at different incident angles was studied by in situ small‐area XPS. The changes in secondary ion profile (30Si+, 44SiO+, 56Si2+, 60SiO2+) during oxygen ion beam bombardment also have been monitored. We present a direct correlation of the changes in secondary ion depth profile with surface composition during sputtering. Evolution of the secondary ion profile obtained from SIMS shows similar trends with variation of oxygen concentration in the crater surface measured by XPS. It is shown that when the oxygen ion beam incidence angle is < 40° silicon dioxide is the dominant species on the crater surface and the matrix ion species ratio (MISR) value for 44SiO+/56Si2+ is higher than for 30Si+/56Si2+. For incidence angles of >40°, the formation of sub‐oxide is favoured and thus the MISR value for 44SiO+/56Si2+ is lower than for 30Si+/56Si2. At 40° bombardment there are similar amounts of SiO2 and sub‐oxides present on the crater surface and the MISR values for 44SiO+/56Si2+ and 30Si+/56Si2+ are also similar. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Rabinovich E Goldberg I Gross Z 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(44):12294-12301
Corrole complexes with gold(I) and gold(III) were synthesized and their structural, photophysical, and electrochemical properties investigated. This work includes the X-ray crystallography characterization of gold(I) and gold(III) complexes, both chelated by a corrole with fully brominated β-pyrrole carbon atoms. The mononuclear and chiral gold(I) corrole appears to be the first of its kind within the porphyrinoid family, while the most unique property of the gold(III) corrole is that it displays phosphorescence at ambient temperatures. 相似文献
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Bokwon Yoon Dr. Pekka Koskinen Dr. Bernd Huber Oleg Kostko Bernd von Issendorff Prof. Hannu Häkkinen Prof. Michael Moseler Dr. Uzi Landman Prof. 《Chemphyschem》2007,8(1):157-161
Ground-state structures and other experimentally relevant isomers of Au(15) (-) to Au(24) (-) clusters are determined through joint first-principles density functional theory and photoelectron spectroscopy measurements. Subsequent calculations of molecular O(2) adsorption to the optimal cluster structures reveal a size-dependent reactivity pattern that agrees well with earlier experiments. A detailed analysis of the underlying electronic structure shows that the chemical reactivity of the gold cluster anions can be elucidated in terms of a partial-jellium picture, where delocalized electrons occupying electronic shells move over the ionic skeleton, whose geometric structure is strongly influenced by the directional bonding associated with the highly localized "d-band" electrons. 相似文献
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The role of the oxidation state of a platinum polycrystalline surface in the electrocatalytic oxidation of C1 to C4 primary alcohols has been studied by using electrochemical techniques, in situ FTIR spectroscopy and X-ray photoelectron spectroscopy. The results revealed that the oxidation state of the Pt surface plays a key role in the oxidation of primary alcohols, and demonstrated that the oxidation of C1 to C4 primary alcohols on a Pt electrode is controlled by the formation of surface oxides on the Pt electrode at different potentials. It was found that the dependence of the reaction process on the oxidation states of the platinum surface yielded similar features in the cyclic voltammogram for oxidation of different primary alcohols at a Pt electrode. According to the effects in the oxidation of primary alcohols, the surface oxides of platinum may be classified as active and poison species. The Pt surface oxides of higher oxidation states (Pt(OH)3 and PtO2) formed at potentials above 1.0 V (SCE) were identified as poison species, while other lower oxidation states of Pt surface oxides such as PtOH, Pt(OH)2 and PtO may be identified as the possible active species for primary alcohol oxidation. 相似文献
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Yeon Jae Ko Haopeng Wang Xiang Li Kit. H. Bowen Prof. Frédéric Lecomte Dr. Charles Desfrançois Prof. Jean‐Christophe Poully Gilles Grégoire Dr. Jean Pierre Schermann Dr. 《Chemphyschem》2009,10(17):3097-3100
Gas‐phase intrinsic structures of intact neutral and anionic glutathione (GSH) have been determined by means of a combination of negative ion photo‐electron spectroscopy and quantum chemistry calculations. The inferred structures of the neutral parents of those peptide anions are canonical (non‐zwitterionic). These intrinsic structures are compared to those already known in aqueous solution or determined by crystallography in binding sites of enzymes. 相似文献
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M S Hegde A Srinivasan K Jagannathan G C Chaturvedi 《Journal of Chemical Sciences》1980,89(2):145-151
Surface oxidation of Co has been investigated at different temperatures in the 300–600 K range at oxygen exposures upto 106 L by XPES and AES techniques. In the XPES, both the valence band and core level bands have been employed to monitor the oxidation
while in the AES, metal Auger intensity ratios as well as O(KLL)/Co(L23M45M45) ratios have been examined. Only CoO is formed on the surface at high oxygen exposures at and above 500 K.
Communication No. 62 from the Solid State and Structural Chemistry Unit. 相似文献