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Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry

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https://www.readbyqxmd.com/read/28816012/periodic-mesoporous-organosilica-films-with-a-tunable-steady-state-mesophase
#1
Murad A Redzheb, Sigrid Bernstorff, Barbara Sartori, Pascal Van Der Voort, Silvia Armini
The mesophase formation in spin-coated periodic mesoporous organosilica (PMO) films aged at a controlled ambient humidity is investigated by time-resolved grazing-incidence small-angle X-ray scattering (GISAXS). The investigation demonstrates the existence of a tunable steady state in PMO spin-coated films. Thus, a film deposited at a relative humidity of 20 % has a lamellar mesophase, whereas a subsequent increase to 70 % leads to a phase transformation resulting in a P63 /mmc space group. On the other hand, an increase of the surfactant to organosilica molar ratio of between 0...
August 16, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28815973/kinetic-parameters-for-the-selective-hydrogenation-of-acetylene-on-gapd2-and-gapd
#2
René R Zimmermann, Tobias Hahn, Wladimir Reschetilowski, Marc Armbrüster
Intermetallic GaPd2 is a highly selective and stable catalyst for the semi-hydrogenation of acetylene. Knowledge of the underlying reaction kinetics is essential to gain a deeper understanding of the selective hydrogenation on this catalytic material. To date, there has been no experimental kinetic data published for this reaction on a well-defined intermetallic catalyst possessing isolated active sites. Kinetic measurements are performed at 140-200 °C, revealing an apparent activation energy of 29(2) kJ mol(-1) ...
August 16, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28815855/solid-state-step-scan-ftir-spectroscopy-of-binuclear-copper-i-complexes
#3
Manuel Zimmer, Fabian Dietrich, Daniel Volz, Stefan Bräse, Markus Gerhards
The electronic ground and excited state structure of two binuclear Cu(I)-NHETPHOS-complexes, which are promising to be implemented in OLEDs (organic light emitting diodes), is investigated by a combination of the time-resolved step-scan FTIR technique and quantum chemical calculations at the DFT level. In contrast to the usual application of step-scan FTIR spectroscopy in solution the herein presented analyses are performed in solid phase, i.e. the Cu(I) complexes are embedded in a KBr matrix (KBr pellet). Applying "solid state" time-resolved step-scan FTIR spectroscopy is of great importance for transition metal complexes, since oftentimes their photophysical properties change when moving from solid to dissolved samples...
August 16, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28815828/exploring-electrical-currents-through-nanographenes-visualization-and-tuning-of-the-through-bond-transmission-paths
#4
Thijs Stuyver, Nathalie Blotwijk, Stijn Fias, Paul Geerlings, Frank De Proft
In this work, electrical currents through nanographenes, a class of alternant hydrocarbons also known as polycyclic aromatic hydrocarbons, in molecular junctions under small bias are explored. We illustrate that when the π-current dominates, i.e. when no quantum interference takes place, the current prefers the direction of the shortest bond (the bond with the highest double bond character) upon entering the molecule from the contacts. As such, the idea of electrons propagating through double bonds from contact to contact, originating from the curly arrow drawings used in a previously established selection rule for transmission, seems to be more deeply rooted in the actual physical process of electron transport than previously anticipated...
August 16, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28810057/crowders-and-cosolvents-major-contributors-to-the-cellular-milieu-and-efficient-means-to-counteract-environmental-stresses
#5
Roland Hermann Alfons Winter, Mimi Gao, Christoph Held, Satyajit Patra, Loana Arns, Gabriele Sadowski
The free energy and conformational landscape of biomolecular systems as well as biochemical reactions depend not only on temperature and pressure, but also only the particular solution conditions. Such conditions include the effects of cosolvents (for example osmolytes) and macromolecular crowding, which are crucial components to understand the energetics and kinetics of biological processes in living system. Such conditions are also important for the understanding of many debilitating diseases, such as those where misfolding and amyloid formation of proteins are involved...
August 15, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28809081/diagnosing-the-internal-architecture-of-zeolite-ferrierite
#6
Joel E Schmidt, Frank C Hendriks, Martin Lutz, L Christiaan Post, Donglong Fu, Dr Bert M Weckhuysen
Large crystals of zeolite ferrierite (FER) are important model systems for spatially resolved catalysis and diffusion studies, though there is considerable variation in crystal habit depending on the chemical composition and employed synthesis conditions. A synergistic combination of techniques has been applied, including single crystal X-ray diffraction, high-temperature in situ confocal fluorescence microscopy, fluorescent probe molecules, wide-field microscopy and atomic force microscopy to unravel the internal architecture of three distinct FER zeolites...
August 15, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28800198/identification-of-crystalline-orientation-of-black-phosphorus-by-optothermal-raman-spectroscopy
#7
Xinwei Wang, Tianyu Wang, Jing Liu, Biao Xu, Ridong Wang, Pengyu Yuan, Meng Han, Shen Xu, Yangsu Xie, Yue Wu
Current polarized Raman-based techniques for identifying the crystalline orientation of black phosphorus suffer big uncertainty and unreliability because of the complex interference involving excitation laser wavelength, scattering light wavelength, and sample thickness. Here, for the first time, we present a new optothermal Raman spectroscopy (OT-Raman) for identifying crystalline orientation. With a physical mechanism based on the anisotropic optical absorption of polarized laser and the resulting heating, the OT-Raman can identify the crystalline orientation explicitly regardless of excitation wavelength and sample thickness by Raman frequency-power differential Φ (=∂ω/∂P)...
August 11, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28799732/excitation-power-modulates-energy-transfer-dynamics-in-a-supramolecular-ruii-feii-ruii-triad
#8
Joachim Kübel, Maria Wächtler, Benjamin Dietzek
Multichromophoric arrays are key to light-harvesting in natural and artificial photosynthesis. A trinuclear, symmetric RuII-FeII-RuII triad may resemble a light-harvesting model system, in which excitation energy from donor units (Ru-terpyridine-fragments) is efficiently transferred to the acceptor (an Fe-terpyridine-fragment). The photoinduced dynamics after simultaneous excitation of more than a single chromophoric unit (donor/acceptor) at varying excitation fluence is investigated in this contribution. Data suggests that energy transfer is decelerated if the acceptor states (on the FeII unit) are not depopulated fast enough...
August 11, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28799692/logic-gate-functions-in-chemomechanical-materials
#9
REVIEW
Hans-Jörg Schneider
Chemomechanical polymers that change their shape or volume on stimulation by multiple external chemical signals, particularly on the basis of selective molecular recognition, are discussed. Several examples illustrate how such materials, usually in the form of hydrogels, can be used for the design of chemically triggered valves or artificial muscles and applied, for example, in self-healing materials or drug delivery. The most attractive feature of such materials is that they can combine sensor and actuator within single units, from nano- to macrosize...
August 11, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28796918/hydrogel-carbon-nanotubes-needle-free-device-for-electrostimulated-skin-delivery
#10
Jean-François Guillet, Emmanuel Flahaut, Muriel Golzio
The permeability of skin allows passive diffusion across the epidermis to reach blood vessels but this is possible only for small molecules such as nicotine. In order to achieve transdermal delivery of large molecules such as insulin or plasmid DNA, permeability of the skin and mainly the permeability of stratum corneum has to be increased. Moreover, alternative routes that avoid the use of needles will improve the quality of life of patients. A method named "electropermeabilization" has been shown to increase skin permeability...
August 10, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28796423/direct-carbonation-of-glycerol-with-co2-catalyzed-by-metal-oxides
#11
Claudio J A Mota, Leonardo Ozório
Five metal oxides (ZnO, SnO2, Fe2O3, CeO2, La2O3) were produced by the sol-gel method and tested in the direct carbonation of glycerol with CO2. Initial tests with Fe2O3 showed that the best reaction condition was 180 °C, 150 bar and 12 h. The other oxides were evaluated at these conditions and were all active to the formation of glycerol carbonate. Zinc oxide was the most active catalyst, with a yield of 8.1% in the organic carbonate. The catalytic activity decreased upon washing and drying the ZnO catalyst between the runs...
August 10, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28792111/solid-state-nmr-h-n-c-h-and-h-n-c-c-3d-4d-correlation-experiments-for-resonance-assignment-of-large-proteins
#12
Hugo Fraga, Charles-Adrien Arnaud, Diego F Gauto, Maxime J C Audin, Vilius Kurauskas, Pavel Macek, Carsten Krichel, Jia-Ying Guan, Jérôme Boisbouvier, Remco Sprangers, Cécile Breyton, Paul Schanda
Solid-state NMR can provide insight into protein structure and dynamics at the atomic level without inherent protein size limitations. However, a major hurdle to studying large proteins by solid-state NMR spectroscopy is related to spectral complexity and resonance overlap, which increase with molecular weight and severely hamper the assignment process. Here we show the use of two sets of experiments that expand the tool kit of 1H-detected assignment approaches, and which correlate a given amide pair either to the two adjacent CO-CA pairs (4D hCOCANH/hCOCAcoNH), or to the amide 1H of the neighboring residue (3D HcocaNH/HcacoNH, which can be extended to up to 5D)...
August 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28792109/interface-engineering-of-perovskite-solar-cells-with-air-plasma-treatment-for-improved-performance
#13
Xiao Ma, Peng Tang, Dong Liu, Lili Wu, Jingquan Zhang, Lianghuan Feng
For high-efficiency perovskite solar cells (PSCs), interface engineering becomes critical for carrier collection from active perovskite material to the transport layer. To enhance power conversion efficiency (PCE), here we demonstrate a novel method named surface plasma treatment on mesoporous TiO2 electron transport layer (ETL) to improve electron extraction and transport properties at the perovskite/TiO2 interface. According to the XPS results, the plasma treatment induced a partial reduction of Ti4+ to Ti3+ within the TiO2 lattice and increased the concentration of oxygen vacancy on the TiO2 surface...
August 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28782155/functionalizing-base-stable-metal-organic-frameworks-for-selective-co2-adsorption-and-proton-conduction
#14
Jian-Rong Jeff Li, Lin-Hua Xie, Yibo Dou, Tao He, Yong-Zheng Zhang, Hao Wu, Xiang-Jing Kong, Xiao-Min Liu
Metal-organic frameworks (MOFs) have shown great application potential in various fields, including CO2 capture and proton conduction. For promoting their practical applications, both optimizing given property and enhancing chemical stability are crucial. In this work, three base-stable isostructural MOFs, [Ni8(OH)4(H2O)2(BDP-X)6] (Ni-BDP-X, H2BDP = 1,4-bis(4-pyrazolyl)benzene, X = -CHO, -CN, -COOH) with different functional groups, were designed, synthesized, and used in CO2 capture and proton conduction. They possess the fcu topological structure with functional nanoscale cavities...
August 7, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28771994/electronic-transport-of-mos2-monolayered-flakes-investigated-by-scanning-electrochemical-microscopy
#15
Olivier Henrotte, Thomas Bottein, Hugo Casademont, Kevin Jaouen, Tiphaine Bourgeteau, Stephane Campidelli, Vincent Derycke, Bruno Jousselme, Renaud Cornut
The amazing properties of 2D materials are envisioned to revolutionize several domains such as flexible electronics, electrocatalysis, or biosensing. Herein we introduce scanning electrochemical microscopy (SECM) as a tool to investigate molybdenum disulfide in a straightforward fashion, providing localized information regarding the electronic transport within chemical vapor deposition (CVD)-grown crystalline MoS2 single layers having micrometric sizes. Our investigations show that within flakes assemblies some flakes are well electrically interconnected, with no detectable contact resistance, whereas others are not electrically connected at all, independent of the size of the physical contact between them...
August 3, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28771977/smart-amphiphilic-janus-microparticles-one-step-synthesis-and-self-assembly
#16
Xue-Hui Ge, Yu-Hao Geng, Jian Chen, Jianhong Xu
Self-assembly is the process to form ordered compound structures. The theories and experiments of nano-sized Janus particles have proved that the assembled cluster structures are related to the unit number. The micro-meter sized amphiphilic Janus particles could also act as surfactants to stabilize droplets and aggregate to the clusters. When the scale order increases to the millimeter size, the connection between particles are usually shape match mechanism. Similar to the millimeter sized particles, sub-millimeter sized particles are larger and heavier that their gravity could not be ignored while the Brownian motion could be neglected...
August 3, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28771914/the-electric-field-standing-wave-effect-in-infrared-transmission-spectroscopy
#17
Thomas Günter Mayerhöfer, Harald Mutschke, Jürgen Popp
When in IR absorbance spectra of films, which were converted from transmission, bands ratios are compared, then it can be noted that even after background correction and removal of interference fringes these band ratios change with the thickness of the films. The main goal of this work is to show that this effect is a consequence of an electric field standing wave based on the coherent superposition of light waves in the film. We further investigate how transmittance and reflectance, as well as absorbance and finally the from absorbance regained index of absorption depend on the thickness of the film and the influences on the positions of bands...
August 3, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28771905/optical-detection-of-photorelease-kinetics-on-gold-and-glass-surfaces-using-streptavidin-coupled-biotinylated-photolabile-protecting-groups-for-nucleosides
#18
Katja Drexler, Julia Smirnova, Marina Galetskaya, Nina Schweizer, Günter Gauglitz, Ulrich Erwin Steiner
Five biotinylated photolabile compounds of the general structure Bt-L₁-NPPOC-X-L₂ have been synthesized, where Bt represents a biotin unit, L₁ a 3,6-dioxa-n-octane or an n-hexane spacer, NPPOC the photolabile protecting group (PLPG) 2-(2-nitrophenyl)propoxycarbonyl, X a thymidine unit as a representative nucleoside, or a direct linkage to L₂, an ω-mercapto- or ω-aminohexoyl linker for coupling to a substrate surface. These compounds served for testing the photocleavage kinetics in self assembled monolayers (SAMs) on gold or glass using surface plasmon resonance (SPR) on gold or reflectometric interference spectroscopy (RIfS) on glass, whereby the biotin moiety offered the possibility to increase the bulkiness of the leaving group by binding to streptavidin, thereby largely enhancing the SPR or RIfS signals...
August 3, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28766864/investigation-of-chemical-bonding-in-in-situ-cryocrystallized-organometallic-liquids
#19
Deepak Chopra, Abhishek Sirohiwal, Dhananjay Dey, Venkatesha R Hathwar
This report presents the crystal structure of organometallic complexes namely (a) (η4-1, 3 Cyclohexadiene) iron tricarbonyl [I] and (b) (Methyl cyclopentadienyl) manganese tricarbonyl [II] (both are liquid at the room temperature), which were determined using state-of-the-art in situ cryocrystallization technique. The bonding features are elucidated using topological analysis of charge density in the framework of Quantum Theory of Atoms in Molecules (QTAIM) and theoretical charge density analysis (multipolar refinement), to decipher the metal-carbonyl, metal-olefin and metal-carbocyclic ligand interactions in these complexes...
August 2, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28766822/quantum-chemical-analyses-of-bh4-and-bh3oh-hydride-transfers-to-co2-in-aqueous-solution-with-potentials-of-mean-force
#20
Mitchell C Groenenboom, John Andrew Keith
Biomimetic hydride transfer catalysts are a promising route to efficiently convert CO2 into more useful products, but a lack of understanding about their atomic scale reaction mechanisms slows their development. To this end, we report a computational quantum chemistry study of how aqueous solvation influences CO2 reduction reactions facilitated by sodium borohydride (NaBH4) and a partially oxidized derivative (NaBH3OH). This work compares 0 K reaction barriers from nudged elastic band calculations to free energy barriers obtained at 300 K using potentials of mean force from umbrella sampling simulations...
August 2, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
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