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Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry

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https://www.readbyqxmd.com/read/29149466/microsecond-timescale-protein-dynamics-a-combined-solid-state-nmr-approach
#1
Petra Rovó, Rasmus Linser
Conformational exchange in proteins is a major determinant in protein functionality. In particular, the μs-ms timescale is associated with enzymatic activity and interactions between biological molecules. We show here that a comprehensive data set of R1ρ relaxation dispersion profiles employing multiple effective fields and tilt angles can be easily obtained in perdeuterated, partly back-exchanged proteins at fast magic-angle spinning and further complemented with chemical-exchange saturation transfer NMR experiments...
November 17, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29144015/elucidating-the-impact-of-chalcogen-content-on-the-photovoltaic-properties-of-oxychalcogenide-perovkskites-namo3-xqx-m-nb-ta-and-q-s-se-te
#2
Heesoo Park, Fahhad H Alharbi, Stefano Sanvito, Nouar Tabet, Fedwa El-Mellouhi
In the quest for non-toxic and stable perovskites for solar cells, we conduct a systematic study of the effect of chalcogen content in oxychalcogenide perovskite using density functional theory (DFT) and quasi-particle perturbation theory. We explore the changes in the electronic structure due to the substitution of O atoms in NaNbO 3 and NaTaO 3 perovskite structures with various chalcogen (S, Se, Te) at different concentrations. Interestingly, the introduction of the chalcogen atoms results in a drastic reduction of the electronic band gap, making some of them fall within the visible range of the solar spectrum...
November 16, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29143420/investigation-of-surface-sulfurization-in-cuin1-xgaxs2-ysey-thin-films-to-enhance-photovoltaic-properties
#3
Haeri Kim, Se Jin Park, Byungwoo Kim, Yun Jeong Hwang, Byoung Koun Min
CuIn1-xGaxS2-ySey (CIGSSe) thin films have attracted a great deal of attention as a promising absorbing material for solar cell applications due to their favorable optical properties (e.g. a direct band gap and high absorption coefficients) and stable structure. Many studies have sought to improve the efficiency of solar cells using these films, and it has been found that surface modification via post heat treatment can lead to surface passivation of surface defects and a subsequent increase in efficiency. The surface properties of solution-processed CIGSSe films are considered to be particularly important in this respect due to the fact they are more prone to defects...
November 15, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29141115/activation-of-dinitrogen-n2-with-a-superalkali-species-li3f2
#4
Heejune Park, Giovanni Meloni
The capability of the superalkali Li_3 F_2 to activate dinitrogen (N_2) is presented. The (Li_3 F_2 )_n N_2 clusters (n = 1 - 6) were investigated first at the MP2/6-311+G(3d2f,2df,2p)//B3LYP/6-311G(2d,d,p) level of theory. Clusters up to n = 4 were also optimized through the CBS-QB3 composite model. The complete dissociation of N_2 was confirmed through visualized molecular orbitals and bond order calculation. The N-N bond is weakened by the addition of Li_3 F_2 superalkali units. The enthalpy of atomization (Δ_at H_0^°) and formation (Δ_f H_0^°), charge flows (∆q), binding energies, and the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are calculated to help explaining the N_2 activation...
November 15, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29139595/structure-and-electronic-properties-of-unnatural-base-pairs-role-of-dispersion-interactions
#5
Ayan Datta, Sk Jahiruddin, Nilangshu Mandal
Recent report of the success of unnatural base pairs (UBPs) like d5SICS-dNaM to be incorporated within the gene sequence and get replicated with DNA is an important milestone in synthetic biology. Followed by this, several other UBPs like dTPT3-dNaM, dTPT3-dFIMO, dTPT3-IMO, dTPT3-FEMO, FTPT3-NaM, FTPT3-FIMO, FTPT3-IMO, FTPT3-FEMO, have demonstrated similar or better retention and fidelity inside cell. Among these base pairs, dNaM-dTPT3 has been optimized to be a better fit inside a pAIO plasmid. Based on both implicit and explicit dispersion corrected density functional theory (DFT) calculations, we show that although the set of UBPs are significantly diverse in their elemental and structural configuration they do share a common trait of favoring a slipped parallel stacked dimer arrangement...
November 15, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29136324/proton-transfer-reaction-dynamics-of-pyranine-in-dmso-water-mixture
#6
Prabhat Kumar Singh, Ankur Awasthi
Photo-induced intermolecular excited-state proton transfer (ESPT) reactions are ubiquitous in chemistry and biology. ESPT reactions are extremely sensitive to the nature of water molecules in its microenvironment and thus serve as a sensitive reporter for the water structure and dynamics in a system. Herein, the photo-induced intermolecular ESPT reaction of 8-Hydroxy pyrene-1, 3, 5-trisulfonic acid (HPTS, also known as Pyranine) has been investigated in various DMSO-water mixtures using steady-state and time-resolved emission spectroscopy...
November 14, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29136312/on-the-performance-of-hybrid-functionals-for-nonlinear-optical-properties-and-electronic-excitations-in-chiral-molecular-crystals-the-case-of-butterfly-shaped-dicinnamalacetone
#7
Pedro Sidónio Pereira Silva, Pablo de Martín-Ramos, Sérgio R Domingos, Maria do Carmo Bota Sousa, Cláudia T Arranja, Abílio J F N Sobral, Manuela Ramos Silva
Purely organic chiral molecular assemblies in the solid state hold great potential for nonlinear optical applications. We report on a newly synthesized molecular system, dicinnamalacetone, an otherwise planar molecule that crystallizes in a disordered noncentrosymmetric form via four different conformations with an overall predominance of a particular helicity. A combined experimental and theoretical approach -including single-crystal X-ray diffraction, Kurtz-Perry and ab initio methods- is employed to characterize the system and at the same time benchmark the performance of hybrid functionals for the prediction of nonlinear optical properties and electronic excitations...
November 14, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29131929/insights-on-the-structure-molecular-weight-and-activity-of-an-antibacterial-protein-polymer-hybrid
#8
Yanxiong Pan, Sunanda Neupane, Jasmin Farmakes, Myungkeun Oh, Kylie Bentz, Yongki Choi, Zhongyu Yang
Protein-polymer conjugates are attractive biomaterials which combine the functions of both proteins and polymers. The bioactivity of these hybrid materials, however, is often reduced upon the conjugation. It is important to determine and monitor the protein structure and active site availability, in order to optimize the polymer composition, attachment point, and abundance. The challenges in probing these insights are the large size and high complexity in the conjugates. Here, we overcome the challenges by combining Electron Paramagnetic Resonance (EPR) spectroscopy and Atomic Force Microscopy (AFM) and characterize the structural insights of antibacterial hybrids formed by polyethylene glycol (PEG) and an antibacterial protein...
November 13, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29131544/synthesis-and-properties-of-open-fullerenes-encapsulating-ammonia-and-methane
#9
Sally Bloodworth, John Gräsvik, Shamim Alom, Karel Kouřil, Stuart J Elliott, Neil J Wells, Anthony J Horsewill, Salvatore Mamone, Mónica Jiménez-Ruiz, Stéphane Rols, Urmas Nagel, Toomas Rõõm, Malcolm H Levitt, Richard John Whitby
We describe the synthesis and characterisation of open fullerene (1) and its reduced form (2) in which CH4 and NH3 are encapsulated, respectively. The 1H NMR resonance of endohedral NH3 is broadened by scalar coupling to the quadrupolar 14N nucleus, which relaxes rapidly. This broadening is absent for small satellite peaks, which are attributed to natural abundance 15N. The influence of the scalar relaxation mechanism on the linewidth of the 1H ammonia resonance is probed by variable temperature NMR. A rotational correlation time of c = 1...
November 13, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29131466/understanding-the-reactive-adsorption-of-h2s-and-co2-in-sodium-exchanged-zeolites
#10
Evgenii O Fetisov, Mansi S Shah, Christopher Knight, Michael Tsapatsis, Joern Ilja Siepmann
Purifying sour natural gas streams containing hydrogen sulfide and carbon dioxide has been a long-standing environmental and economic challenge. In the presence of cation-exchanged zeolites, these two acid gases can react to form carbonyl sulfide and water (H2S + CO2 <=> H2O + COS), but this reaction is rarely accounted for. In this work, we carry out reactive first-principles Monte Carlo (RxFPMC) simulations for mixtures of H2S and CO2 in all-silica and Na- exchanged forms of zeolite beta to understand the governing principles driving the enhanced conversion...
November 13, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29125894/the-stabilization-of-glycosyl-cations-through-cooperative-non-covalent-interactions-a-theoretical-perspective
#11
Antonio Franconetti, Jesús Jiménez-Barbero, Francisca Cabrera-Escribano
A systematic study of the stabilization of glycosyl cations on aromatic rings is reported at the B3LYP, M06-2X and M11 levels of theory. In particular, π-acidic arenes such as fluorobenzenes or naphthalenediimides efficiently stabilize these cations acting cooperatively as sandwich-type ternary cation-π-anion systems. The stabilization and cooperativity in polar (both protic and aprotic) and non-polar solvents has been also evaluated by using the polarizable continuum model. In addition, the role of the protecting group at C-2 position (methyl, acetyl, benzyl, and pivaloyl) for this non-covalent stabilization has been explored, as well as the behaviour of the corresponding 2-deoxy glycosyl cation...
November 10, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29125680/carbon-dioxide-utilization-coming-of-age
#12
EDITORIAL
Paul J A Kenis, Angela Dibenedetto, Tierui Zhang
No abstract text is available yet for this article.
November 10, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29124840/electrochemistry-of-metallo-proteins-attached-through-functional-self-assembled-monolayers-on-gold-and-ferromagnetic-electrodes
#13
Dr Prakash Chandra Mondal, Claudio Fontanesi
We report experimental results of studying electron transfer processes via redox active metallo-proteins bound to mixed self-assembled monolayers (SAMs) on magnetic (nickel, or ultrathin gold-coated nickel) and non-magnetic (gold) electrodes. Metallo-proteins such as hemoglobin (Hb), cytochrome c, and cytochrome c oxidase are attached via electrostatic interactions to free carboxylate or imidazole groups present in mixed SAMs. The formation of both the mixed SAMs and the SAMs-metallo-protein heterostructures were confirmed by advanced surface analysis techniques such as polarization modulation-infrared reflection-absorption spectra (PMIRRAS) and aqueous contact angle (CA) measurements...
November 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29124837/synthetic-ion-channels-and-dna-logic-gates-as-components-of-molecular-robots
#14
Ryuji Kawano
A molecular robot is a next-generation biological robot consisting of biomaterials such as DNA, proteins, and lipids that imitates the actions of microorganisms. Three prerequisites have been proposed for the construction of such a robot: sensor, intelligence, and actuator. This minireview focuses on recent research on synthetic ion channels and DNA computing technologies, which are viewed as potential candidate components of molecular robots. Synthetic ion channels, which are embedded in an artificial cell membrane (lipid bilayer), sense ambient ions or chemicals and incorporate the molecules...
November 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29121449/solvent-effect-on-the-behavior-of-lithium-and-superoxide-ions-in-li-o2-battery-electrolyte
#15
Vladimir Smirnov, Sergey Kislenko
The molecular life of intermediates, namely O2- and Li+, produced during the discharge of aprotic Li-O2 batteries has been investigated by the MD simulation. This work is of potential interest in the development of new electrolytes for the Li-air batteries. We present the results on structure and stability of the Li+ and O2- solvation shells, as well as on thermodynamics and kinetics of the ions association reaction in the following solvents: dimethyl sulfoxide (DMSO), dimethoxyethane (DME), acetonitrile (ACN)...
November 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29120533/structural-insights-from-59co-solid-state-nmr-experiments-on-organocobalt-i-catalysts
#16
Kevin Burgess, Cory Widdifield, Yang Xu, Cesar Leroy, David L Bryce
A series of fumarate-based organocobalt(I) [CpCo(CO)(fumarate)] catalysts are synthesized and characterized by X-ray crystallography, multinuclear (13C and 59Co) solid-state NMR spectroscopy, and 59Co NQR spectroscopy. Given the dearth of 59Co solid-state NMR studies on Co(I) compounds, the present work constitutes the first systematic characterization of the 59Co electric field gradient and chemical shift tensors for a series of cobalt complexes in this oxidation state. While by X-ray crystallography, the molecular geometry about the Co(I) centre is nearly identical in all compounds studied herein, it is shown that, owing to the 59Co nucleus' large chemical shift range, solid-state NMR experiments can detect small structural differences between the individual organocobalt(I) compounds...
November 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29115710/pmo-immobilized-au-i-nhc-complexes-heterogeneous-catalysts-for-sustainable-processes
#17
Pascal van der Voort, Els De Canck, Fady Nahra, Kevin Bevernaege, Sofie Vanden Broeck, Judith Ouwehand, Diederick Maes, Steven P Nolan
A stable Periodic Mesoporous Organosilica (PMO) with accessible sulfonic acid functionalities is prepared via a one-pot-synthesis and is used as solid support for highly active catalysts, consisting of gold(I)-N-heterocyclic carbene (NHC) complexes. The gold complexes are successfully immobilized on the nanoporous hybrid material via a straightforward acid-base reaction with the corresponding [Au(OH)(NHC)] synthon. This catalyst design strategy results in a boomerang-type catalyst, allowing the active species to detach from the surface to perform the catalysis and then to recombine with the solid after all the starting material is consumed...
November 8, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29112777/elucidating-the-distribution-and-speciation-of-boron-and-cesium-in-bcsx-zeolite-catalysts-for-styrene-production
#18
Antonio J Martín, Sharon Mitchell, Olivier Scholder, René Verel, Roland Hauert, Laetitia Bernard, Christopher Jensen, Meinhard Schwefer, Javier Pérez-Ramírez
An improved understanding of the nature and distribution of boron and cesium species in BCsX zeolites is prerequisite to guide future developments in the environmentally attractive yet challenging production of styrene via the side-chain alkylation of toluene with methanol. Here, standard characterization and catalytic tests are complemented by integrated visualization through time-of-flight secondary ion mass spectrometry and energy-dispersive X-ray spectroscopy and detailed assessment by 133Cs and 11B nuclear magnetic resonance spectroscopy, to correlate the properties and performance during the successive ion exchange and impregnation steps in the preparation of both powders and millimeter-sized granules...
November 7, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29106771/tip-enhanced-raman-spectroscopy-a-tool-for-nanoscale-chemical-and-structural-characterization-of-biomolecules
#19
Sebastien Bonhommeau, Sophie Lecomte
Due to its high molecular sensitivity and spatial optical resolution down to subnanometer values, tip-enhanced Raman spectroscopy (TERS) has emerged as a powerful microscopy technique for nanoscale characterization. Progresses in TERS instrumentation and in the manufacturing of efficient TERS tips allow for chemical and structural analysis in various experimental conditions (different wavelengths, substrates and surrounding media). Many biological species have been examined using this technique. Nucleic acids (individual nucleobases, DNA and RNA) can show specific TERS features revealing DNA composition, conformation and defects...
November 6, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29105947/inversion-of-bicyclic-decanes-rotational-spectra-of-the-trans-and-double-cis-conformations-of-2-decalone
#20
Dennis Wachsmuth, Michaela K Jahn, Susana Blanco, Marco A Gigosos, Alberto Lesarri, Jens-Uwe Grabow
The conformational landscape of the bicyclic molecule 2-decalone has been studied in a jet-cooled expansion by using rotational spectroscopy. The investigation covered the frequency region 7-19 GHz using broadband fast-passage IMPACT Fourier-transform microwave techniques. The introduction of the asymmetric carbonyl substituent in the double-chair decalin skeleton originates two distinct inverting conformers with cis ring junction, which were independently identified and characterized in the gas phase. Additionally, a single trans conformer was detected, as expected for the non-inverting equatorial ring junction...
November 6, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
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