28,941 results match your criteria Physical chemistry chemical physics : PCCP[Journal]


Capturing a dynamically interacting inhibitor by paramagnetic NMR spectroscopy.

Phys Chem Chem Phys 2019 Feb 22. Epub 2019 Feb 22.

Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic. and Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic.

Transient and fuzzy intermolecular interactions are fundamental to many biological processes. Despite their importance, they are notoriously challenging to characterize. Effects induced by paramagnetic ligands in the NMR spectra of interacting biomolecules provide an opportunity to amplify subtle manifestations of weak intermolecular interactions observed for diamagnetic ligands. Read More

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http://dx.doi.org/10.1039/c9cp00416eDOI Listing
February 2019

Deep core photoionization of iodine in CHI and CFI molecules: how deep down does the chemical shift reach?

Phys Chem Chem Phys 2019 Feb 22. Epub 2019 Feb 22.

RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.

Hard X-ray electron spectroscopic study of iodine 1s and 2s photoionization of iodomethane (CH3I) and trifluoroiodomethane (CF3I) molecules is presented. The experiment was carried out at the SPring-8 synchrotron radiation facility in Japan. The results are analyzed with the aid of relativistic molecular and atomic calculations. Read More

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http://dx.doi.org/10.1039/c8cp07307dDOI Listing
February 2019

Position-, disorder-, and salt-dependent diffusion in binding-coupled-folding of intrinsically disordered proteins.

Authors:
Xiakun Chu Jin Wang

Phys Chem Chem Phys 2019 Feb 22. Epub 2019 Feb 22.

Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794, USA and State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China.

Successful extensions of protein-folding energy landscape theory to intrinsically disordered proteins' (IDPs') binding-coupled-folding transition can enormously simplify this biomolecular process into diffusion along a limited number of reaction coordinates, and the dynamics subsequently is described by Kramers' rate theory. As the critical pre-factor, the diffusion coefficient D has direct implications on the binding kinetics. Here, we employ a structure-based model (SBM) to calculate D in the binding-folding of an IDP prototype. Read More

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http://dx.doi.org/10.1039/c8cp06803hDOI Listing
February 2019

Experimental and theoretical elucidation of catalytic pathways in TiO-initiated prebiotic polymerization.

Phys Chem Chem Phys 2019 Feb 22. Epub 2019 Feb 22.

CNR-ICCOM, Institute of Chemistry of Organometallic Compounds, via G. Moruzzi 1, I-56124 Pisa, Italy.

The tendency of glycine to form polymer chains on a rutile(110) surface under wet/dry conditions (dry-wet cycles at high temperature) is studied through a conjunction of surface sensitive experimental techniques and sequential periodic multilevel calculations that mimics the experimental procedures with models of decreasing complexity and increasing accuracy. X-ray photoemission spectroscopy (XPS) and thermal desorption spectroscopy (TDS) experimentally confirmed that the dry-wet cycles lead to Gly polymerization on the oxide support. This was supported by all the theoretical characterizations. Read More

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http://dx.doi.org/10.1039/c9cp00167kDOI Listing
February 2019

Tunable electronic properties of an Sb/InSe van der Waals heterostructure by electric field effects.

Phys Chem Chem Phys 2019 Feb 22. Epub 2019 Feb 22.

School of Materials Science and Engineering, Chang'an University, Xi'an, 710064, China.

The electronic properties of an Sb/InSe heterostructure are investigated by using the density functional theory method. A type-II staggered-gap band alignment is achieved from the Sb/InSe vdW heterostructure with the Sb layer dominates the lowest energy holes as well as the lowest energy electrons are contributed by the InSe layer, which facilitates the spatial effective separation of photogenerated electron-hole pairs. Additionally, an indirect-direct band gap transition can be triggered via varying the interlayer distance. Read More

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http://dx.doi.org/10.1039/c8cp07407kDOI Listing
February 2019

Ice Ih vs. ice III along the homogeneous nucleation line.

Phys Chem Chem Phys 2019 Feb 22. Epub 2019 Feb 22.

Departamento de Quimica Fisica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.

Pure water can be substantially supercooled below the melting temperature. The pressures and temperatures where water is observed to freeze in supercooling experiments define the so-called homogeneous nucleation line. The slope of such a line changes from negative to positive as pressure increases. Read More

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http://dx.doi.org/10.1039/c8cp07432aDOI Listing
February 2019

Electronic and magnetic properties of CoPc and FePc molecules on graphene: the substrate, defect, and hydrogen adsorption effects.

Phys Chem Chem Phys 2019 Feb 22. Epub 2019 Feb 22.

Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China.

Transition metal phthalocyanines (TMPcs) are particularly appealing for spintronic processing and data storage devices due to their structural simplicity and functional flexibility. To realize effective control of the spins in TMPc-based systems, it is necessary to quantify how the structural and chemical environment of the molecule affects its spin center. Herein we perform a detailed investigation of the electronic and spintronic properties of vertically stacked heterostructures formed by CoPc or FePc adsorbed on a monolayer of graphene under the influences of the gold substrate, vacancies in graphene, and extra atomic hydrogen coordination on the TMPc. Read More

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http://dx.doi.org/10.1039/c8cp07091aDOI Listing
February 2019

Opportunities and challenges for electrochemistry in studying the electronic structure of nanocrystals.

Phys Chem Chem Phys 2019 Feb 22. Epub 2019 Feb 22.

Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany and Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany.

We review the state-of-the-art of determining the electronic structure of nanocrystals in thin films by electrochemistry. Our core conclusion, the necessity of combining electrochemical with spectroscopic techniques, is illustrated with the holistic analysis of thin films of CdSe nanocrystals cross-linked with electroactive metal β-tetraaminophthalocyanines by differential pulse voltammetry, optical spectroscopy and potential modulated absorption spectroscopy. We show that the same nanocrystals cross-linked with phthalocyanines of different metal centers exhibit rather similar electrochemical signatures, but behave distinctly different in spectroelectrochemical investigations. Read More

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http://dx.doi.org/10.1039/c9cp00301kDOI Listing
February 2019

Temperature and isomeric effects in nanoclusters.

Phys Chem Chem Phys 2019 Feb 22. Epub 2019 Feb 22.

Physical and Theoretical Chemistry, University of Saarland, 66123, Saarbrücken, Germany. and School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China.

The canonical thermodynamics of clusters is determined quantum mechanically in the general case of multiple minima of the potential energy surface (PES) using the superposition approximation. As an illustration of the consequences of our approach, we study in detail the thermodynamic properties of CuN clusters with N from 2 to 150 as a function of cluster size, temperature, and number of isomers. Thereby, for instance, solid-solid transition temperatures for several cluster sizes are determined. Read More

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http://dx.doi.org/10.1039/c9cp00123aDOI Listing
February 2019

Immobilisation of sulphur on cathodes of lithium-sulphur batteries via B-doped atomic-layer carbon materials.

Phys Chem Chem Phys 2019 Feb 22. Epub 2019 Feb 22.

School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, People's Republic of China.

Developing new host materials for cathodes and exploring their binding mechanisms in lithium-sulphur batteries are crucial issues since the present host materials exhibit low sulphur entrapment properties, thus resulting in the rapid decay of overall performance. In this work, we systematically investigated B-doped atomic-layer carbon materials as the cathode hosts of lithium-sulphur batteries via density functional theory calculations. Based on the analysis of optimised molecular structures, binding energies and surface charge densities, we found that B-doping can help materials suppress the dissolution of sulphides during cycles, further improving the performance of lithium-sulphur batteries. Read More

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http://dx.doi.org/10.1039/c8cp07736cDOI Listing
February 2019

Characterization of LiCoO nanoparticle suspensions by single collision events.

Phys Chem Chem Phys 2019 Feb 21. Epub 2019 Feb 21.

Sorbonne Université, CNRS, Laboratoire Interfaces et Systèmes Electrochimiques, 4 place Jussieu, F-75005, Paris, France.

Transient electrochemical experiments associated with the collisions between hydrothermally synthesized LiCoO2 (LCO) nanoparticles/aggregates of different sizes and a polarized gold ultramicroelectrode (UME) were used as a new additive-free analytical tool applied to Li ion insertion compounds. The size of the LCO nanoparticles/aggregates, ranging from 75 to 450 nm, the diffusion coefficient of the LCO nanoparticles/aggregates in suspension (∼8 × 10-9 cm2 s-1), and the Li ion diffusion coefficient within crystalline LCO nanoparticles (∼1.3 × 10-11 cm2 s-1) were estimated from single collision events. Read More

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http://dx.doi.org/10.1039/c9cp00199aDOI Listing
February 2019

Modeling of type IV and V sigmoidal adsorption isotherms.

Phys Chem Chem Phys 2019 Feb 21. Epub 2019 Feb 21.

Institute for Non-Classical Chemistry at Leipzig University, Permoser Str. 15, 04318 Leipzig, Germany.

Based on the biochemical theory of multiple ligand-receptor complexes (Klotz (1946)) a sigmoidal proceeding adsorption isotherm is derived. The special case of an arbitrarily large number of equal interaction sites and a separate one yields an equation which corresponds to the ζ-isotherm, disparately derived by Ward et al. (2007) for surface tension of solid-fluid interfaces. Read More

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http://dx.doi.org/10.1039/c8cp07751gDOI Listing
February 2019

Superconductivity in bilayer graphene intercalated with alkali and alkaline earth metals.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Institute of Physics, Czstochowa University of Technology, Ave. Armii Krajowej 19, 42-200 Czstochowa, Poland.

With the enormous research activity focused on graphene in recent years, it is not surprising that graphene superconductivity has become an attractive area of research. To date, no superconducting properties have been experimentally observed in the pristine form of graphene but controllable structure manipulation is a promising way to induce a superconducting state in graphene-based systems. Therefore, herein we investigate the possible superconductivity in two-layer graphene intercalated with atoms of alkali and alkaline earth metals. Read More

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http://dx.doi.org/10.1039/c9cp00176jDOI Listing
February 2019

Strong influence of weak hydrogen bonding on actinide-phosphonate complexation: accurate predictions from DFT followed by experimental validation.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu 603102, India.

Among the varied classes of weak hydrogen bond, the CHO type is one of immense interest as it governs the finer structures of biological and chemical molecules, hence determining their functionalities. In the present work, this weak hydrogen bond has been shown to strongly influence the complexation behaviour of uranyl nitrate [UO2(NO3)2] with diamyl-H-phosphonate (DAHP) and its branched isomer disecamyl-H-phosphonate (DsAHP). The structures of the bare ligands and complexes have been optimized by density functional theory (DFT) calculations. Read More

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http://dx.doi.org/10.1039/c9cp00479cDOI Listing
February 2019

Magnetic circular dichroism spectra of transition metal complexes calculated from restricted active space wavefunctions.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260-3000, USA.

First principles multiconfigurational restricted active space (RAS) self-consistent field (SCF) or configuration interaction (CI) approaches, augmented with a treatment of spin-orbit coupling by state interaction, were used to calculate the magnetic circular dichroism (MCD) , , and/or for closed- and open-shell transition metal complexes: PdCl42-, PdBr42-, AuCl4-, AuBr4-, MnO4-, CuCl42-, CuBr42-, and Fe(CN)63-. The were determined with a sum-over-states approach. It is shown that reasonably accurate MCD spectra can be obtained directly at a RAS level or at a RAS level augmented with corrections for the dynamic correlation. Read More

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http://dx.doi.org/10.1039/c8cp07849aDOI Listing
February 2019

Charge carrier recombination dynamics in a bi-cationic perovskite solar cell.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Department of Chemistry, Renmin University of China, Beijing 100872, China.

The compositional engineering is of great importance to tune the electrical and optical properties of perovskite and improve the photovoltaic performance of perovskite solar cells. The exploration of the corresponding photoelectric conversion processes, especially the carrier recombination dynamics, will contribute to the optimization of the devices. In this work, perovskite with mixed methylammonium (MA) and formamidinium (FA) as organic cations, MA0. Read More

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http://dx.doi.org/10.1039/c8cp07461eDOI Listing
February 2019

Equilibrium structures of the tetramezine diastereomers and their ratio: joint analysis of gas phase electron diffraction, quantum chemistry, and spectroscopic data.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russia.

For the first time, we applied a gas-phase electron diffraction (GED) method together with vibrational spectroscopy and quantum chemical calculations to investigate the equilibrium geometries of achiral meso and enantiomeric diastereomers of tetramezine [1,2-bis-(3,3-dimethyldiaziridin-1-yl)ethane] and their ratio in the mixture. In the joint structural analysis of these data, a new approach based on PES parameters is used in the framework of a static molecular model (small amplitude motion approximation). The agreement between the theoretical and experimental molecular intensities is characterized by a divergence factor Rf of 5. Read More

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http://dx.doi.org/10.1039/c8cp07607cDOI Listing
February 2019

Electrochemical flow cell enabling operando probing of electrocatalyst surfaces by X-ray spectroscopy and diffraction.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.

The rational improvement of current and developing electrochemical technologies requires atomistic understanding of electrode-electrolyte interfaces. However, examining these interfaces under operando conditions, where performance is typically evaluated and benchmarked, remains challenging, as it necessitates incorporating an operando probe during full electrochemical operation. In this study, we describe a custom electrochemical flow cell that enables near-surface-sensitive operando investigation of planar thin-film catalysts at significant hydrogen evolution reaction (HER) rates (in excess of -100 mA cm-2) using grazing incidence X-ray methods. Read More

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http://dx.doi.org/10.1039/c8cp07423bDOI Listing
February 2019

Membrane pore formation and ion selectivity of the Ebola virus delta peptide.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Department of Physics, Miami, FL 33199, USA and Biomolecular Sciences Institute Florida International University, Miami, FL 33199, USA.

The Ebola virus (EBOV) is a filamentous lipid-enveloped virus that causes severe hemorrhagic fever with a high fatality rate in humans. The EBOV encodes a glycoprotein that when cleaved, produces the delta peptide. Experimental evidence suggests that the delta peptide functions as a viroporin that enhances virus particle release through the host cell membrane. Read More

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http://dx.doi.org/10.1039/c8cp07323fDOI Listing
February 2019

Oxidative addition of carbon dioxide into mesoionics.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Laboratoire de Chimie et Physique Quantiques, IRSAMC-CNRS-UMR5626, Université Paul-Sabatier (Toulouse III), 31062 Toulouse Cedex 4, France.

This work examines the prospect of making stable mesoionic compounds of the type mesomeric betaine R+-CO2- from direct oxidative additions of carbon dioxide to suitably-delocalized singlet carbene moieties, with bold objectives of carbon sequestration and overall energy storage. A set of possible candidates for such mesoionic compounds is theoretically explored through DFT calculations, inspecting coupling paths, thermodynamic and kinetic stabilities, and geometric and electronic structural features. Among others, the addressed cationic parts include aromatic rings in their broader sense, phenalene systems, and odd linear polyenic chains. Read More

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http://dx.doi.org/10.1039/c8cp07321jDOI Listing
February 2019

Theoretical predication of the high hydrogen evolution catalytic activity for the cubic and tetragonal SnP systems.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People's Republic of China.

By means of density functional theory (DFT) calculations, we have systematically investigated the structures and hydrogen evolution reaction (HER) catalytic activities for the cubic and tetragonal SnP systems, both of which can be viewed as the stacking of SnP layers possessing structural features similar to the famous phosphorene. It is revealed that the (111) and (200) facets are the possible exposed surfaces of the cubic structure, while the possible exposed surfaces of the tetragonal structure are (101), (101[combining macron]), (110), (002) and (002[combining macron]) facets. The computed surface energies reveal that the P-terminated (111) surface and the (200) surface of the cubic SnP system as well as the P-terminated (101) and (101[combining macron]) surfaces and the (110) surface of the tetragonal SnP system can be considered as the more stable surfaces, in view of more favorable surface energy. Read More

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http://dx.doi.org/10.1039/c9cp00618dDOI Listing
February 2019

An experimental study of indene pyrolysis with synchrotron vacuum ultraviolet photoionization mass spectrometry.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Clean Combustion Research Centre, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.

Pyrolytic kinetics of indene was studied in a flow reactor at 30 and 760 Torr. Indene and its decomposition products, as well as polycyclic aromatic hydrocarbons (PAHs), were measured with synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Five literature models were selected to reproduce the experimental data and analyze the reaction kinetics of indene. Read More

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http://dx.doi.org/10.1039/c8cp07285jDOI Listing
February 2019

Investigating coordination flexibility of glycerophosphodiesterase (GpdQ) through interactions with mono-, di-, and triphosphoester (NPP, BNPP, GPE, and paraoxon) substrates.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Department of Chemistry, University of Miami, Coral Gables, FL 33146, USA.

In this study, interactions of the catalytically active binuclear form of glycerophosphodiesterase (GpdQ) with four chemically diverse substrates, i.e. NPP (a phosphomonoester), BNPP and GPE (both phosphodiesters), and paraoxon (a phosphotriester) have been investigated using all-atom molecular dynamics (MD) simulations. Read More

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http://dx.doi.org/10.1039/c8cp07031hDOI Listing
February 2019

Tritium trapping and migration mechanisms in LiO: a first-principles study.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Institute of Materials, China Academy of Engineering Physics, 621908, Jiangyou, China.

The tritium recovery behaviors and related mechanisms in lithium-based breeding materials are the major concerns in fusion reactors. In the present work, the energetics of intrinsic point defects and H-related defects in Li2O has been investigated by the first-principles method. The results show that the formation energies, charge states and relative stability of the intrinsic point defects and H-related defects in Li2O under working conditions vary with the energy level. Read More

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http://dx.doi.org/10.1039/c8cp07187jDOI Listing
February 2019

Reductive reactions via excess Li in mixture electrolytes of Li ion batteries: an ab initio molecular dynamics study.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Samsung Advanced Institute of Technology, Samsung Electronics, 130 Samsung-ro, Suwon, Gyeonggi-do 16678, Republic of Korea.

The electro-reduction of battery electrolytes plays a critical role in the formation of solid-electrolyte interphase (SEI) layers on the surfaces of negative electrodes. These layers have a significant influence on the performance of rechargeable battery cells. Using ab initio molecular dynamics, we demonstrate the electro-reduction of mixture electrolytes computationally by adding a certain number of excess Li+ first to form the solvation structure and the same number of electrons later for reductive reactions. Read More

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http://dx.doi.org/10.1039/c8cp04907fDOI Listing
February 2019

Novel superconducting structures of BH under high pressure.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Ames Laboratory-U.S. DOE and Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA.

The crystal structures of boron hydrides in a pressure range of 50-400 GPa were studied using the genetic algorithm (GA) method combined with first-principles density functional theory calculations. BH4 and BH5 are predicted to be thermodynamically unstable. Two new BH2 structures with Cmcm and C2/c space group symmetries, respectively, were predicted, in which the B atoms tend to form two-dimensional sheets. Read More

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http://dx.doi.org/10.1039/c9cp00310jDOI Listing
February 2019

Double graphitic-N doping for enhanced catalytic oxidation activity of carbocatalysts.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Institute of New Energy and Low Carbon Technology and the National Engineering Research Center for Flue Gas Desulfurization, Sichuan University, Chengdu, 610065, P. R. China. and Department of Chemistry and Institute for Computational Engineering and Sciences, the University of Texas at Austin, Austin, Texyas 78731, USA.

Graphitic N (GrN) doping is an effective way to promote the catalytic oxidation activities of pristine graphene, but a low doping density still limits its practical use. Based on DFT calculations, a double graphitic N (GrN) doping method is proposed. When the two GrN atoms are located at two different but nearby hexatomic rings, the dissociation of O2 molecules is significantly facilitated and the subsequently formed oxygen groups remain active for SO2 oxidation. Read More

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http://dx.doi.org/10.1039/c8cp07317aDOI Listing
February 2019

Phase stability of intercalated VO battery cathodes elucidated through the Goldschmidt tolerance factor.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Department of Chemistry, University College London, London, UK.

Orthorhombic V2O5 is a promising Mg battery cathode material, and reversible intercalation in the layered α-phase has been claimed experimentally. However, these results, based on electrochemistry and XRD, are controversial. Previous computational studies have predicted high activation barriers (∼1 eV) for ionic migration in α-V2O5, although improved Mg2+ mobility is expected in the δ-phase. Read More

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http://dx.doi.org/10.1039/c9cp00170kDOI Listing
February 2019

Interface Schottky barrier in HfNT/MSSe (T = F, O, OH; M = Mo, W) heterostructures.

Phys Chem Chem Phys 2019 Feb 20. Epub 2019 Feb 20.

Guizhou Key Laboratory of Economic System Simulation, Guizhou University of Finance and Economics, Guiyang 550004, People's Republic of China.

The Schottky barrier height (SBH) is a critical parameter that determines the carrier transfer at metal/semiconductor interfaces. In this work, the interfacial properties of Hf2NT2/MSSe (T = F, O, OH; M = Mo, W) heterostructures are systematically investigated using first-principles calculations. It is found that, for MoSSe and WSSe, the use of S or Se atomic layers in contact with Hf2NT2 can give significantly different SBHs. Read More

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http://dx.doi.org/10.1039/c9cp00028cDOI Listing
February 2019

Surface engineering of phosphorene nanoribbons by transition metal heteroatoms for spintronics.

Phys Chem Chem Phys 2019 Feb 19. Epub 2019 Feb 19.

Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.

Modulating the electronic and magnetic properties of phosphorene is important for fabricating multi-functional electronic and spintronic devices. Employing density functional theory combined with the non-equilibrium Green's function, we systematically investigate the electronic, magnetic and transport properties of hydrogenated armchair phosphorene nanoribbons chemically modified by 3d transition metal atoms (Sc, Ti, V, Cr, Mn, Fe, Co and Ni). With chemical adsorption of transition metal atoms, the phosphorene nanoribbons exhibit excellent spin-polarized transport properties. Read More

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http://dx.doi.org/10.1039/c9cp00072kDOI Listing
February 2019

Out-of-plane magnetic anisotropy energy in the NiBz molecule.

Phys Chem Chem Phys 2019 Feb 19. Epub 2019 Feb 19.

Centro de Física de Materiales CFM-MPC CSIC-UPV/EHU, Donostia International Physics Center (DIPC), Departamento de Física de Materiales, Fac. de Químicas, UPVEHU, 20018 San Sebastián, Spain.

Organometallic complexes formed by transition metals clusters and benzene molecules have already been synthesized, and in selected cases display magnetic properties controlled by external magnetic fields. We have studied NinBzn complexes made of nickel atoms surrounded by benzene molecules and here we focus specifically on the magnetic molecule Ni3Bz3. By means of calculations including relativistic spin-orbit terms, we show that this molecule reveals a large magnetic anisotropy energy of approximately 8 meV, found with the easy axis perpendicular to the metal atom plane. Read More

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http://dx.doi.org/10.1039/c8cp04251aDOI Listing
February 2019

The 3s Rydberg state as a doorway state in the ultrafast dynamics of 1,1-difluoroethylene.

Phys Chem Chem Phys 2019 Feb 19. Epub 2019 Feb 19.

Institute for Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währingerstr. 17, 1090 Vienna, Austria.

The deactivation dynamics of 1,1-difluoroethylene after light excitation is studied within the surface hopping formalism in the presence of 3s and 3p Rydberg states using multi-state second order perturbation theory (MS-CASPT2). Due to the proximity of the Rydberg π-3s state with the ππ* state, the states are mixed favoring ultrafast exchange of population via a conical intersection that closely resembles the equilibrium structure. After excitation, it is found that the π-3s state acts as a doorway state, trapping the population and delaying internal conversion to the ππ* state, from which deactivation to the closed-shell ground state takes place. Read More

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http://dx.doi.org/10.1039/c8cp07766eDOI Listing
February 2019

Benchmarking quantum chemistry methods for spin-state energetics of iron complexes against quantitative experimental data.

Authors:
Mariusz Radoń

Phys Chem Chem Phys 2019 Feb 19. Epub 2019 Feb 19.

Faculty of Chemistry, Jagiellonian University in Krakow, ul. Gronostajowa 2, 30-387 Kraków, Poland.

The accuracy of relative spin-state energetics predicted by selected quantum chemistry methods: coupled cluster theory at the CCSD(T) level, multiconfigurational perturbation theory (CASPT2, NEVPT2), multireference configuration interaction at the MRCISD+Q level, and a number of DFT methods, is quantitatively evaluated by comparison with the experimental data of four octahedral iron complexes. The available experimental data, either spin-forbidden transition energies or spin crossover enthalpies, are corrected for relevant environmental effects in order to derive the quantitative benchmark set of iron spin-state energetics. Comparison of theory predictions with the resulting reference data: (1) validates the high accuracy of the CCSD(T) method, particularly when based on Kohn-Sham orbitals, giving the maximum error below 2 kcal mol-1 and the mean absolute error (MAE) below 1 kcal mol-1; (2) corroborates the tendency of CASPT2 to systematically overstabilize higher-spin states by up to 5. Read More

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http://dx.doi.org/10.1039/c9cp00105kDOI Listing
February 2019

First-principles study of intrinsic point defects in MgSiAs.

Authors:
P Tuo B C Pan

Phys Chem Chem Phys 2019 Feb 19. Epub 2019 Feb 19.

Key Laboratory of Strongly-Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China. and Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.

MgSiAs2 is a potential infrared-nonlinear optical (IR-NLO) material, due to its fine second harmonic generation (SHG) performance and high laser damage threshold (LDT). In this study we systematically investigate its native point defects including vacancies, interstitials, and antisites using first-principles calculations with the Heyd-Scuseria-Ernzerhof hybrid functional. The defect formation energies and transition levels at the dilute limit are evaluated. Read More

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http://dx.doi.org/10.1039/c9cp00269cDOI Listing
February 2019

On the large apparent Stokes shift of phthalimides.

Phys Chem Chem Phys 2019 Feb 19. Epub 2019 Feb 19.

Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.

The photophysics of N-methylphthalimide (MP) in solution (cyclohexane, ethanol, acetonitrile, and water) was characterized by steady state as well as time resolved fluorescence and absorption spectroscopy. In all solvents the compound exhibits an unusually large Stokes shift of ∼10 000 cm-1. It is attributed to an ultrafast (<100 fs) depletion of the initially excited state, which results in the population of a weakly emitting state. Read More

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http://dx.doi.org/10.1039/c8cp07795aDOI Listing
February 2019

The maximum occupancy condition for the localized property-optimized orbitals.

Phys Chem Chem Phys 2019 Feb 19. Epub 2019 Feb 19.

Faculty of Physics of Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska Str., Kyiv 01601, Ukraine.

It is shown analytically that the Chemist's Localized Property-optimized Orbitals (CLPOs), which are the localized orbitals obtainable from the results of ab initio calculations by the open-source program JANPA (http://janpa.sourceforge.net/) according to the recently proposed optimal property partitioning condition, form the Lewis structure with nearly maximum possible total electron occupancy. Read More

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http://dx.doi.org/10.1039/c8cp07276kDOI Listing
February 2019

Stability and magnetism of FeN high-pressure phases.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia and Skolkovo Institute of Science and Technology, 3 Nobel St., Moscow 143026, Russia.

Most of the experimentally discovered compounds in the iron-nitrogen system belong to the low concentration part of the Fe-N phase diagram. In our paper, which is based on ab initio calculations, we have studied the formation and stability of high-pressure iron mono-nitride phases, and in particular a new magnetic phase with a NiAs-type structure. We have investigated the role of dynamic, thermodynamic and electronic properties, such as electronic correlations and pressure-induced phase stabilisation. Read More

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http://dx.doi.org/10.1039/c8cp07165aDOI Listing
February 2019

Excited state properties of a series of molecular photocatalysts investigated by time dependent density functional theory.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, Narutowicza 11/12, 80233 Gdańsk, Poland.

Time dependent density functional theory calculations are applied on a series of molecular photocatalysts of the type [(tbbpy)2M1(tpphz)M2X2]2+ (M1 = Ru, Os; M2 = Pd, Pt; X = Cl, I) in order to provide information concerning the photochemistry occurring upon excitation of the compounds in the visible region. To this aim, the energies, oscillator strengths and orbital characters of the singlet and triplet excited states are investigated. The structural modifications of the complexes have a strong impact on the excited states properties. Read More

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http://dx.doi.org/10.1039/c9cp00335eDOI Listing
February 2019

Effect of intermediate phases on the optical properties of PbI-rich CHNHPbI organic-inorganic hybrid perovskite.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

Laboratory of Photonics and Nanostructured Materials (DFMNano), Postgraduate course in Materials Science and Engineering of Federal Technological University of Paraná (UTFPR), CEP 86036-370, Londrina, Paraná, Brazil.

Methylammonium lead halide perovskite (CH3NH3PbI3) films, with high PbI2 concentration, were grown by the two-step spin coating method. The influence of the precursor concentration and annealing time on the optical and structural properties of the perovskite films was analyzed by optical absorption, photoluminescence, X-ray diffraction and scanning electron microscopy. The results showed that, in addition to the CH3NH3PbI3 and PbI2 phases, intermediate phases, such as (MA)2(DMF)2Pb3I8, were formed in the films, depending on the time and temperature of annealing, which can tune the optical absorption in the visible spectra. Read More

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http://xlink.rsc.org/?DOI=C8CP06916F
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http://dx.doi.org/10.1039/c8cp06916fDOI Listing
February 2019
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Reaction pathways for HCN on transition metal surfaces.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

Department of Chemistry, University of Illinois at Chicago, 845 W Taylor Street, Chicago, IL 60607, USA.

The adsorption and decomposition of HCN on the Pd(111) and Ru(001) surfaces have been studied with reflection absorption infrared spectroscopy and density functional theory calculations. The results are compared to earlier studies of HCN adsorption on the Pt(111) and Cu(100) surfaces. In all cases the initial adsorption at low temperatures gives rise to a ν(C-H) stretch peak at ∼3300 cm-1, which is very close to the gas phase value indicating that the triple CN bond is retained for the adsorbed molecule. Read More

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http://dx.doi.org/10.1039/c8cp07548dDOI Listing
February 2019

Transition metal-containing molecular devices: controllable single-spin negative differential thermoelectric resistance effects under gate voltages.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

College of Physics and Electronic Engineering, Changshu Institute of Technology, Changshu 215500, China.

Based on the non-equilibrium Green function method combined with density functional theory, we investigate the spin-resolved transport through transition metal (TM) (= Cr, Mn, Fe and Ru)-containing molecular devices in the presence of zigzag graphene nanoribbon (ZGNR) electrodes. The wave-function mismatch for the single-spin component results in a perfect spin-filtering property near the Fermi level. Moreover, we also observe Fano and Breit-Wigner resonance peaks in the transmission spectrum. Read More

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http://dx.doi.org/10.1039/c8cp07049kDOI Listing
February 2019

Discovery of a ferroelastic topological insulator in a two-dimensional tetragonal lattice.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

School of Physics and Technology, University of Jinan, Jinan, Shandong 250022, People's Republic of China.

Ferroelasticity and band topology are two intriguing yet distinct quantum states of condensed matter materials. Their coexistence in a single two-dimensional (2D) lattice, however, has never been observed. Here, we found that the 2D tetragonal HfC monolayer allowed simultaneous presence of ferroelastic and topological orders. Read More

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http://xlink.rsc.org/?DOI=C9CP00272C
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http://dx.doi.org/10.1039/c9cp00272cDOI Listing
February 2019
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Conformation-induced separation of 3-chloropropene from 1-chloropropane through nanoporous monolayer graphenes.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

School of Space and Environment, Beihang University, Beijing 100191, China and CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100190, China.

Achieving ultrahigh selectivity for separating paraffin/olefin mixtures with physical and chemical similarity, especially for halohydrocarbons, is a long-standing challenge in high-purity polymer production. We explored three H-saturated nanoporous graphene (NG) membranes with appropriate pore geometries that can achieve the complete exclusion of 1-chloropropane (C3H7Cl) from C3H5Cl during molecular dynamics simulations. Inferred from thermodynamics calculations, C3H5Cl has a lower energy barrier of penetration than C3H7Cl and the NG membranes show preferential adsorption to C3H5Cl, which facilitate the penetration of C3H5Cl through the pores. Read More

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http://dx.doi.org/10.1039/c9cp00137aDOI Listing
February 2019

Development and application of a comprehensive machine learning program for predicting molecular biochemical and pharmacological properties.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

Department of Bioscience and Biotechnology, Sejong University, 209 Neungdong-ro, Kwangjin-gu, Seoul 05006, Korea.

We establish a comprehensive quantitative structure-activity relationship (QSAR) model termed AlphaQ through the machine learning algorithm to associate the fully quantum mechanical molecular descriptors with various biochemical and pharmacological properties. Preliminarily, a novel method for molecular structural alignments was developed in such a way to maximize the quantum mechanical cross correlations among the molecules. Besides the improvement of structural alignments, three-dimensional (3D) distribution of the molecular electrostatic potential was introduced as the unique numerical descriptor for individual molecules. Read More

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http://dx.doi.org/10.1039/c8cp07002dDOI Listing
February 2019

Using nanotubes to study the phonon spectrum of two-dimensional materials.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

Institute of Materials Chemistry, TU Wien, A-1060 Vienna, Austria.

We propose a convenient method to characterize the acoustic phonon branches of 2D monolayer materials using measurements of the infrared- and Raman-active vibrational modes of nanotubes. The relations we employ are derived from a symmetry analysis based directly on the line groups of nanotubes. We perform extensive ab initio calculations for the MoS2 monolayer and nanotubes to evaluate the method and illustrate all our results. Read More

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http://dx.doi.org/10.1039/c9cp00052fDOI Listing
February 2019

Tetragonal and trigonal MoB monolayers: two new low-dimensional materials for Li-ion and Na-ion batteries.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

Institute of High Energy Physics, Chinese Academy of Science (CAS), Beijing 100049, China. and Dongguan Neutron Science Center, Dongguan 523803, China and Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China.

In this study, we report two new Mo2B2 monolayers and investigate their stabilities, electronic structures, lattice dynamics, and properties as anode materials for energy storage by using the crystal structure prediction technique and first-principles method. The calculated phonon spectra and electrical structures indicate that our predicted tetragonal and trigonal Mo2B2 (tetr- and tri-Mo2B2) monolayers possess excellent electronic conductivity and great stability. The adsorption energies of Li/Na on them are negative enough to ensure stability and safety under operating conditions. Read More

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http://dx.doi.org/10.1039/c9cp00012gDOI Listing
February 2019

Cytochrome c oxidase structures suggest a four-state stochastic pump mechanism.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

University of Bari "Aldo Moro", Department of Basic Medical Sciences, Neurosciences and Sense Organs (SMBNOS), Bari, 70124, Italy.

Cytochrome c oxidase catalyses the terminal step of cellular respiration in eukaryotes and in many prokaryotes. This enzyme reduces molecular oxygen by means of a process coupled with proton pumping. Models for proton pumping activity in cytochrome c oxidase can be divided into two groups, which are still strongly debated to date: one in which haem a is the key player, and another where this role is covered by the oxygen reduction site. Read More

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http://dx.doi.org/10.1039/c8cp07365aDOI Listing
February 2019

Photoluminescence properties of self-assembled chitosan-based composites containing semiconductor nanocrystals.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

Siberian Federal University, Svobodny Prospect 79, 660041 Krasnoyarsk, Russia.

The photoluminescence (PL) properties of composites obtained by embedding green-emitting semiconductor nanocrystals (NCs) of two different types (thiol-capped CdTe and CdSe/ZnS) into chitosan-based biopolymer particles were investigated. The synthesis of self-assembled particles from oppositely charged polysaccharides involved a preliminary electrostatic binding of positively charged chitosan chains by negatively charged functional groups of NC stabilizing ligands. The amount of NCs and the acidity of the solution were found to be important parameters influencing the PL. Read More

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http://dx.doi.org/10.1039/c8cp07051bDOI Listing
February 2019

Raising glass transition temperature of polymer nanofilms as a function of negative interface energy.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

Key Laboratory of Automobile Materials, Ministry of Education (Jilin University), School of Materials Science and Engineering, Jilin University, Changchun 130022, China.

Based on a thermodynamic approach, glass transition temperature (Tg) of substrate-supported polymer nanofilms (s-PNFs) is investigated for carbon-chain polymers, taking the role of the interface energy into consideration. Relative to the Tg depression, originating from the positive interface energy due to the weak interfacial van der Waals interactions, the Tg raise is reversely induced by the negative interface energy, induced by the hydrogen bonds formed between the side-chains of polymers and the surface hydroxyl groups of substrates. Moreover, the Tg raise can be reinforced for s-PNFs with simple side-chains. Read More

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http://dx.doi.org/10.1039/c8cp07267aDOI Listing
February 2019

A consolidated account of electrochemical determination of band structure parameters in II-VI semiconductor quantum dots: a tutorial review.

Phys Chem Chem Phys 2019 Feb 18. Epub 2019 Feb 18.

Department of Chemistry, IIT Delhi, New Delhi 110016, India.

Probing absolute electronic energy levels in semiconductor quantum dots (Q-dots) is crucial for engineering their electronic band structure and hence for precise design of composite nano-structure based devices. The use of electrochemistry has allowed us to investigate size, shape and composition dependent band structure parameters viz. the conduction band edge, valence band edge & quasi-particle gap and to establish novel charge induced phenomena in colloidal semiconductor Q-dots. Read More

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http://dx.doi.org/10.1039/c8cp06847jDOI Listing
February 2019
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