6,759 results match your criteria Chemphyschem : a European journal of chemical physics and physical chemistry[Journal]


Methylene Group Transfer in Carbonyl Compounds Discovered in Silico and Detected Experimentally.

Chemphyschem 2018 Dec 6. Epub 2018 Dec 6.

RUSSIAN FEDERATION.

Previously unknown transformation of aldehydes, ketones and carboxylic acid derivatives leads to the formation of substituted oxiranes, aziridines and azirines as shown by DFT and MP2 computations. Formations of 2,2-dimethyloxirane-d8 from acetone-d6, phenylazirine-d2 from benzonitrile and 2-methyl-2-(4-hydroxyphenyl)-oxirane from 4-hydroxyacetophenone were detected experimentally by electrospray ionization mass-spectrometry with heated desolvating capillary. This reaction is a truly concerted process characterized by high activation barriers (activation enthalpies 320-480 kJ/mol). Read More

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December 2018

Physical Chemistry in all its Diversity.

Chemphyschem 2018 Dec 11. Epub 2018 Dec 11.

Wiley-VCH Verlag GmbH & Co. KGaA, ChemPhysChem, Boschstrasse 12, 69469, Weinheim, Germany.

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December 2018

Spin cross over assisted spin switching and rectification action in half metallic Graphitic Carbon Nitride (g-C4N3).

Chemphyschem 2018 Dec 9. Epub 2018 Dec 9.

JIS College of Engineering Block A, Phase-III, Kalyani, Nadia, West Bengal, India, INDIA.

Herein, we report potential multifunctional spintronic action of half metallic graphitic carbon nitride (g-C4N3). We observed electrostatic spin crossover action at an applied electric field of -0.77 V/nm which, eventually leads to spin switching action and change in sign of bias dependent spin injection coefficient. Read More

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December 2018

Characterization of Brain Metabolism by Nuclear Magnetic Resonance.

Chemphyschem 2018 Dec 7. Epub 2018 Dec 7.

University of Florida, Biochemistry & Molecular Biology, PO Box 100245, 32610-0245, Gainesville, UNITED STATES.

The noninvasive, quantitative ability of nuclear magnetic resonance spectroscopy (NMR) to characterize small molecule metabolites has long been recognized as a major strength of its application in biology. Numerous techniques exist for characterizing metabolism in living, excised, or extracted tissue, with a particular focus on ¹H-based methods due to the high sensitivity and natural abundance of protons. With the increasing use of high magnetic fields, the utility of in vivo ¹H magnetic resonance spectroscopy (MRS) has markedly improved for measuring specific metabolite concentrations in biological tissues. Read More

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December 2018
1 Read

Understanding Local-Field Correction Factors in the Framework of the Onsager-Böttcher Model.

Chemphyschem 2018 Dec 11. Epub 2018 Dec 11.

Université Lyon 1, ILM (UMR 5306), 10 rue Ada Byron, Bâtiment Kastler, 69622, Villeurbanne, FRANCE.

The determination of the appropriate local-field factor for quantifying the response of a molecule to an external electric field is of major importance in optical spectroscopy. Although numerous studies have dealt with the evolution of the optical properties of emitters as a function of their environment, the choice of the model used to quantify local fields is still ambiguous, and sometimes even arbitrary. In this paper, we review the Onsager-Böttcher model, which introduces the polarizability of the probe molecule as the determinant parameter for the local field factor, and we establish a simple conceptual framework encompassing all commonly used models. Read More

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December 2018
1 Read

Single-scan diffusion-ordered NMR spectroscopy of SABRE-hyperpolarized mixtures.

Chemphyschem 2018 Dec 6. Epub 2018 Dec 6.

Centre National de la Recherche Scientifique, Bâtiment 27, 1, avenue de la Terrasse, 91198, Gif-sur-Yvette, FRANCE.

The analysis of complex mixtures of dissolved molecules is a major challenge, especially for systems that gradually evolve, e.g., in the course of a chemical reaction or in the case of chemical instability. Read More

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December 2018
1 Read

Colloidal FeIII, MnIII, CoIII and CuII hydroxides stabilized by starch as catalysts of water oxidation reaction with one electron oxidant Ru(bpy)33.

Chemphyschem 2018 Dec 6. Epub 2018 Dec 6.

Boreskov Institute of Catalysis RAS, pr. Lavrenteva 5, 630000, Novosibirsk, RUSSIAN FEDERATION.

Colloidal catalysts for water oxidation to dioxygen, which are stable on storage and under the reaction conditions, are synthesized based on CoIII, MnIII, FeIII and CuII hydroxides. Stabilization of the colloids with dextrated starch allows the process of hydroxide ageing to be stopped at the stage of the formation of primary nuclei (ca. 2-3 nm from TEM data). Read More

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December 2018
2 Reads

Temperature- and Pressure-induced Structural Transition of Binary (C₄H₈O + CH₄) Clathrate Hydrates.

Chemphyschem 2018 Dec 5. Epub 2018 Dec 5.

The Korea Advanced Institute of Science and Technology KAIST, Chemical & Biomolecular Engineering, 291 Daehak-ro, Yuseo, 34141, Daejeon, KOREA, REPUBLIC OF.

We discover new structure II (sII) hydrate forming agents of two C₄H₈O molecules (2-methyl-2-propen-1-ol and 2-butanone) and report the abnormal structural transition of binary C₄H₈O + CH₄ hydrates between structure I (sI) and sII with varying temperature and pressure conditions. In both (2-methyl-2-propen-1-ol + CH₄) and (2-butanone + CH₄) system, the phase boundary of the two different hydrate phases (sI and sII) exists at the slope change of the phase-equilibrium curve in the semi-logarithmic plots. We confirm the crystal structures of two hydrates synthesized at low (278 K and 6 MPa) and high (286 K and 15 MPa) temperature and pressure conditions by using high resolution powder diffraction and Raman spectroscopy. Read More

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December 2018

Simple Estimates for Eutectic Behavior.

Authors:
Pekka Pyykkö

Chemphyschem 2018 Dec 5. Epub 2018 Dec 5.

Department of Chemistry, University of Helsinki, POB 55 (A. I. Virtasen aukio 1), 00014, Helsinki, Finland.

A simple formula is derived for the eutectic point of an A-B system in terms of the monomer melting points and melting enthalpies. This estimate is tested on several non-ionic or ionic systems, with or without common ions, including choline chloride/urea mixtures. The results are compared with the Schröder-van Laar equation. Read More

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December 2018
2 Reads

Tetrakis(oxadiazolylphenyl)pyrazines: New St. Andrew's Cross- Shaped Liquid Crystals.

Chemphyschem 2018 Dec 4. Epub 2018 Dec 4.

Johannes Gutenberg Universitat Mainz, Institut für Org. Chemie, Duesbergweg 10-14, 55099, Mainz, GERMANY.

π-Conjugated molecules with the shape of St. Andrews cross have been synthesized via fourfold Huisgen reaction. Four 2,5-diaryl-1,3,4-oxadiazol arms are attached to a central pyrazine nucleus. Read More

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December 2018
1 Read

Single-point Attack of Two H O Molecules towards a Lewis Acid Site on the GaAl Clusters for Hydrogen Evolution.

Chemphyschem 2018 Nov 29. Epub 2018 Nov 29.

State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences., 100190, Beijing, China.

The hydrogen evolution reaction (HER) of water with metallic aluminum-based materials provides an important way to address the global energy challenge; however, fundamental mechanism and reaction dynamics governing the chemical and electronic properties remain a debated research topic. Here we further study the HER mechanisms for water splitting on typical 13-atoms clusters, Al Ga and Al , by first-principles DFT calculations. We noted that the doping of a Ga atom into the Al cluster could reduce the transition state barrier for H O dissociation on the metal cluster. Read More

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November 2018

A Quantitative and Reliable Calibration Standard for Dual-Color Fluorescence Cross-Correlation Spectroscopy.

Chemphyschem 2018 Nov 29. Epub 2018 Nov 29.

Institute of Chemistry, ZIK HALOmem and Charles-Tanford-Protein Center, University of Halle, Kurt-Mothes-Str. 3a, 06120, Halle, Germany.

Dual-color Fluorescence Cross-Correlation Spectroscopy (dcFCCS) allows binding analysis of biomolecules. Combining cross- and autocorrelation amplitudes yields binding degrees and concentrations of bound and unbound species. However, non-ideal detection volume overlap reduces the cross-correlation, causing overestimation of the K . Read More

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November 2018

Identification of Individual Reaction Steps in Complex Radical Reactions Involving Gold Nanoparticles.

Chemphyschem 2018 Nov 28. Epub 2018 Nov 28.

University of California, Davis, Department of Chemistry, One Shields Ave, Davis, California, 95616, United States.

A triple-jump model is invoked to help identify individual reaction steps in complex chemical reactions involving radical reactants in the presence of gold nanoparticles. The model consists of three sequential reaction phases: production of radicals, stabilization of radicals, and conversion from radical intermediates to final products. Isolated reaction phases were studied with electron paramagnetic resonance spectroscopy. Read More

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November 2018

Superweak Coordinating Anion as Superstrong Enhancer of Cyanine Organic Semiconductor Properties.

Chemphyschem 2018 Nov 28. Epub 2018 Nov 28.

Laboratory for Functional Polymers, Swiss Federal Laboratories for Materials Science and Technology, Empa, Überlandstrasse 129, Dübendorf, Switzerland.

The superweak tetrakis(nonafluoro-tert-butoxy)aluminate coordinating anion was employed to introduce pseudo-gas-phase conditions to the 2-[5-(1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene)-1,3-pentadien-1-yl]-1,3,3-trimethyl-3H-indolium chromophore. The resulting formation of a photoactive organic-inorganic hybrid salt has led to a highly stabilized excited state of the organic chromophore mainly due to the minimized lattice energy and Coulomb interactions. These highly beneficial features caused by the well dispersed negative charge of the anion have led to an enhanced neat spin-casted film fluorescence intensity, prolonged fluorescence lifetime, smooth thin film surfaces and a record power photovoltaic efficiency of 3. Read More

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November 2018
1 Read

One Dimensional CdS Nanotube vs CdS Bulk Structure for Photocatalytic Water Splitting: Role of Dimensionality.

Chemphyschem 2018 Nov 28. Epub 2018 Nov 28.

Indian Institute of Technology Indore, Discipline of Chemistry, Khandwa Road, 452017, Indore, INDIA.

Using the state-of-the-art density functional theoretical calculations, we have modelled a facetted CdS nanotube (NT) catalyst for photocatalytic water splitting. The overall photocatalytic activity of the CdS photocatalyst has been predicted based on the electronic structures, band edge alignment, and overpotential study. For comparisons, we have also investigated the water spilitting process over the CdS bulk structure. Read More

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November 2018

Interleaved Dual NMR Acquisition of Equivalent Transfer Pathways in TOCSY and HSQC Experiments.

Chemphyschem 2018 Nov 28. Epub 2018 Nov 28.

Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Catalonia.

A dual NMR data acquisition strategy to handle and detect two active equivalent transfer pathways is presented and discussed. We illustrate the power of this time-efficient approach by collecting two different 2D spectra simultaneously in a single experiment: i) TOCSY or HSQC-TOCSY spectra with different mixing times, ii) F2- C-coupled and decoupled HSQC spectra, iii) conventional and pure-shift HSQC spectra, or iv) complementary HSQC and HSQC-TOCSY spectra. Read More

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November 2018

Quantitative Evaluation of Infrared Absorbance Spectra - Lorentz Profile versus Lorentz Oscillator.

Chemphyschem 2018 Nov 27. Epub 2018 Nov 27.

Spectroscopy/Imaging, Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, Germany.

We present the theoretical basis for a profound upgrade of the method of absorbance band fitting ("band deconvolution"), which requires only minute changes in the code of corresponding spectrometer software. This upgrade is based on a (re-)connection of the damped harmonic oscillator model ("Lorentz oscillator") and the Lorentz profile used for band fitting. Based on this reconnection, we provide a proper extension to multiple oscillators. Read More

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November 2018

Multiple Ether-Functionalized Phosphonium Ionic Liquids as Highly Fluid Electrolytes.

Chemphyschem 2018 Nov 27. Epub 2018 Nov 27.

Physical Chemistry, Saarland University, Campus B 2 2, 66123, Saarbrücken, Germany.

Ionic liquids (ILs) are promising electrolytes, although their often high viscosity remains a serious drawback. The latter can be addressed by the introduction of multiple ether functionalization. Based on the highly atom efficient synthesis of tris(2-ethoxyethyl) phosphine, several new phosphonium ionic liquids were prepared, which allows studying the influence of the ether side chains. Read More

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November 2018

Probing effects of the number and positions of -OCH₃ and -CN substituents on color tuning of Ir (III) complex derivatives through a joint study of computation and experiment.

Chemphyschem 2018 Nov 27. Epub 2018 Nov 27.

Sichuan University, Chemistry, 29 Wangjiang road, wuhou section, 610064, Chengdu , CHINA.

We performed a joint theoretical and experimental study on sixteen Ir (III) complexes bearing a similar molecular platform of bis(2-phenylbenzothiozolato-N,C²´) iridium(III) (acetylacetonate) by grafting -OCH₃ groups and/or -CN groups on different positions of the C-related arene moiety of the C^N ligand (C-ring). Our results reveal that the introduction of -CN renders an overall drop in the FMO energy levels while a reverse increase is observed for -OCH₃. The ortho- and para-sites of the C-ring are more effective substitution positions to modulate the HOMO energy level due to the fact that the electronic density of HOMO mainly locates at them while the meta-site would induce a stronger impact on LUMO since the electronic density of LUMO mainly distributes over the position. Read More

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November 2018
3 Reads

The S-S bridge: An experimental-computational mixed estimation of the equilibrium structure of diphenyl disulfide.

Chemphyschem 2018 Nov 26. Epub 2018 Nov 26.

Universidad de Valladolid, Quimica Fisica y Quimica Inorganica Facultad de Ciencias, Paseo de Belen, 7, 47011, Valladolid, SPAIN.

The disulfide bridge (-S-S-) is an important structural motif in organic and protein chemistry, but only a few accurate equilibrium structures are documented. We report the results of supersonic-jet microwave spectroscopy experiments on the rotational spectra of diphenyl disulfide, C6H5-S-S-C6H5 (including all 13C and 34S monosubstituted isotopologues), and the determination of the equilibrium structure by the mixed estimation (ME) method. A single conformation of C2 symmetry was observed in the gas phase. Read More

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November 2018

Metal-ion Binding to Host Defense Peptide Piscidin 3 Observed in Phospholipid Bilayers by Magic Angle Spinning Solid-state NMR.

Chemphyschem 2018 Nov 24. Epub 2018 Nov 24.

College of William and Mary, Applied Science, 540 Landrum Drive, 23185, Williamsburg, UNITED STATES.

Cationic antimicrobial peptides (AMPs) are essential components of the innate immune system. They have attracted interest as novel compounds with the potential to treat infections with multi-drug resistant bacteria. In this study, we investigate piscidin 3 (P3), an AMP that was first discovered in the mast cells of hybrid striped bass. Read More

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November 2018
1 Read

Identifying Terminal Assembly Propensity of Amyloidal Peptides by Scanning Tunneling Microscopy.

Chemphyschem 2018 Nov 22. Epub 2018 Nov 22.

CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, No. 11 ZhongGuanCun BeiYiTiao, 100190, Beijing, P.R. China.

The abnormal accumulation of beta-amyloids (Aβ) in brain is considered as a key initiating cause for Alzheimer's disease (AD) due to their richness in plaques and self-aggregate propensity. In recent studies, N-terminally extended Aβ peptides (NTE-Aβ) with the N-terminus originating prior to the canonical β-secretase cleavage site were found in humans and suggested to have possible relevance to AD. However, the effects of the extended N-terminus on the amyloidegenic structure and aggregation propensity have not been fully elucidated. Read More

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November 2018

Adsorption of Cyclohexane in Pure Silica Zeolites: High-Throughput Computational Screening Validated by Experimental Data.

Chemphyschem 2018 Nov 20. Epub 2018 Nov 20.

Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, Ctra. Utrera km 1. ES-41013, Seville, Spain.

Adsorption of cyclohexane in pure silica zeolites was studied experimentally and by molecular simulations. Based on the adsorption isobars obtained from the quasi-equilibrated temperature adsorption and desorption (QE-TPDA) measurements and reported adsorption isotherms for high-silica zeolites Y, ZSM-5, and ZSM-11 we refined Lennard-Jones parameters for guest-host interactions available in the literature. Adsorption of cyclohexane from equimolar mixture of twisted-boat and chair conformations has been screened in 171 pure silica zeolitic structures using grand canonical Monte Carlo simulations. Read More

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November 2018

Computational Prediction of H and C NMR Chemical Shifts for Protonated Alkylpyrroles: Electron Correlation and Not Solvation is the Salvation.

Chemphyschem 2018 Nov 19. Epub 2018 Nov 19.

Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100, Copenhagen, Denmark.

Prediction of chemical shifts in organic cations is known to be a challenge. In this article we meet this challenge for α-protonated alkylpyrroles, a class of compounds not yet studied in this context, and present a combined experimental and theoretical study of the C and H chemical shifts in three selected pyrroles. We have investigated the importance of the solvation model, basis set, and quantum chemical method with the goal of developing a simple computational protocol, which allows prediction of C and H chemical shifts with sufficient accuracy for identifying such compounds in mixtures. Read More

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November 2018
1 Read
3.419 Impact Factor

Probing Membrane Protein Insertion into Lipid Bilayers by Solid-State NMR.

Chemphyschem 2018 Nov 19. Epub 2018 Nov 19.

Department of NMR based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany.

Determination of the environment surrounding a protein is often key to understanding its function and can also be used to infer the structural properties of the protein. By using proton-detected solid-state NMR, we show that reduced spin diffusion within the protein under conditions of fast magic-angle spinning, high magnetic field, and sample deuteration allows the efficient measurement of site-specific exposure to mobile water and lipids. We demonstrate this site specificity on two membrane proteins, the human voltage dependent anion channel, and the alkane transporter AlkL from Pseudomonas putida. Read More

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November 2018
3 Reads

Microsecond Protein Dynamics from Combined Bloch-McConnell and Near-Rotary-Resonance R1rho Relaxation-Dispersion MAS NMR.

Chemphyschem 2018 Nov 16. Epub 2018 Nov 16.

CEA; CNRS; Universite J. Fourier, Institut de Biologie Structurale, 6, rue Jules Horowitz, 38000, Grenoble, FRANCE.

Studying protein dynamics on microsecond-to-millisecond time scales can provide important insight into protein function. In magic-angle-spinning (MAS) NMR, microsecond dynamics can be visualized by R1rho rotating-frame relaxation dispersion experiments in different regimes of radio-frequency field strengths: at low RF field strength, isotropic-chemical-shift fluctuation leads to "Bloch-McConnell-type" relaxation dispersion, while when the RF field approaches resonance conditions with the MAS frequency ("Near-Rotary-Resonance Relaxation Dispersion", NERRD), bond angle fluctuations become visible through the dipolar/CSA reorientation. Here we explore the joint analysis of both regimes to gain comprehensive insight into motion in terms of geometric amplitudes, chemical-shift changes, populations and exchange kinetics. Read More

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November 2018

Circular Dichroism and Isotropy - Polarity Reversal of Ellipticity in Molecular Films of 1,1'-Bi-2-Naphtol.

Chemphyschem 2018 Nov 16. Epub 2018 Nov 16.

Chair of Physical Chemistry, Chemistry Department & Catalysis Research Center, Technical University of Munich, Lichtenbergstr. 4, D-, 85748, Garching, Germany.

We have studied the circular dichroism (CD), in the ultraviolet and visible regions, of the transparent, chiral molecule 1,1'-Bi-2-naphtol (BINOL) in 1.5 μm thick films. The initial transparent film shows an additional negative cotton effect in the CD compared to solution. Read More

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November 2018

Molecular Dynamics Simulations of Water-Mediated Cholesterol Capture within an Open-Ended Single-Walled Carbon Nanotube.

Chemphyschem 2018 Nov 16. Epub 2018 Nov 16.

Department of Chemical Engineering, Visvesvaraya National Institute of Technology (VNIT), Nagpur, Maharashtra, India.

The excess concentration of cholesterol in the bloodstream can be brought down to a safer level by utilizing a potential cholesterol-binding agent such as a carbon nanotube (CNT). Here, we have probed solvent-mediated interactions between cholesterol and CNT by performing molecular dynamics simulations and potential-of-mean force (PMF) calculations. Simulations predict favorable interactions between water-mediated cholesterol and CNT owing to strong mutual interactions between them, whereas water plays an opposing role in the association. Read More

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November 2018

Self-Assembly of Nanoparticles into Two Dimensional Arrays for Catalytic Applications.

Chemphyschem 2018 Nov 15. Epub 2018 Nov 15.

Brown University, Department of Chemistry, 324 Brook St., Box H, 2912, Providence, UNITED STATES.

Self-assembly of nanoparticles (NPs) is at the heart of nanotechnology, and has shown many potential applications in fabricating nanodevices with highly controlled functionality. Two-dimensional (2D) arrays of NPs can provide a thin and uniform NP array with each NP being exposed on the surface to maximize NP catalysis. This minireview summarizes the recent progress on the fabrication and application of 2D NP arrays. Read More

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November 2018

A Robust and Cost-Efficient Scheme for Accurate Conformational Energies of Organic Molecules.

Chemphyschem 2018 Nov 16. Epub 2018 Nov 16.

Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region, 141700, Russia.

Several standard semiempirical methods as well as the MMFF94 force field approximation have been tested in reproducing 8 DLPNO-CCSD(T)/cc-pVTZ level conformational energies and spatial structures for 37 organic molecules representing pharmaceuticals, drugs, catalysts, synthetic precursors, industry-related chemicals (37conf8 database). All contemporary semiempirical methods surpass their standard counterparts resulting in more reliable conformational energies and spatial structures, even though at significantly higher computational costs. However, even these methods show unexpected failures in reproducing energy differences between several conformers of the crown ether 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6). Read More

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November 2018
2 Reads

B7 Liquid Crystal Filament Growth in Presence of Carbon Nanotubes.

Chemphyschem 2018 Nov 14. Epub 2018 Nov 14.

School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M139PL, United Kingdom.

Liquid crystal phases formed from bent-core mesogens have attracted much interest of the liquid crystal research community, due to the manifestation of chirality effects from achiral molecules. One of the most elusive of the bent-core phases is the B7 phase, which at its early stage often forms in a helical filament fashion. We investigate the growth of such filaments in the presence of single-walled nanotubes to elucidate possible effects on the growth dynamics and helicity of B7 helical filaments. Read More

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November 2018

Matrix-induced Linear Stark Effect of Single Dibenzoterrylene Molecules in 2,3-Dibromonaphthalene Crystal.

Chemphyschem 2018 Nov 14. Epub 2018 Nov 14.

Institute of Physics, Polish Academy of Sciences Al. Lotnikow 32/46, 02-668, Warsaw, Poland.

Absorption and fluorescence from single molecules can be tuned by applying an external electric field - a phenomenon known as the Stark effect. A linear Stark effect is associated to a lack of centrosymmetry of the guest in the host matrix. Centrosymmetric guests can display a linear Stark effect in disordered matrices, but the response of individual guest molecules is often relatively weak and non-uniform, with a broad distribution of the Stark coefficients. Read More

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November 2018
8 Reads

Measurement of very fast exchange rates of individual amide protons in proteins by NMR spectroscopy.

Chemphyschem 2018 Nov 13. Epub 2018 Nov 13.

Interdisciplinary Nanoscience Center, Chemistry, Gustav Wieds Vej 14, 8000, Aarhus, DENMARK.

NMR spectroscopy is a pivotal technique to measure hydrogen exchange rates in proteins. However, currently available NMR methods to measure backbone exchange are limited to rates of up to a few per second. To raise this limit, we have developed an approach that is capable of measuring proton exchange rates up to approximately 10^4 s-1. Read More

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November 2018

On the Use of Thermodynamic Cycles for the Calculation of Standard Potentials for the Oxidation of Solid Metals in Solution.

Chemphyschem 2018 Nov 13. Epub 2018 Nov 13.

Institute of Chemical Research of Catalonia, The Barcelona Institute of Science and Technology Avgda. Països Catalans, 16, 43007, Tarragona, Spain.

The performance of a thermodynamic cycle for the calculation of the standard reduction potential (SRP) of a series of metals is examined. It is found that the introduction of simple entropic corrections substantially improves the agreement with experimental data. The accuracy of the estimations is in the range of 0. Read More

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November 2018

Revisiting the Origin of Bacterial Bioluminescence: QM/MM Study on Oxygenation Reaction of Reduced Flavin in Protein.

Chemphyschem 2018 Nov 11. Epub 2018 Nov 11.

Key Laboratory of Theoretical and Computational Photochemistry Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, P. R. China.

Bacterial bioluminescence is initiated by the oxygenation reaction of reduced flavin mononucleotide in luciferase. This enzymatic oxygenation occurs in a wide range of biological processes including cellular redox metabolism, biocatalysis, biosynthesis and homeostasis. However, little is known about the mechanism of the enzymatic reaction between singlet reduced flavin and triplet oxygen. Read More

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November 2018

Energetic, Topological and Electric Field Analyses of Cation-Cation Nucleic Acid Interactions in Watson-Crick Disposition.

Chemphyschem 2018 Nov 9. Epub 2018 Nov 9.

Université de Lorraine, CNRS, CRM2, Nancy, France.

A theoretical study of the effect of the diprotonation on the nucleic acid bases (A : U, A : T and G : C) in Watson-Crick conformation has been carried out by means of DFT computational methods in vacuum. In addition, the corresponding neutral and monoprotonated binary complexes have been considered. Most of the diprotonated species studied are stable, even though the binding energy is positive due to the overall repulsive electrostatic term. Read More

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November 2018

Probing Adsorption Configurations of Small Molecules on Surfaces by Single-Molecule Tip-Enhanced Raman Spectroscopy.

Chemphyschem 2018 Nov 9. Epub 2018 Nov 9.

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, Anhui, 230026, China.

Determining the adsorption configurations of organic molecules on surfaces, especially for relatively small molecules, is a key issue for understanding the microscopic physical and chemical processes in surface science. In this work, we have applied low-temperature ultrahigh-vacuum tip-enhanced Raman scattering (TERS) technique to distinguish the configurations of small 4,4'-bipyridine (44BPY) molecules adsorbed on the Ag(111) surface. The observed Raman spectra exhibit notable differences in the spectral features which can be assigned to three different molecular orientations, each featuring a specific fingerprint pattern based on the TERS selection rule that determines the distribution of the relative intensities of different vibrational peaks. Read More

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November 2018
6 Reads

In situ Second-Harmonic Generation Circular Dichroism with Submonolayer Sensitivity.

Chemphyschem 2018 Nov 7. Epub 2018 Nov 7.

Chair of Physical Chemistry Chemistry Department & Catalysis Research Center, Technical University of Munich, Lichtenbergstr. 4, D-, 85748, Garching, Germany.

In this work, we present an experimental setup for the in situ and ex situ study of the optical activity of samples, which can be prepared under ultra-high vacuum (UHV) conditions by second-harmonic generation circular dichroism (SHG-CD) over a broad spectral range. The use of a racemic mixture as a qualified reference for the anisotropy factor is described and, as an example, the chiroptical properties of 1.5 μm thick (multilayers) as well as sub-monolayer thin films of the R- and S-enantiomer of 1,1'-Bi-2-naphthol (BINOL) evaporated onto BK7 substrates were investigated. Read More

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November 2018
3 Reads

t-Si : A Novel Silicon Allotrope.

Chemphyschem 2018 Nov 6. Epub 2018 Nov 6.

Functional Materials Laboratory (FML) School of Materials & Mineral Resources, Xi'an University of Architecture and Technology, Xi'an, 710055, People's Republic of China.

Utilizing first principle calculations, a novel Si silicon allotrope in the I4 /amd space group with tetragonal symmetry (denoted as t-Si below) is proposed in this work. In addition, also its structural, anisotropic mechanical, and electronic properties along with its minimum thermal conductivity κ were predicted. The mechanical and thermodynamic stability of t-Si were evaluated by means of elastic constants and phonon spectra. Read More

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November 2018
1 Read
3.420 Impact Factor

Catalyst-Substrate Effects on Biocompatible SABRE Hyperpolarization.

Chemphyschem 2018 Nov 5. Epub 2018 Nov 5.

University of York, Department of Chemistry Heslington, York, YO10 5DD, UK.

The hyperpolarization technique, Signal Amplification by Reversible Exchange (SABRE), has the potential to improve clinical diagnosis by making molecular magnetic resonance imaging in vivo a reality. Essential to this goal is the ability to produce a biocompatible bolus for administration. We seek here to determine how the identity of the catalyst and substrate affects the cytotoxicity by in vitro study, in addition to reporting how the use of biocompatible solvent mixtures influence the polarization transfer efficiency. Read More

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November 2018
1 Read

Enhancement of the Nuclear Spin Noise Signal Using Wavelet Transform.

Chemphyschem 2018 Nov 2. Epub 2018 Nov 2.

NMR Research Centre, Indian Institute of Science, Bangalore, 560012, India.

Spin noise spectroscopy has attracted considerable attention recently owing partly to intrinsic interest in the phenomenon and partly to its significant application potential. Here, we address the inherent problem of low sensitivity of nuclear spin noise and examine the utility of wavelet transform to mitigate this problem by distinguishing real peaks from the noise contaminated data. Suppression of the random circuit noise and the consequent enhancement of the correlated nuclear spin noise signal have been demonstrated with discrete wavelet transform. Read More

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November 2018
12 Reads

Design, Synthesis and Computational Study of Fluorinated Quinoxaline-Oligothiophene-based Conjugated Polymers with Broad Spectral Coverage.

Chemphyschem 2018 Oct 31. Epub 2018 Oct 31.

Flinders Institute for Nanoscale Science and Technology, Flinders University, Sturt Road, Bedford Park, Adelaide, SA 5042, Australia.

Donor-acceptor (D-A) copolymers typically show two absorption peaks in the visible region, flanking a valley region of limited absorptivity. One strategy for more panchromatic light harvesting is to incorporate side-groups orthogonal to the polymer backbone, which enable 2D π conjugation and can give rise to additional absorption peaks. Here we design and synthesize two D-A polymers which both carry a fluorinated quinoxaline acceptor unit, but while P1 includes a benzodithiophene donor moiety with thiophene side-groups (2D-BDT), the P2 polymer lacks 2D conjugation in its simpler pentathiophene donor segment. Read More

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October 2018
1 Read

Hydroxyl Groups of Exceptionally High Acidity in Desilicated Zeolites Y.

Chemphyschem 2018 Oct 29. Epub 2018 Oct 29.

Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, Niezapominajek 8, PL-30239, Krakow, Poland.

The desilication of dealuminated zeolite Y in NaOH/tetrabutylammonium hydroxide mixtures produces hierarchical zeolite Y containing a micropore system as well as mesopores of significant volume and surface. IR studies evidenced that a new kind of hydroxyls was formed if desilication was realized above 318 K. This new kind of acidic hydroxyls is characterized by IR band at 3600 cm . Read More

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October 2018
1 Read

TiNF and Related Analogues of TiO : A Combined Experimental and Theoretical Study.

Chemphyschem 2018 Oct 29. Epub 2018 Oct 29.

New Chemistry Unit, Theoretical Science Unit and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore-, 560064, India.

Aliovalent anion substitution in inorganic materials brings about marked changes in properties, as exemplified by N,F-codoped metal oxides. Recently, complete substitution of oxygen in ZnO by N and F was carried out to generate Zn NF. In view of the important properties of TiO , we have attempted to prepare TiNF by employing an entirely new procedure involving the reaction of TiN with TiF . Read More

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October 2018
3 Reads

Niobium doping in BiVO4: an interplay between effective mass, stability and pressure.

Chemphyschem 2018 Oct 29. Epub 2018 Oct 29.

University of Texas at Arlington, Physics, Box 19059, 76019, Arlington, UNITED STATES.

We have applied density functional theory to study the electronic structure changes caused by Nb incorporation in BiVO4 and the application of external pressure. The overall solubility of Nb in BiVO4 is usually high, and the presence of oxygen vacancies affect the dopability of Nb in BiVO4. Through the analyses of the chemical-potential landscape, we have determined the single-phase stability zone of BiVO4 with the Nb doping. Read More

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October 2018
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The Structural Signs of Sweetness in Artificial Sweeteners: A Rotational Study of Sorbitol and Dulcitol.

Chemphyschem 2018 Oct 29. Epub 2018 Oct 29.

Grupo de Espectroscopía Molecular (GEM) Edificio Quifima, Laboratorio de Espectroscopia y Bioespectroscopia Unidad Asociada CSIC, Parque Científico Uva, Universidad de Valladolid, 47011, Valladolid, Spain.

A gas-phase study on the artificial sweeteners sorbitol and dulcitol has been carried out for the first time by using a combination of chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy and laser ablation (LA). The isolation conditions provided by the supersonic expansion reveal the intrinsic conformational structures of these sweeteners. The three and five observed conformers for sorbitol and dulcitol, respectively, are stabilized by networks of cooperative intramolecular hydrogen bonds between vicinal hydroxyl groups in clockwise or counterclockwise arrangements. Read More

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October 2018

ArCH : A Detectable Noble Gas Molecule.

Chemphyschem 2018 Oct 29. Epub 2018 Oct 29.

University of Trento, Department of Physics, Via Sommarive 14, 38050, Povo Trento, Italy.

The noble gas molecular cation, ArCH , has been observed in mass spectrometry experiments, and the present work is providing high-level quantum chemical predictions for the vibrational and rotational spectroscopic data necessary to observe this molecule in situ in other laboratory conditions. The Ar-C stretch in this cation is a bright fundamental vibrational frequency that should be observable in the early regions of the far-infrared at 421.2 cm for the universally most common Ar isotope. Read More

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October 2018

Universal Method for Electrostatic Interaction Energies Estimation with Charge Penetration and Easily Attainable Point Charges.

J Chem Theory Comput 2018 Nov 7. Epub 2018 Nov 7.

Biological and Chemical Research Centre, Department of Chemistry , University of Warsaw , ul. Żwirki i Wigury 101 , 02-089 Warszawa , Poland.

Our new model of electron density augmented by point charges (aug-PROmol) provides an estimation of electrostatic interaction energies including penetration effects ( ChemPhysChem 2016, 17, 2455-2460). In this paper we prove that it can be applied using sources of point charges other than those from direct restrained fitting to electrostatic potential (RESP). We used a newly established databank of tabulated invariom point charges and a widely known semiempirical method. Read More

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November 2018
7 Reads

Interacting Quantum Atoms Approach and Electrostatic Solvation Energy: Assessing Atomic and Group Solvation Contributions.

Chemphyschem 2018 Oct 25. Epub 2018 Oct 25.

Departamento de Química Física y Analítica, Universidad de Oviedo, Julián Clavería 8, 33006, Oviedo (Asturias, Spain.

The interacting quantum atoms (IQA) method decomposes the total energy of a molecular system in terms of one- and two-center (atomic) contributions within the context of the quantum theory of atoms in molecules. Here we incorporate electrostatic continuum solvent effects into the IQA energy decomposition. To this end, the interaction between the solute electrostatic potential and the solvent screening charges as defined within the COSMO solvation model is now included in a new version of the PROMOLDEN code, allowing thus to apply IQA in combination with COSMO-quantum chemical methods as well as to partition the electrostatic solvation energy into effective atomic and group contributions. Read More

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October 2018
9 Reads

Crowding and Confinement Can Oppositely Affect Protein Stability.

Chemphyschem 2018 Oct 24. Epub 2018 Oct 24.

Key Laboratory of Magnetic Resonance in Biological Systems State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan Collaborative Innovation Center of Chemistry for Life Sciences, Wuhan, Institute of Physics and Mathematics Chinese Academy of Sciences, Wuhan, 430071, P. R. China.

Proteins encounter crowded and confined macromolecular milieus in living cells. Simple theory predicts that both environments entropically stabilize proteins if only hard-core repulsive interactions are considered. Recent studies show that chemical interactions between the surroundings and the test protein also play key roles such that the overall effect of crowding or confinement is a balance of hard-core repulsions and chemical interactions. Read More

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October 2018
3.420 Impact Factor