7,294 results match your criteria Chemphyschem : a European journal of chemical physics and physical chemistry[Journal]


The Impact of Leaving Group Anomericity on the Structure of Glycosyl Cations of Protected Galactosides.

Chemphyschem 2020 Jul 11. Epub 2020 Jul 11.

Freie Universitat Berlin, Institute of Chemistry and Biochemistry, Takustrasse 3, 14195, Berlin, GERMANY.

It has been reported that fragments produced by glycosidic bond breakage in mass spectrometry-based experiments can retain a memory of their anomeric configuration, which has major implications for glycan sequencing. Here we use cryogenic vibrational spectroscopy and ion mobility-mass spectrometry to study the structure of B-type fragments of protected galactosides. Cationic fragments were generated from glycosyl donors carrying trichloroacetimidate or thioethyl leaving groups of different anomeric configuration. Read More

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http://dx.doi.org/10.1002/cphc.202000473DOI Listing

Unidimensional Approximation of the Diffuse Electrical Layer in the Inner Volume of Solid Electrolyte Grains in Absence of Background Ions.

Chemphyschem 2020 Jul 9. Epub 2020 Jul 9.

Institute of Chemistry and Chemical Technology SB RAS, Federal Research Center "Krasnoyarsk Science Center SB RAS", Laboratory for Catalytic Conversion of Renewable Resources, Akademgorodok 50/24, 660036, Krasnoyarsk, RUSSIAN FEDERATION.

In this paper we continue working on our theory of electrical double layers resulting exclusively from dissociation of a solid electrolyte, which we previously proposed as a medium for catalytic interaction between solid cellulose and solid acid catalysts of hydrolysis. Two theoretical unidimensional models of the inner grain volume are considered: an infinitely long cylindrical pore, and a gel electrolyte near a grain outer surface. Despite the model simplicity, the predictions for the cylindrical pore case are in semi-quantitative agreement with literature data on electroosmotic experiments, adequately explaining high proton selectivity of sulfonic membranes, and decline of such selectivity at high background acid concentration. Read More

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http://dx.doi.org/10.1002/cphc.202000455DOI Listing

Effect of alkali metal cations on length and strength of hydrogen bonds in DNA base pairs.

Chemphyschem 2020 Jul 9. Epub 2020 Jul 9.

Politechnika Warszawska, Faculty of Chemistry, POLAND.

For many years non-covalently bonded complexes of nucleobases have attracted considerable interest. However, there is a lack of information about the nature of hydrogen bonding between nucleobases when the bonding is affected by metal coordination to one of the nucleobases and how the individual hydrogen bonds and aromaticity of nucleobases respond to the presence of the metal cation. Here we report a DFT computational study of nucleobase pairs interacting with alkali metal cations. Read More

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http://dx.doi.org/10.1002/cphc.202000434DOI Listing

Enhancement of Ion Pairing of Sr(II) and Ba(II) Salts by a Tritopic Ion-Pair Receptor in Solution.

Chemphyschem 2020 Jul 8. Epub 2020 Jul 8.

Max Planck Institute for Polymer Research, Department of Molecular Spectroscopy, Ackermannweg 10, 55128, Mainz, GERMANY.

Tritopic ion-pair receptors can bind bivalent salts in solution; yet, these salts have a tendency to form ion-pairs even in the absence of receptors. The extent to which such receptors can enhance ion pairing has however remained elusive. Here, we study ion pairing of M2+ (Ba2+, Sr2+) and X- (I-, ClO-4-) in acetonitrile with and without a dichlorooxacalix[2]-arene[2]triazine-related receptor containing a pentaethylene-glycol moiety. Read More

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http://dx.doi.org/10.1002/cphc.202000507DOI Listing

Atomic-scale studies of Fe3O4(001) and TiO2(110) surfaces following immersion in CO2-acidified water.

Chemphyschem 2020 Jul 8. Epub 2020 Jul 8.

Technische Universitat Wien, Wien, AUSTRIA.

Difficulties associated with the integration of liquids into a UHV environment make surface-science style studies of mineral dissolution particularly challenging. Recently, we developed a novel experimental setup for the UHV-compatible dosing of ultrapure liquid water, and studied its interaction with TiO 2 and Fe 3 O 4 surfaces. Here, we describe a simple approach to vary the pH through the partial pressure of CO 2 (p CO2 ) in the surrounding vacuum chamber, and use this to study how these surfaces react to an acidic solution. Read More

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http://dx.doi.org/10.1002/cphc.202000471DOI Listing

Conservation of ultrafast photoprotective mechanisms with increasing molecular complexity in sinapoyl malate derivatives.

Chemphyschem 2020 Jul 7. Epub 2020 Jul 7.

AgroParisTech, Agro-Biotechnologies Industrielles, FRANCE.

Sinapoyl malate is a natural plant sunscreen molecule which protects leaves from harmful ultraviolet radi- ation. Here, the ultrafast dynamics of three sinapoyl malate derivatives, sinapoyl L-dimethyl malate, sinapoyl L-diethyl malate and sinapoyl L-di- t -butyl malate, have been studied us- ing transient electronic absorption spectroscopy, in a dioxane and methanol solvent environment to investigate how well pre- served these dynamics remain with increasing molecular com- plexity. In all cases it was found that, upon photoexcitation, deactivation occurs via a trans-cis isomerisation pathway within ∼ 20-30 ps. Read More

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http://dx.doi.org/10.1002/cphc.202000429DOI Listing

H QUOSY 2D-NMR Experiments in Weakly Aligning Systems: From the Conventional to the Ultrafast Approach.

Chemphyschem 2020 Jul 7. Epub 2020 Jul 7.

Université Paris-Saclay, ICMMO, UMR CNRS 8182, RMN en Milieu Orienté, Bât. 410, 15, rue du Doyen Georges Poitou, UFR d'Orsay, 91405, Orsay cedex, France.

We describe three anisotropic ultrafast (UF) QUadrupolar Ordered SpectroscopY (QUOSY) 2D-NMR experiments (referred to as ADUF 2D NMR spectroscopy) designed for recording the H homonuclear 2D spectra of weakly aligned (deuterated) solutes in sub-second experiment times. These new ADUF 2D experiments derive from the Q-COSY, Q-resolved and Q-DQ 2D pulse sequences (J. Am. Read More

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http://dx.doi.org/10.1002/cphc.202000336DOI Listing

On the Threshold Photoelectron Spectrum of Fulvenone, a Reactive Ketene Derivative in Lignin Valorization.

Chemphyschem 2020 Jul 6. Epub 2020 Jul 6.

Ben-Gurion University of the Negev, Chemistry, ISRAEL.

Unveiling reaction mechanisms by isomer-selective detection of reactive intermediates requires advanced spectroscopic knowledge. We study the photoionization of fulvenone (c-C 5 H 4 =C=O), a reactive ketene species relevant in catalytic pyrolysis of lignin, which was generated by pyrolysis of 2-methoxy acetophenone. The highresolution threshold photoelectron spectrum (TPES) with vacuum ultraviolet synchrotron radiation revealed well-resolved vibrational transitions, assigned to ring deformation modes of the cyclopentadienyl moiety. Read More

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http://dx.doi.org/10.1002/cphc.202000477DOI Listing

Raman Spectroscopic Signature of Ectoine Conformations in Bulk Solution and Crystalline State.

Chemphyschem 2020 Jul 6. Epub 2020 Jul 6.

Uni Stuttgart, Institute for Computational Physics, Allmandring 3, 70569, Stuttgart, GERMANY.

Recent crystallographic results revealed conformational changes of zwitterionic ectoine upon hydration. By means of confocal Raman spectroscopy and density functional theory calculations, we present a detailed study of this transformation process as part of a Fermi resonance analysis. The corresponding findings highlight that all resonant couplings are lifted upon exposure to water vapor as a consequence of molecular binding processes. Read More

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http://dx.doi.org/10.1002/cphc.202000457DOI Listing

Optical Spectroscopy and Excited-State Dynamics of Eu -Doped Bismuth Borate Glasses Containing CuO.

Chemphyschem 2020 Jul 6. Epub 2020 Jul 6.

Department of Chemistry and Physics, Augusta University, Augusta, GA, 30904, USA.

Bismuth borate glasses containing phosphors and luminescent rare-earths are of interest for applications in light-emitting devices. Herein, the influence of CuO impurities on red-emitting Eu -doped bismuth borate glasses of the 25Bi O -15BaO-10Li O-50B O type was investigated by various spectroscopic methods. The glasses were prepared by the melt-quench technique and characterized by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, UV/Vis optical absorption (OA), and photoluminescence (PL) spectroscopy including decay kinetics assessment. Read More

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http://dx.doi.org/10.1002/cphc.202000396DOI Listing

Nanoscale structure in short-chain ionic liquids.

Chemphyschem 2020 Jul 5. Epub 2020 Jul 5.

ESRF, ESRF, FRANCE.

The temperature ( T ) and cationic chain length ( n ) evolution of the nanoscale structure of the sub-layering-threshold members of a model family of room temperature ionic liquids (RTILs) is  investigated by x-ray scattering. The measured  curves are computer-resolved into individual Teubner-Strey-like lineshapes. The polar-apolar layering is found to start at n=3 . Read More

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http://dx.doi.org/10.1002/cphc.202000548DOI Listing

Dispersion and Interaction of Charged Fluorescent Dyes in Protein-Polymer Surfactant based Non-aqueous Liquid.

Chemphyschem 2020 Jul 3. Epub 2020 Jul 3.

Indian Institute of Technology Bombay, Chemistry, INDIA.

Viscous, non-aqueous liquid comprising stoichiometric conjugates of polymer surfactant-bovine serum albumin (PS-pBSA) is used as a host matrix for the dispersion of chemically distinct hydrophilic dyes. Using a combination of bright field polarized optical microscopy and fluorescence spectroscopy, we investigate the dispersion of dry and powdered cationic (Rhodamine 6G; Rh6G) and anionic (Fluorescein; FL) dyes in the PSpBSA liquid at room temperature. As the dyes disperse and dissolve in the PSpBSA liquid there is a pronounced increase in emission intensity of the dye. Read More

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http://dx.doi.org/10.1002/cphc.202000443DOI Listing

The affinity of some Lewis bases for Hexafluoroisopropanol as a reference Lewis acid: an ITC/DFT study.

Chemphyschem 2020 Jul 3. Epub 2020 Jul 3.

Univerzitet u Beogradu, Faculty of Chemistry, SERBIA.

To figure out the possible role of 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) as well as to provide reference thermochemical data in solution, the formation of Lewis acid-base complexes between HFIP (Lewis acid) and a series of 8 different Lewis bases (3 sulfoxides, 3 Nsp2 pyridine derivatives, 1 aromatic amine, 1 cyclic aliphatic ether) was examined by Isothermal Titration Calorimetry (ITC) experiments and static Density Functional Theory augmented with Dispersion (DFT-D) calculations. Measured ITC association enthalpy values ΔHa spanned -9.3 kcal/mol to -14 kcal/mol. Read More

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http://dx.doi.org/10.1002/cphc.202000560DOI Listing

Unravelling the role of water in ultrafast excited-state relaxation dynamics within nano-architectures of Chlorophyll a.

Chemphyschem 2020 Jul 3. Epub 2020 Jul 3.

Indian Institute of Science Education and Research Mohali, Chemical Sciences, INDIA.

Water plays a pivotal role in structural stability of supramolecular pigment assemblies designed for natural light harvesting (for example, chlorosome antenna complex) as well as their artificial analogs. However, the dynamic role of water in the context of excite-state relaxation has not been explored till date, which we report here. Using femtosecond transient absorption spectroscopy, here we investigate the excited state dynamics of two types of nano-scale assemblies of chlorophyll-a having different structural motifs, rod-shaped and micellar assemblies, that depends on the water content. Read More

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http://dx.doi.org/10.1002/cphc.202000487DOI Listing

Mechanisms, methods of tracking and applications of DNA walkers: A review.

Chemphyschem 2020 Jul 2. Epub 2020 Jul 2.

Aarhus University, Interdisciplinary Nanoscience Center (iNANO), Gustav Wieds Vej 14, 8000, Aarhus, DENMARK.

In recent years, DNA nanotechnology expanded its scope from structural DNA nanoarchitecture towards designing dynamic and functional nanodevices. This progress has been evident in the development of an advanced class of DNA nanomachines, the so-called DNA walkers. They represent an evolution of basic switching between distinctly defined states into continuous motion. Read More

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http://dx.doi.org/10.1002/cphc.202000235DOI Listing

Chiral, Thermally Irreversible and Quasi-Stealth Photochromic Dopant to Control Selective Reflection Wavelength of Cholesteric Liquid Crystal.

Chemphyschem 2020 Jul;21(13):1343-1344

Department of Advanced Materials Chemistry, Graduate School of Engineering Science, Yokohama National University, Tokiwadai, Hodogaya, Yokohama, 240-8501, Japan.

The front cover artwork is provided by the group of Prof. Emeritus Yasushi Yokoyama and Prof. Takashi Ubukata. Read More

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http://dx.doi.org/10.1002/cphc.202000508DOI Listing

Combined Spectroscopic and TD-DFT Analysis to Elucidate Substituent and Acidochromic Effects in Organic Dyes A Case Study on Amino- vs. Nitro-Substituted 2,4-Diphenylquinolines.

Chemphyschem 2020 Jun 30. Epub 2020 Jun 30.

Universidade Federal de Sao Paulo, Department of Chemistry, BRAZIL.

A combined spectroscopic and TD-DFT case study was performed, to identify a robust method to calculate the complex near UV/Vis absorption spectra of various amino- vs. nitro-substituted 2,4-diphenylquinolines, which vary strongly under neutral and successively acidic conditions. For this, different DFT functionals were tested for geometry optimization and the TD part to calculate the neutral and different protonated species in a fast screening approach, i. Read More

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http://dx.doi.org/10.1002/cphc.202000452DOI Listing

Effect of Remote Substituents on the Torquoselectivity of 3-Silyl Cyclobutene Derivatives Ring Opening Reaction.

Chemphyschem 2020 Jun 30. Epub 2020 Jun 30.

Universidad del Pais Vasco /IKERBASQUE, Departamento de Química Orgánica I, Av Tolosa 72, 20018, Donostia/San Sebastián, SPAIN.

We have quantum chemically studied the structure and nature of 1-substituted 3-trimethylsilyl cyclobutenes and 2,2-disubstituted-7-trimethylsilyl bycyclo[4.2.0]octa-1(6),3-dienes comparing their reactivity to archetypal 3-substituted cyclobutene systems using density functional theory at M06-2X(PCM)/TZ2P level. Read More

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http://dx.doi.org/10.1002/cphc.202000451DOI Listing

From very strong to inexistent Be-Be bonds in the interactions of Be2 with π-systems.

Chemphyschem 2020 Jun 29. Epub 2020 Jun 29.

Consejo Superior de Investigaciones Cientificas, Instituto de Quimica Medica, SPAIN.

High-level ab initio calculations; Be-Be bonds; π-systems; Strong Lewis acids. Read More

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http://dx.doi.org/10.1002/cphc.202000412DOI Listing

Morphological and Interaction Characteristics of Surface Active Ionic Liquids and Palmitic Acid in Mixed Monolayers.

Chemphyschem 2020 Jun 29. Epub 2020 Jun 29.

University of Saskatchewan, Chemistry, CANADA.

A series of water soluble, surface-active ionic liquids (SAILs), namely, 1-alkyl-3-methyl imidazolium chlorides ([C n - mim ]Cl) and their mixtures with palmitic acid (PA) were investigated in Langmuir monolayers and Langmuir-Blodgett films. It was inferred from the surface pressure-area isotherms that C 16 - mim -IL mixed non-ideally with PA and stabilized the binary mixed films. In addition, the residence of mim -IL at the water surface was enhanced as a function of the increasing alkyl side chain length. Read More

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http://dx.doi.org/10.1002/cphc.202000359DOI Listing

Gas Phase Formation of Methylgermylene (HGeCH3).

Chemphyschem 2020 Jun 28. Epub 2020 Jun 28.

University of Hawaii at Manoa, 2545 McCarthy Mall, 96822, Honolulu, UNITED STATES.

The methylgermylene molecule (HGeCH 3 ;X 1 A') has been synthesized via the bimolecular gas phase reaction of ground state methylidyne radicals (CH) with germane (GeH 4 ) under single collision conditions in crossed molecular beams experiments. Augmented by electronic structure calcu-la-tions, this elementary reaction was found to proceed thro-ugh barrierless insertion of the methylidyne radical in one of the four ger-ma-nium - hydrogen bonds on the doublet potential energy surface yielding the germylmethyl (CH 2 GeH 3 ;X 2 A') collision complex. This insertion is followed by a hydrogen shift from germanium to carbon and uni-mole-cular decomposition of the methylgermyl (GeH 2 CH 3 ;X 2 A') intermediate by atomic hydrogen elimi-nation leading to singlet methylgermylene (HGeCH 3 ;X 1 A'). Read More

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http://dx.doi.org/10.1002/cphc.202000392DOI Listing

Cu Atomic Chain Supported on Graphene Nanoribbon for Effective Conversion of CO2 to Ethanol.

Chemphyschem 2020 Jun 25. Epub 2020 Jun 25.

Peking University, MSE, Haidian, 100871, Beijing, CHINA.

Cu catalysts are well-known for their good performance in CO2 conversion. Compared to CO and CH4 production, C2 products have higher volumetric energy densities and are more valuable in industrial application. In this work, we screened the catalytic ability of C2 production on several 1D Cu atomic chain structures and find that Cu edge-decorated zigzag graphene nanoribbon (Cu-ZGNR) is capable of catalyzing CO2 to ethanol, and CH3CH2OH is the main C2 product with a maximum free energy change of 0. Read More

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http://dx.doi.org/10.1002/cphc.202000476DOI Listing

Morphology, Structure, and Dynamics of Pentacene Thin Films and their Nanocomposites with [C2C1im][NTf2] and [C2C1im][OTF] Ionic Liquids.

Chemphyschem 2020 Jun 24. Epub 2020 Jun 24.

Universidade do Porto Faculdade de Ciencias, Departamento de Química e Bioquímica, PORTUGAL.

In this study, a homogeneous thin film growth of pentacene onto indium tin oxide (ITO) coated glass surfaces is explored using a high-resolution and reproducible vapor deposition methodology. Moreover, vacuum thermal evaporation of ionic liquids (ILs) ([C 2 C 1 im][NTf 2 ] and [C 2 C 1 im][OTF]) onto ITO, gold/palladium (AuPd) and pentacene surfaces were performed. A greater wettability behavior of ILs is observed for surfaces containing AuPd. Read More

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http://dx.doi.org/10.1002/cphc.202000431DOI Listing

Single Quality Factor for Enthalpy-Entropy Compensation, Isoequilibrium and Isokinetic Relationships.

Chemphyschem 2020 Jun 23. Epub 2020 Jun 23.

Materials for Energy Conversion and Storage, Department of Chemical Engineering, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands.

Enthalpy-entropy compensation (EEC) is very often encountered in chemistry, biology and physics. Its origin is widely discussed since it would allow, for example, a very accurate tuning of the thermodynamic properties as a function of the reactants. However, EEC is often discarded as a statistical artefact, especially when only a limited temperature range is considered. Read More

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http://dx.doi.org/10.1002/cphc.202000390DOI Listing

Two dimensional oblique molecular packing within a model peptide ribbon aggregate.

Chemphyschem 2020 Jun 23. Epub 2020 Jun 23.

Division of Physical Chemistry, Lund University, SE-22100, Lund, Sweden.

A K (A=alanine, K=lysine) model peptides self-assemble into ribbon-like β-sheet aggregates. Here, we report an X-ray diffraction investigation on a flow-aligned dispersion of these self-assembly structures. The two-dimensional wide-angle X-ray scattering pattern suggests that peptide pack in a two-dimensional oblique lattice, essentially identical to the crystalline packing of polyalanine, A (for n>4). Read More

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http://dx.doi.org/10.1002/cphc.201901126DOI Listing

In Silico Design of Cylindrophanes: The Role of Functional Groups in a Fluoride Selective Host.

Chemphyschem 2020 Jun 23. Epub 2020 Jun 23.

Universidade de Franca, Núcleo de pesquisa em ciências exatas e tecnológicas, Franca, BRAZIL.

Molecular recognition is the key driver in the formation of supramolecular complexes, enabling the selective encapsulation of specific guests. Here, we explore the delicate balance between different energetic terms in the formation of an efficient host for fluoride anions based on a cylindrophane structure, which can be achieved by the incorporation of NH 2 + ligand sites into a cyanuric acid based cyclophane framework, resulting a close proximity between the ammonium hydrogens and the F - anion. This study describes the character and contribution of different energetic and repulsive terms that favor the efficient inclusion of fluoride. Read More

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http://dx.doi.org/10.1002/cphc.202000321DOI Listing

The negative ion formation by the thermal surface ionization of sulfur dioxide (SO2).

Chemphyschem 2020 Jun 22. Epub 2020 Jun 22.

Uniwersytet Marii Curie-Sklodowskiej, Department of Biophysics, Pl. M. Curie-Skłodowskiej 1, 20-031, Lublin, POLAND.

The generation of negative ions from SO2 in the gas phase was studied using the thermal surface ionization method. Six anion types were measured: O-, S-, SO-, SO2- and with m/z = 96 and m/z = 128. The most intense formed anion was S-. Read More

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http://dx.doi.org/10.1002/cphc.202000388DOI Listing

From Femtosecond to Nanosecond Laser Microstructuring of Conical Aluminum Surfaces by Reactive Gas Assisted Laser Ablation.

Chemphyschem 2020 Jun 19. Epub 2020 Jun 19.

Fraunhofer Heinrich Hertz Institute HHI, Fiber Optical Sensor Systems, Am Stollen 19 H, 38640, Goslar, Germany.

A conical microstructure is one of the most versatile surface textures obtained by ultrashort laser micromachining. Besides an increased surface area, unique surface properties such as superhydrophilicity, increased absorptivity; and thermal emissivity can be tailored. On metals, usually ultrashort laser pulses in the femtosecond to low picosecond range are used to obtain these surface structures, whereas nanosecond laser pulses favor melting processes. Read More

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http://dx.doi.org/10.1002/cphc.202000418DOI Listing

Centerband-Only Detection of Exchange NMR with Natural-Abundance Correction Reveals an Expanded Unit Cell in Phenylalanine Crystals.

Chemphyschem 2020 Jun 17. Epub 2020 Jun 17.

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

The NMR pulse sequence CODEX (centerband-only detection of exchange) is a widely used method to report on the number of magnetically inequivalent spins that exchange magnetization via spin diffusion. For crystals, this rules out certain symmetries, and the rate of equilibration is sensitive to distances. Here we show that for C CODEX, consideration of natural abundance spins is necessary for crystals of high complexity, demonstrated here with the amino acid phenylalanine. Read More

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http://dx.doi.org/10.1002/cphc.202000517DOI Listing

Feasibility of N Reduction on the V Anchored 1T-MoS Monolayer: A Density Functional Theory Study.

Chemphyschem 2020 06;21(12):1217

School of Energy and Power Engineering, Jiangsu University of Science and Technology, 212003, Zhenjiang, Jiangsu, China.

The front cover artwork is provided by the groups of Prof. BeiBei, Xiao and Lei, Yang (Jiangsu University of Science and Technology, China) as well as Dr. ErHong, Song (Shanghai Institute of Ceramics, Chinese Academy of Sciences, China). Read More

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http://dx.doi.org/10.1002/cphc.202000460DOI Listing

Tuning the Redox Chemistry of a Cr/SiO2 Phillips Catalyst for Controlling Activity, Induction Period and Polymer Properties.

Chemphyschem 2020 Jun 15. Epub 2020 Jun 15.

Utrecht University, Dept. of Inorganic Chemistry and Catalysis, Universiteitsweg 99, 3584 CG, Utrecht, NETHERLANDS.

The Cr/SiO2 Phillips catalyst has taken a central role in ethylene polymerization ever since its discovery. This catalyst is unique compared to other polymerization catalysts, since it is active without the addition of a metal-alkyl co-catalyst. However, metal-alkyls can be added for scavenging poisons, enhancing the catalyst activity, reducing the induction period and altering polymer characteristics. Read More

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http://dx.doi.org/10.1002/cphc.202000488DOI Listing

Using a Nitrophenol Cocktail Screen to Improve Catalyst Down-selection.

Chemphyschem 2020 Jun 11. Epub 2020 Jun 11.

Department of Chemistry, University of Central Florida, Orlando, Florida, 32816, USA.

The catalytic reduction of 4-nitrophenol (4NP) with excess NaBH is the benchmark model for quantifying catalytic activity of nanoparticles. Although broadly useful, the reaction can be very selective. This can lead to false positives and negatives when utilized for catalyst down-selection from a broader materials candidate pool. Read More

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http://dx.doi.org/10.1002/cphc.202000400DOI Listing

Speeding up Viedma Deracemization through Water catalyzed and Reactant Self-catalyzed Racemization.

Chemphyschem 2020 Jun 9. Epub 2020 Jun 9.

Institut für Organische Chemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Department Chemie und Pharmazie, Henkestrasse 42, 91054, Erlangen, GERMANY.

Viedma deracemization is based on solution phase racemization, dissolution of racemic or scalemic conglomerates and crystal growth through autocatalytic cluster formation. With rate limiting racemization, its acceleration by appropriate catalysts may result in speeding up deracemization. A conglomerate forming chiral compound may principally racemize directly, or via reverse of its formation reaction. Read More

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http://dx.doi.org/10.1002/cphc.202000493DOI Listing

Pristine graphene as a racemization catalyst for axially chiral BINOL.

Chemphyschem 2020 Jun 8. Epub 2020 Jun 8.

The University of Western Australia, School of Molecular Sciences, 35 Stirling Highway, 6009, Perth, AUSTRALIA.

Despite versatile applications of functionalized graphene in catalysis, applications of pure, unfunctionalized graphene in catalysis are in their infancy. This work uses both computational and experimental approaches to show that single-layer graphene can efficiently catalyze the racemization of axially chiral BINOL in solution. Using double-hybrid density functional theory (DHDFT) we calculate the uncatalyzed and catalyzed Gibbs free reaction barrier heights in a number of representative solvents of varying polarity: benzene, diphenyl ether, dimethylformamide (DMF), and water. Read More

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http://dx.doi.org/10.1002/cphc.202000426DOI Listing

Changes in Electron Structure of the Triple Bond in Substituted Acetylene and Diacetylene Derivatives.

Chemphyschem 2020 Jun 8. Epub 2020 Jun 8.

Warsow University, Department of Chemistry, Pasteura 1, 02-093, Warsaw, POLAND.

The substituent effect is usually considered by means of various Hammett-like substituent constants and is most often related to aromatic systems. Unlike this, we present results of our research on the influence of 27 substituents spanning a wide range of electronic properties, from strongly electron-withdrawing to strongly electron-donating, on the electron structure of X-substituted acetylenes and diacetylenes - thus the systems which until now have practically not been subject of any deeper studies. It is shown that the interaction through triple bond(s) is associated with a significant advantage of resonance effects and that the substituent effect transmitted by the C≡C-C≡C unit is about half of that transmitted by the C≡C unit alone. Read More

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http://dx.doi.org/10.1002/cphc.202000378DOI Listing

Non-conventional Hydrogen Bonding and Aromaticity: A Systematic Study on Model Nucleobases and Their Solvated Clusters.

Chemphyschem 2020 Jun 7. Epub 2020 Jun 7.

National Institute of Science Education and Research, School of Chemical Sciences, Sachivalaya Marg, Institute of Physics Campus, Sachivalaya Marg, PO: Sainik School, 751005, Bhubaneswar, INDIA.

The conceptual development of aromaticity is essential to rationalize and understand the structure and behavior of aromatic heterocycles. This work addresses for the first time, the interconnection between aromaticity and sulfur/selenium centered hydrogen bonds (S/SeCHBs) involved in representative heterocycle models of canonical nucleobases (2-Pyridone; 2PY) and its sulfur (2-Thiopyridone; 2TPY) and selenium (2-Selenopyridone; 2SePY) analogs. The nucleus-independent chemical shift (NICS) and gauge induced magnetic current density (GIMIC) values suggested significant reduction of aromaticity upon replacement of exocyclic carbonyl oxygen with sulfur and selenium. Read More

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http://dx.doi.org/10.1002/cphc.202000386DOI Listing

Do Xylylenes Isomerize in Pyrolysis?

Chemphyschem 2020 Jun 5. Epub 2020 Jun 5.

Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525 ED, Nijmegen, The, Netherlands.

We report infrared spectra of xylylene isomers in the gas phase, using free electron laser (FEL) radiation. All xylylenes were generated by flash pyrolysis. The IR spectra were obtained by monitoring the ion dip signal, using a IR/UV double resonance scheme. Read More

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http://dx.doi.org/10.1002/cphc.202000317DOI Listing

Negative Refraction in the Visible and Strong Plasmonic Resonances in Photonic Structures of the Electride Material Mg N.

Chemphyschem 2020 Jun 4. Epub 2020 Jun 4.

Institute of Physics, State Academy of Sciences, Unjong District, Pyongyang, Democratic People's Republic of Korea.

Natural hyperbolic materials have recently attracted great attention due to their capability of supporting spatial mode frequency much higher than artificial metamaterials and the advantage that they do not require nanofabrication processes. For practical applications, however, hyperbolic bulk materials with lower optical losses in shorter wavelength range should be developed. This work presents the electronic structure and dielectric response of an electride Mg N, revealing that this material exhibits hyperbolic responses with low optical loss in the visible and plasmonic responses with high-quality in the near-infrared range. Read More

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http://dx.doi.org/10.1002/cphc.202000351DOI Listing

Two Equivalent Internal Rotations in the Microwave Spectrum of 2,6-Dimethylfluorobenzene.

Chemphyschem 2020 Jun 4. Epub 2020 Jun 4.

Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA) CNRS UMR 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, 61 avenue du Général de Gaulle, 94010, Créteil, France.

Large amplitude motion of methyl groups in isolated molecules is a fundamental phenomenon in molecular physics. The methyl torsional barrier is sensitive to the steric and electronic environment in the surrounding of the methyl group, making the methyl group a detector of the molecular structure. To probe this effect, the microwave spectrum of 2,6-dimethylfluorobenzene, one of the six isomers of dimethylfluorobenzene, was measured using two pulsed molecular jet Fourier transform microwave spectrometers operating in the frequency range from 2 to 40 GHz. Read More

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http://dx.doi.org/10.1002/cphc.202000419DOI Listing

Delicate Balance of Non-Covalent Forces Govern the Biocompatibility of Graphitic Carbon Nitride towards Genetic Materials.

Chemphyschem 2020 Jun 4. Epub 2020 Jun 4.

Indian Association for the Cultivation of Science, Department of Spectroscopy, 2A & 2B Raja Subodh Mallick Road, Jadavpur, 700032, Kolkata, INDIA.

Despite a plethora of suggested technological and biomedical applications, the nanotoxicity of two-dimensional (2D) graphitic carbon nitride (g-C3N4) towards biomolecules remains elusive. To address this issue, we employ all-atom classical molecular dynamics simulations and investigate the interactions between nucleic acids and g-C3N4. It is revealed that, toxicity is modulated through a subtle balance between electrostatic and van der Waals interactions. Read More

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http://dx.doi.org/10.1002/cphc.202000385DOI Listing

Through-Space Polar-π Interactions in 2,6-Diarylthiophenols.

Chemphyschem 2020 06;21(11):1080

Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230, Odense, Denmark.

The front cover artwork is provided by Marijn Maas from the group of Prof. Jasmin Mecinović (University of Southern Denmark). The image shows the stabilization of thiols by aromatic rings, as a result of energetically favorable SH-π interactions in a designed small molecule and in proteins. Read More

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http://dx.doi.org/10.1002/cphc.202000414DOI Listing

Geometrical Evolution and Formation of the Photoproduct in the Cycloreversion Reaction of a Diarylethene Derivative Probed by Vibrational Spectroscopy.

Chemphyschem 2020 Jun 2. Epub 2020 Jun 2.

Division of Frontier Materials Science and, Center for Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan.

The geometrical evolution of the reactant and formation of the photoproduct in the cycloreversion reaction of a diarylethene derivative were probed using time-resolved absorption spectroscopies in the visible to near-infrared and mid-infrared regions. The time-domain vibrational data in the visible region show that the initially formed Franck-Condon state is geometrically relaxed into the minimum in the excited state potential energy surface, concomitantly with the low-frequency coherent vibrations. Theoretical calculations indicate that the nuclear displacement in this coherent vibration is nearly parallel to that in the geometrical relaxation. Read More

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http://dx.doi.org/10.1002/cphc.202000315DOI Listing

Unraveling the Origin of Differentiable 'Turn-On' Fluorescence Sensing of Zn and Cd Ions with Squaramides.

Chemphyschem 2020 Jun 2. Epub 2020 Jun 2.

Department of Chemistry, Indian Institute of Technology Bombay Powai, Mumbai, 400076, India.

A squaramide ring conjugated with Schiff-bases decorated with hydroxy and methoxy functional groups differentially senses zinc and cadmium ions, which turn on the fluorescence. The feebly emitting free ligands light up in the presence of zinc and cadmium acetates, with the acetate ion playing a pivotal role as a conjugate anion. The selective and differentiable emission responses for zinc and cadmium ions make these ligands efficient multi-analyte sensing agents. Read More

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http://dx.doi.org/10.1002/cphc.202000332DOI Listing

Molecular Motions and Interactions in Aqueous Solutions of Thymosin-β , Stabilin CTD and Their 1 : 1 Complex, Studied by H-NMR Spectroscopy.

Chemphyschem 2020 Jul 8;21(13):1420-1428. Epub 2020 Jun 8.

Department of Experimental Solid State Physics Wigner Research Centre, Konkoly-Thege út 29-33., 1121, Budapest, Hungary.

Wide-line H NMR measurements were extended and all results were interpreted in a thermodynamics-based new approach on aqueous solutions of thymosin-β (Tβ ), stabilin cytoplasmic domain (CTD), and their 1 : 1 complex. Energy distributions of potential barriers controlling the motion of protein-bound water molecules were determined. Heterogeneous and homogeneous regions were found in the protein-water interface. Read More

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http://dx.doi.org/10.1002/cphc.202000264DOI Listing

Alteration in Cross Diffusivities Governs the Nature and Dynamics of Spatiotemporal Pattern Formation.

Chemphyschem 2020 May 28. Epub 2020 May 28.

Department of Chemistry, Indian Institute of Technology (IIT), Bombay, Powai, Mumbai, 400076, India.

Realizing spatiotemporal patterns out of a chemical reaction diffusion system remains an experimental challenge owing to the difficulty in overcoming the stringent condition of diffusion driven instability. Herein, by considering the spatially extended Gray-Scott model system, we have investigated how the cross diffusivities of the reactants involved influence the nature and dynamics of spatiotemporal patterns. Our study unravels that in absence of diffusion driven instability, spatially inhomogeneous patterns can be obtained for the Gray-Scott model system, and unstable time dependent patterns can be stabilized just by adjusting cross diffusivities of the reactants. Read More

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http://dx.doi.org/10.1002/cphc.202000142DOI Listing

Insight into Out-of-Layer Fluctuations in the Smectic A Stability of 3,5-Diarylisoxazole Liquid Crystals.

Chemphyschem 2020 Jul 3;21(13):1408-1419. Epub 2020 Jun 3.

Institute of Chemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, 91501970, RS, Brazil.

Polar-terminated 3,5-diarylisoxazole liquid crystals (ILCs) were synthetized and characterized. ILCs are composed by rigid core 3,5-diarylisoxazol, alkyl chain and polar-terminated flexible spacer. Hydroxyl-, ketal- and 1,2-diol-terminated ILCs rendered smectic C and A mesophase, while bromine-terminated ILCs showed smectic A and B mesophase, for monosubstituted and linear ILCs. Read More

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http://dx.doi.org/10.1002/cphc.202000276DOI Listing

Hydrogen-Bonded Complexes of Fluorophenylacetylenes: To Fluoresce or Not?

Chemphyschem 2020 May 27. Epub 2020 May 27.

Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.

The hydrogen-bonded complexes of fluorophenylacetylenesexhibit unusual and interesting fluorescence turn ON/OFF behaviour following excitation to ππ* (S ) state. The fluorescence switching behaviour can be realized by (i) "change in the intermolecular structure, (ii) change in the position of fluorine substitution and (iii) change in the hydrogen bonding partner or a combination thereof. Experiments indicate that the ≡C-H⋅⋅⋅X (X=O, N) hydrogen bonding with the acetylenic group plays a pivotal role in this switching behaviour. Read More

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http://dx.doi.org/10.1002/cphc.202000306DOI Listing
May 2020
3.419 Impact Factor

On the Formation of the Popcorn Flavorant 2,3-Butanedione (CH COCOCH ) in Acetaldehyde-Containing Interstellar Ices.

Chemphyschem 2020 May 26. Epub 2020 May 26.

Department of Chemistry and W. M. Keck Research Laboratory in Astrochemistry, University of Hawai'i at Manoa 2545 McCarthy Mall, Honolulu, HI, 96822, USA.

Acetaldehyde (CH CHO) is ubiquitous throughout the interstellar medium and has been observed in cold molecular clouds, star forming regions, and in meteorites such as Murchison. As the simplest methyl-bearing aldehyde, acetaldehyde constitutes a critical precursor to prebiotic molecules such as the sugar deoxyribose and amino acids via the Strecker synthesis. In this study, we reveal the first laboratory detection of 2,3-butanedione (diacetyl, CH COCOCH ) - a butter and popcorn flavorant - synthesized within acetaldehyde-based interstellar analog ices exposed to ionizing radiation at 5 K. Read More

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http://dx.doi.org/10.1002/cphc.202000116DOI Listing

Molecular Dynamics Simulation of Small Molecules Interacting with Biological Membranes.

Chemphyschem 2020 May 25. Epub 2020 May 25.

School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute and, Curtin Institute for Computation, Curtin University, Perth, WA 6845, Australia.

Cell membranes protect and compartmentalise cells and their organelles. The semi-permeable nature of these membranes controls the exchange of solutes across their structure. Characterising the interaction of small molecules with biological membranes is critical to understanding of physiological processes, drug action and permeation, and many biotechnological applications. Read More

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http://dx.doi.org/10.1002/cphc.202000219DOI Listing