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    6298 results match your criteria Chemphyschem : a European journal of chemical physics and physical chemistry[Journal]

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    Elucidating the Impact of Chalcogen Content on the Photovoltaic Properties of Oxychalcogenide Perovkskites NaMO3-xQx (M=Nb,Ta, and Q=S,Se,Te).
    Chemphyschem 2017 Nov 16. Epub 2017 Nov 16.
    Hamad Bin Khalifa University, Qatar Environment and Energy Research Institute, Qatar Environment and Energy Research Institute, P. O. Box 5825, 000, Doha, QATAR.
    In the quest for non-toxic and stable perovskites for solar cells, we conduct a systematic study of the effect of chalcogen content in oxychalcogenide perovskite using density functional theory (DFT) and quasi-particle perturbation theory. We explore the changes in the electronic structure due to the substitution of O atoms in NaNbO 3 and NaTaO 3 perovskite structures with various chalcogen (S, Se, Te) at different concentrations. Interestingly, the introduction of the chalcogen atoms results in a drastic reduction of the electronic band gap, making some of them fall within the visible range of the solar spectrum. Read More

    Investigation of surface sulfurization in CuIn1-xGaxS2-ySey thin films to enhance photovoltaic properties.
    Chemphyschem 2017 Nov 15. Epub 2017 Nov 15.
    Korea Institute of Science and Technology, Clean Energy Research Center, Hwarang-ro 14-gil 5, Seongbuk-gu, 136-791, Seoul, KOREA, REPUBLIC OF.
    CuIn1-xGaxS2-ySey (CIGSSe) thin films have attracted a great deal of attention as a promising absorbing material for solar cell applications due to their favorable optical properties (e.g. a direct band gap and high absorption coefficients) and stable structure. Read More

    Activation of dinitrogen (N2) with a superalkali species, Li3F2.
    Chemphyschem 2017 Nov 15. Epub 2017 Nov 15.
    University of San Francisco, Chemistry, 2130 Fulton St, 94117, San Francisco, UNITED STATES.
    The capability of the superalkali Li_3 F_2 to activate dinitrogen (N_2) is presented. The (Li_3 F_2 )_n N_2 clusters (n = 1 - 6) were investigated first at the MP2/6-311+G(3d2f,2df,2p)//B3LYP/6-311G(2d,d,p) level of theory. Clusters up to n = 4 were also optimized through the CBS-QB3 composite model. Read More

    Structure and Electronic Properties of Unnatural Base Pairs: Role of Dispersion Interactions.
    Chemphyschem 2017 Nov 15. Epub 2017 Nov 15.
    IACS, INDIA.
    Recent report of the success of unnatural base pairs (UBPs) like d5SICS-dNaM to be incorporated within the gene sequence and get replicated with DNA is an important milestone in synthetic biology. Followed by this, several other UBPs like dTPT3-dNaM, dTPT3-dFIMO, dTPT3-IMO, dTPT3-FEMO, FTPT3-NaM, FTPT3-FIMO, FTPT3-IMO, FTPT3-FEMO, have demonstrated similar or better retention and fidelity inside cell. Among these base pairs, dNaM-dTPT3 has been optimized to be a better fit inside a pAIO plasmid. Read More

    Proton Transfer Reaction Dynamics of Pyranine in DMSO-Water Mixture.
    Chemphyschem 2017 Nov 14. Epub 2017 Nov 14.
    Bhabha Atomic Research Centre, Radiation and Photochemistry Division, 400085, Mumbai, INDIA.
    Photo-induced intermolecular excited-state proton transfer (ESPT) reactions are ubiquitous in chemistry and biology. ESPT reactions are extremely sensitive to the nature of water molecules in its microenvironment and thus serve as a sensitive reporter for the water structure and dynamics in a system. Herein, the photo-induced intermolecular ESPT reaction of 8-Hydroxy pyrene-1, 3, 5-trisulfonic acid (HPTS, also known as Pyranine) has been investigated in various DMSO-water mixtures using steady-state and time-resolved emission spectroscopy. Read More

    On the performance of hybrid functionals for nonlinear optical properties and electronic excitations in chiral molecular crystals: the case of butterfly-shaped dicinnamalacetone.
    Chemphyschem 2017 Nov 14. Epub 2017 Nov 14.
    Universidade de Coimbra Faculdade de Ciencias e Tecnologia, Department of Physics, Rua Larga, P-3004-516, Coimbra, PORTUGAL.
    Purely organic chiral molecular assemblies in the solid state hold great potential for nonlinear optical applications. We report on a newly synthesized molecular system, dicinnamalacetone, an otherwise planar molecule that crystallizes in a disordered noncentrosymmetric form via four different conformations with an overall predominance of a particular helicity. A combined experimental and theoretical approach -including single-crystal X-ray diffraction, Kurtz-Perry and ab initio methods- is employed to characterize the system and at the same time benchmark the performance of hybrid functionals for the prediction of nonlinear optical properties and electronic excitations. Read More

    Insights on the Structure, Molecular Weight, and Activity of an Antibacterial Protein-Polymer Hybrid.
    Chemphyschem 2017 Nov 13. Epub 2017 Nov 13.
    North Dakota State University, Chemistry and Biochemistry, 1231 Albrecht Blvd, NDSU Ladd Hall 208, 58108-6050, Fargo, UNITED STATES.
    Protein-polymer conjugates are attractive biomaterials which combine the functions of both proteins and polymers. The bioactivity of these hybrid materials, however, is often reduced upon the conjugation. It is important to determine and monitor the protein structure and active site availability, in order to optimize the polymer composition, attachment point, and abundance. Read More

    Synthesis and Properties of Open Fullerenes Encapsulating Ammonia and Methane.
    Chemphyschem 2017 Nov 13. Epub 2017 Nov 13.
    University of Southampton, School of Chemistry, Highfield, SO17 1BJ, Southampton, UNITED KINGDOM.
    We describe the synthesis and characterisation of open fullerene (1) and its reduced form (2) in which CH4 and NH3 are encapsulated, respectively. The 1H NMR resonance of endohedral NH3 is broadened by scalar coupling to the quadrupolar 14N nucleus, which relaxes rapidly. This broadening is absent for small satellite peaks, which are attributed to natural abundance 15N. Read More

    Understanding the Reactive Adsorption of H2S and CO2 in Sodium-Exchanged Zeolites.
    Chemphyschem 2017 Nov 13. Epub 2017 Nov 13.
    University of Minnesota, Department of Chemistry, 207 Pleasant Street SE, 55455, Minneapolis, UNITED STATES.
    Purifying sour natural gas streams containing hydrogen sulfide and carbon dioxide has been a long-standing environmental and economic challenge. In the presence of cation-exchanged zeolites, these two acid gases can react to form carbonyl sulfide and water (H2S + CO2 <=> H2O + COS), but this reaction is rarely accounted for. In this work, we carry out reactive first-principles Monte Carlo (RxFPMC) simulations for mixtures of H2S and CO2 in all-silica and Na- exchanged forms of zeolite beta to understand the governing principles driving the enhanced conversion. Read More

    The stabilization of glycosyl cations through cooperative non-covalent interactions. A theoretical perspective.
    Chemphyschem 2017 Nov 10. Epub 2017 Nov 10.
    Department of Organic Chemistry Faculty of Chemistry, University of Seville C/ Profesor García González 1, 41012 Sevilla (Spain), 41012, Sevilla, SPAIN.
    A systematic study of the stabilization of glycosyl cations on aromatic rings is reported at the B3LYP, M06-2X and M11 levels of theory. In particular, π-acidic arenes such as fluorobenzenes or naphthalenediimides efficiently stabilize these cations acting cooperatively as sandwich-type ternary cation-π-anion systems. The stabilization and cooperativity in polar (both protic and aprotic) and non-polar solvents has been also evaluated by using the polarizable continuum model. Read More

    Electrochemistry of Metallo-Proteins Attached through Functional Self-Assembled Monolayers on Gold and Ferromagnetic Electrodes.
    Chemphyschem 2017 Nov 9. Epub 2017 Nov 9.
    Universita degli Studi di Modena e Reggio Emilia, Engineering, Via Vivarelli 10, 41125, Modena, ICELAND.
    We report experimental results of studying electron transfer processes via redox active metallo-proteins bound to mixed self-assembled monolayers (SAMs) on magnetic (nickel, or ultrathin gold-coated nickel) and non-magnetic (gold) electrodes. Metallo-proteins such as hemoglobin (Hb), cytochrome c, and cytochrome c oxidase are attached via electrostatic interactions to free carboxylate or imidazole groups present in mixed SAMs. The formation of both the mixed SAMs and the SAMs-metallo-protein heterostructures were confirmed by advanced surface analysis techniques such as polarization modulation-infrared reflection-absorption spectra (PMIRRAS) and aqueous contact angle (CA) measurements. Read More

    Synthetic Ion Channels and DNA Logic Gates as Components of Molecular Robots.
    Chemphyschem 2017 Nov 9. Epub 2017 Nov 9.
    Tokyo Noko Daigaku, Biotechnology and Life Science, 2-24-16 Naka-cho, Koganei, JAPAN.
    A molecular robot is a next-generation biological robot consisting of biomaterials such as DNA, proteins, and lipids that imitates the actions of microorganisms. Three prerequisites have been proposed for the construction of such a robot: sensor, intelligence, and actuator. This minireview focuses on recent research on synthetic ion channels and DNA computing technologies, which are viewed as potential candidate components of molecular robots. Read More

    Solvent effect on the behavior of lithium and superoxide ions in Li-O2 battery electrolyte.
    Chemphyschem 2017 Nov 9. Epub 2017 Nov 9.
    Joint Institute for High Temperatures of the Russian Academy of Sciences, Laboratory of Plasma Physics, Izhorskaya st. 13 Bd.2, 125412, Moscow, RUSSIAN FEDERATION.
    The molecular life of intermediates, namely O2- and Li+, produced during the discharge of aprotic Li-O2 batteries has been investigated by the MD simulation. This work is of potential interest in the development of new electrolytes for the Li-air batteries. We present the results on structure and stability of the Li+ and O2- solvation shells, as well as on thermodynamics and kinetics of the ions association reaction in the following solvents: dimethyl sulfoxide (DMSO), dimethoxyethane (DME), acetonitrile (ACN). Read More

    Structural insights from 59Co solid-state NMR experiments on organocobalt(I) catalysts.
    Chemphyschem 2017 Nov 9. Epub 2017 Nov 9.
    University of Ottawa, Chemistry, 10 Marie Curie Pvt., K1N6N5, Ottawa, CANADA.
    A series of fumarate-based organocobalt(I) [CpCo(CO)(fumarate)] catalysts are synthesized and characterized by X-ray crystallography, multinuclear (13C and 59Co) solid-state NMR spectroscopy, and 59Co NQR spectroscopy. Given the dearth of 59Co solid-state NMR studies on Co(I) compounds, the present work constitutes the first systematic characterization of the 59Co electric field gradient and chemical shift tensors for a series of cobalt complexes in this oxidation state. While by X-ray crystallography, the molecular geometry about the Co(I) centre is nearly identical in all compounds studied herein, it is shown that, owing to the 59Co nucleus' large chemical shift range, solid-state NMR experiments can detect small structural differences between the individual organocobalt(I) compounds. Read More

    PMO-immobilized Au(I)-NHC complexes: Heterogeneous catalysts for sustainable processes.
    Chemphyschem 2017 Nov 8. Epub 2017 Nov 8.
    Universiteit Gent, Campus Sterre, Building S-3, Krijgslaan 281, 9000, Ghent, BELGIUM.
    A stable Periodic Mesoporous Organosilica (PMO) with accessible sulfonic acid functionalities is prepared via a one-pot-synthesis and is used as solid support for highly active catalysts, consisting of gold(I)-N-heterocyclic carbene (NHC) complexes. The gold complexes are successfully immobilized on the nanoporous hybrid material via a straightforward acid-base reaction with the corresponding [Au(OH)(NHC)] synthon. This catalyst design strategy results in a boomerang-type catalyst, allowing the active species to detach from the surface to perform the catalysis and then to recombine with the solid after all the starting material is consumed. Read More

    Elucidating the Distribution and Speciation of Boron and Cesium in BCsX Zeolite Catalysts for Styrene Production.
    Chemphyschem 2017 Nov 7. Epub 2017 Nov 7.
    ETH Zurich, Institute for Chemical and Bioengineering, Vladimir-Prelog-Weg 1, HCI E125, CH-8093, Zurich, SWITZERLAND.
    An improved understanding of the nature and distribution of boron and cesium species in BCsX zeolites is prerequisite to guide future developments in the environmentally attractive yet challenging production of styrene via the side-chain alkylation of toluene with methanol. Here, standard characterization and catalytic tests are complemented by integrated visualization through time-of-flight secondary ion mass spectrometry and energy-dispersive X-ray spectroscopy and detailed assessment by 133Cs and 11B nuclear magnetic resonance spectroscopy, to correlate the properties and performance during the successive ion exchange and impregnation steps in the preparation of both powders and millimeter-sized granules. The results highlight a significant impact of catalyst scale up on the effective introduction of boron species, originating chemical heterogeneity that is linked to selectivity losses. Read More

    Tip-Enhanced Raman Spectroscopy: a Tool for Nanoscale Chemical and Structural Characterization of Biomolecules.
    Chemphyschem 2017 Nov 6. Epub 2017 Nov 6.
    Centre National de la Recherche Scientifique, Chemistry, Allée Geoffroy Saint Hilaire, 33600, Pessac, FRANCE.
    Due to its high molecular sensitivity and spatial optical resolution down to subnanometer values, tip-enhanced Raman spectroscopy (TERS) has emerged as a powerful microscopy technique for nanoscale characterization. Progresses in TERS instrumentation and in the manufacturing of efficient TERS tips allow for chemical and structural analysis in various experimental conditions (different wavelengths, substrates and surrounding media). Many biological species have been examined using this technique. Read More

    Inversion of Bicyclic Decanes: Rotational Spectra of the Trans and Double Cis Conformations of 2-Decalone.
    Chemphyschem 2017 Nov 6. Epub 2017 Nov 6.
    Institut für Physikalische Chemie & Elektrochemie, Lehrgebiet A, Gottfried-Wilhelm-Leibniz-Universität, Callinstrasse 3A, D-, 30167, Hannover, Germany.
    The conformational landscape of the bicyclic molecule 2-decalone has been studied in a jet-cooled expansion by using rotational spectroscopy. The investigation covered the frequency region 7-19 GHz using broadband fast-passage IMPACT Fourier-transform microwave techniques. The introduction of the asymmetric carbonyl substituent in the double-chair decalin skeleton originates two distinct inverting conformers with cis ring junction, which were independently identified and characterized in the gas phase. Read More

    Preservation of Nuclear Spin Order by Precipitation.
    Chemphyschem 2017 Nov 3. Epub 2017 Nov 3.
    University of Southampton, Chemistry, Department of Chemistry, University Road, University of Southampton, SO17 1BJ, Southampton, UNITED KINGDOM.
    We demonstrate that non-equilibrium nuclear spin order survives precipitation from solution and redissolution. The effect is demonstrated on 13C- and 2H-labeled sodium fumarate, with precipitation and dissolution achieved by altering the pH. The lifetime of the spin magnetization in the precipitate suspension is found to be much longer than in solution. Read More

    Bulky counterions: enhancing the two-photon excited fluorescence of gold nanoclusters.
    Chemphyschem 2017 Nov 3. Epub 2017 Nov 3.
    UMR5306 CNRS Universit� Claude Bernard Lyon 1, Institut Lumi�re Mati�re, 5 rue de la Doua, Cit� Lyonnaise de l'Environnement et de l'Analyse, 69100, Villeurbanne, FRANCE.
    Increasing fluorescence quantum yields of ligand-protected gold nanoclusters has attracted wide research interest. The strategy consisting in using bulky counterions has been found to dramatically enhance the fluorescence. In this communication, we push forward this concept to the nonlinear optical regime. Read More

    Multi-site cooperativity in alkali-exchanged faujasites for the production of biomass derived aromatics.
    Chemphyschem 2017 Nov 3. Epub 2017 Nov 3.
    Delft University of Technology, Inorganic Systems Engineering, Van der Maasweg 9, 2629 HZ , Delft, NETHERLANDS.
    The catalytic Diels-Alder cycloaddition/dehydration (DAC/D) reaction of furanics with ethylene is a promising route to bio-derived aromatics. The reaction can be catalyzed by alkali-exchanged faujasites. Herein, we present the results of periodic DFT calculations based on accurate structural models of alkali-exchanged zeolites, revealing the fundamental roles of confinement and the nature of the exchangeable cations in zeolite micropores for the performance of faujasite-based catalysts in the DAC/D-reaction. Read More

    CF2 -Bridged C60 Fullerene Dimers and their Optical Transitions.
    Chemphyschem 2017 Nov 2. Epub 2017 Nov 2.
    Department of Materials, University of Oxford, Oxford, OX1 3PH, United Kingdom.
    Fullerene dyads bridged with perfluorinated linking groups have been synthesized through a modified arc-discharge procedure. The addition of Teflon inside an arc-discharge reactor leads to the formation of dyads, consisting of two C60 fullerenes bridged by CF2 groups. The incorporation of bridging groups containing electronegative atoms lead to different energy levels and to new features in the photoluminescence spectrum. Read More

    The Transferability of Topologically Partitioned Electron Correlation Energies in Water Clusters.
    Chemphyschem 2017 Nov 2. Epub 2017 Nov 2.
    Manchester Institute of Biotechnology (MIB), the University of Manchester, 131 Princess Street, Manchester, M1 7DN, Great Britain), Fax: (+44) 161 3064511.
    The electronic effects that govern the cohesion of water clusters are complex, demanding the inclusion of N-body, Coulomb, exchange and correlation effects. Here we present a much needed quantitative study of the effect of correlation (and hence dispersion) energy on the stabilization of water clusters. For this purpose we used a topological energy partitioning method called Interacting Quantum Atoms (IQA) to partition water clusters into topological atoms, based on a MP2/6-31G(d,p) wave function, and modified versions of GAUSSIAN09 and the Quantum Chemical Topology (QCT) program MORFI. Read More

    TADF material design - Photophysical background and case studies focusing on Cu(I) and Ag(I) complexes.
    Chemphyschem 2017 Oct 30. Epub 2017 Oct 30.
    Ural Federal University, Mira 19, Ekaterinburg, 620002, Russia, GERMANY.
    In organic light emitting diodes (OLEDs), it is required to harvest all singlet and triplet excitons that are generated in the emission layer. This can be achieved using the effect of thermally activated delayed fluorescence (TADF) according to the singlet harvesting mechanism. In this investigation, we focus on photoluminescence properties and crucial requirements for designing Cu(I) and Ag(I) based materials that exhibit short TADF decay times τ(TADF) at high emission quantum yields. Read More

    Polymer Segments at the Folding Limit: Raman Scattering for the Diglyme Benchmark.
    Chemphyschem 2017 Oct 27. Epub 2017 Oct 27.
    Institut für Physikalische Chemie, Georg-August-Universität Göttingen, Tammannstraße 6, 37077, Göttingen, Germany.
    Methyl-capped polyethers model flexible polar polymer chains. Their intrinsic all-trans conformational preference gives way to folded conformations if the chain is sufficiently long. We find by Raman cryospectroscopy in the gas phase and quantum chemical calculations that diglyme still prefers the stretched state, although folded variants come very close in energy. Read More

    In-situ flow MAS NMR and synchrotron PDF analyses of the local response of the Brønsted acidic site in SAPO-34 during hydration at elevated temperatures.
    Chemphyschem 2017 Oct 27. Epub 2017 Oct 27.
    SINTEF, Materials and Chemistry, Forskningsveien 1, 0373, Oslo, NORWAY.
    In-situ flow magic-angle spinning nuclear magnetic resonance (MAS NMR) and synchrotron based pair distribution function (PDF) analyses have been applied to study water's interactions with the Brønsted acidic site and the surrounding framework up to 300 °C for NMR and 700 °C for PDF in the SAPO-34 catalyst. 29Si enrichment of the sample enabled detailed NMR investigations of the T-atom generating the Brønsted site. From NMR we observed dehydration above 100 °C and a coalescence of Si peaks due to local framework adjustments. Read More

    Multi-Component Uptake of Dye Molecules by Films of Nanoporous Metal-Organic Frameworks.
    Chemphyschem 2017 Oct 26. Epub 2017 Oct 26.
    Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
    Nanoporous materials, such as metal-organic frameworks (MOFs), enable the separation of various molecular mixtures. Thus, detailed knowledge of multi-component diffusion properties of the guest molecules in the pores is vital. Here, UV/Vis absorption spectroscopy combined with step-by-step-synthesized MOF films with high transparency are used to measure the multi-component dye uptake and diffusion in a straightforward fashion. Read More

    Improved Free-Energy Landscape Quantification Illustrated with a Computationally Designed Protein-Ligand Interaction.
    Chemphyschem 2017 Oct 25. Epub 2017 Oct 25.
    Univ. of Colorado & NIST, JILA, 440 UCB, 80309, Boulder, UNITED STATES.
    Quantifying the energy landscape underlying protein-ligand interactions leads to an enhanced understanding of molecular recognition. A powerful yet accessible single-molecule technique is atomic force microscopy (AFM)-based force spectroscopy, which generally yields the zero-force dissociation rate constant (koff) and the distance to the transition state (Δx‡). Here, we introduce an enhanced AFM assay and apply it to probe the computationally designed protein DIG10. Read More

    Surface-Enhanced Raman Spectroscopy Characterization of Salt Induced Aggregation of Gold Nanoparticles.
    Chemphyschem 2017 Oct 25. Epub 2017 Oct 25.
    Virginia Tech, Civil and Environmental Engineering, 415 Durham Hall , 24061, Blacksburg, UNITED STATES.
    Low frequency (<300 cm-1) vibrational interactions between gold surfaces and dissolved halides in water were investigated by surface enhanced Raman spectroscopy (SERS). Experiments with NaF, NaCl, NaBr, and NaI salts indicate that the Raman shifts of the Au-X- SERS bands correlate with the bond-strength of the corresponding covalent interaction. These low frequency SERS bands open up new means to investigate the aggregation of nanoparticles in aqueous environments. Read More

    2D Spherulites of a Semi-Fluorinated Alkane: Controlled Access to Either Radial Or Ring-Banded Morphologies.
    Chemphyschem 2017 Oct 23. Epub 2017 Oct 23.
    University of Strasbourg, Institut Charles Sadron (ICS CNRS), 23 rue du Loess, 67034, Strasbourg, France.
    Thin films of a semi-fluorinated alkane cast onto solid substrates consist of well-formed two-dimensional non-birefringent ring-banded and/or radial spherulites. Controlling the experimental conditions allows orientation of the crystallization toward either radial-only or ring-banded-only morphologies. Intermediate states were also captured in which both radial and ring-banded spherulites coexist. Read More

    Phase Equilibrium of TiO2 Nanocrystals in Flame-Assisted Chemical Vapor Deposition.
    Chemphyschem 2017 Oct 23. Epub 2017 Oct 23.
    Stanford University, Mechanical Engineering, Building 520, Room 221, 452 Escondido Mall, 94305-3032, Stanford, UNITED STATES.
    Nano-scale titanium oxide (TiO2) is a material useful for a wide range of applications. In a previous study, we showed that TiO2 nanoparticles of both rutile and anatase crystal phases could be synthesized over the size range of 5 to 20 nm in flame-assisted chemical vapor deposition. While rutile was unexpectedly dominant in oxygen-lean synthesis conditions, anatase is the preferred phase in oxygen-rich gases. Read More

    Optimized Synthesis of ZSM-11 Catalysts using 1,8-Diaminooctane as a Structure-Directing Agent.
    Chemphyschem 2017 Oct 23. Epub 2017 Oct 23.
    University of Houston, Chemical and Biomolecular Engineering, 4726 Calhoun Road, S222 Engineering Building 1, 77204, Houston, UNITED STATES.
    Developing new zeolite catalysts for (petro)chemical applications is nontrivial owing to challenges that include the identification of commercially-viable syntheses. The vast majority of syntheses require the use of an organic structure-directing agent (OSDA), which has economic and environmental shortcomings. In the search for alternative zeolites to common industrial catalysts, such as ZSM-5 (MFI), a promising candidate is ZSM-11 (MEL), a close structural analogue of MFI. Read More

    Unexpected Crystallization Patterns of Zinc Boron Imidazolate Framework ZBIF-1: NMR Crystallography of Integrated Metal-Organic Frameworks.
    Chemphyschem 2017 Oct 19. Epub 2017 Oct 19.
    Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovskeho nam. 2, 162 06, Prague 6, Czech Republic.
    Framework materials, that is, metal-organic frameworks (MOFs) and inorganic frameworks (zeolites), are porous systems with regular structures that provide valuable properties suitable for sorption, catalysis, molecular sieving, and so on. Herein, an efficient, experimental/computational strategy is presented that allows detailed characterization of a polycrystalline MOF system, namely, zinc boron imidazolate framework ZBIF-1, with two integrated unit cells on the atomic-resolution level. Although high-resolution (1) H, (11) B, (13) C, and (15) N MAS NMR spectra provide valuable structural information on the coexistence of two distinct asymmetric units in the investigated system, an NMR crystallography approach combining X-ray powder diffraction, solid-state NMR spectroscopy, and DFT calculations allowed the exact structure of the secondary crystalline phase to be firmly defined and, furthermore, the mutual interconnectivity of the two crystalline frameworks to be resolved. Read More

    Non-oxidative Coupling of Methane to Ethylene Using Mo2C/[B]ZSM-5.
    Chemphyschem 2017 Oct 16. Epub 2017 Oct 16.
    University of Delaware, Chemical and Biomolecular Engineering, 150 Academy St, 19711, Newark, UNITED STATES.
    Methane non-oxidative coupling to ethylene was investigated on Mo2C/[B]ZSM-5 catalyst at 923 K and atmospheric pressure. In contrast to Mo2C/[Al]ZSM-5 catalysts for methane aromatization, this material exhibits very high ethylene selectivity (>90%) and low aromatics (benzene and naphthalene) selectivity. The much weaker Brønsted acidity of [B]ZSM-5 leads to a slow rate of ethylene oligomerization. Read More

    The selective role of long range forces in the stereodynamics of ion-molecule reactions: The He+ + methyl formate case from guided ion beam experiments.
    Chemphyschem 2017 Oct 18. Epub 2017 Oct 18.
    Universita degli Studi di Trento, Dipartimento di Fisica, Via Sommarive 14, 38123, Trento, ITALY.
    Long range intermolecular forces play a crucial role in controlling the outcome of ion-molecule chemical reactions, such as those determining the disappearance of organic or inorganic "complex" molecules recently detected in various regions of the interstellar medium due to collisions with abundant interstellar atomic ions (e.g. H+ and He+). Read More

    Protocol for Computational Enzymatic Reactivity Based on Geometry Optimisation.
    Chemphyschem 2017 Oct 16. Epub 2017 Oct 16.
    University of Porto, PORTUGAL.
    Enzymes play a biologically essential role in performing and controlling an important share of the chemical processes occurring in life. However, despite their critical role in nature, attaining a clear understanding of the way an enzyme acts is still cumbersome. Computational enzymology is playing an increasingly important role in this field of research. Read More

    Fast Lithium-Ion Transportation in Crystalline Polymer Electrolytes.
    Chemphyschem 2017 Oct 16. Epub 2017 Oct 16.
    East China Normal University, Physics Department, North Zhongshan Road 3663#, 200062, Shanghai, CHINA.
    Fast lithium-ion transportation is found in the crystalline polymer electrolytes, α-CD-PEOn/Li+ (n = 12, 40), prepared by self-assembly of α-cyclodextrin (CD), polyethylene oxide (PEO) and Li+ salts. A detailed solid-state NMR study combined with X-ray diffraction technique reveals the unique structural features of the samples, that is, a) the tunnel structure formed by the assembled CDs, providing the ordered long-range pathway for Li+ ion transportation; b) the all-trans conformational sequence of the PEO chains in the tunnels, attenuating significantly the coordination between Li+ and the EO segments. The origin of the fast lithium-ion transportation has been attributed to these unique structural features. Read More

    Effect of Porosity Size on Carbon Dioxide Adsorption of Porous Liquid Based on Hollow Silica.
    Chemphyschem 2017 Oct 15. Epub 2017 Oct 15.
    Northwestern Polytechnical University, School of Science, CHINA.
    Porous liquid is a kind of burgeoning material that possesses huge potential in gas separation and gas adsorption. Pore size has a dramatic influence on the gas adsorption of porous liquids. In this article, we chose hollow silica nanoparticles as cores, 3-(trihydroxysilyl)-1-propanesulfonic acid (SIT) as corona and cheap industrial reagent polyether amine (M2070) as canopy to obtain a new type of porous liquid. Read More

    How Chi Sequence Modifies RecBCD Single-Stranded DNA Translocase Activities.
    Chemphyschem 2017 Oct 15. Epub 2017 Oct 15.
    National Taiwan Univ, Dept. of Chemistry, No. 1, Sec. 4, Roosevelt Road, 10617, Taipei, TAIWAN.
    E. coli RecBCD initiates homologous repair as well as degrades foreign DNA. Recognition of chi sequence (5'-GCTGGTGG-3') switches RecBCD from a destructive, nucleolytic mode into a repair-active one that promotes RecA-mediated recombination. Read More

    On-Surface Synthesis of Adenine Oligomers via Ullmann Reaction.
    Chemphyschem 2017 Oct 13. Epub 2017 Oct 13.
    Interdisciplinary Materials Research Center, Tongji-Aarhus Joint Research Center for Nanostructures and Functional Nanomaterials, College of Materials Science and Engineering, Tongji University, Caoan Road 4800, Shanghai, 201804, P. R. China.
    Despite the fact that DNA bases have been well-studied on surface, the on-surface synthesis of one-dimensional DNA analogs through in situ reactions is still an interesting topic to be investigated. Herein, from the interplay of high-resolution scanning tunneling microscopy (STM) imaging and density functional theory (DFT) calculations, we have delicately designed a halogenated derivative of adenine as precursor to realize the combination of DNA bases and Ullmann reaction, and then successfully synthesized adenine oligomers on Au(111) via Ullmann coupling. This model system provides a possible bottom-up strategy of fabricating adenine oligomers on surface, which may further give access to man-made DNA strands with multiple bases. Read More

    Ferromagnetism and Half-Metallicity in a High-Band-Gap Hexagonal Boron Nitride System.
    Chemphyschem 2017 Oct 13. Epub 2017 Oct 13.
    Discipline of Chemistry, Indian Institute of Technology (IIT) Indore, Indore. M.P., 453552, India.
    Metal-free half-metallicity is the subject of intense research in the field of spintronics devices. Using density functional theoretical calculations, atom-thin hexagonal boron nitride (h-BN)-based systems are studied for possible spintronics applications. Ferromagnetism is observed in patterned C-doped h-BN systems. Read More

    Ultrafast dynamics of a fluorescent tetrazolium compound in solution.
    Chemphyschem 2017 Oct 13. Epub 2017 Oct 13.
    Ruhr-Universitat Bochum, Physikalische Chemie II, Universitätsstraße 150, 44801, Bochum, GERMANY.
    Tetrazolium salts are exploited in various fields of research by virtue of their low reduction potentials. Increasingly, associated applications also attend to the photochemical and luminescence properties of these systems. Here, we investigate the photo-induced dynamics of phenyl-benzo[c]tetrazolo-cinnolinium chloride (PTC), one of the very few known fluorescent tetrazolium compounds, using time-correlated single-photon counting, femtosecond fluorescence upconversion, and ultrafast transient absorption spectroscopy. Read More

    Unravelling the Redox-catalytic Behavior of Ce(4+) Metal-Organic Frameworks by X-ray Absorption Spectroscopy.
    Chemphyschem 2017 Oct 13. Epub 2017 Oct 13.
    Centre for Surface Chemistry and Catalysis, Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F P.O. box 2461, 3001, Leuven, Belgium.
    The introduction of Ce(4+) as a structural cation has been shown to be a promising route to redox active metal-organic frameworks (MOFs). However, the mechanism by which these MOFs act as redox catalysts remains unclear. Herein, we present a detailed study of the active site in [Ce6 O4 (OH)4 ]-based MOFs such as Ce-UiO-66, involved in the aerobic oxidation of benzyl alcohol, chosen as a model redox reaction. Read More

    Effect of Water Addition during Preparation on the Early-Time Photodynamics of CH3 NH3 PbI3 Perovskite Layers.
    Chemphyschem 2017 Oct 12. Epub 2017 Oct 12.
    MESA+ Institute for Nanotechnology, University of Twente, 7500, AE, Enschede, The Netherlands.
    The effect of water addition during preparation of a CH3 NH3 PbI3 layer on the photodynamics is studied by femtosecond transient absorption. Both the regular perovskite and the aqueous analogue show charge thermalisation on a timescale of about 500 fs. This process is, however, less pronounced in the latter layer. Read More

    Band-Gap Engineering of Graphene Heterostructures via Substitutional Doping with B3N3.
    Chemphyschem 2017 Oct 11. Epub 2017 Oct 11.
    University of Tsukuba, JAPAN.
    We investigated the energetics and electronic structures of B3N3-doped graphene using the density functional theory with the generalized gradient approximation. Our calculations showed that all of the B3N3-doped graphene structures were semiconductors, irrespective of the periodicity of the B3N3 embedded into the graphene network, in contrast to graphene nanomeshes which are either semiconductors or metals depending on the mesh arrangement. The B3N3-doped graphene has small effective masses for both electron and hole. Read More

    The structure of diphenyl ether-methanol in the electronically excited and ionic ground states: A combined IR/UV spectroscopic and theoretical study.
    Chemphyschem 2017 Oct 11. Epub 2017 Oct 11.
    Technische Universitat Kaiserslautern, Physikalische Chemie, Erwin-Schroedingerstrasse 52, 67663, Kaiserslautern, GERMANY.
    Diphenyl ether offers competing docking sites for methanol: the ether oxygen as a common hydrogen bond acceptor and the pi-system of each phenyl ring allowing for OH-pi interactions driven by electrostatic, induction and dispersion forces. Based on investigations in the electronic ground state (S0) we present a detailed study on the electronically excited state (S1) and the ionic ground state (D0), in which an impact on the structural preference is expected compared to the S0 state. Dispersion forces in the electronically excited state are analyzed by comparing the computed binding energies at the coupled-cluster-singles and approximate coupled-cluster-singles-doubles levels of theory (CC2 approximation). Read More

    Impact of the Long-Range Electronic Effect of a Fluorous Ponytail on Metal Coordination during Solvent Extraction.
    Chemphyschem 2017 Oct 11. Epub 2017 Oct 11.
    Laboratoire des Systèmes Hybrides pour la Séparation, Institut de Chimie Séparative de Marcoule, BP17171, F-30207, Bagnols sur Cèze, France.
    With the need for a precise description of the long-range electronic effects of a perfloroalkyl chain (F-ponytail) grafted onto metal chelators, we studied in detail the effect of a spacer inserted between the polar complexing head and the F-ponytail, in relation to the metal coordination ability of the resulting molecules. The prepared molecules were then applied for the extraction of various metals from an aqueous phase into an organic phase, and the optimum spacer length could be estimated to be between three and four methylene units, according to the extraction conditions. The study also revealed the difficulty of modeling and anticipating the tiny energy differences involved in the extraction process and the importance in peculiar cases to go beyond only these studied inductive effects to understand better the factors that govern the stabilization of a metallic cation in a complex fluorous phase. Read More

    Ionic Self-Assembled Derivative of Tetraphenylethylene: Synthesis, Enhanced Solid-State Emission, Liquid-Crystalline Structure, and Cu(2+) Detection Ability.
    Chemphyschem 2017 Oct 10. Epub 2017 Oct 10.
    Beijing National Laboratory for Molecular Sciences, College of Chemistry, Peking University, Beijing, 100871, P.R. China.
    A novel tetraphenylethylene complex composed of 4',4'',4''',4''''-(ethene-1,1,2,2-tetrayl)tetrabiphenyl-4-carboxylic acid (H4 ETTC) and dimethyldioctadecylammonium bromide (DOAB) with enhanced solid-state emission is designed and synthesized through an ionic self-assembly (ISA) strategy. The aggregation-induced emission property, phase behavior, and supramolecular structure of the complex are characterized by a combination of experimental measurements. The experimental results reveal that the ISA complex can self-assemble into an ordered helical supramolecular structure with enhanced luminescent properties, although the ETTC cores possess extensive conjugation and high rigidity. Read More

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