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Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry

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https://www.readbyqxmd.com/read/30221834/hydrogen-generating-ru-pt-bimetallic-photocatalysts-based-on-phenyl-phenanthroline-peripheral-ligands
#1
Laura O'Reilly, Qing Pan, Nivedita Das, Kasper Wenderich, Jeroen Korterik, Johannes Vos, Dr Mary Pryce, Annemarie Huijser
Recent studies on hydrogen generating supramolecular bimetallic photocatalysts indicate a more important role of the peripheral ligands than expected, motivating us to design a Ru/Pt complex with 4,7-diphenyl-1,10-phenanthroline peripheral ligands. Photoinduced intra- and inter-ligand internal conversion processes have been investigated using transient absorption spectroscopy, spanning the femto- to nanosecond timescale. After photoexcitation and ultrafast intersystem crossing, triplet states localised on either the peripheral ligands or on the bridging ligand/catalytic unit are populated in a non-equilibrated way...
September 17, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30221826/dimethylammonium-incorporation-in-lead-acetate-based-mapbi%C3%A2-perovskite-solar-cells
#2
Wouter Franssen, Bardo Bruijnaers, Victor Portengen, Arno Kentgens
Over the last years, several different pathways have been suggested for producing perovskite thin films for solar cell applications. While the merit of these methods with respect to the solar cell efficiency have been shown, the actual composition of the resulting thin films is often not investigated. Here, we show that methylammonium lead iodide films produced using lead acetate as a lead source can have up to 15% dimethylammonium incorporated into their crystal structure, even though this ion is often consider to be too large for incorporation...
September 17, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30221816/probing-polymer-chain-conformation-and-fibril-formation-of-peptide-conjugates
#3
Zhanna Evgrafova, Bruno Voigt, Monika Baumann, Madlen Stephani, Wolfgang H Binder, Jochen Balbach
Covalent conjugates between a synthetic polymer and a peptide hormone were used to probe the molecular extension of these macromolecules and how the polymer modifies the fibril formation of the hormone. NMR spectroscopy of 15N labeled parathyroid hormone (PTH) was employed to visualize the conformation of the conjugated synthetic polymer, triggered by small temperature changes via its lower critical solution temperature. A shroud-like polymer conformation dominated the molecular architecture of the conjugated chimeras...
September 17, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30216679/conformations-and-binding-properties-of-thiametoxam-and-clothianidin-neonicotinoid-insecticides-to-nicotinic-acetylcholine-receptors-the-contribution-of-sigma-hole-interactions
#4
Zakaria Alamiddine, Steeve H Thany, Jérôme Graton, Jean-Yves LE Questel
Structural features and molecular interactions properties of thiamethoxam (THA) and clothianidin (CLO), two neonicotinoids, have been investigated through a combined approach based on a wide range of molecular modeling methods and x-ray structures observations. Despite their close chemical structures, significant differences are emphasized by QM (DFT), docking, Molecular Dynamics, and QM/QM' calculations. Thus, for the first time, their propensity to interact through chalcogen bond interactions is highlighted...
September 14, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30216615/clusters-of-the-ionic-liquid-1-hydroxyethyl-3-methylimidazolium-picrate-from-theoretical-prediction-in-the-gas-phase-to-experimental-evidence-in-the-solid-state
#5
Sumit K Panja, Haddad Boumediene, Johannes Kiefer
The interonic interactions determine the macroscopic properties of ionic liquids (ILs). Hence, unravelling the relationships between the microscopic and the macroscopic scales is the key for a rational design. In the present work, we make a step towards understanding how the physicochemical effects in small gas phase clusters of a hydroxyl functionalized imidazolium-picrate IL relate with the molecular structure and interactions of the corresponding solid material taking 1-hydroxyethyl-3-methylimidazolium picrate, C2OHmimPic, as an example...
September 14, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30207624/nanometer-scale-multiplexed-super-resolution-imaging-with-an-economic-3d-dna-paint-microscope
#6
Alexander Auer, Thomas Schlichthaerle, Johannes Woehrstein, Florian Schueder, Maximilian Strauss, Heinrich Grabmayr, Ralf Jungmann
Optical super-resolution microscopy is rapidly changing the way imaging studies in the biological and biomedical sciences are conducted. Due to the unique capability of achieving molecular contrast using fluorescent labels and sub-diffraction resolution down to a few tens of nanometers, super-resolution is developing as an attractive imaging modality. While the increased spatial resolution has already enabled structural studies at unprecedented molecular detail, the wide-spread use of super-resolution approaches as a standard characterization technique in biological laboratories has thus far been prevented by mainly two issues: (1) Intricate sample preparation and image acquisition and (2) costly and complex instrumentation...
September 12, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30204288/is-raman-optical-activity-spectroscopy-sensitive-to-beta-turns-in-proteins-secondary-structure-and-side-chain-dependence
#7
Carl Mensch, Christian Johannessen
β-turns are essential for the structure and function of proteins. The spectroscopic technique Raman optical activity (ROA) has been suggested to be sensitive to such structural elements of proteins in solution. Three spectral features have been reported to mark β-turns in protein ROA spectra: being a negative band at 1220 cm-1, positive intensity around 1290 cm-1 and negative intensity around 1340-1380 cm-1. In this work, density functional theory calculations demonstrated that these assignments are inaccurate as these spectral regions are not robust and sense the exact secondary structure surrounding the β-turn as well...
September 11, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30204284/photodynamics-and-luminescence-of-mono-and-tri-nuclear-lanthanide-complexes-in-gas-phase-and-solution
#8
Florian Liedy, Florian Bäppler, Eugen Waldt, Yevgeniy Nosenko, Dimitri Imanbaew, Asamanjoy Bhunia, Munendra Yadav, Rolf Diller, Manfred M Kappes, Peter W Roesky, Detlef Schooss, Christoph Riehn
Lanthanide ions (DyIII, EuIII) are stabilized by coordination with two Schiff base ligands (H4L, 2,2'-{[(2-aminoethyl)imino]bis[2,1-ethanediyl-nitriloethylidyne]}bis-2-hydroxy-benzoic acid) in compounds [Dy{H3L}2](NO3)(EtOH)(H2O)8 (1) and [Eu{H3L}2](NO3)(H2O)8 (3). The latter is reported here for the first time. Both luminescence and ultrafast photodynamics after photoexcitation via a ligand absorption band (∼400 nm) have been studied. In solution, only the [Eu{H3L}2]+ ([3]+) complex displays the typical lanthanide emission lines, whereas in gas phase both, [Dy{H3L}2]+ ([1]+) and [3]+, show their corresponding transitions depending on excitation energy...
September 11, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30203923/polar-effects-control-the-gas-phase-reactivity-of-para-benzyne-analogs
#9
Huaming Sheng, Xin Ma, Hao-Ran Lei, Jacob Milton, Weijuan Tang, Chunfen Jin, Jinshan Gao, Ashley M Wittrig, Enada F Archibold, John J Nash, Hilkka I Kenttämaa
We report herein a gas-phase reactivity study on a para-benzyne cation and its three cyano-substituted, isomeric derivatives performed using a dual-linear quadrupole ion trap mass spectrometer. All four biradicals were found to undergo primary and secondary radical reactions analogous to those observed for the related monoradicals, indicating the presence of two reactive radical sites. The reactivity of all biradicals is substantially lower than that of the related monoradicals, as expected based on the singlet ground states of the biradicals...
September 11, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30199592/iridium-%C3%AE-carboxyimine-complexes-hyperpolarized-with-parahydrogen-exist-in-nuclear-singlet-states-before-conversion-into-iridium-carbonates
#10
Simon Duckett, Ben J Tickner, Wissam Iali, Soumya S Roy, Adrian C Whitwood
The formation and hyperpolarization of an [Ir(H)₂(amine)(IMes)(η²-imine)]Cl complex that can be created in a hyperpolarized nuclear singlet state is reported. These complexes are formed when an equilibrium mixture of pyruvate, amine (benzylamine or phenylethylamine), and the corresponding imine condensation product, react with preformed [Ir(H)₂(amine)₃(IMes)]Cl. These iridium α-carboxyimine complexes exist as two regioisomers differentiated by the position of amine. When examined with para-hydrogen the hydride resonances of the isomer with amine trans to hydride become strongly hyperpolarized...
September 10, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30198105/polyanionic-polydentate-europium-complexes-as-bright-one-or-two-photon-bioprobe
#11
Olivier Maury, François Riobé, Chantal Andraud, Boris Le Guennic, Henri Sund, Harri Takalo, Alain Duperray, Alexei Grichine, Yuan-Yuan Liao
A family of europium (III) complexes based on a polydentate ligand functionalized by charge transfer antennae presents remarkable one and two photon photophysical proper-ties in water or buffer. A detailed analysis of their emission properties suggests that the wrapping of the ligand around the central rare-earth ion results in an overall Cs symmetry in agreement with the theoretical simulation and that about 65-70% of the emission intensity concentrated in the hypersensitive 5D0 → 7F2 transition at 615 nm...
September 10, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30193005/anion-exchange-at-the-liquid-solid-interface-of-ultrathin-ionic-liquid-films-on-ag-111
#12
Matthias Lexow, Bettina S J Heller, Florian Maier, Hans-Peter Steinrück
Thin ionic liquid (IL) films play an important role in many applications. To obtain a better understanding of the ion distribution within IL mixture films, we sequentially deposited ultrathin layers of two ILs with the same cation but different anions onto Ag(111), and monitored their dynamic behaviour by angle-resolved X-ray photoelectron spectroscopy. Upon depositing [C8C1Im][PF6] on top of a wetting layer of [C8C1Im][Tf2N] at room temperature (RT), we found a pronounced enrichment of the [Tf2N]- anions at the IL/vacuum interface, due to a rapid anion exchange at the IL/solid interface...
September 7, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30192059/hidden-dicarbene-nature-of-acetylenes-and-captodative-bonding-on-carbon
#13
Cherumuttathu H Suresh, Padinjare Veetil Bijina
DFT derived molecular electrostatic potential (MESP), ¹³C NMR chemical shift (δ), bond order and coordination reactions show that alkynes (RCCR) attain 1,2-dicarbene nature during CCR angle bending. Alkyne carbon atoms of bent structures exhibit MESP features unique to lone-pair bearing atoms, δ around 200 ppm typical for carbene centers and large reduction in CC triple bond character. Lone pair bearing atoms of R substituents enhance the carbene character. The bent alkynes can be trapped with Lewis acids (BH₃, BF₃, AlF₃ and AlCl₃) as the lone pairs developed on carbon centers provide strong donor type dative bonding...
September 7, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30183138/intramolecular-proton-and-charge-transfer-of-pyrene-based-trans-stilbene-salicylic-acids-applied-to-detection-of-aggregated-proteins
#14
Jun Zhang, Jun Wang, Alexander Sandberg, Xiongyu Wu, Sofie Nyström, Harry LeVine Iii, Peter Konradsson, Per Hammarström, Bo Durbeej, Mikael Lindgren
Two analogues to the fluorescent amyloid probe 2,5-bis(4'-hydroxy-3'-carboxy-styryl)benzene (X-34) were synthesized based on the trans-stilbene pyrene scaffold (Py1SA and Py2SA). The compounds show strikingly different emission spectra when bound to preformed Aβ1-42 fibrils. This remarkable emission difference is retained when bound to amyloid fibrils of four distinct proteins, suggesting a common binding configuration for each molecule. Density functional theory calculations show that Py1SA is twisted, while Py2SA is more planar...
September 5, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30178918/chiral-purity-of-crystals-using-low-frequency-raman-spectroscopy
#15
Irena Nemtsov, Yitzhak Mastai, Yaakov R Tischler, Hagit Aviv
The pharmaceutical industry is in need of new techniques to identify chirality of solids due to regulatory and safety concerns regarding the biological activity of enantiomers. In this study, we present for the first time, the application of low-frequency Raman spectroscopy as a new and sensitive method for analyzing chiral purity of crystals. Using this method, we were able to identify small amounts, as low as 1% w/w of an enantiomer in racemic crystals. In order to demonstrate the capabilities of the method, we used a model system based on chiral crystals of enantiopure, racemic crystals, and their mixtures in various ratios...
September 4, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30171653/mixed-valence-compounds-auo2-and-aus
#16
Meng Tang, Yanmei Zhang, Siya Li, Xi Wu, Yan Jia, Guochun Yang
Mixed-valence compounds are of great interest due to their interesting properties and wide applications. Recently, gold (Au) chemistry has experienced an unprecedented development. However, Au with mixed-valence states in Au-O compounds have not been reported thus far. Here, two hitherto unknown AuO2 and AuS compounds with mixed-valence character were identified with the aid of first-principles swarm structure searching calculations. AuO2 consists of quasi-square AuO4 moiety and AuO6 octahedron in which Au shows the mixed-valence states of III and V, the first example in Au-O binary compounds...
August 31, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30159998/temperature-dependent-shape-changes-of-ice-nanoclusters-on-ag-100
#17
Georgijs Bakradze, Karina Morgenstern
We investigate the influence of the annealing temperature on the evolution of the ice nanoclusters' geometry by means of low-temperature scanning tunneling microscopy. The clusters, grown at 110 K on Ag(100), gradually increase in height and their shape becomes more compact during annealing at 120 K, 125 K, and 130 K. The increase in height indicates an upward mass transport and reflects a stronger water-water than water-surface bonding. The change in shape, quantitatively expressed as an increase in fractal dimension, is driven by a reduction of the total energy of the step edge...
August 30, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30156047/the-%C3%AF-hole-coulombic-interpretation-of-trihalide-anion-formation
#18
Timothy Clark, Jane S Murray, Peter Politzer
It is shown that the interactions of dihalogen molecules XY with halide anions Z- to form trihalide anions (XYZ)- can be satisfactorily described as Coulombic, involving the σ-holes on the atoms Y, but only if polarization is taken into account. We have approximated the polarizing effect of the halide anion Z- by means of a unit negative point charge. The CCSD/aug-cc-pVTZ computed interaction energies interaction energies ΔE correlate well with the most positive electrostatic potentials associated with the induced σ-holes over a ΔE range of -12 to -63 kcal mol-1...
August 28, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30151973/a-structural-basis-for-129-xe-hyper-cest-signal-in-tem-1-%C3%AE-lactamase
#19
Benjamin W Roose, Serge D Zemerov, Yanfei Wang, Marina A Kasimova, Vincenzo Carnevale, Ivan J Dmochowski
Genetically encoded (GE) contrast agents detectable by magnetic resonance imaging (MRI) enable non-invasive visualization of gene expression and cell proliferation at virtually unlimited penetration depths. Using hyperpolarized 129 Xe in combination with chemical exchange saturation transfer, an MR contrast approach known as hyper-CEST, enables ultrasensitive protein detection and biomolecular imaging. GE MRI contrast agents developed to date include nanoscale proteinaceous gas vesicles as well as the monomeric bacterial proteins TEM-1 β-lactamase (bla) and maltose binding protein (MBP)...
August 27, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/30142233/multiscale-simulation-of-the-interaction-and-adsorption-of-ions-on-a-hydrophobic-graphene-surface
#20
Luohao Chen, Yanan Guo, Zhijun Xu, Xiaoning Yang
The adsorption of ions on a graphene surface is very important to control relevant graphene-based processes. In this work, a multiscale simulation was carried out to study the adsorption of Na+ /Cl- ions on graphene by combining quantum mechanics calculations and molecular dynamics (MD) simulations. The interaction energies of the ions with graphene were computed using density functional theory (DFT). It was found that the ions show strong interaction with a graphene cluster and the overwhelming portion of the interaction energy is the ion-π orbital interaction...
August 24, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
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