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    6397 results match your criteria Chemphyschem : a European journal of chemical physics and physical chemistry[Journal]

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    Spectroscopic and Hydrodynamic Characterisation of DNA-Linked Gold Nanoparticle Dimers in Solution using Two-Photon Photoluminescence.
    Chemphyschem 2018 Feb 21. Epub 2018 Feb 21.
    Univ Rennes, CNRS, SATIE-UMR8029, 35000, Rennes, France.
    Two-photon photoluminescence (TPPL) emission spectra of DNA-gold nanoparticle (AuNP) monoconjugates and the corresponding DNA-linked AuNP dimers are obtained by photon time-of-flight spectroscopy. This technique is combined with two-photon photoluminescence fluctuation correlation spectroscopy (TPPL-FCS) to simultaneously monitor the optical and hydrodynamic behaviour of these nano-assemblies in solution, with single-particle sensitivity and microsecond temporal resolution. In this study, the AuNPs have an average core diameter of 12 nm, which renders their dark-field plasmonic light scattering too weak for single-particle imaging. Read More

    Formation Mechanism of Atmospheric Ammonium Bisulfate: Hydrogen-Bond-Promoted Nearly Barrierless Reactions of SOwith NHand HO.
    Chemphyschem 2018 Feb 20. Epub 2018 Feb 20.
    Department of Physics, City University of Hong Kon, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, China.
    Particulate matter (PM) air pollution threatens the health of people and ecosystems worldwide. As the key component of PM, ammonium sulfate plays a critical role in the formation of aerosol particles; thus, there is an urgent need to know the detailed mechanisms for its formation in the atmosphere. Through a quantum chemistry study, we reveal a series of nearly barrierless reactions that may occur in clusters/droplets in the atmosphere leading to the formation of ammonium bisulfate (NHHSO), the precursor of ammonium sulfate. Read More

    Controlling the Outgrowth and Functions of Neural Stem Cells: The Effect of Surface Topography.
    Chemphyschem 2018 Feb 19. Epub 2018 Feb 19.
    Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), Heraklion, 71003, Greece.
    Neural stem cells (NSCs) are self-renewing cells that generate the major cell types of the central nervous system, namely neurons, astrocytes and oligodendrocytes, during embryonic development and in the adult brain. NSCs reside in a complex niche where they are exposed to a plethora of signals, including both soluble and physical signals such as compressive and shear stresses, but also discontinuities and differences in morphology of the extracellular environment, termed as topographical features. Different approaches that incorporate artificial micro- and nano-scale surface topographical features have been developed aiming to recapitulate the in vivo NSC niche discontinuities and features, particularly for in vitro studies. Read More

    Electronic structure characterisation of cross-linked sulfur polymers.
    Chemphyschem 2018 Feb 16. Epub 2018 Feb 16.
    Cross-linked polymers of elemental sulfur are of potential interest for electronic applications as they enable facile thin film processing of an abundant and cheap starting material. In this paper, we characterize the electronic structure of a cross-linked sulfur / diisopropenyl benzene (DIB) polymer by a combination of soft and hard X-ray photoelectron spectroscopy. Two different approaches for enhancing the conductivity of the polymer are compared: the addition of selenium in the polymer synthesis and the addition of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) during film preparation. Read More

    Characterizing the Effects of a "Switchable Water" Additive on the Aqueous Solubility of Small Molecules.
    Chemphyschem 2018 Jan 25. Epub 2018 Jan 25.
    Department of Chemistry, Queen's University, Kingston, ON, K7L 3N6, Canada.
    "Switchable water" is an aqueous solution containing a water-soluble amine additive that exhibits CO-switchable properties, such as large changes in ionic strength, by forming an ammonium bicarbonate salt. Switchable water has been used to reversibly "salt-out" organic compounds from water. This study explores the salting out of several compounds in switchable water when COis present and also explores the solubility of small molecules in switchable water, compared to pure water, when COis absent. Read More

    Microstructured Photo-Crosslinked Poly(Trimethylene Carbonate) for Use in Soft Lithography Applications: A Biodegradable Alternative for Poly(Dimethylsiloxane).
    Chemphyschem 2018 Feb 13. Epub 2018 Feb 13.
    University of Twente, Biomaterials Science and Technology, PO Box 217, Zuidhorst 235, 7500 AE, Enschede, NETHERLANDS.
    Photo-crosslinkable poly(trimethylene carbonate) (PTMC) macromers were used to fabricate microstructured surfaces. Microstructured PTMC surfaces were obtained by hot embossing the macromer against structured silicon masters, subsequent photo-crosslinking then results in network formation. The microstructures of the master could be precisely replicated, shrinkage being limited. Read More

    Micropolarity and Hydrogen-Bond Donor Ability of Environmentally Friendly Anionic Reverse Micelles Explored by UV/Vis Absorption of a Molecular Probe and FTIR Spectroscopy.
    Chemphyschem 2018 Feb 8. Epub 2018 Feb 8.
    Departamento de Química, Universidad Nacional de Río Cuarto, Agencia Postal # 3, C.P., X5804BYA, Río Cuarto, Argentina.
    In the present work we show how two biocompatible solvents, methyl laurate (ML) and isopropyl myristate (IPM), can be used as a less toxic alternative to replace the nonpolar component in a sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) reverse micelles (RMs) formulation. In this sense, the micropolarity and the hydrogen-bond ability of the interface were monitored through the use of the solvatochromism of a molecular probe (1-methyl-8-oxyquinolinium betaine, QB) and Fourier transform infrared spectroscopy (FTIR). Our results demonstrate that the micropolarity sensed by QB in ML RMs is lower than in IPM RMs. Read More

    Unsupervised Screening of Vibrational Spectra by Principal Component Analysis for Identifying Molecular Clusters.
    Chemphyschem 2018 Feb 6. Epub 2018 Feb 6.
    Technische Thermodynamik and MAPEX Center for Materials and Processes, Universität Bremen, Badgasteiner Str. 1, 28359, Bremen, Germany.
    Vibrational spectra are commonly used to study molecular interactions in solutions. However, the data analysis is often demanding and requires significant experience in order to obtain meaningful results. This study demonstrates that principal component analysis (PCA) can serve as an unsupervised tool for initial screening of non-ideal mixture systems. Read More

    Microfabricated Probes for Studying Brain Chemistry: A Review.
    Chemphyschem 2018 Feb 5. Epub 2018 Feb 5.
    Department of Chemistry, University of Michigan, 930 N. University Ave, Ann Arbor, MI, 48109, USA.
    Probe techniques for monitoring in vivo chemistry (e.g., electrochemical sensors and microdialysis sampling probes) have significantly contributed to a better understanding of neurotransmission in correlation to behaviors and neurological disorders. Read More

    Spin-Noise-Detected Two-Dimensional Nuclear Magnetic Resonance at Triple Sensitivity.
    Chemphyschem 2018 Feb 4. Epub 2018 Feb 4.
    Institute of Organic Chemistry, Johannes Kepler, University Linz, Altenbergerstraße 69, 4040, Linz, Austria.
    A major breakthrough in speed and sensitivity of 2 D spin-noise-detected NMR is achieved owing to a new acquisition and processing scheme called "double block usage" (DBU) that utilizes each recorded noise block in two independent cross-correlations. The mixing, evolution, and acquisition periods are repeated head-to-tail without any recovery delays and well-known building blocks of multidimensional NMR (constant-time evolution and quadrature detection in the indirect dimension as well as pulsed field gradients) provide further enhancement and artifact suppression. Modified timing of the receiver electronics eliminates spurious random excitation. Read More

    Size-Dependent Phase Separation in Emulsion Droplets.
    Chemphyschem 2018 Feb 4. Epub 2018 Feb 4.
    State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, P. R. China.
    Phase separation occurs in emulsion droplets containing poly (ethylene glycol) diacrylate (PEGDA), glycerol, and ethanol to form a glycerol-in-PEGDA structure, and the phase separation process is found to depend on the droplet size. The mechanism of this size-dependent phase separation is dependent on the droplet sizes changing the phase separation time by changing the evaporation speed of mutual solvent ethanol, and the relationship between the separation time T and the droplet diameter D is derived as T≈D, which has been validated by experiment results. According to this finding, the structures of the droplets can be designed by applying UV curing at different stages of the phase separation, and the monodispersity of droplets is necessary to achieve polymerized particles with the same structure. Read More

    Identifying Different Halogen/Hydrogen Bonding Interaction Modes in the Binary Systems Containing An Acetate Ionic Liquid and Various Halobenzenes.
    Chemphyschem 2018 Feb 1. Epub 2018 Feb 1.
    Tsinghua University, Departemnt of Chemistry, Qinghua Yuan, Haidian District, 100084, Beijing, CHINA.
    To elucidate the nature of noncovalent interactions between ionic liquids (ILs) and halogenated molecules is of particular importance for both fundamental research and drug development. In this work, the noncovalent interactions between 1-butyl-3-methyl-imidazolium acetate and three halobenzenes C6F5X (X=I, Br, H) were investigated. The iodine derivative shows the strongest interaction with the IL, followed by C6F5Br and C6F5H. Read More

    A High Performance Application Specific Integrated Circuit for Electrical and Neurochemical Traumatic Brain Injury Monitoring.
    Chemphyschem 2018 Jan 31. Epub 2018 Jan 31.
    Imperial College London, Bioengineering, Exhibition Road, SW7 2AZ, London, UNITED KINGDOM.
    This paper presents the first application specific integrated chip (ASIC) for the monitoring of patients who have suffered a Traumatic Brain Injury (TBI). By monitoring the neuralphysiological (ECoG) and neurochemical (glucose, lactate and potassium) signals of the injured human brain tissue, it is possible to detect spreading depolarisations, which have been shown to be associated with poor TBI patient outcome. This paper describes the testing of a new 7. Read More

    Huge Charge-Transfer Energy in LiFePO4 Revealed by Full-Multiplet Calculation for the Fe L3-edge Soft X-ray Emission Spectra.
    Chemphyschem 2018 Jan 31. Epub 2018 Jan 31.
    We analyzed the Fe 3d electronic structure in LiFePO4/FePO4 (LFP/FP) nanowire with a high cyclability by using soft X-ray emission spectroscopy (XES) combined with configuration-interaction full-multiplet (CIFM) calculation. The ex situ Fe L2,3-edge resonant XES (RXES) spectra for the LFP and FP are ascribed to oxidation states of Fe2+ and Fe3+, respectively. CIFM calculations for Fe2+ and Fe3+ states reproduced the Fe L3 RXES spectra for LFP and FP, respectively. Read More

    Diffusion, ion pairing and aggregation in 1-ethyl-3-methylimidazolium-based ionic liquids studied by 1H and 19F PFG NMR: Effect of temperature, anion and glucose dissolution.
    Chemphyschem 2018 Jan 31. Epub 2018 Jan 31.
    University of Cambridge, UNITED KINGDOM.
    In this work, using 1H and 19F PFG NMR, we probe the effect of temperature, ion size/type and glucose dissolution on the rate of transport in 1-ethyl-3-methylimidazolium ([EMIM]+)-based ionic liquids by measuring self-diffusion coefficients. Using such data, we are able to establish the degree of ion pairing and quantify the extent of ionic aggregation during diffusion. For the neat 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]) a strong degree of ion pairing is observed. Read More

    How does the Encapsulation of Porphyrinic Photosensitizers into Polymer Matrices affect their Self-association and Dynamic Properties?
    Chemphyschem 2018 Jan 31. Epub 2018 Jan 31.
    University of Berne, Chemistry and Biochemistry, Freiestrasse 3, 3012, Bern, SWITZERLAND.
    Photodynamic Therapy (PDT) with porphyrinic photosensitizers largely relies on efficient drug formulations in order to prevent porphyrin aggregation and enhance water solubility and stability in physiologic environments. In this study, we compare two polymeric carrier systems, polyvinylpyrrolidone (PVP) and block copolymer micelles (BCMs) formed by the poloxamer Kolliphor P188 (KP) for their encapsulation efficiencies of porphyrin- (xPP) and chlorin e6 (xCE) derivatives. Monomerization, loading efficiency and dynamic properties were examined by 1H NMR spectroscopic chemical shift titration, DOSY and T2 relaxation time measurements. Read More

    Isotropic/Anisotropic NMR Editing by Resolution-Enhanced NMR Spectroscopy.
    Chemphyschem 2018 Jan 31. Epub 2018 Jan 31.
    Universitat Autònoma de Barcelona, Servei RMN, Facultat de Ciències, 08193, Bellaterra, SPAIN.
    Modern resolution-enhanced NMR techniques can monitor the in-situ discrimination of co-existing isotropic and anisotropic contributions of small molecules dissolved in weakly aligning PMMA/CDCl3 media. The simultaneous sign-sensitive determination of accurate deltaDELTA(iso-aniso)(1H), deltaDELTA(iso-aniso)(13C) and/or isotropic 1JCH and anisotropic 1TCH coupling constants (and consequently 1H-13C RDCs and 1H/13C RCSAs) can be performed from spectral-aliased HSQC spectra. Read More

    Structural Change of a Single Ag Nanoparticle Observed by Dark-field Microspectroscopy.
    Chemphyschem 2018 Jan 31. Epub 2018 Jan 31.
    State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing, 210023, China.
    Silver nanoparticles (AgNPs) have been widely used as photocatalysts and nanosensors. Observation of the spectroscopy of a single AgNP greatly helps us understand the catalytic characteristics and morphology change of the AgNP during reactions. In the present study, AgNPs physically adsorbed on indium tin oxide (ITO) conductive glass were electrochemically reduced and oxidized, and the plasmonic resonance Rayleigh scattering (PRRS) spectrum of an individual AgNP was observed under a dark-field microscopy (DFM) equipped with a spectrometer. Read More

    pH effect on Aβ42 monomer and fibril-like oligomers---A decoding in silico for the pK roles of charged residues.
    Chemphyschem 2018 Jan 29. Epub 2018 Jan 29.
    University of Jinan, School of Chemistry and Chemical Engineering, No.336, , Nanxinzhuang West Road, 250022, Jinan , CHINA.
    Amyloid peptide (Aβ) is the key to develop AD. Experiments had confirmed that different acidity influences directly not only the structural morphology and its population of Aβ oligomers but also the toxicity. The atomic-level association between the pH, charged residues and Aβ properties remains obscure. Read More

    Trapping One Electron between Three Beryllium Atoms: Very Strong One-Electron Three-Center Bonds.
    Chemphyschem 2018 Jan 29. Epub 2018 Jan 29.
    Dep. de Química, Facultad de Ciencias, Módulo 13, and Institute of Advanced Chemical Sciences (IadChem), Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, Cantoblanco, E-28049 Madrid, Spain.
    The ability of a set of beryllium-substituted cyclohexane derivatives to trap electrons was determined by evaluating their electron affinities at the G4(MP2) level of theory. The nature of bonding and the effect of the different substituents attached to beryllium were studied by different computational methods (quantum theory of atoms in molecules, electron localization function, natural bond orbital, and analysis of the spin density), revealing the existence of a one-electron/Becyclic bonding in trisubstituted species. This peculiar bond is the key for the high electron affinity values found in the tri-BeX derivatives (X=F, Cl, CN), such as the triberyllium cyano derivatives of cyclohexane, reaching values of 294 kJ mol, only marginally smaller than the values reported for tetracyanoethylene (305 kJ mol) and for some fullerenes (306 kJ mol). Read More

    Tuning Aromaticity of para-Substituted Benzene Derivatives with an External Electric Field.
    Chemphyschem 2018 Jan 26. Epub 2018 Jan 26.
    Theoretical and Structural Chemistry Group, Faculty of Chemistry, University of Łódź, Pomorska 163/165, 90-236, Łódź, Poland.
    Substituent effects are phenomena which play an important role in organic chemistry, especially when aromatic species are considered. For this class of systems, the question of the interrelation between substituent effect and aromaticity arises. The relationship between aromaticity and substituent effects appears to be of a competitive nature. Read More

    Electronic rearrangement in molecular plasmons : An electron density and electrostatic potential-based study.
    Chemphyschem 2018 Jan 23. Epub 2018 Jan 23.
    Indian Institute of Science Education and Research Mohali, Chemical Sciences, Sector 81,, Knowledge city,, Manauli P. O., S. A. S Nagar, 140306, Mohali, INDIA.
    Plasmonic modes in single-molecule systems have been previously identified by scaling two-electron interactions while calculating excitation energies. Analysis of transition dipole moments for states of polyacenes based on configuration interaction was yet another method characterizing molecular plasmons. From our calculations using time-dependent density functional theory (TD-DFT) at B3LYP/cc-pVTZ basis, both the peaks were found to result from the same set of electronic transitions i. Read More

    The Controversial Orientation of Adenine on Gold and Silver.
    Chemphyschem 2018 Jan 22. Epub 2018 Jan 22.
    Université de Montréal, Chemistry, 2900, boul. Édouard-Montpetit, H3C 3J7, Montreal, CANADA.
    In which orientation does adenine adsorb on gold and silver surfaces? This question has been a matter of debate for over 30 years. Since the dawn of surface-enhanced Raman spectroscopy (SERS), it and other techniques such as tip-enhanced Raman spectroscopy (TERS), surface-enhanced infrared absorption spectroscopy (SEIRAS), scanning tunneling microscopy (STM), density functional theory (DFT) simulations, and more, have been used in numerous attempts to answer this seemingly straightforward yet important question. Herein, the timeline and recent advances on this topic are explored, and the frequently contradictory findings are put into context and discussed. Read More

    On the Synthesis of Chocolate Flavonoids (Propanols, Butanals) in the Interstellar Medium.
    Chemphyschem 2018 Jan 22. Epub 2018 Jan 22.
    Department of Chemistry, University of Hawai'i at Manoa, 2545 McCarthy Mall, Honolulu, HI, 96822, USA.
    Complex organic molecules are ubiquitous in star- and planet-forming regions as well as on comets such as on 67P/Churyumov-Gerasimenko, but their origins have remained largely unexplained until now. Here, we report the first laboratory detection of distinct CHO (propanol, methyl ethyl ether) and CHO (n-butanal, i-butanal) isomers formed within interstellar analog ices through interaction with ionizing radiation. This study reveals that complex organics with propyl (CH) and butyl (CH) groups can be synthesized easily in deep space and may act as key evolutionary tracers of a cosmic ray driven non-equilibrium chemistry in low temperature interstellar ices at 10 K. Read More

    On the Action of General Anesthetics on Cellular Function: Barbiturate Alters the Exocytosis of Catecholamines in a Model Cell System.
    Chemphyschem 2018 Jan 22. Epub 2018 Jan 22.
    Department of Chemistry and Molecular Biology, University of Gothenburg, Kemivägen 10, 41296, Gothenburg, Sweden.
    General anesthetics are essential in many areas, however, the cellular mechanisms of anesthetic-induced amnesia and unconsciousness are incompletely understood. Exocytosis is the main mechanism of signal transduction and neuronal communication through the release of chemical transmitters from vesicles to the extracellular environment. Here, we use disk electrodes placed on top of PC12 cells to show that treatment with barbiturate induces fewer molecules released during exocytosis and changes the event dynamics perhaps by inducing a less stable fusion pore that is prone to close faster during partial exocytosis. Read More

    Investigation of Microalgal Carotenoid Content Using Coherent Anti-Stokes Raman Scattering (CARS) Microscopy and Spontaneous Raman Spectroscopy.
    Chemphyschem 2018 Jan 22. Epub 2018 Jan 22.
    Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany.
    The yield of high-value products, such as pigments that could be extracted from microalgae, is affected by various nutritional and physical factors. Consequently, there is a need for fast visualization techniques that investigate the responses of individual microalgal cells to changing environmental conditions without introducing perturbations. Here, we apply CARS microscopy to map the distribution of pigments in the diatoms Ditylum brightwellii and Stephanopyxis turris and report their relative change in response to varying light cycles using a marker-based watershed analysis of the acquired images. Read More

    Application of the Interacting Quantum Atoms Approach to the S66 and Ionic-Hydrogen-Bond Datasets for Noncovalent Interactions.
    Chemphyschem 2018 Jan 22. Epub 2018 Jan 22.
    Departamento de Química Física y Analítica, Universidad de Oviedo, Julián Clavería 8., 33006, Oviedo (Asturias), Spain.
    The interacting quantum atoms (IQA) method can assess, systematically and in great detail, the strength and physics of both covalent and noncovalent interactions. The lack of a pair density in density functional theory (DFT), which precludes the direct IQA decomposition of the characteristic exchange-correlation energy, has been recently overcome by means of a scaling technique, which can largely expand the applicability of the method. To better assess the utility of the augmented IQA methodology to derive quantum chemical decompositions at the atomic and molecular levels, we report the results of Hartree-Fock (HF) and DFT calculations on the complexes included in the S66 and the ionic H-bond databases of benchmark geometry and binding energies. Read More

    How and Why Does Helium Permeate Nonporous Arsenolite Under High Pressure?
    Chemphyschem 2018 Jan 17. Epub 2018 Jan 17.
    Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warszawa, Poland.
    Investigations into the helium permeation of arsenolite, the cubic, molecular arsenic(III) oxide polymorph AsO, were carried out to understand how and why arsenolite helium clathrate AsO⋅2 He is formed. High-pressure synchrotron X-ray diffraction experiments on arsenolite single crystals revealed that the permeation of helium into nonporous arsenolite depends on the time for which the crystal is subjected to high pressure and on the crystal history. The single crystal was totally transformed into AsO⋅2 He within 45 h under 5 GPa. Read More

    Reaction Mechanism for Direct Cyclization of Linear C, C, and CAlkenes over H-ITQ-13 Zeolite Investigated Using Density Functional Theory.
    Chemphyschem 2018 Feb 25;19(4):496-503. Epub 2018 Jan 25.
    State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi, 030001, PR China), Fax: (+86) 351-4041153.
    Although dienes or trienes have been shown to be possible precursors for cyclization, direct cyclization of alkenes or alkoxides has not been systematically studied yet. Thus, the reaction mechanism of cyclization of linear alkenes over H-ITQ-13 was investigated here by density functional theory considering dispersive interactions (DFT-D). The similar free energy of different linear alkoxides of the same carbon number suggests that they can co-exist in the H-ITQ-13 intersection at 673. Read More

    Towards the Detection of Explosive Taggants: Microwave and Millimetre-Wave Gas-Phase Spectroscopies of 3-Nitrotoluene.
    Chemphyschem 2018 Jan 12. Epub 2018 Jan 12.
    Laboratoire de Physico-Chimie de l'Atmosphère (LPCA), EA 4493, Université du Littoral Côte d'Opale, Maison de la Recherche en Environnement Industriel 2 (MREI2), 189A, Avenue Maurice Schumann, 59140, Dunkerque, France.
    The monitoring of gas-phase mononitrotoluenes is crucial for defence, civil security and environmental interests because they are used as taggant for TNT detection and in the manufacturing of industrial compounds such as dyestuffs. In this study, we have succeeded to measure and analyse at high-resolution a room temperature rotationally resolved millimetre-wave spectrum of meta-nitrotoluene (3-NT). Experimental and theoretical difficulties have been overcome, in particular, those related to the low vapour pressure of 3-NT and to the presence of a CHinternal rotation in an almost free rotation regime (V=6. Read More

    Brain-Cortex Microglia-Derived Exosomes: Nanoparticles for Glioma Therapy.
    Chemphyschem 2018 Jan 12. Epub 2018 Jan 12.
    Univ. Lille, Inserm, U-1192-Laboratoire Protéomique, Réponse Inflammatoire et Spectrométrie de Masse-PRISM, F-59000, Lille, France.
    The function and integrity of the nervous system require interactive exchanges among neurons and glial cells. Exosomes and other extracellular vesicles (EVs) are emerging as a key mediator of intercellular communication, capable of transferring nucleic acids, proteins and lipids influencing numerous functional and pathological aspects of both donor and recipient cells. The immune response mediated by microglia-derived exosomes is most prominently involved in the spread of neuroinflammation, neurodegenerative disorders, and brain cancer. Read More

    The Photoconversion of Phytochrome Includes an Unproductive Shunt Reaction Pathway.
    Chemphyschem 2018 Jan 11. Epub 2018 Jan 11.
    Institut für Chemie, Sekr. PC14, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany.
    Phytochromes are modular bimodal photoswitches that control gene expression for morphogenetic processes in plants. These functions are triggered by photoinduced conversions between the inactive and active states of the photosensory module, denoted as Pr and Pfr, respectively. In the present time-resolved resonance Raman spectroscopic study of bacterial representatives of this photoreceptor family, we demonstrate that these phototransformations do not represent linear processes but include a branching reaction back to the initial state, prior to (de)activation of the output module. Read More

    Theoretical Investigation of the Infrared Spectrum of 5-Bromo-2,4-pentadiynenitrile from a CCSD(T)/B3LYP Anharmonic Potential.
    Chemphyschem 2018 Jan 11. Epub 2018 Jan 11.
    CNRS/Université Pau & Pays Adour, Institut Des Sciences Analytiques Et De Physico-Chimie Pour L'environnement Et Les Materiaux, Umr5254, 64000, Pau, France.
    On the grounds of a hybrid CCSD(T)/B3LYP/aug-cc-pVTZ anharmonic potential and the use of a variational and variational-perturbational methods, the IR spectra of 5-bromo-2,4-pentadiynenitrile (BrCN) is revisited in the mid-infrared region up to 4500 cm. A position and intensity analysis of our theoretical results allow us to assign the fundamental bands together with their combinations and overtones, in the aforementioned range of frequencies. The main objective of this work is to give an "a priori" complete IR spectrum of BrCN, which can be used as a guide for the low-intensity bands in areas not completely studied so far. Read More

    Drug-Induced Micelle-to-Vesicle Transition of a Cationic Gemini Surfactant: Potential Applications in Drug Delivery.
    Chemphyschem 2018 Jan 10. Epub 2018 Jan 10.
    Applied Chemistry Department, S. V. National Institute of Technology, Surat-, 395007, Gujarat, India.
    An impetus for the sustained interest in the formation of vesicles is their potential application as efficient drug-delivery systems. A simple approach for ionic surfactants is to add a vesicle-inducing drug of opposite charge. In ionic gemini surfactants (GSs) two molecules are covalently linked by a spacer. Read More

    Intraparticle Diffusional versus Site Effects on Reaction Pathways in Liquid-Phase Cross Aldol Reactions.
    Chemphyschem 2018 Feb 6;19(4):386-401. Epub 2018 Feb 6.
    Department of Chemical Engineering, University of Massachusetts Amherst, 159 Goessmann Laboratory, 686 N Pleasant, Amherst, MA, 01003, USA.
    Chemo- and regioselectivity in a heterogeneously catalyzed cross aldol reaction were directed by tuning the nature of the sites, textural properties, and reaction conditions. Catalysts included sulfonic acid-functionalized resins or SBA-15 with varying particle size or pore diameter, H-BEA zeolites, and Sn-BEA zeotype; conditions were 25 °C to 170 °C in organic media. Benzaldehyde and 2-butanone yielded branched (reaction at -CH- of butanone) and linear (reaction at -CH) addition and condensation products; and fission of the branched aldol led to β-methyl styrene and acetic acid. Read More

    Sub-ensemble monitoring of DNA strand displacement using multiparameter single-molecule FRET.
    Chemphyschem 2018 Jan 5. Epub 2018 Jan 5.
    University of Glasgow, School of Chemistry, University Avenue, G12 8QQ, Glasgow, UNITED KINGDOM.
    Non-enzymatic DNA strand displacement is an important mechanism in dynamic DNA nanotechnology. Here we show that the large parameter space that is accessible by single-molecule FRET is ideal for the simultaneous monitoring of multiple reactants and products of DNA strand exchange reactions. We monitored the strand displacement from double-stranded DNA (dsDNA) by single-stranded DNA (ssDNA) at 37 °C; the data were modelled as a second-order reaction approaching equilibrium, with a rate constant of ca. Read More

    Quantitative Comparison of Enzyme Immobilization Strategies for Glucose Biosensing in Real-Time Using Fast-Scan Cyclic Voltammetry Coupled with Carbon-Fiber Microelectrodes.
    Chemphyschem 2018 Jan 9. Epub 2018 Jan 9.
    Department of Chemistry, NC State University, 2620 Yarbrough Dr., Campus Box 8204, Raleigh, NC, 27695-8204, USA.
    Electrochemical monitoring of non-electroactive species requires a biosensor that is stable and selective, with sensitivity to physiological concentrations of targeted analytes. We have combined glucose oxidase-modified carbon-fiber microelectrodes with fast-scan cyclic voltammetry for real-time measurements of glucose fluctuations in brain tissue. Work presented herein quantitatively compares three approaches to enzyme immobilization on the microelectrode surface-physical adsorption, hydrogel entrapment, and entrapment in electrospun nanofibers. Read More

    Ranking Power of the SQM/COSMO Scoring Function on Carbonic Anhydrase II-Inhibitor Complexes.
    Chemphyschem 2018 Jan 8. Epub 2018 Jan 8.
    Institute of Organic Chemistry and Biochemistry of the, Czech Academy of Sciences, Flemingovo nam. 2, 16610, Prague 6, Czech Republic.
    Accurate prediction of protein-ligand binding affinities is essential for hit-to-lead optimization and virtual screening. The reliability of scoring functions can be improved by including quantum effects. Here, we demonstrate the ranking power of the semiempirical quantum mechanics (SQM)/implicit solvent (COSMO) scoring function by using a challenging set of 10 inhibitors binding to carbonic anhydrase II through Znin the active site. Read More

    Exploring molecular and thermodynamic properties of zwitterions vs ionic liquids: A comprehensive computational analysis to develop advanced separation processes.
    Chemphyschem 2018 Jan 7. Epub 2018 Jan 7.
    Universidad Autonoma Madrid, Chemical Engineering, cantoblanco universidad, 28045, Madrid, SPAIN.
    Zwitterions ionic liquids (ZIs) are compounds in which both counterions are covalently tethered, conferring them with unique characteristics; however, most of their properties are still unknown, remaining a bottleneck to exploit practical applications. Herein, molecular and fluid properties of ZIs and their mixtures are explored by means of quantum chemical analysis based on density functional theory (DFT) and COSMO-RS method, and compared against homologous ILs, to provide a comprehensive overview on the effect of the distinct structures on their physicochemical and thermodynamic behavior. Overall, ZIs were revealed as compounds with higher polarity and stronger hydrogen bonding capacity, implying higher density, viscosity and melting point, and even lower volatility than structurally similar ILs. Read More

    A Comparative Study on the Photophysics and Photochemistry of Xanthene Dyes in the Presence of Polyamidoamine (PAMAM) Dendrimers.
    Chemphyschem 2018 Jan 7. Epub 2018 Jan 7.
    Grupo de Fotoquímica, Departmento de Química, Universidad Nacional de Río Cuarto, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 5800 Río Cuarto, Córdoba, Argentina.
    The photophysical and photochemical properties of the xanthene dyes Eosin Y, Erythrosin B, and Rose Bengal are evaluated in the presence of amino-terminated polyamidoamine (PAMAM) dendrimers of relatively high generation (G3-G5) in alkaline aqueous solution. UV/Vis absorption and fluorescence spectra of the dyes show bathochromic shifts, which correlate with the size of the dendrimer. Binding constants (K) are calculated from absorption data. Read More

    Integrated Multifunctional Micelles Co-Self-Assembled from Polypeptides Conjugated with Natural Ferulic Acid and Lipoic Acid for Doxorubicin Delivery.
    Chemphyschem 2018 Jan 9. Epub 2018 Jan 9.
    Biomedical Polymers Laboratory, and Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, China), Fax: (+86) 512-65880098.
    The development of safe, easily accessible, and multifunctional nanocarriers is a big topic in nanomedicine research. Here, integrated multifunctional micelles (IMM) were developed by co-self-assembly of poly(ethylene glycol)-b-poly(l-lysine) derivatives with natural ferulic acid (FA) or lipoic acid (LA). FA confers IMM with intrinsic antitumor activity, improved loading of doxorubicin (DOX) through π-π stacking, and reduced DOX cardiotoxicity. Read More

    Mapping Perfluoroalkyl Effects in Togni-Type Reagents by Thermolysis.
    Chemphyschem 2018 Jan 3. Epub 2018 Jan 3.
    Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zürich, Vladimir-Prelog-Weg 1/2, 8093, Zürich, Switzerland.
    We present the thermolysis of cyclic hypervalent iodine(III) perfluoroalkyl transfer reagents carried out in standard GC-MS instrumentation. Through heating, these structures undergo fragmentation to afford perfluoroalkyl radicals FCand each reagent can be characterized by means of a threshold temperature, T(n). This parameter T(n) not only reflects the stability of the FC-I bond, but potentially also carries information regarding fundamental properties of the linear perfluoroalkyl chains. Read More

    Investigating Protein-Ligand Interactions by Solution Nuclear Magnetic Resonance Spectroscopy.
    Chemphyschem 2018 Jan 4. Epub 2018 Jan 4.
    Institute of Chemistry, University of Graz, Heinrichstrasse 28, A-8010, Graz, Austria.
    Protein-ligand interactions are of fundamental importance in almost all processes in living organisms. The ligands comprise small molecules, drugs or biological macromolecules and their interaction strength varies over several orders of magnitude. Solution NMR spectroscopy offers a large repertoire of techniques to study such complexes. Read More

    Modeling the Interaction of Carbon Monoxide with Flexible Graphene: From Coupled Cluster Calculations to Molecular-Dynamics Simulations.
    Chemphyschem 2018 Jan 4. Epub 2018 Jan 4.
    Instituto de Ciencia Molecular, Universitat de València, Catedràtic José Beltrán 2, 46980, Paterna, Spain.
    The interaction of CO with graphene was studied at different theoretical levels. Quantum-mechanical calculations on finite graphene models with the use of coronene for coupled cluster calculations and circumcoronene for B97D calculations showed that there was no preferential site for adsorption and that the most important factor was the orientation of CO relative to graphene. The parallel orientation was preferred, with binding energies around 9 kJ molat the CCSD(T) and B97D levels, which was in good agreement with experimental findings. Read More

    Improved Photoactivity of Pyroxene Silicates by Cation Substitutions.
    Chemphyschem 2018 Jan 4. Epub 2018 Jan 4.
    Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Doha, Qatar.
    We investigated the possibility of band structure engineering of pyroxene silicates with chemical formula ABSiOby proper cation substitution. Typically, band gaps of naturally formed pyroxene silicates such as NaAlSiOare quite high (≈5 eV). Therefore, it is important to find a way to reduce band gaps for these materials below 3 eV to make them usable for optoelectronic applications operating at visible light range of the spectrum. Read More

    Simple, Green, and High-Yield Production of Boron-Based Nanostructures with Diverse Morphologies by Dissolution and Recrystallization of Layered Magnesium Diboride Crystals in Water.
    Chemphyschem 2018 Jan 3. Epub 2018 Jan 3.
    Department of Chemical Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar, 382355, India.
    Layered metal diborides that contain metal atoms sandwiched between boron honeycomb planes offer a rich opportunity to access graphenic forms of boron. We recently demonstrated that magnesium diboride (MgB) could be exfoliated by ultrasonication in water to yield boron-based nanosheets. However, knowledge of the fate of metal boride crystals in aqueous phases is still in its incipient stages. Read More

    Covalent Bonding of Chlorogenic Acid Induces Structural Modifications on Sunflower Proteins.
    Chemphyschem 2018 Feb 24;19(4):459-468. Epub 2018 Jan 24.
    Biobased Chemistry and Technology, Wageningen University, 6708WG, Wageningen, The Netherlands.
    Proteins and phenols coexist in the confined space of plant cells leading to reactions between them, which result in new covalently bonded complex molecules. This kind of reactions has been widely observed during storage and processing of plant materials. However, the nature of the new complex molecules and their physicochemical properties are largely unknown. Read More

    Grain Size Modulation and Interfacial Engineering of CH3NH3PbBr3 Emitter Films through Incorporation of Tetraethylammonium Bromide.
    Chemphyschem 2018 Jan 3. Epub 2018 Jan 3.
    School of Materials Science & Engineering, College of Engineering, 50 Nanyang Avenue, NTU Singapore, Singapore, SINGAPORE.
    Metal halide perovskites have demonstrated breakthrough performances as absorber and emitter materials for photovoltaic and display applications, respectively. However, despite enabling low manufacturing costs, the propensity for defect formation with solution-based processing has led to an increasing need for defect passivation of perovskites. Here, we present an inexpensive and facile method to remedy surface defects through a post-deposition treatment process using branched alkylammonium cation species. Read More

    Photophysics of a UV-B Filter 4-Methylbenzylidene Camphor: Intersystem Crossing Plays an Important Role.
    Chemphyschem 2017 Dec 30. Epub 2017 Dec 30.
    Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, China.
    4-Methylbenzylidene camphor (4MBC) is a frequently used ultraviolet (UV) filter in commercial sunscreens, which is experimentally found to undergo efficient intersystem crossing to triplet manifolds followed by predominant radiationless decay to the ground state. However, its photophysical mechanism is unclear. Herein, we have employed combined CASPT2 and CASSCF methods to study the spectroscopic properties, geometric and electronic structures, conical intersections and crossing points, and excited-state deactivation channels of 4MBC. Read More

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