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Physical Chemistry Chemical Physics: PCCP

Z Wojnarowska, E Thoms, B Blanchard, S N Tripathy, P Goodrich, J Jacquemin, J Knapik-Kowalczuk, M Paluch
Modern ionic liquids (ILs) are considered green solvents for the future applications due to their inherited advantages and remarkable transport properties. One of the ubiquitous properties of ILs is their intrinsic ionic conductivity. However, understanding of the super-Arrhenius behavior of the ionic conductivity process at elevated pressure still remains elusive and crucial in glass science. In this work, we investigate the ion transport properties of 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide: [C4mim][NTf2], 1-butylimidazolium bis[(trifluoromethyl)-sulfonyl]imide: [C4Him][NTf2] and 1-butylimidazolium hydrogen sulfate: [C4Him][HSO4] ILs in the supercooled liquid state using dielectric spectroscopy at ambient and high pressure...
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
Manjusha C Padole, Bhanu P Gangwar, Aman Pandey, Aditi Singhal, Sudhanshu Sharma, Parag A Deshpande
The synthesis of novel and efficient catalysts for acetylene hydrogenation exhibiting high selectivity towards ethylene is important due to the presence of selective acetylene hydrogenation reaction in petrochemical processing. Since adsorption of C2 gases constitutes the primary step in catalytic hydrogenation and governs the selectivity of the catalysts, we have explored the C2-adsorption potential of reducible CeO2-based systems. The adsorption of C2-gases over CeO2-based materials was assessed using experimental in situ spectroscopic techniques and in silico theoretical studies based on density functional theory...
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
P Cayado, C F Sánchez-Valdés, A Stangl, M Coll, P Roura, A Palau, T Puig, X Obradors
The kinetics of oxygen incorporation (in-diffusion process) and excorporation (out-diffusion process), in YBa2Cu3O6+x (YBCO) epitaxial thin films prepared using the chemical solution deposition (CSD) methodology by the trifluoroacetate route, was investigated by electrical conductivity relaxation measurements. We show that the oxygenation kinetics of YBCO films is limited by the surface exchange process of oxygen molecules prior to bulk diffusion into the films. The analysis of the temperature and oxygen partial pressure influence on the oxygenation kinetics has drawn a consistent picture of the oxygen surface exchange process enabling us to define the most likely rate determining step...
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
G Gatti, D Costenaro, C Vittoni, G Paul, V Crocellà, E Mangano, S Brandani, S Bordiga, M Cossi, L Marchese, C Bisio
Hybrid organic-inorganic SBA-15 silicas functionalized with increasing amounts of amino groups were studied in this work aiming to evaluate the effects of their physico-chemical properties on CO2 capture ability. Three different amino-silane species were used: 3-aminopropyltriethoxysilane (APTS), 3-(2-aminoethyl)aminopropyltrimethoxysilane (EAPTS) and 3-[2-(2-aminoethyl)aminoethyl] aminopropyltrimethoxysilane (PAPTS). More specifically, samples were prepared by using two methods, following a post-synthesis grafting procedure and a one-pot preparation method...
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
Mirjam Falge, Friedrich Georg Fröbel, Volker Engel, Stefanie Gräfe
If the adiabatic approximation is valid, electrons smoothly adapt to molecular geometry changes. In contrast, as a characteristic of diabatic dynamics, the electron density does not follow the nuclear motion. Recently, we have shown that the asymmetry in time-resolved photoelectron spectra serves as a tool to distinguish between these dynamics [Falge et al., J. Phys. Chem. Lett., 2012, 3, 2617]. Here, we investigate the influence of an additional, moderately intense infrared (IR) laser field, as often applied in attosecond time-resolved experiments, on such asymmetries...
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
A R Milosavljević, P Rousseau, A Domaracka, B A Huber, A Giuliani
Collisions of 375 keV Xe(25+) ions with trapped mass/charge selected poly-anions of the cytochrome C protein (∼12.5 kDa) were studied by coupling a linear quadrupole ion trap with low-energy ion beam facility. Tandem mass spectra were recorded for the protein precursor charge states ranging from -9 to -17. The present work reports the first study of slow highly charged ion collisions with poly-anions. A high signal to noise ratio allowed the study of the intensity of single and multiple electron removal by a projectile, as well as associated neutral losses, as a function of the target charge state...
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
Utuq Ablikim, Cédric Bomme, Evgeny Savelyev, Hui Xiong, Rajesh Kushawaha, Rebecca Boll, Kasra Amini, Timur Osipov, David Kilcoyne, Artem Rudenko, Nora Berrah, Daniel Rolles
The fragmentation dynamics of 2,6- and 3,5-difluoroiodobenzene after iodine 4d inner-shell photoionization with soft X-rays are studied using coincident electron and ion momentum imaging. By analyzing the momentum correlation between iodine and fluorine cations in three-fold ion coincidence events, we can distinguish the two isomers experimentally. Classical Coulomb explosion simulations are in overall agreement with the experimentally determined fragment ion kinetic energies and momentum correlations and point toward different fragmentation mechanisms and time scales...
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
Jorge Royes, Víctor Polo, Santiago Uriel, Luis Oriol, Milagros Piñol, Rosa M Tejedor
Chiral photoinduction in a photoresponsive gel based on an achiral 2D architecture with high geometric anisotropy and low roughness has been investigated. Circularly polarized light (CPL) was used as a chiral source and an azobenzene chromophore was employed as a chiral trigger. The chiral photoinduction was studied by evaluating the preferential excitation of enantiomeric conformers of the azobenzene units. Crystallographic data and density functional theory (DFT) calculations show how chirality is transferred to the achiral azomaterials as a result of the combination of chiral photochemistry and supramolecular interactions...
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
Jiří Kessler, Shigeki Yamamoto, Petr Bouř
Folding of proteins into insoluble amyloidal fibrils is implicated in a number of biological processes. Optical spectroscopy represents a convenient tool to monitor such structural variations. Recently, characteristic changes in Raman optical activity (ROA) spectra of insulin during a pre-fibrillar stage were reported but not supported by a theoretical model. In the present study, molecular dynamics and the density functional theory are used to simulate the spectra and understand the connection between the structure, and ROA and Raman spectral intensities...
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
Kosuke Beppu, Saburo Hosokawa, Takuya Shibano, Akito Demizu, Kazuo Kato, Kenji Wada, Hiroyuki Asakura, Kentaro Teramura, Tsunehiro Tanaka
This study proves that a small amount of Pd loading (1 wt%) on Sr3Fe2O7-δ can dramatically enhance the oxygen-storage properties of Sr3Fe2O7-δ. The topotactic oxygen intake and release between Sr3Fe2O6.75 and Sr3Fe2O6 takes place in response to gas switching between an O2 flow and H2 flow, regardless of the presence or absence of Pd loading. The effect of Pd loading is significant for the oxygen-release process under H2 atmosphere; that is, highly dispersed Pd metal nanoparticles sized less than 1 nm formed on Pd/Sr3Fe2O7-δ to promote H2 dissociation, resulting in the improvement of the oxygen-release temperature and rate...
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
C M Handley, C L Freeman
Correction for 'A new potential for methylammonium lead iodide' by C. M. Handley et al., Phys. Chem. Chem. Phys., 2017, 19, 2313-2321.
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
Vikash Sharma, Chanderbhan Chotia, Tarachand, Vedachalaiyer Ganesan, Gunadhor S Okram
Nickel nanoparticles (NPs) are promising candidates for various applications, including biomedical ones, as they have good magnetic properties as well as high thermal conductivity. We used well-characterized Ni NPs of average Scherrer sizes from 1.31 nm to 22.23 nm and investigated the effects of the primary particle size, size distribution and dielectric environments, and of separately adding non-ionic polyvinylpyrrolidone (PVP), cationic cetyltrimethylammonium bromide (CTAB) and anionic ethylenediaminetetraacetic acid (EDTA) in ethanol, on their stability and agglomeration behaviour using atomic force microscopy (AFM), particle size analysis and zeta potential study through dynamic light scattering (DLS) combined with UV-visible spectroscopy data...
May 18, 2017: Physical Chemistry Chemical Physics: PCCP
Francesco Nastasi, Giuseppina La Ganga, Sebastiano Campagna, Zois Syrgiannis, Francesco Rigodanza, Stefania Vitale, Antonino Licciardello, Maurizio Prato
Herein, the synthesis and the photophysical and redox properties of a new perylene bisimide (PBI) species (L), bearing two 1,10-phenanthroline (phen) ligands at the two imide positions of the PBI, and its dinuclear Ru(ii) and Os(ii) complexes, [(bpy)2Ru(μ-L)Ru(bpy)2](PF6)4 (Ru2; bpy = 2,2'-bipyridine) and [(Me2-bpy)2Os(μ-L)Os(Me2-bpy)2](PF6)4 (Os2; Me2-bpy = (4,4'-dimethyl)-2,2'-bipyridine), are reported. The absorption spectra of the compounds are dominated by the structured bands of the PBI subunit due to the lowest-energy spin-allowed π-π* transition...
May 18, 2017: Physical Chemistry Chemical Physics: PCCP
Alessandro Iagatti, Barbara Patrizi, Andrea Basagni, Agnese Marcelli, Andrea Alessi, Stefano Zanardi, Roberto Fusco, Mario Salvalaggio, Laura Bussotti, Paolo Foggi
The relationships between the photophysics and structural properties of 4,7-dithien-2-yl-2,1,3-benzothiadiazole as a function of solvent polarity are investigated both experimentally and by computational methods. Stationary fluorescence measurements are consistent with a model envisaging the presence of three types of conformers in equilibrium in the ground state. They are characterized by different relative orientations of the thiophene rings. Due to a low rotational barrier, the sample in solution is characterized by a distribution of relative internal orientations...
May 18, 2017: Physical Chemistry Chemical Physics: PCCP
Michael Mauksch, Svetlana B Tsogoeva
Polycyclic fully conjugated hydrocarbons in which aromatics are fused to aromatics - or aromatics to antiaromatics - are important as potential organic semiconductors. Herein we explore the only remaining fusion pattern of antiaromatics to antiaromatics. It is shown computationally that the central antiaromatic unit (cyclobutadiene or pentalene) in such a three-unit polycyclic hydrocarbon, generated by fusion of three antiaromatic molecules, turns aromatic according to magnetic shielding (NICS) criteria. The resulting neutral 4N electron molecules possess a 4N π electron perimeter with pronounced CC bond length equalization (as indicated by the HOMA geometric index) and significant aromatic stabilization energies (computed using the isomerization-stabilization method) and could be promising synthetic targets with small HOMO-LUMO gaps...
May 18, 2017: Physical Chemistry Chemical Physics: PCCP
Muath Nairat, Morgan Webb, Michael P Esch, Vadim V Lozovoy, Benjamin G Levine, Marcos Dantus
The optically populated excited state wave packet propagates along multidimensional intramolecular coordinates soon after photoexcitation. This action occurs alongside an intermolecular response from the surrounding solvent. Disentangling the multidimensional convoluted signal enables the possibility to separate and understand the initial intramolecular relaxation pathways over the excited state potential energy surface. Here we track the initial excited state dynamics by measuring the fluorescence yield from the first excited state as a function of time delay between two color femtosecond pulses for several cyanine dyes having different substituents...
May 18, 2017: Physical Chemistry Chemical Physics: PCCP
Lei Yang, Yanjie Guo, Dongfeng Diao
Recently, water flow confined in nanochannels has become an interesting topic due to its unique properties and potential applications in nanofluidic devices. The trapped water is predicted to experience high pressure in the gigapascal regime. Theoretical and experimental studies have reported various novel structures of the confined water under high pressure. However, the role of this high pressure on the dynamic properties of water has not been elucidated to date. In the present study, the structure evolution and interfacial friction behavior of water constrained in a graphene nanochannel were investigated via molecular dynamics simulations...
May 18, 2017: Physical Chemistry Chemical Physics: PCCP
Michael Stenrup, Elisa Pieri, Vincent Ledentu, Nicolas Ferré
A minimal electrostatic model is introduced which aims at reproducing and analyzing the visible-light absorption energy shift of a protein with pH. It relies on the existence of a protein structure, the prediction of titratable amino-acid pKa values and a very limited set of parameters. Applied to the case of the photochromic Anabaena sensory rhodopsin protein, the model succeeds in reproducing qualitatively the reported experimental data, confirming the importance of aspartic acid 217 in the observed blue shift in the λmax of ASR at neutral pH...
May 18, 2017: Physical Chemistry Chemical Physics: PCCP
Quanli Gu, Dan Shen, Zhen Tang, Wei Wu, Peifeng Su, Yong Xia, Zhijun Yang, Carl O Trindle
The binding strength and collective effects of multiple H-bonds in the glycolic acid-water dimer were studied in comparison to the aromatic analog, 9-hydroxy-9-fluorene carboxylic acid (9HFCA). Quantitative analysis by the generalized Kohn-Sham energy decomposition analysis shows that the energy difference in each specific physical interaction, from a glycolic acid-water dimer to a 9HFCA-water dimer, is small and amounts to less than 5% of the binding energy of the 9HFCA-water dimer. Extensive comparison of further, similar H-bonded complexes with widely varying binding strengths reinforces their excellent analogy in that the fluorene group acts as a non-interfering spectator for intermolecular H-bonding interactions...
May 18, 2017: Physical Chemistry Chemical Physics: PCCP
Avanendra Singh, Kartik Senapati, Biswarup Satpati, Pratap K Sahoo
We report the synthesis of a unique zinc oxide nanorod structure in which an amorphous ZnO layer is sandwiched between two identical crystalline segments of ZnO. A simple hydrothermal reaction method was used for this purpose, which allowed us to tune the amorphous and crystalline sections of the nanorods via reaction temperature. A systematic study of the morphology and dimensions of the nanorods grown under various conditions was performed using a combination of scanning and transmission electron microscopy...
May 18, 2017: Physical Chemistry Chemical Physics: PCCP
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