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Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry

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https://www.readbyqxmd.com/read/28106335/competition-between-cation-solvent-and-cation-anion-interactions-in-imidazolium-ionic-liquids-with-polar-aprotic-solvents
#1
Bogdan A Marekha, Oleg N Kalugin, Marc Bria, Toshiyuki Takamuku, Slobodan Gadžurić, Abdenacer Idrissi
Subtle interplay between ion solvation and association was analyzed in mixtures of imidazolium-based ionic liquids (ILs) with polar aprotic solvents. Site-specific pattern of cation-solvent and cation-anion interactions was disclosed by means of a careful analysis of the 1H and 13C NMR chemical shift mixture composition dependence. It was established that less polar but more donating γ-butyrolactone is more prone to establish H-bonds with the imidazolium ring hydrogen atoms of IL cations than propylene carbonate, particularly at the H2 site and at high dilutions xIL < 0...
January 20, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28098421/hexagonal-boron-nitride-h-bn-sheets-decorated-with-oli-ona-and-li2-f-molecules-for-enhanced-energy-storage
#2
Syeda Rabab Naqvi, Gollu Sankar Rao, Wei Luo, Rajeev Ahuja, Tanveer Hussain
First-principles electronic structure calculations were carried out on hexagonal boron nitride (h-BN) sheets functionalized with small molecules, such as OLi, ONa, and Li2 F, to study their hydrogen (H2 ) storage properties. We found that OLi and ONa strongly adsorb on h-BN sheets with reasonably large inter-adsorbent separations, which is desirable for H2 storage. Ab initio molecular dynamics (MD) simulations further confirmed the structural stability of OLi-BN and ONa-BN systems at 400 K. On the other hand, Li2 F molecules form clusters over the surface of h-BN at higher temperatures...
January 18, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28097772/laser-irradiation-induced-melting-and-reduction-reaction-for-the-formation-of-pt-based-bimetallic-alloy-particles-in-liquids
#3
Changhao Liang, Shouliang Wu, Enmei Dai, Yixing Ye, Jun Liu, Zhenfei Tian, Yunyu Cai, Xiaoguang Zhu, Yechuang Han
Laser melting in liquids (LML) is one of the most effective methods to prepare bimetallic alloys, the formation process of which is always research focus but still ambiguous. In this paper, we prepared two types of Pt-based bimetallic alloys by LML, including Pt-Au alloys and Pt-iron group metal (iM = Fe/Co/Ni) alloys, and investigated the corresponding mechanisms of alloying process. Detailed component and structural characterizations indicate that laser irradiation induced a quite rapid formation process (not exceed 10 s) of Pt-Au alloy nanospheres, and the crystalline structures of Pt-Au alloys is determined by the monometallic constituents with higher content...
January 18, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28097770/bond-strength-and-reactivity-scales-for-lewis-superacid-adducts-a-comparative-study-with-in-otf-3-and-al-otf-3
#4
Guillaume Compain Compain, Lauri Sikk, Lionel Massi, Jean-François Gal, Elisabet Duñach
Metal triflates, often called Lewis superacids, are potent catalysts for organic synthesis. However, the reactivity of a given Lewis superacid toward a given base is difficult to anticipate. A systematic screening of catalysts is often necessary when developing synthetic methodologies. Presented herein is the development of quantitative reactivity and bond strength scales by using mass spectrometry (MS). By applying collision induced dissociation (CID) technique to the adducts formed between Lewis superacids Al(OTf)3 or In(OTf)3 with a series of amides bases, including monodentate and bidentate ligands, different dissociation pathways were observed...
January 18, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28097755/a-solution-processable-liquid-crystalline-semiconductor-for-low-temperature-annealed-air-stable-n-channel-field-effect-transistors
#5
Resul Ozdemir, Donghee Choi, Mehmet Ozdemir, Hyekyoung Kim, Sinem Tuncel Kostakoğlu, Mustafa Erkartal, Hyungsug Kim, Choongik Kim, Hakan Usta
A new solution-processable and air-stable liquid-crystalline n-channel organic semiconductor (α,ω-2OD-TIFDMT) employing a donor-acceptor-donor (D-A-D) type of π-conjugation has been designed, synthesized, and fully characterized. The new semiconductor exhibits a low LUMO energy (-4.19 eV) and a narrow optical band gap (1.35 eV). Typical pseudo focal-conic fan-shaped texture of a hexagonal columnar liquid crystalline (LC) phase was observed over a wide temperature range. The spin-coated semiconductor thin-films shows the formation of large (~0...
January 17, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28095594/mixed-metal-tungsten-oxide-photoanode-materials-made-by-pulsed-laser-in-liquids-synthesis
#6
Carl M Blumenfeld, Marcus Lau, Harry B Gray, Astrid M Müller
Globally scalable sunlight-driven devices that convert solar energy into storable fuels will require efficient light absorbers that are made of non-precious elements. Suitable photoanode materials are yet to be discovered. Here we utilised the timesaving nature of pulsed-laser in liquids synthesis and prepared a series of neat and mixed-metal tungsten oxide photoanode materials to investigate the effect of ad-metals on optical and photocurrent generation properties. We obtained sub-μm-sized materials with different colours from W, Al, Ta, or first-row transition metal targets in water or aqueous ammonium metatungstate solutions...
January 17, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28094887/exploring-the-influence-of-aggregation-on-the-structure-and-fluorescent-properties-of-a-tetraphenylethylene-derivative-a-theoretical-study
#7
Ying-Chen Duan, Yong Wu, Jun-Ling Jin, Dong-Mei Gu, Yun Geng, Min Zhang, Zhongmin Su
The case that aggregation brings a huge influence on the structure and fluorescent property of 5-(4-(1,2,2-triphenylvinyl)phenyl)thiophene-2-carbaldehyde (P4TA) was detailedly investigated here by employing both quantum mechanics and molecular mechanics. Besides the isolated molecule, the aggregated molecule both in water and crystal state was studied by focusing on the comparison of photoelectronic properties, including the geometrical and electronic structures at ground and excited states, emission and internal conversation properties...
January 17, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28092133/why-are-dithienylethene-linked-biscobaltocenes-so-hard-to-photoswitch
#8
Jürgen Heck, Alejandra Escribano, Torben Steenbock, Carmen Herrmann, Conrad Stork
Attaching an organometallic unit to a dithienylethene (DTE) molecular switch can allow to vary its switching and spectroscopic properties, and to create switchable magnetic properties. In this work, two different dithienylethene molecular switches were used as a bridge between two cobalt sandwich units. The only difference between the switching cores was in the size of the cycloalkene ring connecting both thiophene rings. The complexes present different oxidation states for the cobalt atoms, which were demonstrated to determine the switching reaction...
January 16, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28092122/how-size-determines-the-value-of-gold-economic-aspects-of-wet-chemical-and-laser-based-metal-colloid-synthesis
#9
Sandra Jendrzej, Bilal Gökce, Matthias Epple, Stephan Barcikowski
Gold is one of the most valuable materials, but its monetary value is even enhanced by size reduction from bullions to colloidal nanoparticles by a factor of 400. Wet-chemical reduction with subsequent centrifugation and pulsed laser ablation in liquids are frequently used for pure colloidal gold synthesis. Both methods provide similar physicochemical nanoparticle properties but are quite different synthesis techniques. However, surprisingly little is discussed about cost effects inherent to those methods. Both methods have in common that labor effort poses the majority of synthesis costs...
January 16, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28090745/side-group-induced-polymorphism-in-self-assembled-monolayers-3-5-bis-trifluoromethyl-benzenethiolate-films-on-au-111
#10
Asif Bashir, Eric Sauter, Najd Al-Refaie, Michael Rohwerder, Michael Zharnikov, Waleed Azzam
The structure and molecular organization of self-assembled monolayers (SAMs) depend on a complex interplay of intermolecular and molecule-substrate interactions, so that even a small change of molecular composition can results in noticeable changes in the SAM structure. Here we show that the decoration of the most basic aromatic SAM constituent, benzenethiol, with two trifluromethyl groups leads to distinct polymorphism in the respective SAMs, with the appearance of a specific structural phase or a combination of several different phases being dependent on the parameters of the preparation procedure...
January 15, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28087990/the-modification-of-onsager-reaction-field-and-its-application-on-spectral-parameters
#11
Xinyu Wang, Rina Dao, Jia Yao, De Peng, Haoran Li
Solvent polarity is an important solvent property. The Onsager's theory of reaction field was the most classic model to describe the solvent effects and was widely used in relating dielectric constant and other solvent polarity parameters. In this study, a modified semi-empirical reaction field was presented to relate electron transition energies or hyperfine coupling constants with the dielectric constants of solvents. In previous works, this relationship was well established by traditional Onsager reaction field for non-hydrogen bonding systems but failed for hydrogen bonding systems...
January 14, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28078728/radical-and-diradical-formation-in-naphthalene-diimides-through-simple-chemical-oxidation
#12
Sangsu Lee, Fang Miao, Hoa Phan, Tun Seng Herng, Jun Ding, Jishan Wu, Dongho Kim
We successfully synthesized, for the first time, naphthalene diimide (NDI) radical and diradical by simple chemical oxidation using lead (IV) dioxide. The formation of (di)radical is confirmed through UV/Vis/NIR absorption, 1H NMR and EPR measurements. In particular, temperature dependent EPR, SQUID and quantum calculations demonstrated that the generated NDI diradical has singlet diradical character of y = 0.69 in the ground state. Subsequent characterization of these (di)radical revealed their stabilities, large TPA cross-sections and short excited-state lifetimes...
January 12, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28071852/environmental-and-excitation-power-effects-on-the-ratiometric-upconversion-luminescence-based-temperature-sensing-using-nanocrystalline-nayf4-yb3-er3
#13
Iko Hyppänen, Niina Perälä, Riikka Arppe, Michael Schäferling, Tero Soukka
The luminescence intensity ratio (LIR) of the green emissions of the near-infrared excited NaYF4:Yb3+,Er3+ nanocrystals is a promising method for temperature sensing. Here, the influence of excitation power density, excitation pulse length, excitation wavelength, silica shell, and solvent on the LIR and its temperature response is reported. Primary objective is to study the LIR mechanism and the impact of measurement and environmental parameters on the calibration and precision of the LIR. The LIR value is demonstrated to be unaffected by the excitation intensity in the studied range...
January 10, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28070980/vibrational-spectrum-of-excited-state-and-huang-rhys-factors-by-coherent-wave-packets-in-time-resolved-fluorescence
#14
Gyeongjin Lee, Junwoo Kim, So Young Kim, Dong Eon Kim, Taiha Joo
Coherent nuclear wave packet motions in an electronic excited state of a molecule have been measured directly by time-resolved spontaneous fluorescence with an unprecedented time resolution by employing two photon absorption excitation and fluorescence upconversion by noncollinear sum frequency generation. With estimated time resolution of ~25 fs, we were able to record wave packet motions of vibrational modes up to 1600 cm1 for coumarin 153 in ethanol. Two-color transient absorption at 13 fs time resolution has been measured to confirm the result...
January 10, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28070927/lead-sulfide-selenide-quantum-dots-and-gold-copper-alloy-nanoparticles-augment-light-harvesting-of-solar-cells
#15
Aparajita Das, Melepurath Deepa, Partha Ghosal
Lead-sulfide-selenide (PbSSe) quantum dots (QDs) and gold-copper (AuCu) alloy nanoparticles (NPs) are incorporated in a cadmium sulfide (CdS)/titanium oxide (TiO2) photoanode for the first time for enhanced conversion of solar energy to electricity. PbSSe QDs with a band gap of 1.02 eV, extend the light harvesting range of the photoanode from visible to the near infrared region. The conduction band (CB) edge of PbSSe QDs is wedged between the CBs of TiO2 and CdS; this additional level coupled with a good electrical conductivity of the dots facilitate charge transport and collection, for a high power conversion efficiency (PCE) of 4...
January 10, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28070929/doping-effects-on-the-adsorption-of-a-no-molecule-on-an-anatase-101-surface
#16
Wei Xiao, Qin Liu, Liangliang Liu
NO adsorption on n-type and p-type modified anatase (101) surfaces is studied with first principle calculations. Both types of modifications can facilitate the adsorption of a NO molecule on an anatase (101) surface. The adsorption mechanisms for these two types of adsorption are different. On n-type modified surfaces, the N atom of the NO molecule is bonded to a surface Ti₅c ion, that is, the unpaired electron on the π* orbital of the NO molecule forms a bond with an extra 3d electron of the surface Ti ion...
January 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28067987/effects-of-water-intercalation-and-tribochemistry-on-mos2-lubricity-an-ab%C3%A2-initio-molecular-dynamics-investigation
#17
Giacomo Levita, Maria C Righi
To date, no clear conclusion has been reached on the atomistic mechanisms that govern the observed decrease of lubricating capabilities of MoS2 in humid environments. Based on ab initio molecular dynamic calculations, we show that intercalated water molecules hinder the sliding motion of both regular and defective layers considerably, with the velocities decaying exponentially with time. However, in the presence of an applied load and exposed edge terminations, water is rapidly removed from the interface and is adsorbed on the edges either in undissociated form or as OH/H fragments...
January 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28067985/the-role-of-a-double-molecular-anchor-on-the-mobility-and-self-assembly-of-thiols-on-au-111-the-case-of-mercaptobenzoic-acid
#18
Miriam Candelaria Rodríguez González, Pilar Carro, Evangelina Pensa, Carolina Vericat, Roberto Salvarezza, Alberto Hernández Creus
The dynamics of the self-assembly process of thiol molecules on Au(111) is affected by the interplay between molecule-substrate and molecule-molecule interactions. Therefore, it is interesting to explore the effect of a second anchor to the gold surface, in addition to the S atom, on both the order and the feasibility of phase transitions in self-assembled monolayers. To assess the role of an additional O anchor, we have compared the adsorption of two mercaptobenzoic acid isomers, 2-mercaptobenzoic acid (2-MBA) and 4-mercaptobenzoic acid (4-MBA), on Au(111)...
January 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28067460/donor-acceptor-control-in-grown-in-glass-ga-oxide-nanocrystals-by-crystallization-driven-heterovalent-doping
#19
Alberto Paleari, Nikita V Golubev, Elena S Ignat'eva, Vladimir N Sigaev, Angelo Monguzzi, Roberto Lorenzi
Incorporation of doping ions in nanocrystals is a strategy for providing nanophases with functions directly related to ion features. At the nanoscale, however, doping can also activate more complex effects mediated by perturbation of nanophase size and structure. Here we report a paradigmatic case in which we modify grown-in-glass γ-Ga2O3 nanophases via nickel or titanium doping of the starting glass, so as to control the concentration of oxygen and gallium vacancies responsible for the light emission. Optical absorption and luminescence show that Ni2+ and Ti4+ ions enter into the nanophase, but differential-scanning-calorimetry and x-ray-diffraction indicate that Ni and Ti also work as modifiers of nanocrystal growth...
January 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28066974/hydrogen-mobility-and-protein-water-interaction-in-proteins-of-solid-state
#20
Kalman Tompa, Monika Bokor, Dorina Ágner, Dávid Iván, Denes Kovacs, Tamas Verebélyi, Peter Tompa
In this work we lay the groundwork of characterizing the mobility of hydrogen-hydrogen pairs (proton-proton radial vectors) in proteins in the solid state that contains only residual water. In this novel approach we introduce new ways of analyzing and interpreting data, by: i) representing hydrogen mobility (HM) and melting diagram (MD) data recorded by wide-line 1H-NMR as a function of fundamental temperature (thermal excitation energy); ii) suggesting novel mode of interpretation of these parameters that sheds light on details of protein-water interaction such as the exact amount of water molecules and the distribution of barrier potentials pertaining to their rotational and surface translational mobility; iii) relying on directly determined physical observables...
January 8, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
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