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Physical Chemistry Chemical Physics: PCCP

Masahiro Kinoshita, Tomohiko Hayashi
The association of nonpolar solutes is generally believed to be entropy driven, which has been shown to be true for the contact of small molecules, ellipsoids, and plates. However, it has been reported with surprise that a model cavity-ligand binding is entropy opposed. How can these apparently conflicting behaviors be elucidated? Here, we calculate the potential of mean force between hard-sphere solutes with various diameters in water and its entropic and enthalpic components using a statistical-mechanical theory for molecular liquids...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
Anuraag Gaddam, Hugo R Fernandes, Bertrand Doumert, Lionel Montagne, José M F Ferreira
The current study reports on the relaxation behaviour of lithium silicate based glasses as probed by NMR spectroscopy. A total of four glass compositions were studied with the parent composition being 28Li2O-72SiO2, and added dopants of Al and B. All the compositions showed significant differences in the NMR spectra of both annealed and non-annealed glasses demonstrating the structural relaxation behaviour. We extended our binary statistical mechanical model to these complex compositions to study the relaxation behaviour...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
G Sikora, E Kepten, A Weron, M Balcerek, K Burnecki
Modern live-imaging fluorescent microscopy techniques following the stochastic motion of labeled tracer particles, i.e. single particle tracking (SPT) experiments, have uncovered significant deviations from the laws of Brownian motion in a variety of biological systems. Accurately characterizing the anomalous diffusion for SPT experiments has become a central issue in biophysics. However, measurement errors raise difficulty in the analysis of single trajectories. In this paper, we introduce a novel surface calibration method based on a fractionally integrated moving average (FIMA) process as an effective tool for extracting both the magnitude of the measurement error and the anomalous exponent for autocorrelated processes of various origins...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
Zhen Liu, Guozhu Li, Tong Cui, Abhishek Lahiri, Andriy Borodin, Frank Endres
In this work, we report on the influence of an organic ligand on the electrodeposition of Zn from an ionic liquid (IL) electrolyte. Zinc oxide was first dissolved in a protic IL. By introducing a 2-methylimidazole (2-MIm) ligand, the electronic environment of zinc ions, Zn(ii) complexes and the structure of the IL are considerably altered, as verified by both X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Due to the electron donation effect of the ligand, the zinc ions become less positively charged and exhibit a lower binding energy by -0...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
Alejandro D Somoza, Ke-Wei Sun, Rafael A Molina, Yang Zhao
Self-assembled supramolecular aggregates are excellent candidates for the design of efficient excitation transport devices. Both artificially prepared and natural photosynthetic aggregates in plants and bacteria present an important degree of disorder that is supposed to hinder excitation transport. Besides, molecular excitations couple to nuclear motion affecting excitation transport in a variety of ways. We present an exhaustive study of exciton dynamics in disordered nanorings with long-range interactions under the influence of a phonon bath taking the LH2 system of purple bacteria as a model...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
Bo Xiong, Yih-Chung Chang, Cheuk-Yiu Ng
By employing the sequential electric field pulsing scheme for vacuum ultraviolet (VUV) laser pulsed field ionization-photoion (PFI-PI) detection, we have successfully recorded the spin-orbit and rovibronic state resolved VUV-PFI-PI spectra for O2(+)(a(4)Πu5/2,3/2,1/2,-1/2: ν(+) = 0-2; J(+)) and O2(+)(X(2)Πg3/2,1/2: ν(+) = 21-23; J(+)), indicating that O2(+)(a(4)Πu) and O2(+)(X(2)Πg) ions in these spin-orbit and rovibronic states can be prepared for ion-molecule collision studies. The present experiment is concerned with the measurement of absolute integral cross sections (σ's) of the charge transfer reactions, O2(+)(a(4)Πu5/2,3/2,1/2,-1/2: ν(+) = 1, 2; J(+)) [O2(+)(X(2)Πg1/2,3/2: ν(+) = 22, 23)] + Ar → Ar(+) + O2...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
Dongwei Ma, Benyuan Ma, Zhiwen Lu, Chaozheng He, Yanan Tang, Zhansheng Lu, Zongxian Yang
In this study, the interaction between gas molecules, including H2O, N2, CO, NO, NO2 and N2O, and a WSe2 monolayer containing an Se vacancy (denoted as VSe) has been theoretically studied. Theoretical results show that H2O and N2 molecules are highly prone to be physisorbed on the VSe surface. The presence of the Se vacancy can significantly enhance the sensing ability of the WSe2 monolayer toward H2O and N2 molecules. In contrast, CO and NO molecules highly prefer to be molecularly chemisorbed on the VSe surface with the non-oxygen atom occupying the Se vacancy site...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
He Su, Qiyang Wu, Hongyan Wang, Hui Wang
The binding energy is of great importance in understanding the formation and stability of noncovalent interactions. However, the determination of the binding energy with high precision and efficiency in medium- and long-range noncovalent interactions is still challenging for quantum chemistry. Here, we assess the performance of random-phase approximation (RPA), a fully non-local fifth-rung of the Jacob ladder functional, in determining the binding energy of cation-π systems (cation = Li(+), Na(+), Be(2+), Mg(2+), Al(+), and NH4(+); π = C6H6), which, to the best of our knowledge, has not been investigated...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
Rashid R Valiev, Heike Fliegl, Dage Sundholm
Magnetic and spectroscopic properties of a number of formally antiaromatic carbaporphyrins, carbathiaporphyrins and isophlorins with 4n π electrons have been investigated at density functional theory and ab initio levels of theory. The calculations show that the paratropic contribution to the magnetically induced ring-current strength susceptibility and the magnetic dipole-transition moment between the ground and the lowest excited state are related. The vertical excitation energy (VEE) of the first excited state decreases with increasing ring-current strength susceptibility, whereas the VEE of the studied higher-lying excited states are almost independent of the size of the ring-current strength susceptibility...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
Keat Hoe Yeoh, Tiem Leong Yoon, Duu Sheng Ong, Thong Leng Lim, Yusuf Zuntu Abdullahi
Using first-principles calculations, we carry out systematic studies on the electronic, magnetic and structural properties of halogenated β-phase antimonene. We consider two different levels of halogen adatom coverage i.e. Θ = 1/8 and Θ = 1/18. It is found that F, Cl and Br adatoms act as acceptors whereas the I adatom acts as a donor. For a high coverage of Θ = 1/8, halogenated β-phase antimonene exhibits metallic characteristics. With a lower coverage of Θ = 1/18, through the adsorption of F, Cl and Br the semiconducting unstrained antimonene becomes metallic...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
Preeti Garg, Gurpreet Kaur, Ganga Ram Chaudhary, Santosh L Gawali, P A Hassan
Among the self-assembled forms of surfactants, vesicles/liposomes are a highly promising and interesting feature of surfactants, which are usually formed from water insoluble surfactants. Herein, we demonstrate the formation of liposomes from single-chain cationic surfactants with the help of metals as a part of the counter ion, and these metal embedded liposomes are termed as metalosomes. It is a noteworthy advancement in the area of self-assembled molecular structures since we report the preparation of metal embedded liposomes (metalosomes) from a water soluble single chain cationic surfactant, which is otherwise a property or an arrangement made by double tailed surfactants, or more precisely lipids that are poorly water soluble...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
Wenbo Jiang, Yicheng Qiang, Meijiao Liu, Weihua Li, Feng Qiu, An-Chang Shi
The phase behavior of binary blends composed of AB diblock and (A'B)n star copolymers is studied using the polymeric self-consistent field theory, focusing on the formation and stability of the stable tetragonal phase of cylinders. In general, cylindrical domains self-assembled from AB-type block copolymers are packed into a hexagonal array, although a tetragonal array of cylinders could be more favourable for lithography applications in microelectronics. The polymer blends are designed such that there is an attractive interaction between the A and A' blocks, which increases the compatibility between the two copolymers and thus suppresses the macroscopic phase separation of the blends...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
I E Kłosowska-Chomiczewska, W Artichowicz, U Preiss, C Jungnickel
We created a model to predict CMC of ILs based on 704 experimental values published in 43 publications since 2000. Our model was able to predict CMC of variety of ILs in binary or ternary system in a presence of salt or alcohol. The molecular volume of IL (Vm), solvent-accessible surface (Ŝ), solvation enthalpy (ΔsolvG(∞)), concentration of salt (Cs) or alcohol (Ca) and their molecular volumes (Vms and Vma, respectively) were chosen as descriptors, and Kernel Support Vector Machine (KSVM) and Evolutionary Algorithm (EA) as regression methodologies to create the models...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
Wenhui Sun, Zesheng An, Peiyi Wu
The distinct thermal transition behavior of thermoresponsive block polymers based on poly(ethylene glycol)methyl ether acrylate (PEGA) and their corresponding disulfide-cross-linked nanogels was studied by using FTIR measurements in combination with two-dimensional correlation spectroscopy (2Dcos). Spectral analysis clearly reveals that the sharp thermal transition of the precursor polymer is accompanied by a forced hydration process induced by the formation of hydrogen bonds between the entrapped water molecules and the C[double bond, length as m-dash]O groups, while the nanogel with a relatively continuous thermal transition is related to the existence of various dehydrating states of the C[double bond, length as m-dash]O groups...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
Zhenlong Zhao, Mruthunjaya Uddi, Nikolai Tsvetkov, Bilge Yildiz, Ahmed F Ghoniem
CO2 splitting via thermo-chemical or reactive redox has emerged as a novel and promising carbon-neutral energy solution. Its performance depends critically on the properties of the oxygen carriers (OC). Ceria is recognized as one of the most promising OC candidates, because of its fast chemistry, high ionic diffusivity, and large oxygen storage capacity. The fundamental surface ion-incorporation pathways, along with the role of surface defects and the adsorbates remain largely unknown. This study presents a detailed kinetics study of CO2 splitting using CeO2 and Ce0...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
Inho Nam, Jongseok Park, Soomin Park, Seongjun Bae, Young Geun Yoo, Jeong Woo Han, Jongheop Yi
Correction for 'Observation of crystalline changes of titanium dioxide during lithium insertion by visible spectrum analysis' by Inho Nam et al., Phys. Chem. Chem. Phys., 2017, 19, 13140-13146.
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
Johanna Klyne, Matthias Schmies, Mitsuhiko Miyazaki, Masaaki Fujii, Otto Dopfer
The structure and activity of peptides and proteins strongly rely on their charge state and the interaction with their hydration environment. Here, infrared photodissociation (IRPD) spectra of size-selected microhydrated clusters of cationic acetanilide (AA(+), N-phenylacetamide), AA(+)-(H2O)n with n ≤ 3, are analysed by dispersion-corrected density functional theory calculations at the ωB97X-D/aug-cc-pVTZ level to determine the stepwise microhydration process of this aromatic peptide model. The IRPD spectra are recorded in the informative X-H stretch (νOH, νNH, νCH, amide A, 2800-3800 cm(-1)) and fingerprint (amide I-II, 1000-1900 cm(-1)) ranges to probe the preferred hydration motifs and the cluster growth...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
Siew San Tan, Susumu Yanagisawa, Kouji Inagaki, Yoshitada Morikawa, Mohammad B Kassim
An absorbance-based sensor employing ruthenium bipyridyl with a phenanthroline-fused benzoylthiourea moiety formulated as [Ru(ii)(bpy)2(phen-nBT)](PF6)2 {bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, nBT = n-benzoylthiourea} has been synthesized and characterized by elemental analyses, mass spectrometry, and infrared, ultraviolet-visible, luminescence and nuclear magnetic resonance spectroscopy. The changes in the intensity of absorption and emission of the complex induced by functionalization of the benzoylthiourea ligands with amino and carbonyl in their protonated and deprotonated forms were studied experimentally...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
Marc Benjamin Hahn, Susann Meyer, Maria-Astrid Schröter, Hans-Jörg Kunte, Tihomir Solomun, Heinz Sturm
Ectoine, a compatible solute and osmolyte, is known to be an effective protectant of biomolecules and whole cells against heating, freezing and extreme salinity. Protection of cells (human keratinocytes) by ectoine against ultraviolet radiation has also been reported by various authors, although the underlying mechanism is not yet understood. We present the first electron irradiation of DNA in a fully aqueous environment in the presence of ectoine and at high salt concentrations. The results demonstrate effective protection of DNA by ectoine against the induction of single-strand breaks by ionizing radiation...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
Sramana Kundu, Vaibhav S Prabhudesai, E Krishnakumar
We demonstrate the efficient formation of carbon-nitrogen bonds starting from CH4 and NH3 on a metal surface at cryogenic temperatures. Electrons in the energy range of 1-90 eV are used to initiate chemical reactions in mixed molecular films of CH4 and NH3 at ∼15 K, and the products are detected by performing temperature programmed desorption (TPD). Extensive dehydrogenation occurs at all energies giving the products CH2NH and HCN in preference to CH3NH2. This is likely to do with the energetics of the reactions and the subsequent stability of these species in the condensed film...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
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