Synthesis,Crystal Structure and Properties of a Novel Decavanadate Complex with One-dimensional Chain Involving Sodium and ＇Bis-tris＇ Ligand

By using a flexible multidentate ligand,bis(2-hydroxyethyl)iminotris(hydroxyhydroxylmethy)methane('bis-tris':H5L),the title complex {[Na(H6L)2]2}n·nV10O28(1) has been successfully synthesized under self-assembly condition and characterized by IR spectroscopy,elemental analysis,PXRD and single-crystal X-ray diffraction.The crystal structure belongs to an orthorhombic system,space group Cmca with a = 23.752(2),b = 13.5360(8),c = 18.5377(11) ,V = 5960.1(7),Z = 8,Dc = 2.055 g/cm3,F(000) = 3744,μ = 1.630 mm-1,the final R = 0.0283 and wR = 0.0759 for 3353 observed reflections with I > 2σ(I).This complex consists of decavanadate [V10O28]6-motifs as counter anions intercalated with one-dimensiond chains of the composition [Na(H6L)2]n3n+.And significant intermolecular O-H…O hydrogen-bonding interactions lead to a three-dimensional supramolecular framework.     

Evaluation of antioxidant and cytoprotective activities of Arnica montana L. and Artemisia absinthium L. ethanolic extracts

ABSTRACT: BACKGROUND: Arnica montana L. and Artemisia absinthium L. (Asteraceae) are medicinal plants native to temperate regions of Europe, including Romania, traditionally used for treatment of skin wounds, bruises and contusions. In the present study, A. montana and A. absinthium ethanolic extracts were evaluated for their chemical composition, antioxidant activity and protective effect against H2O2-induced oxidative stress in a mouse fibroblast-like NCTC cell line. RESULTS: A. absinthium extract showed a higher antioxidant capacity than A. montana extract as Trolox equivalent antioxidant capacity, Oxygen radical absorbance capacity and 2,2-diphenyl-1-picrylhydrazyl free radical-scavenging activity, in correlation with its flavonoids and phenolic acids content. Both plant extracts had significant effects on the growth of NCTC cells in the range of 10--100 mg/L A. montana and 10--500 mg/L A. absinthium. They also protected fibroblast cells against hydrogen peroxide-induced oxidative damage, at the same doses. The best protection was observed in cell pre-treatment with 10 mg/L A. montana and 10--300 mg/L A. absinthium, respectively, as determined by Neutral red and lactate dehydrogenase assays. In addition, cell pre-treatment with plant extracts, at these concentrations, prevented morphological changes induced by hydrogen peroxide. Flow-cytometry analysis showed that pre-treatment with A. montana and A. absinthium extracts restored the proportion of cells in each phase of the cell cycle. CONCLUSIONS: A. montana and A. absinthium extracts, rich in flavonoids and phenolic acids, showed a good antioxidant activity and cytoprotective effect against oxidative damage in fibroblast-like cells. These results provide scientific support for the traditional use of A. montana and A. absinthium in treatment of skin disorders.     

The Interactions of Spore‐Coat Morphogenetic Proteins Studied by Single‐Molecule Recognition Force Spectroscopy

Bacillus subtilis can form a spore, which is a dormant type of cell, when its external environment becomes unsuitable for vegetative growth. The spore is surrounded by a multilayered proteinaceous shell called a spore coat, which plays a crucial role in dormancy and germination. Of the over 70 proteins that form the spore coat, only a small subset of them affect its morphogenesis; they are referred to as morphogenetic proteins. How these morphogenetic proteins interact, and furthermore, how they build the ordered, functional coat layers is not well understood. Elucidating the self‐assembly mechanism of individual proteins into such a complex structure may contribute to its potential use in nano‐biotechnology applications for preparing highly organized, robust, and resistant proteinaceous layers. Herein, direct, noncovalent, low‐affinity interactions between the spore‐coat morphogenetic proteins SpoIVA, SpoVID, and SafA were studied by using single‐molecule recognition force spectroscopy in vitro for the first time. Based on the real‐time examination of interactions between these three proteins, a series of dynamic kinetic data were obtained. It was also observed that the SafA–SpoVID interaction was stronger than that of SafA–SpoIVA.     

Theoretical calculations of the substituent effect on molecular properties of the RCN⋯HF hydrogen-bonded complexes with R = NH2, CH3O,CH3, OH,SH, H,Cl, F,CF3, CN and NO2

DFT calculations with B3LYP and PBE1PBE functionals and 6–311++G(d,p) basis set have been performed in order to obtain molecular geometries, binding energies and vibrational properties of the RCN?HF H-bonded complexes with R = NH₂, CH₃O, CH₃, OH, SH, H, Cl, F, CF₃, CN and NO₂. As expected, it has been verified as a red-shift of the HF stretching frequency (ν_HF), in conformity with the elongation of the bond after complexation. On the other hand, the CN stretching frequency (ν_CN) is blue-shifted and corresponds to a shortening of the bond. The binding energies (ΔE_c), including BSSE and ZPVE corrections, show a linear correlation with several structural, electronic and vibrational properties. In particular, an important linear dependence between the binding energy and the calculated dipole moment of the free RCN molecule (μ_RCN) has been found. This result suggests that μ_RCN can be a useful quantity in order to predict the ability of this fragment to form a hydrogen-bond. The IR intensities of stretching and bending modes of complexed HF acid fragment are adequately interpreted through the atomic polar tensor of the hydrogen atom in HF using the modified CCFO model for infrared intensities. The new vibrational modes arising from complexation show several interesting features.     

Multisoliton ejection from an amplifying potential trap

We study theoretically the dynamics of a beam launched inside an amplifying trap potential. Raising the amplification transforms the dynamics from linear tunneling at low amplification to periodic ejection of a sequence of identical solitons (when the amplification rate exceeds the tunneling rate) and, at strong amplification, to nonperiodic multisoliton ejection.     

The delocalized effective degrees of freedom of a black hole at low frequencies

Identifying the fundamental degrees of freedom of a black hole poses a long-standing puzzle. Recently Goldberger and Rothstein forwarded a theory of the low frequency degrees of freedom within the effective field theory approach, where they are relevancy ordered but of unclear physical origin. Here these degrees of freedom are identified with near-horizon but non-compact gravitational perturbations which are decomposed into delocalized multipoles. Their world-line (kinetic) action is determined within the classical effective field theory (CLEFT) approach and their interactions are discussed. The case of the long-wavelength scattering of a scalar wave off a Schwarzschild black hole is treated in some detail, interpreting within the CLEFT approach the equality of the leading absorption cross section with the horizon area. Fifth Award in the 2008 Essay Competition of the Gravity Research Foundation.     

Hybrid polymer inorganic materials prepared from ternary microemulsions

The microemulsion system containing vinyl acetate (Vac), silane derivatives tetraethoxysilane (TEOS), methacryloxypropyltrimethoxysilane (MPTS), vinyltriethoxysilane (VTES), methyltriethoxysilane (MeTES), octyltriethoxysilane (OTES), nonylphenol etoxylated with 25 mol of ethylene oxyde (NPEO₂₅) and water was studied. It was established that the probability of microemulsion formation increases with surfactant concentration. The microenviroment of the solubilization of the VAc and of silane derivatives in the aggregates of NPEO₂₅ was affected by their polarity. Hybrid materials were obtained by sol-gel reaction of silane derivatives combined with free-radical polymerization of VAc. The change of the glass transition temperature and of thermal stability of the polymer chains in the presence of the inorganic one proved the formation of simultaneous polymer inorganic hybrids.     

Evaluation of proton conductivity of sulfonated polyimide/dihydroxy naphthalene charge‐transfer complex hybrid membranes

Sulfonated polyimide (SPI)/dihydroxynaphthalene (DHN) charge‐transfer (CT) complex hybrid films were investigated as possible alternative for polymer electrolyte membranes in polymer electrolyte fuel cells. SPI/DHN CT complex hybrid films include CT complexes, which might work as electronic conductors, and sulfonic acid units, which could work as proton conductors. Therefore, the origin of the conductivity of SPI/DHN complex hybrid films was evaluated by four‐probe impedance measurements in the through‐plane direction of the films. The obtained conductivity of the CT complex hybrid films increased with the increase of ion exchange capacity of the CT films and the decrease of CT complex concentration in the films. These results indicated that proton transfer dominantly occurred in the CT complex hybrid films. Proton conductivity of the CT complex hybrid films consisting of 2,6‐ or 1,5‐DHN showed the similar values, although the molecular geometries of the CT complex were different. The activation energy values for proton conductivity in the CT films were approximately the same as that of Nafion 212. Water uptake (WU) results were also conducted and suggest that CT complex formation could control the degree of WU of the films and prevent dissolution of SPI. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2991–2997     

Experimental and theoretical study of charge‐transfer complex hybrid polyimide membranes

The nanostructure of sulfonated polyimide (SPI)/dihydroxynaphthalene (DHN) derivative charge‐transfer (CT) complex hybrid films, which are noble alternative polymer electrolyte membranes (PEMs), is determined by a combined visible spectroscopy/quantum mechanical approach. From the visible spectra of SPI/2,6‐dihydroxynaphthalene (2,6‐DHN) and 1,5‐dihydroxynaphthalene (1,5‐DHN) CT complex hybrid films, it is confirmed that these films have different maximum wavelength, although difference of the molecular structure is small. From the calculation based on the experimental result, SPI and DHNs form multiple interactions consisting of not only CT interaction, but also hydrogen bonding in multilayered structures. CT interaction between SPI and DHN defines the DHN position in the SPI matrix, with DHN sitting in the cavity formed between SPIs. The molecular structure of the CT films derived from the multiple and complex interactions can recognize small differences in the structural isomers and bring changes of the optical property. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 293–298     

NMR of 27 Al in paramagnetic single-crystal DyAl2

NMR of ²⁷Al was observed in a spherical single crystal of DyAl₂ in the paramagnetic state. The well split quadrupole spectrum yielded a quadrupole frequency ν_Q = 561 kHz and hyperfine constant H_hf^p = -3.17 kOe/n_B. The anisotropy of the spectrum is well explained by the dipolar interaction.