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227 results on '"Xuan, Xiaopeng"'

42. Volumetric studies of ion solvation in propylene carbonate + N,N-dimethylformamide electrolyte solutions

Author

Zhao, Yang, Wang, Jianji, Xuan, Xiaopeng, and Lin, Ruisen

Subjects
Solvation -- Analysis, Ionic solutions -- Analysis
Abstract

Apparent molar volumes [V.sub.2,[phi]] and standard partial molar volumes [V.sup.[omicron].sub.2,[phi]] for tetraethylammonium bromide ([Et.sub.4]NBr), tetrapropylammonium bromide ([Pr.sub.4]NBr), tetrabutylammonium bromide ([Bu.sub.4]NBr), and tetrahexylammonium bromide ([Hex.sub.4]NBr) have been determined at 298.15 K from precise density measurements in solvent mixtures of propylene carbonate (PC) with N,N-dimethylformamide (DMF). Combined with our previous data for LiCl[O.sub.4] and LiBr in the same solvents, ionic molar volumes of [Li.sup.+], [Et.sub.4][N.sup.+], [Pr.sub.4][N.sup.+], [Bu.sub.4][N.sup.+], [Hex.sub.4][N.sup.+], and related anions have been deduced from the extrapolation method suggested by Conway and co-workers. It is shown that the molar volumes of these cations are quite independent of the nature of the solvent and the composition of the solvent mixtures, in contrast to those of CI[O.sub.4.sup.-] and [Br.sup.-] anions. This suggests that the Lewis-base-type solvents with similar molecular volumes have similar interactions with [Li.sup.+]. The constancy in partial molar volume for tetraalkylammonium ions provides helpful evidence for the lack of solvation of large tetraalkylammonium cations in organic solvents. These findings have been interpreted using scaled-particle theory. The results are discussed in terms of ion solvation, packing effects of solvent molecules in the solvation shell, and the electrostriction of solvents. Key words: ionic volumes, propylene carbonate, N,N-dimethylformamide, solvent mixtures, solvation, lithium batteries.

Published
2003

49. Syntheses, structures and fluorescence properties of cadmium coordination polymers with triangular 1,3-bis[2-(4′-pyridyl)ethenyl]benzene and linear dicarboxylic acids

Author

Wang Yuting, Liang Rui, Guo Yongkang, Yue Fangfang, and Xuan Xiaopeng

Subjects
chemistry.chemical_classification, Thermogravimetric analysis, Cadmium, 010405 organic chemistry, Stereochemistry, Organic Chemistry, chemistry.chemical_element, Crystal structure, Polymer, 010402 general chemistry, 01 natural sciences, Fluorescence, 0104 chemical sciences, Analytical Chemistry, Inorganic Chemistry, Crystallography, chemistry.chemical_compound, chemistry, Benzene, Spectroscopy, Powder diffraction
Abstract

Three new polymeric complexes [Cd3(1,3-BPEB)3(1,4-BDC)3·2H2O]n (1), [Cd2(1,3-BPEB)2(4,4′-BPDC)2]n (2) and [Cd2(1,3-BPEB)2(4,4′-STDC)2]n (3) (1,3-BPEB = 1,3-bis[2-(4′-pyridyl)ethenyl]benzene, 1,4-BDC = 1,4-benzenedicarboxylic acid, 4,4′-BPDC = 4,4′-biphenyldicarboxylic acid and 4,4′-STDC = 4,4′-stilbenedicarboxylic acid) have been prepared by the solvothermal reaction of 1,3-BPEB, Cd(NO3)2·4H2O and dicarboxylic acids. Single-crystal X-ray diffraction reveals that these complexes have novel complicated structures. Complex 1 is a 3-D network structure by linking Cd atoms with 1,4-BDC and 1,3-BPEB ligands. Complex 2 shows a 3-D interpenetrating layered structure formed by three networks which derived from bridged Cd atoms with 4,4′-BPDC and 1,3-BPEB ligands. Complex 3 has a fivefold interpenetrating 3-D coordination framework by linking Cd atoms with 4,4′-STDC and 1,3-BPEB ligands. The dicarboxylic acids afford different coordination modes to bind Cd atoms in these three complexes. Additionally, these compounds were further characterized by PXRD, FT-IR spectroscopy and thermogravimetric (TG) analysis. Their fluorescence spectra were also determined and analyzed in the solid state at room temperature.

Published
2016
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