共查询到20条相似文献,搜索用时 369 毫秒
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V.G. Charalampopoulos K. Viras H.S. Karayianni G. Kakali 《Supramolecular chemistry》2013,25(9):499-510
At T < 250 K, the polyiodide inclusion complex (α-cyclodextrin)2·Sr0.5·I5·17H2O displays two separate relaxation processes due to both the frozen-in proton motions in an otherwise ordered H-bonding network and the order–disorder transition of some normal H-bonds to flip-flop ones. At T>250 K, the AC-conductivity is dominated by the combinational contributions of the disordered water network, the mobile Sr2+ ions, the polyiodide charge-transfer interactions and the dehydration process. The evolution of the Raman spectroscopic data with temperature reveals the coexistence of four discrete pentaiodide forms. In form (I) (I? 3·I2 ? I2·I? 3), the occupancy ratio (x/y) of the central I? ion differs from 50/50. In form (IIa) (I2·I? ·I2) x/y = 50/50, whereas in its equivalent form (IIb) (I2·I? ·I2) * as well as in form (III) (I? 3·I2), x/y = 100/0 (indicative of full occupancy). Through slow cooling and heating, the inverse transformations (I) → (IIa) and (IIa) → (I) occur, respectively. 相似文献
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M. Wiśniewska V. Bogatyrov I. Ostolska K. Szewczuk-Karpisz K. Terpiłowski A. Nosal-Wiercińska 《Adsorption》2016,22(4-6):417-423
The poly(vinyl alcohol) (PVA) influence on the adsorption and electrokinetic properties of the mixed oxide Mn x O y –SiO2/polymer solution system was examined. Three oxides differing with the Mn x O y contents were applied (0.2; 1 and 3 mmol/g SiO2, respectively). The PVA with the molecular weight 100 kDa was characterized with the acetate groups content equal to 14 %. Adsorption, solid surface charge and zeta potential measurements were made as a function of solution pH (3–10). The obtained results showed that the PVA adsorption amount strongly depends on not only the solution pH, but also manganese oxide content on the mixed oxide surface. The higher solution pH value (or Mn x O y content) is, the higher polymer adsorption is obtained. The PVA addition to the solid suspension causes minimal changes of the mixed oxide surface charge density, whereas the zeta potential of solid particles increases significantly in the polymer presence. 相似文献
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Yusaku Eda Kennosuke Itoh Yoshio N. Ito Mamoru Fujitsuka Tetsuro Majima 《Supramolecular chemistry》2013,25(9):517-523
2,6-Bis(porphyrin)-substituted 3,5-dimethylpyrazine and its zinc complex bound C70 to yield 1:1 inclusion complexes, which were characterised by ESI-MS, UV–vis, fluorescence and NMR spectroscopies. Association constants of the C70 complexes were determined by fluorescence and NMR spectral analyses. A decrease in absorbance of the Soret band of the pyrazine derivative by the effect of C70 was observed, suggesting the existence of a charge transfer interaction between C70 and porphyrin. Experimentally reliable values for the association constants were obtained by the NMR method and were about six times larger than those of the corresponding C60 complexes. Palladium complexation of the porphyrin–pyrazine ligand was found to enhance the association with fullerene. The association constant of 2,6-bis(porphyrin-Zn)-substituted 3,5-dimethylpyrazine-Pd(II) complex with C70 was determined to be 8400 ± 900 M? 1. From the comparison of the association constants, it was found that inclusion room for C70 in the Pd(II) complex was maintained, juxtaposed between porphyrins attached to the opposite sides of the pyrazine ligands. 相似文献