排序方式: 共有32条查询结果,搜索用时 15 毫秒
31.
Ivan Petkov Asya Petinova Stanimir S. Stoyanov Stefan Metsov Stefan I. Stoyanov 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(3-4):329-338
The effect of native and randomly methylated β-CDs on the absorption and steady-state fluorescence spectra of 2-(4-dimethylaminostyryl)-3-(2-hydroxyethyl)-benzothiazolium
chloride (DHB) in aqueous buffer solutions with various pH values was studied. The inclusion with both CDs at pH 7.2 barely
changed the UV spectra, whereas significant variations were produced in the emission spectra in all buffer solutions. In all
cases the CDs increase guest fluorescence. The 1:1 stoichiometry of the inclusion complexes of the dye with both CDs was established
according to the modified Benesi-Hildebrand method. Binding constant values were calculated using the iterative nonlinear
least-squares regression approach. The pH of the solution and the type of the CD affected complex stability. The results indicate
that native β-CD possesses better complexing ability towards DHB than randomly substituted β-CD and that the most stable inclusion
complexes are formed in basic medium because of the structural changes in the guest molecule. In basic medium an attempt is
made to interpret the proposed mechanism in terms of molecular rearrangement which take place as the dye penetrates the CD
cavity. 相似文献
32.