Host¨Cguest complexes of some cucurbit[n]urils with the hydrochloride salts of some imidazole derivatives

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• 作者：Yan Feng ; Sai-Feng Xue ; Zhi-Fang Fan ; Yun-Qian Zhang ; Qian-Jiang Zhu and Zhu Tao
• 关键词：Host– ; guest complexes ; Normal cucurbit[n = 6 ; 7 ; 8]urils ; Sym ; tetramethyl ; cucurbit[6]uril ; Imidazole derivatives ; 1H NMR spectroscopy ; Binding constant ; Crystal structure
• 刊名：Journal of Inclusion Phenomena and Macrocyclic Chemistry
• 出版年：2009
• 出版时间：June, 2009
• 年：2009
• 卷：64
• 期：1-2
• 页码：121-131
• 全文大小：691.3 KB

文摘

Interaction between the normal cucurbit[n]urils (n = 6,7,8; Q[6], Q[7], Q[8]) and a sym-tetramethyl-substituted cucurbit[6]uril derivative (TMeQ[6]) with the hydrochloride salts of some imidazole derivatives N-(4-hydroxylphenyl)imidazole (g1), N-(4-aminophenyl)imidazole (g2), 2-phenylimidazole (g3) in aqueous solution was investigated by using 1H NMR spectroscopy, electronic absorption spectroscopy and fluorescence spectroscopy, as well as by using a single crystal X-ray diffraction determination. The 1H NMR spectra analysis established a basic interaction model in which inclusion complexes with a host:guest ratio of 1:1 forms for the Q[6]s and Q[7] cases, while with a host:guest ratio of 1:2 form for the Q[8] cases. It was common that the hosts selectively bound the phenyl moiety of the guests. Absorption spectrophotometric and fluorescence spectroscopic analysis in aqueous solution defined the stability of the host–guest inclusion complexes at pH 5.8 with a host:guest ratio of 1:1 form quantitatively as logK values between 4 and 5 for the smaller hosts Q[6 or 7]s, while with a host:guest ratio of 1:2 form quantitatively as logK values between 11 and 12 for the host Q[8]. Two single crystal X-ray structures of the inclusion complexes TMeQ[6]-g2 ¡¤ HCl and TMeQ[6]-g3 ¡¤ HCl showed the phenyl moiety of these two guests inserted into the host cavity, which supported particularly the 1H NMR spectroscopic study in solution.