Yukio Yamamoto*, Y. Yoshida, S. Tagawa
Aug 1, 1996
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Journal
Bulletin of the Chemical Society of Japan
Abstract
Inclusion complexation of 4-biphenylcarboxylate (BPC−), 4-biphenylacetate (BPA−), and 4-biphenylsulfonate (BPS−) with α-cyclodextrin (α-CD) has been investigated by a pulse radiolysis method. The one-electron reduction of BPC− and BPS− by the hydrated electron was effectively retarded by the 1 : 2 complexation with α-CD as well as by the 1 : 1 complexation with β-CD investigated in our previous study. The retarding effect of α-CD was observed at much higher host concentrations than that of β-CD. No apparent effect of α-CD was observed on the one-electron reduction of BPA−, but the effect of β-CD was similar to those for BPC− and BPS−. The result indicates that the methylene group of BPA− sterically inhibits the formation of the 1 : 2 complex. The rate constant for the one-electron reduction of the 1 : 2 complex of BPC− with α-CD was 1.0 × 109 dm3 mol−1 s−1, which is smaller than that of the 1 : 1 complex with β-CD, 2.5 × 109 dm3 mol−1 s−1. It is demonstrated that the biphenylyl group of the 1 : 2 complex ...