One-electron Reduction and Electron Transfer Reaction Controlled by Cyclodextrin Inclusion Complexation

环糊精(CDS)在水溶液中与各种有机分子形成包合物，这取决于它们的疏水空腔和客体分子的大小。预置脉冲辐解研究由包合物配位控制芳香族羧酸盐和磺酸盐的单电子还原。芳香电解质水溶液的脉冲辐解导致溶质的芳香族部分被水合电子单电子还原。当CD腔中含有疏水的芳香族部分时，反应被有效地延缓。因此，联苯-4-羧酸酯(BPC)、联苯-4-辛酸酯(BPA)和联苯基-4-磺酸盐(BPS)的单电子还原反应的速率常数通过与β-CD的络合而显著降低，其空穴最适合联苯基团。类似地，1-吡喃-1-羧酸酯(PYC)、4-吡喃-1-丁酸(PYB)和1-磺酸(PYS)的单电子还原为r…考察了磺酸盐混合物溶液的单电子还原反应和电子转移反应的控制。用β-和伽马-镉实现了对BPS和Pys混合溶液的选择性还原。Pys与α-CD的络合作用也有效地抑制了还原的BPS向Pys的电子转移。络合效应的pH依赖性表明，由于BPA的亚甲基的空间位阻效应，BPC与α-CD之间形成了1：2的络合物，而BPC与α-CD之间没有形成1：2的络合物。2与γ-Cd的络合物，以及PYC和PYS的络合物随着客体的单电子还原而发生结构变化。由脉冲辐解数据确定了BPC、BPA和BPS的1：1络合物的缔合常数。较少

Cyclodextrins (CDs) form inclusion complexes with various organic molecules in aqueous solution depending on the sizes of their hydrophobic cavities and of the guest molecules. The preset pulse radiolysis study is concerned with the one-electron reduction of aromatic carboxylates and sulfonates controlled by the inclusion comlexation. The pulse radiolysis of aqueous solutions of the aromatic electrolytes results in the one-electron reduction of the aromatic moieties of the solutes by the hydrated electron. The reaction is effectively retarded when the hydrophobic aromatic moieties are included in the CD cavities. Thus, the rate constants for the one-electron reduction of biphenyl-4-carboxylate (BPC), biphenyl-4-asetate (BPA) and biphenyl-4-sulfonate (BPS) are appreciably reduced by the complexation with beta-CD,whose cavity best fits to the biphenylyl group. Similarly, the one-electron reduction of pyrene-1-carboxylate (PyC), 4-pyren-1-ylbutyrate (PyB) and pyrene-1-sulfonate (PyS) is r … More etarded by the best fitting gamma-CD.The control of the one-electron reduction and electron transfer reactions has been examined for the solutions of mixtures of the sulfonates. The selective reduction of a mixed BPS and PyS solution has been achieved by using beta-and gamma-CDs. The electron transfer from the reduced BPS to PyS is also retarded effectively by the complexation of PyS with gamma-CD.The pH dependence of the effect of the complexation has demonstrated that a 1 ; 2 complex is formed between BPC and alpha-CD but not between BPC and alpha-CD because of the steric effect of the methylene group of BPA.The apparent retarding effect of alpha-CD on the one-electron reduction of BPC is observed at much higer host concentrations compared with that of beta-CD.PyC,PyB and PyS form 2 ; 2 complexes with gamma-CD,and the complexes of PyC and PyS undergo a structural change upon the one-electron reduction of the guests. The association constants of the 1 ; 1 complexes of BPC,BPA and BPS have been determined from the pulse radiolysis data. Less