紫外光谱法研究环糊精对2，4-滴丙酸甲酯对映体的包合作用

Inclusion interaction of cyclodextrins and 2,4-dichlorprop methyl ester enantiomers by UV spectra.

采用紫外光谱法研究β-环糊精（B-CD）、羧甲基-阻环糊精（CM-B-CD）和部分甲基化-β-环糊精（PM-G-CD）对2，4-滴丙酸甲酯包合作用的对映体差异．在298．15～318．15K的温度范围内，3种环糊精均能与2，4-滴丙酸甲酯形成1：1型的包合物，其包合常数值大小依次为KPM-β-CD》KcM-β-CD，且随着温度的升高而降低．经计算，热力学参数△G、△H和△S均为负值，说明包合反应是放热反应且能自发进行，焓变是形成包合物的主要驱动力．对于同-环糊精主体而言，R-2，4-滴丙酸甲酯比S-2，4-滴丙酸甲酯易于被包合，且KR/KS的顺序与包合常数K值的次序-致．

The enantioselective inclusion interaction of various cyclodextrins （β-CD, PM-β-CD, CM-β- CD） with R/S-2,4-dichlorprop methyl ester （R/S-2,4-D） was studied by UV spectra technique. The results show that all cyclodextrins formed 1 ： 1 inclusion complexes with 2,4-D, the order of binding constants of three types cyclodextrins and 2,4-D was KpM-CD〉〉 KCMM-β-CD〉Kβ-CD Between 298.15 K and 318. 15 K, the binding constants decreased as the temperature increased. All Gibbs free energy AG, enthalpy change △H, and entropy change AS determined were negative, suggesting that the inclusion interaction was exothermic and spontaneously occurred by balance of enthalpy driven and entropy opposed. R-2,4-D was easier enclosed than S-2,4-D by the same kind of cyclodextrins and the order of KR/Ks was accordance with the order of binding constants.