联喹啉桥联双环糊精对染料客体分子的协同键合

Cooperative Binding of Dyes by Biquinolino Modified β-cyclodextrin Dimers

采用荧光光谱滴定的方法测定了一系列联喹啉桥联双环糊精在磷酸缓冲溶液中(25℃,pH=7.2)与几种染料客体分子形成化学计量比为1∶1的超分子配合物的稳定常数.结果表明,拥有刚性和大π电子体系的联喹啉桥联双环糊精比相应的联吡啶桥联双环糊精对三角形的RhB分子和线形的AR分子具有更强的分子键合能力.二维核磁的研究证实,桥联双环糊精对客体分子强的键合能力起源于在一个分子内两个环糊精单元的协同键合.桥联双环糊精对染料客体分子的选择键合能力从主-客体间的尺寸/形状匹配以及几种弱相互作用力的协同效应进行了讨论.

The complex stability constants for the 1∶1 inclusion complexation of 2,2'-biquinoline-4,4'- dicarboxy-bridged bis(β-cyclodextrin)s with dye guests have been determined by means of fluorescent titra- tion at 25 ℃ in phosphate buffer solution (pH 7.2). Possessing more rigid and bigger π-electron systems of tethers, biquinolino-modified β-cyclodextrin dimers can form more stable complexes with not only the T-shaped RhB but also the linear guest AR than the corresponding bipyridino-tethered bis(β-cyclodextrin)s. 2D NMR investigations for the complexation between host and guest validated the cooperative binding of bis(β-cyclodextrin)s with dye guests. The inclusion complexation behaviors of bis(β-cyclodextrin)s with dyes were discussed from the viewpoints of size/shape-fitting relationship between host and guest as well as the cooperative contribution of several weak forces.