Cucurbituril Class Round Of Alkyl System And Spices Molecular Inclusion Mechanism Test

Nowadays supramolecular chemistry or host-guest chemistry has become one of the hot fields of chemical research. Cucurbit[n]urils are cyclic methylene-bridged glycoluril oligomers whose shape resembles a pumpkin. The defining features of cucurbit[n]urils are their two portals lined by carbonyl groups that provide entry to their hydrophobic cavity. Due to their special structure, cucurbit[n]urils are becoming a series of new hosts after crown ether, cyclodextrin and calixarene, and are one of the important investigation of the supramolecular chemistry.In the first part of the paper, a series of N, N'-bisalkyl-1,3-(4,4'-bispyridyl)propane guests have been synthesized from 1,3-(4,4'-bispyridyl)propane. The interaction and the models of self-assembly psedorotaxanes of cucurbit[6,7,8]uril with these synthetic guests have been investigated by using ~1H NMR technique and electronic absorption spectroscopy method. The experimental results revealed that for Q[7]-PCn system, the interaction model was influenced by both the concentration of the host Q[7] and the length of the aliphatic substituents chains of the guest. For Q[6]-PCn system, the interaction model was decided by the structure of the guest most. For Q[8]-PCn, Although the electronic absorption spectroscopy showed that the Q[8] were interacted with PCn in a 1:1 ratio, the ~1HNMR spectra didn't offer a visible information to decline the detail.In the second party of the paper, inclusion behaviors of cucurbit[n, n = 7,8]urils and a spice molecular indole (g) and were investigated. The UV, Fluorescence and ~1H NMR spectra revealed that the host Q[7] or Q[8] included the guest g to form a molecular capsule. Thermodynamics study revealed that the formation of inclusion complex between Q[n] with g was favored by both enthalpic and entropy factor caused by the hydrophobic cavity interaction of cucurbit[n]urils. The kinetic property of the host-guest interaction monitored by UV spectroscopy showed that for different hosts, the rate constants of Q[n]-g system were influenced by a different way. The TG-DSC technique showed that the inclusion solid was more stable to hight temperature than the guest. A another molecular inclusion complex formed by Q[8] and wanillin was also instituded by X-ray technique.