瓜环对氨基酸的分子识别研究

Molecular Recognition of Aminoacid by Cucurbiturils

使用1HNMR和UV-Vis光谱法研究了七、八元瓜环对九种天然氨基酸盐酸盐的分子识别作用.结果表明,瓜环对芳香侧基取代的L-酪氨酸、L-色氨酸、L-苯丙氨酸均能进行有效识别,而侧链上不带芳香基团的氨基酸,如L-组氨酸、L-谷氨酸、L-蛋氨酸、L-缬氨酸、L-白氨酸、L-丙氨酸,与这些瓜环的作用相对较弱.对于七元瓜环,主客体间都以1∶1化学计量比形成包结物,并得到它们相互作用的稳定常数;八元瓜环与L-酪氨酸及L-色氨酸也以1∶1形成包结物,而与L-苯丙氨酸以1∶2形成包结物.L-酪氨酸、L-色氨酸和L-苯丙氨酸荧光性质研究表明,七、八元瓜环既可成为这些氨基酸荧光性质的增敏试剂,也可成为它们荧光淬灭试剂,这与氨基酸的结构有关.

Molecular recognition properties of cucurbit（n）urils （n=7, 8） [Q（7）, Q（8）] toward aminoacid hydrochlorides were studied by ^1H NMR and UV-Vis methods. The experimental results reveals that such hosts can exhibit a special recognition property toward an aromatic moiety of the aromatic aminoacids such as L-Tyr, L-Try and L-Phe, and a weak binding toward other aminoacids without the aromatic moiety, such as L-Ala. Q（7） with these guests always formed a host-guest complex with a 1 ： 1 ratio, and based on this model, the sta- bility constants of the host-guest complexes were obtained. Q（8） with L-Tyr or L-Try formed a host-guest complex with a 1 ： 1 ratio. However, Q（8） with a 1 ： 2 ratio with L-Phe formed a host-guest complex. Studies on fluorescence properties of the aminoacids show that Q（7） or Q（8） could be an agent of fluorescence enhancement or fluorescence quenching, which was related to the structure of a certain aminoacid.