β-环糊精对四氯联苯胺的包合作用

Inclusion of tetrachlorobenzidine by β-cyclodextrins

制备以β-环糊精(β-CD)为主体,2,2′,5,5′-四氯联苯胺(TCB)为客体的固态包合物,通过核磁共振氢谱(~1H NMR)和红外光谱(FT-IR)分析了包合物的形成。利用紫外吸收光谱研究了β-CD及其衍生物羧甲基-β-环糊精(CMBCD)对TCB的包合行为,并用Job法和Benesi-Hildebrand双倒数法分别获得β-CD及CMBCD与TCB之间的包合比和包合常数。结果表明,β-CD和CMBCD均可与TCB形成包合比为1:1的包合物,包合常数分别为727.9 L·mol^(-1)和1647L·mol^(-1),且经羧甲基修饰之后的β-环糊精对TCB的包合能力明显优于β-环糊精。

This paper has synthesized the solid inclusion complex of 2,2＇,5,5＇-tetrachlorobenzidine （TCB） as a guest with β-cyclodextrin （β - CD） as a host by using the coprecipitation method, and characterized its existence by using nuclear magnetic resonance （1H NMR） spectroscopy and Fourier transform infrared （ βF - IR） spectra. The NMR analysis indicates that chemical shifts of β- CD protons （3 -H, 5 - H） move to the up-field after the formation of the inclusion complex. At the same time, the FT - IR spectra suggest that the TCB molecules strongly interact with β CD through the hydrogen bonds. In addition, we have also investigated the processes for TCB to be ineluded by β - CD and its derivatives, carboxymethyl-β-eyclodextrin sodium salt （CMBCeD） in the aqueous solution, by means of ultraviolet absorption spectroscopy. The ultraviolet absorption signals of TCB can also be remarkably intensified with β - CD or CMBCD added. Furthermore, we have also determined the stoichiometric ratio of TCB/β - CD to TCB/CMBCD in the complexes with the JOB method, with the inclusion constants （K） for the inclusion complexes obtained as the result of using Benesi-Hildebrand equation. The results of our experiments show that both β - CD and CMBCD were reacting to TCB in an inclusion complex with a stoichiometric ratio of 1 ： 1 with the in- clusion constants for β - CD and CMBCD being 727.9 L tool-1 and 1 647 L＂ tool- 1, respectively. Moreover, the K values for CMBCD complexes tend to be greater than those for β - CD, indicating that the introduction of the carboxymethyl group into the β - CD has further stabilized the inclusion complex of TCB/CMBCD, for which both hydrophobic effect and the electrostatic force are involved. Since the polyehlorinated biphenyls （PCBs） are ubiquitous pollutants highly detrimental to the environment and human health due to their low biodegradability and accumulation tendency, it is worthy for further research for new techniques to eliminate PCBs. The above results in this experiment contribute to finding a possible strategy to pre-eoneentration of PCBs from wastewater recycling of β CD by forming inclusive complexes.