摘要:
A novel ditopic receptor possessing two complexation sites and bearing 1,3-alternate conformation based thiacalix[4]arene was prepared. The binding behaviors with Na+, K+ and Ag+ ions have been examined by H-1 NMR titration experiment in (CDCl3/CD3CN; 10:1, v/v) solution. The job plots proves 1:1 complexation of 1,3-alternate-4 with Na+, K+ and Ag+ ions. Although the formation of heterogeneous dinuclear complexes was not clearly observed, the exclusive formation of mononuclear complexes of 1,3-alternate-4 with metal cations is of particular interest with positive/negative allosteric effect in thiacalix[4]arene family. These findings further demonstrate that preorganization, suitable conformational changes and affinity have a pronounced effect on the complexation process between the two different arms placed at the two edges of the thiacalix[4]arene cavity. (c) 2013 Elsevier B.V. All rights reserved.