Heteroditopic thiacalix[4]arene receptor having ester and bipyridyl moieties for ions binding with positive/negative allosteric effect

• A novel heteroditopic thiacalix[4]arene receptor was synthesized.
• The bound ability of bipyridine site to Ag+ has been improved in the presence of Na+ or K+.
• The negative allosteric effect observed for Na+ or K+ is due to great conformational changes upon complexation of Ag+.

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 1H 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.

A novel ditopic receptor possessing two complexation sites for ions with positive/negative allosteric effect by bearing 1,3-alternate conformation based thiacalix[4]arene was prepared and evaluated.Figure optionsDownload as PowerPoint slide