Calix[4]pyrroles: Old Yet New Anion-Binding Agents

摘要

Anions play essential roles in biological processes; indeed, it is believed that they participate in 70% of all enzymatic reactions. There is, therefore, intense effort being devoted to the problem of anion complexation and recognition. In the molecular recognition arena, a number of research groups have followed nature's lead and have designed and synthesized receptors that use hydrogen bonds alone, or in concert with electrostatic interactions, to coordinate to anions. Nonetheless, there remains atpresent a critical need for additional anion-complexing agents that are either easy to make or inherently selective in their substrate-binding properties. Recently, as the result of our work with polypyrrole macrocycles, it occurred to us that the porphyrinogens, a venerable class of molecules, might serve as such easy-to-make anion-binding agents. We now report that this is indeed the case.