TRANSITION-METAL AND ORGANIC REDOX-ACTIVE MACROCYCLES DESIGNED TO ELECTROCHEMICALLY RECOGNIZE CHARGED AND NEUTRAL GUEST SPECIES

This chapter reviews macrocyclic receptor molecules that contain an electrochemical responsive signaling function—that is, a redox-active center, in close proximity to a host-binding site. Depending on the complementary nature of the host cavity, these systems can, in principle, be designed to recognize electrochemically the binding of any charged or neutral inorganic or organic guest specie, through either space electrostatic interactions or electrostatic communication, via various bond linkages between the receptor site and the redox center. Evidently selective binding of a particular guest specie coupled with an electrochemical response is of paramount importance for future potential prototypes of new amperometric molecular sensory devices. The review of these types of systems is conveniently subdivided according to the nature of the target complexant—that is, a cation (metal, ammonium), anion (halide, nitrate, sulfate, phosphate, and so on), or neutral (organic or inorganic) guest. Stimulated by nature and, particularly, by the idea of modeling “coupled reactions,” that is, reactions that mutually influence each other that are known to play a fundamental role in the biological processes, such as ion transport and oxidative phosphorylation, current attention has focused on a new generation of abiotic host molecules that contain responsive or signaling functions appended to or as an integral part of a host macrocyclic framework. © 1992, Academic Press, Inc.