Anion-π Interactions in Supramolecular Chemistry and Catalysis

Abstract

Non-covalent interactions play a major role in supramolecular chemistry and biochemistry by dominating the central parts of living systems since they dictate the functionality of many biological and host-guest systems. A good comprehension of the different non-covalent forces is necessary for the rational design of new drugs and developing improved synthetic receptors capable to function in competitive media. Interactions involving aromatic rings (or π-systems in general) are very relevant in supramolecular chemistry, exemplified by the cation–π interaction and its importance in protein structure and enzyme catalysis. From a traditional point of view, the π-system is usually considered as electron rich (π-basic). The naissance of the counterintuitive anion–π interaction –the attractive interaction between an anion and an electron poor π-system (π-acid)– was somewhat controversially discussed by the scientific community. However, in the last decade a great deal of theoretical and experimental investigations has time-honored the anion–π interaction as an important supramolecular bond. Herein we describe the physical nature of this noncovalent interaction and the different strategies that can be used to modulate its strength. Finally, selected state-of-the-art reports illustrating the rational utilization of the anion–π interaction in supramolecular chemistry (anion receptors), biological applications and catalysis are described in this chapter.