Calix[5]arene Self-Folding Cavitands: A New Family of Bio-Inspired Receptors with Enhanced Induced Fit Behavior

Self-folding cavitands represent the quintessential form of bioinspired synthetic receptors, featuring deep hydrophobic cavities that engage in host-guest chemistry reminiscent of that operating in biomolecules. Although remarkable proof-of-concept applications have been reported, the narrow and rigid spaces of the legacy resorcin[4]arene derived hosts constitute a liability towards the development of specific applications in catalysis, sensing or sequestration. While notable efforts to expand the size of the cavities have been reported, the development of confined spaces reproducing the highly adaptable nature of biological receptors is a largely unaddressed issue. This review summarizes the development of a new family of calix[5]arene derived self-folding cavitands displaying enhanced induced fit and conformational selection phenomena. Our approach capitalizes on hydrogen bonding preorganization rather than the covalent restriction approaches customary of conventional supramolecular chemistry.