Supramolecular Control of Biomimetic Coordination – ZnII Cavity Complexes Presenting Two Differentiated Labile Sites in cis Positions

Abstract

AbstractA supramolecular approach to model the active sites of metalloenzymes is to associate a cavity with a tripodal coordination core. One key feature of many enzymes is the possible binding of two different ligands in cis positions relative to each other, which has not yet been described for cavity complexes. Here, the bowl shape of resorcinarene allows such a coordination environment for ZnII complexes. A detailed NMR study with various carboxylic acids evidences size‐, shape‐, and, thus, regioselectivity for carboxylate coordination in the endo position, the exo position, or both. The coordination of diketonates unambiguously demonstrates the relative cis position of the two labile sites present in the tris(imidazole)zinc(II) bowl complex. An interesting intramolecular exchange process was also observed. Finally, a comparison with calix[6]arene‐based complexes (so‐called funnel complexes) further highlights the key role of the cavity in the control of properties of the metal ion.