Hydrogen Bonding Cavities Regulating Redox Behavior and Binding of Metal-Bound Ligands

Binding of 3,5-di-tert-butyl-1,2-benzochatechol (H2DTBC) at ZnII complexes of a tetradentate, tripodal ligand L is significantly enhanced (36−4.6 × 104 fold), and its reduction potential shifted (90−270 mV) to more positive values by introducing one to three amino hydrogen bond donors. The structure of one of the [(L)Zn(DTBC)] complexes is reported and shows intramolecular N−H···O hydrogen bonding between the ligand-based amino group and the ZnII-bound chatecholate, which provides an explanation for the observed behavior.