Photorelease of caged alcohols from artificial metalloenzymes

Abstract

Nature frequently employs metalloenzymes to catalyze biological reactions. In the literature there is precedent for artificial metalloenzymes that serve to selectively cleave coordinated peptide and ester linkages. These systems take advantage of metal-ligand coordination and activation of a carbonyl functional group, resulting in hydrolysis. This project aims to hydrolyze a caged alcohol or amide with a photoactivated metal-ligand complex. Hydrolysis of the caged molecule is dependent upon metal-ligand complex formation and stoichiometry, photochemical isomerization of an alkene, Lewis acid activation of a carbonyl species, and nucleophilic attack by metal-bound H2O. The photoisomerization from trans to cis is driven to completion by the coordination of the latter to the metal. The ester hydrolysis is most efficient when the ligand to metal ratio is 1:1. Several ligand systems were synthesized with these factors in mind. The synthesis, characterization, and investigation of these systems as well as possible applications are discussed.