Enantioselective photoreduction of tris(acetylacetonato)cobalt(III) by 1,4-dihydropyridine derivatives in the presence of molecular aggregates

Abstract

Enantioselective photoreduction of Δ- and Λ-tris(acetylacetonato)cobalt(III)([Co(acac)₃]) by achiral or chiral 1,4-dihydronicotinamide derivatives has been performed in the presence of molecular aggregates. Although appreciable enantioselectivity is not observed for the photoreduction of [Co(acac)₃] by chiral 1,4-dihydronicotinamides in micellar systems, achiral 1-benzyl-1,4-dihydronicotinamide (BNAH) reduces Δ-[Co(acac)₃] in preference to the Λ-form in the presence of bovine serum albumin (BSA). The 1,4-dihydronicotinamide derivative covalently bound to BSA also reduces [Co(acac)₃] enantioselectively. Activation parameters for the highly enantioselective reaction between photoexcited BNAH and [Co(acac)₃] in the presence of BSA have been estimated and are discussed.