Chiral recognition between dissymmetric Ln(dpa)33- and cobalt(III)-nucleotide complexes in aqueous solution. Enantioselective luminescence quenching as a probe of intermolecular chiral discrimination

Abstract

Time-resolved chiroptical luminescence spectroscopy is used to investigate enantioselective excited-state quenching processes in solution samples that contain a racemic mixture of chiral luminophores and a small concentration of dissymmetric quencher molecules. The luminophores are Ln(dpa) 3 3- complexes (Ln≡Eu 3+ or Tb 3+ , dpa≡a dipicolinate dianion) that have tris(terdentate) chelate structures of D 3 symmetry with either left-handed (Λ) or right-handed (4) configurational chirality about the trigonal axis. The quenchers are 6-coordinate Co(III) complexes with the general stoichiometric formula Co(NH 3 ) 4 (ndp) or Co(NH 3 ) 4 (ntp), were ndp denotes a diphosphate nuceotide ligand and ntp denotes a triphosphate nucleotide ligand.