Carboxylic and phosphate ester hydrolysis catalysed by bivalent zinc and copper metallosurfactants

Abstract

The syntheses of three new lipophilic ligands are reported: N^α-(1,10-phenanthrolin-2-ylmethyl)-N^τ-dodecylhistamine (1), N-dodecyl-2-aminomethyl-1,10-phenanthroline (2), and N^α-(2-pyridylmethyl)-N^τ-dodecylhistamine (3). Mixed micellar systems made of complexes of these ligands with Zn^II and Cu^II in the presence of an inert cosurfactant (CTABr or Brij 35) are efficient catalysts in the hydrolysis of p-nitrophenyl picolinate (PNPP) and diphenyl-p-nitrophenyl phosphate (DPPNPP). Kinetic studies strongly indicate the formation of a reactive ternary complex composed of metal ion, ligand, and substrate. These synzymes operate via a metal–hydroxide-ion catalysed mechanism and exhibit turn-over behaviour while retaining their full catalytic activity.