Unprecedented reactivity of alkoxo/hydroxide-bridged dinuclear copper(II) complexes as artificial carboxylesterase: Effects of Gemini 16-6-16 micelles and bimetallic synergistic effect

Under almost neutral conditions, excess four orders of magnitude rate enhancement was given for the hydrolysis of p-nitrophenyl picolinate (PNPP) by an alkoxo/hydroxide-bridged dinuclear copper(II) complex (Cu2L) in Gemini 16-6-16 micellar solution. A control investigation showed that a mononuclear analogue (CuL) was approximately 288.7- and 199.3-fold less active than the as-prepared dinuclear one in both of 16-6-16 micelles and aqueous solution, suggesting the vital roles of the two coorperative Cu(II) centres of Cu2L. Furthermore, 2.74- and 2.6-fold kinetic advantage in Gemini 16-6-16 micelles was achieved in contrast with in buffered aqueous solution and CTAB micellar solution at pH 7.0, respectively.