Hydrolytic reactivities of p-nitrophenyl picolinate accelerated by Schiff base Co(II) complexes in micellar solutions

Two Schiff base Co(II) complexes were synthesized and used to catalyze the hydrolysis of p-nitrophenyl picolinate (PNPP) in Gemini 16-2-16 micellar solution. For comparison, hydrolytic kinetics of PNPP was respectively investigated in the micellar solutions of three kinds of conventional single-chain cationic, anionic, and nonionic surfactants, i.e., hexadecyltrimethylammonium bromide (CTAB), n-lauroylsarcosine sodium (LSS), and polyoxyethylene(23) lauryl ether (Brij35). Experimental results showed that the one complex with small Schiff base ligands exhibited better catalytic activity than the other one with bigger ligands towards the PNPP hydrolysis under comparable conditions, which testified that a relatively open catalytic site is essential for tuning the activities of the two mimic hydrolases. Moreover, compared effects of various micellar solutions demonstrated that Gemini 16-2-16 micellar solution is the best reaction medium relative to its single-chain analogs.