Metallomicellar catalysis: catalytic cleavage of p-nitrophenyl picolinate by Cu2+ complex of 4-chloride-2,6-bis(N-hydroxyethylaminomethyl)-benzophenol in micellar solution.

The hydrolysis of p-nitrophenyl picolinate (PNPP) catalyzed by the Cu(II) complex of 4-chloride-2,6-bis(N-hydroxyethylaminomethyl)-benzophenol was investigated kinetically by observing the rates of release of p-nitrophenol in the presence of three surfactants, which are hexadecyltrimethylammonium bromide, n-lauroylsarcosine sodium, and polyoxyethylene23 lauryl ether, at different pH and 25 degrees C. The scheme for the reaction involving a ternary complex comprising ligand, metal ion, and substrate in a micelle was established, and the relative kinetic and thermodynamic parameters were determined, including first-order rate constant (kN), association constant (Ks) for ternary complex, and pKa for the hydroxide ion of the ternary complex. The reaction mechanism was discussed.