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-hydroxyethyl-aminomethyl)-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 polyoxyethylene(23) lauryl ether, at different pH and 25°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 (k_N), association constant (K_s) for ternary complex, and pK_a for the hydroxide ion of the ternary complex. The reaction mechanism was discussed.