Metallomicellar Catalytic Hydrolysis of NPP by Cu^IINi^II Heterodinuclear Complexes Containing Diamine Groups in Brij35 Micellar Solution

Abstract

The hydrolysis of p‐nitrophenyl phosphate (NPP) catalyzed by metallomicelles formed from four asymmetry Cu^IINi^II heterodinuclear oxamido‐bridged complexes, whose ligands contain different diamine groups, and nonionic surfactant Brij35 has been investigated quantitatively at the pH range of 6.0–10.5 and 25°C, respectively. The results indicated that the rates of catalytic hydrolysis of NPP by four complexes in Brij35 micellar solution were all largely enhanced under the experimental conditions. The order of effectiveness of the four complexes in Brij35 micellar solutions toward hydrolysis of NPP was found to be: complex I>complex II>complex III>complex IV. The different catalytic function of four complexes may be attributed to the different activation abilities of coordinated water molecules induced by different polarities of ligands, which has been discussed in detail. Meanwhile, kinetic studies show that the active species in the catalytic hydrolysis of NPP may be the aquo‐hydroxy form and that the mechanism of the reaction involves intramolecular nucleophilic attack of the nickel‐bound hydroxide ion on phosphoryl of NPP. The studies suggested that the metallomicelle containing Cu^IINi^II heterodinuclear oxamido‐bridged complexes with two coordinated H₂O molecules may be a potential catalyst for the hydrolysis of NPP.

Keywords:

• Hydrolysis of NPP
• metallomicellar catalysis
• heterodinuclear complex
• diamine groups
• nucleophilic reaction

Acknowledgment

This work was supported by the National Natural Science Foundation of China (Grant No: 20173038 and 20107004).