Kinetics of Hydrolysis of an Activated Phosphate Ester in Brij35 Micelle Containing a Macrocyclic Complex of Cu(II) OR Ni(II)

Abstract

A macrocyclic ligand and its corresponding Cu(II) and Ni(II) complexes were synthesized and characterized. The kinetics of hydrolysis of bis( p-nitrophenyl) phosphate (BNPP, an activated phosphate diester) in Brij35 micelle containing each macrocyclic complex was investigated. The metallomicelles made up of the macrocyclic metal complex and micelle, as a mimic hydrolytic metalloenzyme, display higher catalytic activity although they do not attain the catalytic efficiency of enzymes. The analysis of specific absorption spectra show that the course of the catalytic BNPP reaction is different from that of the spontaneous hydrolysis of BNPP, and is an intramolecular nucleophilic substitution reaction. Based on the analytical results of the specific absorption spectra, an intramolecular nucleophilic substitution mechanism for the catalytic hydrolysis of BNPP is proposed, a correlative kinetic mathematical model is established, and the corresponding thermodynamic and kinetic constants are calculated. The validity of the mechanism and the proposed mathematical model is confirmed by the results of this study.