The Metallomicelle of Lanthanide Metal (Ce, La) Aza-Macrocyclic Complexes with a Carboxyl Branch: The Catalytic Activity and Mechanism in the Hydrolysis of a Phosphate Diester

Abstract

An aza-macrocyclic ligand, 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-N/- acetic acid (L), was synthesized and characterized. The chemical composition of the complexes (CeL and LaL) was determined by a UV–Vis spectrophotometric method and kinetic Job plot. Two metallomicellar systems made of an lanthanide metal complex and n-lauroylsarcosine (LSS) micelle were used as catalyst in the hydrolysis of bis(4-nitrophenyl) phosphate ester (BNPP), and their catalytic activity was studied by the comparative method. The interaction between the complex and BNPP in the metallomicelle was studied by its fluorescent spectroscopy. The catalytic rate of BNPP hydrolysis was measured kinetically by UV–Vis spectrophotometry. The results indicate that CeL systems (aqueous solution and metallomicelle) exhibit higher catalytic activity than those of the LaL systems in BNPP hydrolysis, and the micelle provides an effective catalytic environment in the catalytic reaction. A reaction mechanism was also proposed on the basis of the results.