Hydrolysis of PNPP Catalyzed by Metallomicelles Made of Schiff Base Cobalt(II) Complexes

Abstract

It has been reported that two cobalt(II) complexes of the Schiff base with morpholino or aza-crown ether pendants were synthesized and characterized, and the metallomicelles made up of the two cobalt(II) complexes and surfactants(LSS, Brij35, CTAB), as mimic hydrolytic metalloenzyme, were used in catalytic hydrolysis of carboxylic ester (PNPP) over a pH range of 7.0–8.2. The results clearly revealed that the metallomicelles made of the aforementioned cobalt(II) complexes and the surfactants are both efficient for catalyzing PNPP hydrolysis with about three orders of magnitude in rate acceleration compared with the background rate of PNPP spontaneous hydrolysis. The effect of different surfactant micelles on the catalytic hydrolysis of PNPP in the metallomicelles follows the order: LSS > Brij35 > CTAB. The results showed that the Schiff base cobalt(II) complexes and their metallomicelles as hydrolase mimics exhibit good catalytic activity and similar catalytic character to natural enzyme.

Keywords:

• Carboxylic ester
• catalytic kinetics
• metalloenzyme
• mimic hydrolase
• schiff base cobalt(II) complexes

Acknowledgments

The work was supported by the Key Scientific and Technological Project issued by Ministry of Education of China (No. 208118), the Key Project of the Science and Technology Department of Zigong (No. 08C01), and the Specialized Research Fund for the Doctoral Program of Sichuan University of Science and Engineering (No. 2009ZR1).