Hydrolysis Kinetics of p-Nitrophenyl Picolinate Catalyzed by Mono-Schiff Base Complexes with Aza-Crown Ether or Morpholino Pendants in CTAB Surfactant Micellar Solution

Abstract

Two mono-Schiff base manganese (III) and cobalt (II) complexes with benzo-10-aza-crown ether pendants (), and the analogy with morpholino pendants () have been synthesized and employed as models for hydrolase enzymes to promote the hydrolysis of p-nitrophenyl picolinate (PNPP) in the buffered CTAB micellar solution. The kinetic mathematical model and mechanism cleavage on PNPP hydrolysis catalyzed by these complexes was proposed. The effects of complexes structure and reactive temperature on the rate of catalytic PNPP hydrolysis have been also examined. The results showed that the reactive rate increases with pH of the buffered CTAB micellar solution; all four complexes exhibited high activity for the catalytic PNPP hydrolysis in the buffered CTAB micellar solution. In comparison with the crown-free analogy and , the crowned Schiff base complexes and exhibit higher catalytic activity for promoting PNPP hydrolysis.

Keywords:

• Aza-crown ether mono-Schiff base complexes
• CTAB micellar solution
• mimic hydrolase
• p-nitrophenyl picolinate
• synthesis

Acknowledgments

The authors gratefully acknowledge financial support from China National Natural Science Foundation (No. 20072025), Key Project of Sichuan Province Education Office (No. 2005D007), and Key Scientific and Technological Project Issued by Ministry of Education of China (No. 208118).

Notes

Condition: 25 ± 0.1°C, I = 0.1 mol·dm⁻³ KNO₃, [Tris] = 0.1 mol·dm⁻³, [complex] = 1.0 × 10⁻⁵ mol·dm⁻³, [CTAB] = 1.0 × 10⁻³ mol·dm⁻³.