Studies on p-Nitrophenyl Picolinate (PNPP) Cleavage by Mono-Schiff Base Complexes with Aza-Crown Ether or Morpholino Pendants in CTAB Micellar Solution

• Published in: Journal of dispersion science and technology Vol. 30; no. 5; pp. 656 - 663
• Main Authors: Li, Jian-Zhang, Huang, Sheng-Tian, Feng, Fa-Mei, Xu, Bin, Jiang, Wei-Dong, Zeng, Xian-Cheng, Qin, Sheng-Ying
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 20.04.2009; Taylor & Francis
• Subjects: Benzo-10-aza-crown ether; Catalysis; catalytic kinetics; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Micelles. Thin films; mimic hydrolase; mono-Schiff base complexes; p-nitrophenyl picolinate; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Water; Cationic surfactant; Activity; Crown compound; Time; Manganese III; Ionic surfactant; Mechanism; Schiff base; Cobalt II; pH; Mathematical model; Structure; Catalytic reaction; Enzyme; mimic hydrolase; Benzo-10-aza-crown ether; Cobalt complex; Buffer solution; Complexes; nitrophenyl picolinate; catalytic kinetics; Quaternary ammonium compound; Hydrolysis; Kinetic model; mono-Schiff base complexes; Thermodynamic parameter; Hydrolases; Kinetics; Kinetic parameter; Micellar solution
• ISSN: 0193-2691; 1532-2351
• DOI: 10.1080/01932690802598937

Two mono-Schiff base manganese (III) and cobalt (II) complexes with benzo-10-aza-crown ether pendants , and the analogous with morpholino pendants have been employed as models to mimic hydrolase in p-nitrophenyl picolinate (PNPP) in the buffered CTAB micellar solution. The kinetics and the mechanism on PNPP hydrolysis catalyzed by these complexes were investigated. The kinetic mathematical model of PNPP cleavage catalyzed by these complexes was proposed. The relative kinetic and thermodynamic parameters were determined. The effects of complexes structure and reactive temperature on the rate of catalytic PNPP hydrolysis have been also examined. The results showed that the rate for the catalytic PNPP hydrolysis was increased following the increase of pH of the buffered CTAB micellar solution; four complexes can efficiently accelerate the catalytic cleavage of PNPP in the buffered CTAB micellar solution. Compared with the crown-free analogous and , the crowned Schiff base complexes exhibit more high catalytic activity for promoting PNPP hydrolysis. The pseudo-first-order-rate ( k obs ) for the PNPP hydrolysis catalyzed by the complex in the CTAB micellar solution is 2.02 × 10 4 times than that of PNPP spontaneous hydrolysis in water at pH = 7.00, 25°C, [S] = 2.0 × 10 −4 mol dm −3 .