氮杂冠醚或吗啉基取代的单Schiff碱配合物催化α-吡啶甲酸对硝基苯酯水解

两种含5-取代苯并-10-氮杂-15-冠-5的Schiff碱锰(III)、钴(II)配合物( , )及其吗啉基取代的类似物( , ) 用于催化α-吡啶甲酸对硝基苯酯(PNPP)水解。探讨了氮杂冠醚Schiff 碱配合物催化PNPP水解的动力学和机理；提出了配合物催化PNPP水解的动力学模型；考察了配合物结构、反应温度、缓冲溶液pH值等对PNPP水解反应的影响。结果表明，在25℃条件下随着缓冲溶液pH值的增大，催化PNPP水解速率提高；含取代苯并-10-氮杂-15-冠-5的Schiff碱配合物表现出更高的催化活性。根据阿累尼乌斯公式和不同温度下的表观一级常数求出水解反应的表观活化能。

Hydrolysis of p‐Nitrophenyl Picolinate Catalyzed by Mono‐Schiff Base Complexes with Aza‐crown Ether or Morpholino Pendants

Mono‐Schiff base cobalt(II) and manganese(III) complexes with either benzo‐10‐aza‐crown ether pendants (CoL₂¹, MnL₂¹Cl) or morpholino pendants (CoL₂², MnL₂²Cl) have been employed as models for hydrolase enzymes by studying the kinetics of their hydrolysis reactions with p‐nitrophenyl picolinate (PNPP). The kinetic mathematical model of PNPP cleavage catalyzed by these complexes was proposed. The effects of complex structures and reaction temperature on the rate of catalytic PNPP hydrolysis have been also examined. The results showed that the rate increases with pH of the buffer solution and four complexes exhibited high activity in the catalytic PNPP hydrolysis. Compared with the crown‐free analogy CoL₂² and MnL₂²Cl, the crowned Schiff base complexes (CoL₂¹, MnL₂¹Cl) exhibit higher catalytic activity. The pseudo‐first‐order‐rate ( k_obs ) for the PNPP hydrolysis catalyzed by the complex MnL₂¹Cl containing benzo‐10‐aza‐crown ether is 923‐fold higher than that of spontaneous hydrolysis of PNPP at pH=7.00, 25 °C, S] =2.0×10^?4 mol·dm^?3.