Studies on PNPP Hydrolysis Catalyzed by Schiff Base Cobalt(II) Complexes Containing Benzoaza‐15‐crown‐5

Abstract

Three novel Schiff base cobalt(II) complexes containing benzoaza-15-crown-5, CoL 1 , CoL 2 and CoL 3 were synthesized and characterized, and these complexes were used in catalytic hydrolysis of carboxylic ester (PNPP, p-nitrophenyl picolinate) as mimic hydrolytic metalloenzyme. The analysis of specific absorption spectra of the hydrolytic reaction systems indicated that the catalytic hydrolysis involved the key intermediates formed by PNPP with cobalt(II) complexes. The CoL 3 bearing the electron withdrawing group shows better catalytic activity due to its stabilization effect on active species MLS -. The catalytic mechanism of PNPP hydrolysis was also proposed. The kinetic parameter of PNPP catalytic hydrolysis has been calculated and the activation energy for the catalytic hydrolysis is 43.69, 39.76 and 35.44 kJ•mol -1 , respectively.

Metallomicellar Catalysis: Hydrolysis of Pnpp by Crowned Schiff Base Cobalt(Ii) Complexes in Micellar Solution

“…Hence, from Scheme 1, the reaction rate equation is [27]: Metallomicellar catalysis 175 www.prkm.co.uk…”

p‐Nitrophenyl Picolinate Cleavage by Unsymmetrical Bis‐Schiff Base Manganese(III) and Cobalt(II) Complexes with Aza‐Crown Ether or Morpholino Pendants

“…11,12 Previously, the catalytic performances of monoSchiff base complexes with aza-crown ether or morpholino pendants in p-nitrophenyl picolinate (PNPP) hydrolysis have been reported. [13][14][15][16][17] In this paper, with hopes of further investigating the reaction kinetics and mechanism of PNPP hydrolysis catalyzed by unsymmetrical bis-Schiff base complexes, four unsymmetrical bis-Schiff base complexes with either benzo-10-azacrown ether pendants (MnL 1 Cl, MnL 2 Cl) or morpholino pendant (MnL 3 Cl, CoL 3 ) have been employed as models for hydrolase enzymes by studying the kinetics of their hydrolysis reactions with PNPP. Compared with the crown-free analogous MnL 3 Cl and CoL 3 , the effect of ligand structure and crown ether ring in the complexes on PNPP catalytic hydrolysis has also been discussed.…”

Hydrolysis of bis(4-nitrophenyl) phosphate ester catalysed by a surfactant ligand cobalt(II) complex

“…Many mimetic models of hydrolase have been widely applied in the study of ester hydrolysis, such as the hydrolysis of carboxylic acid esters [7][8][9][10], amino acid esters [11,12] and phosphate esters [13][14][15][16][17]. In our previous research [18][19][20], we have studied the effects of different characteristic substituents in crown Schiff base metal complexes on their catalytic activity. In this paper, the surfactant ligand 2,2' ,2''-(dodecylammonio)triacetate (L) was synthesised and characterised and the kinetics of hydrolysis of bis(4-nitrophenyl) phosphate (BNPP) in the catalytic system containing 2,2' ,2''-(dodecylammonio)triacetate (L) and bound cobalt(II) have been studied as artificial hydrolytic metalloenzymes.…”