Metallovesicular catalytic hydrolysis of p-nitrophenyl picolinate catalyzed by zinc(II) complexes of pyridyl ligands in vesicular solution

The hydrolysis of p-nitrophenyl picolinate (PNPP) catalyzed by the Zn(II) complexes of 6-(n-butyloxymethyl)-2-(hydroxymethyl)pyridine and 6-(n-dodecyloxymethyl)-2-(hydroxymethyl)pyridine was kinetically investigated by observation of the rates of release of p-nitrophenol in a vesicular solution at different pH values and temperatures. A 1:1 ligand:Zn2+ stoichiometry was found to produce the most active species based on a kinetic version of the Job plot analysis. Experimental results also showed that the complex formed from ligand 2 and Zn2+ exhibited a more remarkable rate acceleration effect on the hydrolysis of PNPP in vesicular solution than that formed from ligand 1 and Zn2+.

Graphical abstractThe apparent rate constants for the hydrolysis of PNPP in vesicular solution were at first seen to increase with increasing pH value, and then decrease with further increases in the pH.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The catalytic hydrolysis of PNPP was investigated in a vesicular solution. ► Vesicles mimic the microenvironment of the reaction. ► The catalytic mechanism in terms of the ternary complex kinetic model was studied. ► The kinetic and thermodynamic parameters at different pH values were calculated.