A novel dinucleating ligand-containing hexabenzimidazoles and its dinuclear zinc complex bridged by a carboxylate group for the hydrolysis of 2-hydroxypropyl-p-nitrophenyl phosphate

Abstract

A dinuclear zinc(II) complex with the ligand bis{tris[2-(1-methylbenzimidazole-2-yl)ethyl]-methylamine}nitrilotriacetic acid sodium salt, L, was synthesized and characterized. Complex formation of L with Zn 2+ in aqueous acetone was studied by Zn 2+ titration using 1H NMR and UV-vis spectroscopies. Analysis of the titration data indicates the formation of a dizinc complex. The ν as(COO -) and ν s(COO -) stretches were observed at 1572 and 1450 cm -1, respectively. The low separation of the stretches, Δ exp = 115 cm -1, is an indication of chelating coordination of the carboxylate group between the two zinc(II) ions. The catalytic activity of [LZn 2] 3+1, as a model for phosphatase that catalyze chemical transformation of phosphate ester, in the hydrolysis of the RNA model, 2-hydroxypropyl p-nitrophenyl phosphate, was examined in aqueous acetone buffer solution, pH 7.0-9.5. The mechanism of the catalytic hydrolysis suggests that the rate of acceleration is due to what is called double Lewis acid activation. © The Author(s) 2009.