Promotion of phosphoester hydrolysis by MoO2Cl2L (L bipyridine derivatives, H2O, no ligand), MoO2(CH3)(2)L (L bipyridine derivatives) and related inorganice-organic hybrids in aqueous media

Abstract

The compounds MoO2Cl2L (L = 2,2'-bipyridine (bipy) (1); 4,4'-di-tert-butyl-2,2'-bipyridine (di-Bu-t-bipy) (2)), [MoO2Cl2(H2O)(2)]center dot(diglyme)(2) (3), MoO2Cl2 (4), MoO2(CH3)(2)L (L bipy (5); di-Bu-t-bipy (6)), [MoO3(bipy)] n (7), {[MoO3(bipy)][MoO3(H2O)]} n (8), [Mo8O22(OH)(4)(di-Bu-t-bipy)(4)] (9) and MoO3 (10) were tested as phosphoester bond hydrolysis promoters in aqueous media. Sodium para-nitrophenylphosphate (pNPP) was used as a model substrate for the phosphoester bond hydrolysis reaction, which was performed at 55 degrees C, using D2O as solvent and 100 or 10 mol% of the chosen promoter. The progression of all the reactions was monitored by H-1 NMR spectroscopy. All studied systems promote phosphoester bond hydrolysis. The best performance was obtained with MoO2Cl2L compounds (1-4) and with the inorganiceorganic hybrid {[MoO3(bipy)][MoO3(H2O)]}(n) (8). The studied compounds originate either homogeneous or solid/liquid biphasic systems. For the biphasic systems (1, 2, 5-9), the solid phase was recovered at the end of the reaction and characterized by FT-IR spectroscopy. (C) 2014 Elsevier B. V. All rights reserved.