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

Abstract

The compounds MoO2Cl2L (L = 2,2′-bipyridine (bipy) (1); 4,4′-di-tert-butyl-2,2′-bipyridine (di-tBu-bipy) (2)), [MoO2Cl2(H2O)2]·(diglyme)2 (3), MoO2Cl2 (4), MoO2(CH3)2L (L = bipy (5); di-tBu-bipy (6)), [MoO3(bipy)]n (7), {[MoO3(bipy)][MoO3(H2O)]}n (8), [Mo8O22(OH)4(di-tBu-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 °C, using D2O as solvent and 100 or 10 mol% of the chosen promoter. The progression of all the reactions was monitored by 1H NMR spectroscopy. All studied systems promote phosphoester bond hydrolysis. The best performance was obtained with MoO2Cl2L compounds (1–4) and with the inorganic–organic 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.