Promotion of phosphoester hydrolysis by MoO_2Cl_2L (L = bipyridine derivatives, H_2O, no ligand), MoO_2(CH_3)_2L (L = bipyridine derivatives) and related inorganic-organic hybrids in aqueous media

摘要

The compounds MoO_2Cl_2L (L = 2,20-bipyridine (bipy) (1); 4,4'-di-tert-butyl-2,2'-bipyridine (di-tBu-bipy) (2)), [MoO_2Cl_2(H_2O)_2]·(diglyme)_2 (3), MoO_2Cl_2 (4), MoO_2(CH_3)_2L (L = bipy (5); di~-tBu-bipy (6)), [MoO_3(bipy)]_n (7), {[MoO_3(bipy)][MoO_3(H_2O)]}_n (8), [Mo_8O_(22)(OH)_4(di-~tBu-bipy)_4] (9) and MoO_3 (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 D_2O 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 MoO_2Cl_2L compounds (1-4) and with the inorganic-organic hybrid {[MoO_3(bipy)][MoO_3(H_2O)]}_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.