POMSimulatorA method for understanding the Multi-Equilibria and Self-Assembly Processes of Polyoxometalates

Abstract

In this thesis we have developed POMSimulator, a novel computational method that predicts the aqueous speciation of molecular oxoclusters as well as the formation mechanism. In our first work we tested this methodology with a model system: the octamolybdate, [Mo8O26]4−.1 We reported the speciation diagrams of molybdates with high accuracy, and we proposed a reaction mechanism considering the acid-base equilibria. Next, we extended this methodology to all the isopolyoxomolybdates and -tungstates.2 We described the formation of larger clusters such as: [H32Mo36O128]8−, [W12O42]12−, [W12O40]8−, and [W10O32]4−. Besides, we introduced phase diagrams in our methodology to obtain a better overview of the speciation at different concentrations. Recently, we have applied POMSimulator t polyoxovanadates, -niobates, and tantalates.3 We showed that accurate formation constants could be computed for the three metal-oxo systems. We proposed a vanadate intermediate, [V5O14]3−, which could be involved in the interconversion of the decavanadate, [V10O28]6−, and the metavanadates, [VnO3n]n− (n=4,5,6). Furthermore, we reported the speciation diagram of niobates including paramount clusters such as [H9Nb24O72]15− and [Nb7O22]9−. In conxiii trast, we found no evidence of the formation of the tantalum analogues. Nonetheless, we observed the formation of the decatantalate, [Ta10O28]6−, even though it has not been synthesized yet due to its poor solubility in water. Overall, we believe that our method can find a very promising synergy with experimental chemistry.