Reaction of layered vanadium phosphorus oxides, VOPO4·2H2O and VOHPO4·0.5H2O, with amines and formation of exfoliative intercalation compounds

Abstract

Reactions of layered vanadium phosphorus oxides, VOPO4·2H2O and VOHPO4·0.5H2O, with aliphatic and aromatic amines were investigated with regard to the formation of intercalation compounds. VOPO4·2H2O was intercalated with 4-butylaniline, and the obtained intercalation compound was exfoliated by stirring in THF. The layered structure of the intercalation compound was reconstructed by removal of the solvent from the suspension of exfoliated solid, while ordering of the restacked layers was sensitive to the experimental conditions. The reactions with 4-butylaniline for prolonged periods caused partial collapse of the layered structure, indicating metastability of the intercalated structure. VOPO4·2H2O formed intercalation compounds with aniline and 4-anilinoaniline as well as 4-butylaniline. On the other hand, reactions with n-alkylamines, which are more basic than aromatic amines, brought about collapse of the layered structure of VOPO4·2H2O. In addition, VOHPO4·0.5H2O did not react with aromatic amines such as aniline and pyridine, while reactions with n-alkylamines did not give intercalation compounds but led to the formation of salts, where the structure of the host lattice was not retained.