Increased Water Solubility of Molybdenum Trioxide Induced by β-Cyclodextrin

Increased water solubility of molybdenum trioxide (MoO3) induced by β-cyclodextrin (CD), with solubility dependent on β-CD concentration is reported. The dynamic equilibrium established between MoO3 precipitation and dissolution shifted towards dissolution upon the addition of aqueous β-CD, to form a bluish-grey product. This was confirmed to be of β-CD and MoO4 2- by: (1) X-ray photoelectron spectroscopy showed decreased Mo 3d5/2 and 3d3/2 binding energies of the product compared with those of MoO3; (2) a strong band at 213 nm and new broad peak near 775 nm of the product were attributed to MoO and Mo―O bond absorption; (3) a downfield shift of β-CD protons due to the effect of MoO4 2- ions. An interaction between β-CD and MoO4 2- has been revealed and hints at the possibility of exploiting it for improving MoO3 physical properties