Three new inorganic-organic hybrid materials based on inorganic cluster, [(PO4)M12O36]•nH2O (M = Mo, W)

Three new inorganic-organic hybrid materials based on heteropolyoxometalates, [L-C6H14NO2](3)[(PO4)Mo12O36]center dot 3H(2)O (1), [L-C5H10NO2](3)[(PO4)W12O36]center dot H2O (2), and [C2H7N2O](3)[(PO4)W12O36]center dot 4H(2)O (3), where C6H14NO2, C5H10NO2, and C2H7N2O are protonated L-leucine, L-proline, and methyl urea, respectively, have been synthesized and structurally characterized by some physico-chemical methods. Elemental analyses, IR, Raman, mass, UV, and H-1 NMR spectroscopies of the title hybrid materials indicate that there are van der Waals interactions between 0 atoms of the heteropolyoxometalates and water molecules, as well as the N and 0 atoms of the amino acids and methyl urea moieties. The molecular structures of synthesized hybrid materials contain discrete entities of L-leucinium, L-prolinium or methyluronium and water molecules that surround every [(PO4)M12O36](3-) anion, over the extended crystalline network. The observed bands in Raman spectra of (2) and (3) demonstrate that the [(PO4)W12O36](3-) anion retains its "Keggin structure". At pH = 4 - 7, the characteristic bands of the Keggin anion [(PO4)M12O36](3-)(M = Mo, W) appear at 210 and 260 nm in the UV spectra, respectively.