Syntheses, structures and properties of dimeric rare earth derivatives based on monovacant Keggin-type polyoxotungstates

Three lanthanide (Ln) substituted polyoxometalates [{(alpha-PW11O39H2)Ln(H2O)(eta(2),mu-1,1)-CH3COO}(2)](10) (Ln = Dy(III) for 1, Y(III) for 2, Lu(III) for 3) have been synthesized successfully in moderate aqueous solution and characterized by elemental analyses, IR spectra, UV spectroscopy, thermogravimetric analyses, fluorescence spectra, X-ray powder diffraction (XRPD) and single-crystal X-ray diffraction. The structure analyses reveal that 1-3 are isostructural and constructed by two mono-lanthanide substituted units [(alpha-PW11O39H2) Ln(H2O)(eta(2),mu-1,1)-CH3COO](5), which are bridged by two (eta 2,mu-1,1)-acetato ligands. The solid-state photoluminescence properties of 1-3 were studied and the results indicate that only 1 demonstrates yellow luminescence. Magnetic measurements reveal that 1 shows spin-orbital coupling interactions and weak antiferromagnetic exchange interactions. (C) 2012 Elsevier B.V. All rights reserved.