Spectroscopic properties of neodymium(III)-containing polyoxometalates in aqueous solution

The spectroscopic properties of the neodymium(III)-containing polyoxometalates (POMs) Nd(PW(11)O(39))(2)](11-), Nd(PMo(2)W(9)O(39))(2)](11-), Nd(PMo(4)W(7)O(39))(2)](11-), Nd(PMo(6)W(5)O(39))(2)](11-), Nd(SiMo(2)W(9)O(39))(2)](13-), Nd(P(2)W(17)O(61))(2)](17-), NdW(10)O(36)](9-), NdP(5)W(30)O(110)](12-) and NdAs(4)W(40)O(140)](25-) are described. Absorption spectra of aqueous solutions of the complexes have been recorded and the transition intensities are parameterised in terms of the Judd-Ofelt intensity parameters Omega(lambda) (lambda=2, 4, 6). Marked differences were found between the luminescence lifetimes of the complexes of the type Nd(POM) and those of the type Nd(POM)(2), due to a better shielding of the neodymium(III) ions from the bulk water molecules in the latter type of complexes.