Syntheses, Crystal Structures and Solid-State Properties of the Lanthanoid-Containing Nanoclusters [(Ln2PW10O38)4(W3O8)(OH)4(H2O)2]26-

A series of lanthanoid-substituted polyoxometalates have been synthesized by a self-assembly process in potassium chloride solution by the reaction of dilacunary [P2W19O69-(H2O)](14-) with mid- and late-lanthanoid Ln(NO3)(3)center dot nH(2)O salts leading to the formation of the tetrameric tungstophosphates [(Ln(2)PW(10)O(38))(4)(W3O8)(OH)(4)(H2O)(2)](26-) [Ln = Y3+ (1), Sm3+ (2), Eu3+ (3), Gd3+ (4), Tb3+ (5), Dy3+ (6), Ho3+ (7), Er3+ (8), Tm3+ (9), Yb3+ (10)]. The polyanions were isolated as potassium or mixed-alkali salts. Most of the compounds were characterized by single-crystal X-ray diffraction and various analytical techniques, such as FTIR, UV/Vis, P-31 NMR and photoluminescence spectroscopy, magnetism, as well as thermogravimetric analysis. The FTIR spectra suggest that all the compounds are isomorphous. The crystal structures of these complexes consist of four A-[alpha-PW10O36](7-) units, each incorporating two Ln(III) ions to create four Keggin-like anions that further assemble with three additional tungstate units to form a tetramer species with C-2 symmetry. The photoluminescent properties of 3a and 6a were investigated following photoexcitation at room temperature. The magnetic properties of 3a, 4a, 5a and 6a were investigated at room temperature, the complexes exhibiting paramagnetic behaviour.