Abstract
A series of [H(3)O](+)[LnL(4)](-)·nH(2)O complexes (n = 1-3, Ln = Nd, (1), Sm (2), Eu (3), Tb (4); HL = 3-methyl-1-phenyl-4-formylpyrazole-5-one) were synthesized and characterized. The structures of the Sm(III) and Eu(III) complexes were investigated by X-ray diffraction. The isostructutal crystalls 2 and 3 consist the tetrakis [LnL(4)](-) anions which are linked by H-bonding with the hydroxonium counter-ion and water molecules. The lanthanide ion is situated in the center of distorted tetragonal antiprism formed by eight oxygen atoms of 4-formyl-5-hydroxypyrazolonate anions. The Tb(III) and Sm(III) complexes show strong luminescence in solid state, whereas the Eu(III) and Nd(III) complexes show low luminescence activity.