Syntheses, crystal structures and luminescent properties of two novel lanthanide/4-pya complexes:: [Ln(4-pya)3(H2O)2]2 (Ln = Eu, La;: 4-pya = trans-4-pyridylacrylate)

Reactions of Ln(2)O(3) and trans-4-pyridylacrylic acid (4-Hpya) in EtOH/H2O or MeOH/H2O produced two new lanthanide/4-pya complexes [Ln(4-pya)(3)(H2O)(2)](2) (1: Ln = Eu; 2: Ln = La) in low yields. However, reactions of LnCl(3) center dot 6H(2)O with 4-Hpya/aqueous ammonia in EtOH/H2O or MeOH/H2O gave rise to 1 or 2 in higher yields. Both compounds were structurally characterized by elemental analysis, IR spectroscopy and X-ray analysis. Compounds 1 center dot 2EtOH center dot 2H(2)O and 2 center dot 2MeOH center dot 2H(2)O were confirmed to possess one-dimensional polymeric chain structures. In the structure of 1, each Eu(III) adopts a monocapped square-antiprism coordination geometry and each dimer [Eu(4-pya)3(H2O)(2)](2) within the chain is interconnected by two pairs of different bridging 4-pya ligands. On the other hand, each La(III) of 2 takes a bicapped square-antiprism coordination geometry and each dimer [La(4-pya)3(H2O)(2)](2) within the chain is linked by two pairs of tridentate bridging 4-pya ligands. The luminescent properties of 1 and 2 in the solid state were investigated. (c) 2005 Elsevier B.V. All rights reserved.