Hydrothermal syntheses and structural studies of lanthanide coordination polymers involving in-situ decarboxylation and their luminescence properties

Abstract

Lanthanide coordination polymers with the formula [Ln(pydc) 2]·H2O (Ln = La, 1; Nd, 2; pydc = 3,4-pyridinedicarboxylate) and [Ln(pydc)(ina)(H2O)2] (Ln = Sm, 3; Eu, 4; Tb, 5; Dy, 6; pydc = 3,4-pyridinedicarboxylate, ina = isonicotinate) were synthesized by treating LnIII nitrates with 3,4-pyridinedicarboxylic acid under hydrothermal conditions. Single-crystal and powder X-ray diffraction studies indicate that these lanthanide coordination polymers adopt two different structures. The lighter lanthanide compounds 1 and 2 consist of extended two-dimensional layer structures with the thickness of ca. 1.7 nm. While the heavier lanthanide compounds 3-6 have pydc-bridged double chain structures with one chelating carboxylate group of ina ligand and two water molecules on each metal center. Interestingly, decarboxylation occurred and pydc was partially transformed into ina in the hydrothermal reactions of 3-6. The fluorescence activities of compounds 4 and 5 are reported. © 2005 Wiley-VCH Verlag GmbH & Co. KGaA.