Syntheses, structures, and photoluminescence of three-dimensional lanthanide coordination polymers with 2,5-pyridinedicarboxylic acid

Four new open-framework Coordination polymers of lanthanide 2,5-pyridinedicarboxylates, with the formulas Pr2(pydc)(3)(H2O)(2) (1), Ln(pydc)(Hpydc) (Ln = Tb (2), Er (3). Eu (5)). and Gd(pydc)(nic)(H2O) (4) (H(2)pydc = 2,5-pyridinedicarboxylic acid, Hnic = nicotinic acid), have been hydrothermally synthesized and four of them (except Eu (5)) have been structurally characterized. Complex 1 consists of two types of ligand-binding modes contributing to link the PrO7N(H2O) polyhedral chains to three-dimensional (3D) open-framework architecture. Complexes 2 and 3 are isostructural and feature unique 3D cage-like supramolecular frameworks remarkably different from that of 1, owing to the different ligand-bridging pattern. Complex 4, however, has the distinct 3D open-framework architecture due to the presence of unexpected nicotinate ligands, which may be derived from pydc ligands via in-situ decarboxylation under the hydrothermal condition. (C) 2008 Elsevier Inc. All rights reserved.