Synthesis, structures and properties of lead coordination polymers based on pyridinedicarboxylate ligand.

Two new Pb(II) coordination polymers, namely, [Pb(Hpydc) 2 ] n (1), [Pb(Hpydc) 2 (H 2 O)] n ·2n(H 2 O) (2) (H 2 pydc ​= ​2,5-pyridinedicarboxylic acid) have been prepared by the reaction of PbCl 2 with pyridinedicarboxylic acid and fully characterized. Compound 1 contains 'sql' topological layers built from one-dimensional (1D) Pb-carboxylate infinite chains, and the layers are further packed into a 3D architecture by strong hydrogen bonds interactions. Compound 2 consists of 1D infinite chains containing Pb-dimers. The 3D supramolecular Pb(II) coordination complex of 2 is created by π – π interactions between the pyridine rings of the Hpydc ligands. In addition, solid-state properties of thermal stability and fluorescence for these crystalline materials are also presented. Time-dependent density functional theory (TDDFT) calculations reveal that the mechanism of the fluorescence emissions are dominantly resulted from the ligand-to-metal charge transfer (LMCT) and partial the intraligand π→π∗ and/or n→π∗ transitions for 1 and 2 , which are in good agreement with their fluorescence spectra and crystal structure. Two 3D supramolecular structural Pb(II)/pyridinedicarboxylate complexes have been synthesized and characterized by chemical methods. The two compounds contain different Pb-carboxylate infinite chains. They display intense and broad emission bands and can be probably used as fluorescence materials. [Display omitted] Research Highlights: • Two Pb(II)/pyridinedicarboxylate complexes have been synthesized. • The two compounds contain different Pb-carboxylate infinite chains. • They display intense and broad emission bands. • They can be probably used as fluorescence materials. [ABSTRACT FROM AUTHOR]