Tuning 1-D Pb(II) Coordination Polymers by Flexible and Semirigid Dicarboxylates: Synthesis, Structure and Properties

Two new one-dimensional (1-D) Pb(II) coordination polymers, namely, [Pb(3-pdip)(L)]·H2O (1) and [Pb(3-pdip)(L2)] (2) [LH2 = 1,6-hexanedioic acid, LH2 = homophthalic acid, 3-pdip = 2-(3-pyridyl)imidazo[4,5-f]1,10-phenanthroline] have been obtained from hydrothermal reactions of Pb(II) nitrate with the phenanthroline derivative and the two dicarboxylic acids. Single-crystal X-ray diffraction analysis reveals that compound 1 is a staircase-like double-chain coordination polymer constructed from binuclear [Pb2N4O8] subunits and pairs of [L1]2− anions. Compound 2 is a linear coordination polymer connected via two μ2-η:η carboxylate groups from [L2]2− anions. Furthermore, adjacent chains of 1 and 2 are extended into 3-D supramolecular networks by hydrogen bonds and π-π stacking interactions. The organic carboxylic acids with different flexibility determine the structures of the coordination polymers. Moreover, the thermal stabilities and photoluminescence properties of compounds 1 and 2 were investigated.