# Pyridine- and imidazoledicarboxylates of Zinc: Hydrothermal Synthesis, Structure, and Properties

Mahata, Partha and Natarajan, Srinivasan (2005) Pyridine- and imidazoledicarboxylates of Zinc: Hydrothermal Synthesis, Structure, and Properties. In: European Journal of Inorganic Chemistry (11). pp. 2156-2163.

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The reaction of hetrocyclic dicarboxylic acids, such as pyridine-2,5-dicarboxylic acid and imidazole-4,5-dicarboxylic acid,under hydrothermal conditions in the presence of an appropriate zinc salt yields three new zinc coordination polymers $^{0} _{\infty} [{Zn_{2}(H_{2}O)_{4}}{C_{5}H_{3}N(COO)_{2}}_{2}](1), ^{1} _{\infty} [{Zn(C_{12}H_{8}N_{2})}{C_{5}H_{3}N(COO)_{2}} . 0.5H_{2}O] (2)$, and $^{1} _{\infty} [{Zn(C_{12}H_{8}N_{2})}{C_{3}HN_{2}(COO)_{2}}] (3)$. While 1 forms with a zero-dimensional molecular rectangular box structure, 2 and 3 have zig-zag one-dimensional chain structures. The $Zn^{2+}$ ions are coordinated by both the carboxylate oxygen atoms and also by the nitrogen atoms of the heterocycles. The 1,10-phenanthroline molecules in 2 and 3 act as a secondary ligands and occupy the inter-chain spaces. The moderate hydrogen-bond interaction energy in 1 and the \pi...\pi interactions in 2 and 3 appear to play an important role for the structural stability. The structures of 2 and 3 appear to be related, even though they are formed with different carboxylic acids. All three compounds exhibit photoluminescence at room temperature.