Structural diversity induced by ligand geometry: From two-dimensional to three-dimensional coordination polymers with pyridine

Two coordination polymers with two-dimensional and three-dimensional structures are, {[Zn-3(bdc)(3)(py)(2)]center dot 2NMP}(n) (1) (H(2)bdc = 1,4-benzenedicarboxylic acid) and [Zn-2(NO3-)(btc)(nmp)(2)(py)](n) (2) (H(3)btc = 1,3,5-benzenetricarboxylic acid), synthesized by hot-solution reactions of Zn(NO3)(2)center dot 6H(2)O, pyridine (py) and two different ligands in N-methylpyrrolidone (NMP). {[Zn-3(bdc)(3)(py)(2)]center dot 2NMP}(n) exhibits two-dimensional networks with trizinc subunits [Zn-3(COO)(6)py(2)] stacking with a layer-by-layer alignment, and there are strong pi-pi interactions involving py from adjacent layers. [Zn-2(NO3-)(btc)(nmp)(2)(py)](n) has a three-dimensional structure containing two independent zinc ions, tetrahedral ZnO4 and octahedral ZnNO5. Based on X-ray studies, the coordination polymers {[Zn-3(bdc)(3)(py)(2)]center dot 2NMP}(n) (1) have a porous structure with NMP guest molecules. In contrast, X-ray studies revealed that coordination polymer [Zn-2(NO3-)(btc)(nmp)(2)(py)](n) (2) had a larger void that was inhabited by coordinated py and NMP. In addition, the form of the two coordination polymers changed from two-dimensional to three-dimensional with transformation of the ligand geometry.