Observation of Structural Diversity Based on the Cationic Influence in a Series of Zn/Cd Pyridine Carboxylate Coordination Compounds

In this study, we used a 6-methyl-2,3-pyridine dicarboxylate ligand to develop the frameworks. Two novel compounds, [Zn2(L)2(H2O)4] (1) and [Cd(L)(H2O)] (2) (where L = 6-methyl-pyridine-2,3-dicarboxylate) were produced. The compounds were characterized by elemental analysis, powder X-ray diffraction, Fourier-transform infrared spectroscopy and single crystal X-ray crystallography. We successfully tuned the framework dimensionality by varying the size of the metal ions from small Zn to large Cd ions. Single crystal X-ray investigations of compound 1 show a good dimeric motif, while compound 2 shows a 2D network. In compound 1, the dimeric units are further bonded by strong hydrogen bonds and create a 3D network whereas compound 2 produces a 2D layer that in turn connects via short contacts to form a 3D network in the crystallographic space.