Polymorphous One-Dimensional Tetrapyridylporphyrin Coordination Polymers Which Structurally Mimic Aryl Stacking Interactions

Two 3D cadmium coordination networks 3infinity[Cd(Hpdc)(H2O)] (1) and 3infinity[Cd3 (pdc)2(H2O)2] (2) have been synthesized from hydrothermal solutions at 150°C. Singlephased samples of both compounds can be isolated by adjusting the acidity level of the reactions. Both structures are constructed by a single, multifunctional ligand, 3,5pyrazoledicarboxylic acid (H3pdc), in different coordination modes. Both 1 and 2 crystallize in the monoclinic crystal system, space group P21/c (No. 14) with a=6.436(1) ?, b=12.283(2) ?, c=8.934(2) ?, beta=104.23(3)°, Z=4 for 1, and a=9.744(2) ?, b=9.821(2) ?, c=7.496 (1) ?, Z=2 for 2. Both compounds represent new structure types. All metal atoms are sevenfold coordinated in 1 and six-fold coordinated in 2. A comparison is made between the title compounds and related lanthanide series on the coordination habit of the metals and the ligand, as well as the effect of pH on the final products. TGA studies indicate that loss of coordinated water molecules in 1 and 2 occurs at around 213 and 179°C, respectively, and the decomposition process completes at about 620 and 480°C for 1 and 2, respectively.