Synthesis and structural characterization of metal azolate/carboxylate frameworks incorporating the 1-H-pyrazol-3,4,5-tricarboxylate ligand

The tetratopic ligand 1-H-pyrazol-3,4,5-tricarboxylic acid (H4PZTC) has been used for the first time to prepare the new metal azolate/carboxylate (MAC) frameworks [Co3(HPZTC)2(H2O)6]·2H2O (MAC-1), [Co(H2PZTC)(DMF)(H2O)]2 (MAC-2) and [Cd2(PZTC)(H2O)2] (MAC-3), along either conventional or solvothermal routes. As assessed by thermogravimetric analysis, before decomposition the three MAC frameworks undergo partial decarboxylation over 200 °C. Powder X-ray diffraction unveiled 1-D chains alternating monomeric and dimeric units in MAC-1, 1-D hydrogen bonded strands of dimeric units in MAC-2 and a 3-D non-porous network in MAC-3.