Metal-directed supramolecular architectures based on the bifunctional ligand 2,5-bis(1H-1,2,4-triazol-1-yl)terephthalic acid

By the solvothermal reactions of 2,5-bis(1H-1,2,4-triazol-1-yl)terephthalic acid (H₂L) with transition-metal ions, two novel polymeric complexes, namely, poly[diaqua[μ₄-2,5-bis(1H-1,2,4-triazol-1-yl)terephthalato]cobalt(II)], [Co(C₁₂H₆N₆O₄)(H₂O)₂]_n, (1), and poly[[diaqua[μ₄-2,5-bis(1H-1,2,4-triazol-1-yl)terephthalato]nickel(II)] dihydrate], {[Ni(C₁₂H₆N₆O₄)(H₂O)₂]·2H₂O}_n, (2), were isolated. Both polymers have been characterized by FT-IR spectroscopy, elemental analysis and single-crystal X-ray diffraction analysis. The complexes have similar two-dimensional layered structures and coordination modes. Furthermore, the two-dimensional layered structures bear distinct intermolecular hydrogen-bonding interactions and π-π stacking interactions to form two different three-dimensional supramolecular networks based on 4⁴-subnets. The structural variation depends on the nature of the metal cations. The results of variable-temperature magnetization measurements (χ_MT-T and χ_M^-1-T) show that complexes (1) and (2) display antiferromagnetic behaviour.