Hydrothermal synthesis and structural characterization of novel Zn-triazole-benzenedicarboxylate frameworks

Three new metal-organic coordination polymers were synthesized hydrothermally using Zn2+ ion, 1,2,4-triazole, and 1,4-benzenedicarboxylic acid (BDC): Zn-5(H2O)(2)(C2H2N3)(4)(C8H4O4)(3)center dot 3.9H(2)O (1), Zn-2(C2H2N3)(2)(C2H3N3)(C8H4O4)center dot 2.5H(2)O (2), and Zn-4(H2O)(2)(C2H2N3)(4)(C8H4O4)(2)center dot 14H(2)O (3). Their crystal structures were determined by single-crystal X-ray diffraction. Their thermal properties were examined by thermogravimetric analysis. Structure 1 crystallizes in the monoclinic P2(1)/n space group with a = 10.192(2) angstrom, b = 17.764(4) angstrom, c = 24.437(5) angstrom, beta = 91.19(3)degrees, and V = 4423.3(15) angstrom(3). Structure 2 crystallizes in the triclinic P (1) over bar space group with a 7.797(2) angstrom, b = 10.047(2) angstrom, c = 13.577(3) angstrom, alpha = 110.18(3)degrees, beta = 105.46(3)degrees, gamma = 93.90(3)degrees, and V = 947.0(3) angstrom(3). Structure 3 crystallizes in monoclinic P2(1)/n space roup with a = 13.475(3) angstrom, b = 26.949(5) angstrom, c = 13.509(3) angstrom, beta = 95.18(3)degrees, and V = 4885.7(17) angstrom(3). In structure 1, the units of the triazole-Zn polyhedra are linked by BDC in a zigzag fashion to create the stacking of phenyl groups along the a axis. In structure 2, both triazole and BDC bridge Zn polyhedra in the (011) plane, resulting in the eight-membered channels along the a axis. In the case of structure 3, the BDC links the Zn polyhedra along the b axis to form a pillared open framework. This structure is the most porous of the compounds presented in this work.