Hydrothermal Synthesis and Structural Characterization of Novel Zn−Triazole−Benzenedicarboxylate Frameworks

Three new metal−organic coordination polymers were synthesized hydrothermally using Zn 2+ ion, 1,2,4-triazole, and 1,4-benzenedicarboxylic acid (BDC): Zn 5 (H 2 O) 2 (C 2 H 2 N 3 ) 4 (C 8 H 4 O 4 ) 3 ·3.9H 2 O ( 1 ), Zn 2 (C 2 H 2 N 3 ) 2 (C 2 H 3 N 3 )(C 8 H 4 O 4 )·2.5H 2 O ( 2 ), and Zn 4 (H 2 O) 2 (C 2 H 2 N 3 ) 4 (C 8 H 4 O 4 ) 2 ·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 P 2 1 / n space group with a = 10.192(2) Å, b = 17.764(4) Å, c = 24.437(5) Å, β = 91.19(3)°, and V = 4423.3(15) Å 3 . Structure 2 crystallizes in the triclinic P 1̄ space group with a = 7.797(2) Å, b = 10.047(2) Å, c = 13.577(3) Å, α = 110.18(3)°, β = 105.46(3)°, γ = 93.90(3)°, and V = 947.0(3) Å 3 . Structure 3 crystallizes in monoclinic P 2 1 / n space group with a = 13.475(3) Å, b = 26.949(5) Å, c = 13.509(3) Å, β = 95.18(3)°, and V = 4885.7(17) Å 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.