Synthesis and Structural Determination of Four Novel Metal−Organic Frameworks in a Zn−3-Amino-1,2,4-Triazole System

Four new coordination polymer compounds have been prepared using 3-amino-1,2,4-triazole (AmTRZ) as an organic linker, namely, ZnCl(AmTRZ) ( 1 ), Zn(HCO 2 )(AmTRZ) ( 2 ), Zn 5 (OH) 2 (AmTRZ) 6 (NO 3 ) 2 ·6H 2 O ( 3 ), and Zn 5 (OH)(AmTRZH)(AmTRZ) 6 (HCO 2 ) 3 ·5H 2 O ( 4 ). They were synthesized under mild hydro- or solvothermal conditions using water or dimethylformamide as solvent. Their crystal structures were characterized by single-crystal X-ray diffraction techniques, and thermal properties of all compounds were examined by thermogravimetric analysis. Isostructural compounds 1 and 2 ( Pbca, a = 9.389(1) Å, b = 10.115(1) Å, c = 11.571(2) Å, V = 1098.9(3) Å 3, Z = 8 for 1 and a = 9.198(1) Å, b = 10.341(1) Å, c = 12.577(2) Å, V = 1196.2(3) Å, Z = 8 for 2 ) display a two-dimensional layer structure where Zn centers are linked by AmTRZ molecules to form gridlike layers containing eight-membered rings. Structure 3 ( Pa 3̄, a = 15.0448(6) Å, V = 3405.3(2) Å 3, Z = 4) is a dense three-dimensional framework, featuring seven-membered channels where water and nitrate anions are located. Structure 4 ( I 4/ m, a = 19.2576(9) Å, c = 20.286(2) Å, V = 7523.2(9) Å 3, Z = 8) is built from porous Zn−AmTRZ layers containing 12- and 8-membered rings, which are connected to each other by dinuclear Zn tetrahedra building units. Water and formate anions occupy the void inside the framework.