Two metal–organic frameworks with unique high-connected binodal network topologies: synthesis, structures, and catalytic properties

{[Cd3(btec)(btx)0.5(μ3-OH)(H2O)]·H2O}n (1) and [Cu2(btec)(btx)1.5]n (2), two novel cadmium(II) and copper(II)-based high-connected metal–organic frameworks, with both 1,2,4,5-benzenetetracarboxylate (btec) and 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (btx) as mixed ligands were hydrothermally synthesized and structurally characterized. Both MOFs have three-dimensional (3D) structures, but different framework topologies and ligand linkage modes. 1 possesses an unprecedented binodal (4,12)-connected topology structure, in which the ligand btec serves as a rare dodecadentate and ordinary octadentate in two types of coordination modes. Meanwhile, 2 exhibits a binodal (4,7)-connected topological network with an enneadentate coordination geometry of the btec ligand. Both MOFs provide novel examples of designing and synthesizing novel binodal MOFs, and demonstrate that the 1,2,4,5-benzenetetracarboxylic acid ligand with rich coordination chemistry information is useful in the construction of binodal highly-connected nets. In addition, the catalytic performance of 2 has also been checked. 2 is active as a catalyst for the degradation of methyl orange.