Syntheses, structures, and properties of three cadmium(II) complexes constructed from aromatic polycarboxylate and flexible triazole synthons

Three new coordination compounds {[Cd(btrp)(ip)(H2O)]·2.5H2O}n (1) {[Cd(btrp)(hip)(H2O)]·3H2O}n (2) and {[Cd(btrp)2(H2O)2]·H2O·2H2btc}n (3) (btrp = 1,3-bis(1,2,4-triazol-1-yl)propane, H2ip = isophthalic acid, H2hip = 5-hydroxy isophthalic acid, H3btc = benzene-1,3,5-tricarboxylic acid) have been synthesized and structurally characterized. Both 1 and 2 feature two similar 2D layer structures, and the resulting 2D structures are interconnected by hydrogen-bond and π⋯π interactions to lead to 3D supramolecular architectures. 3 possesses 1D positive double-stranded chains. In the framework of 3, the free H2btc ligands also constitute into supremolecular 1D negative chains through classical hydrogen-bonding interactions (OH⋯O). The two kinds of 1D chains constructs into 3D supramolecular architectures through hydrogen-bonding and electrostatic interactions. Luminescence analyses were performed on all the three compounds, 1 and 2 show strong fluorescent emissions in the solid state at room temperature.

► Mixed-ligand strategy is an important method for construction of new frameworks.
► Each ligand in the system has an important influence on the final structure.
► Three new Cd(II) complexes have been isolated.
► Two of them display strong blue emissions at room temperature.