Zn(ii) and Cd(ii) coordination networks based on N-donor ligands: synthesis, crystal structures, and sensing of nitroaromatic explosives

Abstract

Four novel coordination networks based on N-donor ligand, [Zn(L)Cl]_n (1), [Cd₂(L)Cl₃]_n (2), [Zn(L)₂(H₂O)₂]_n (3), and [Cd(L)₂(H₂O)₂]_n (4) (HL = 5-(4-(1,2,4)triazol-1-yl-phenyl-1H-tetrazole) were synthesized and structurally characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), infrared spectrophotometry (IR), and elemental analysis. The structure of 1 displays a two-dimensional (2D) structure with (6, 3) topology, which extends to a three-dimensional (3D) supramolecular network by C–H⋯Cl weak interactions, compound 2 can be described as a 3D 5,9-connected network based on the assembly of binuclear cadmium clusters and L ligands. Ligand in 3 and 4 is synthesized in situ, the complexes are isostructural and possess one-dimensional (1D) double chains, which further connect by O–H⋯N weak interactions to form 2D supramolecules. The configurations of 1–4 span from 1D, 2D to 3D network, which indicates that metal ions, counterions and weak interactions play important roles in the formation of the coordination polymers. Furthermore, all compounds exhibit high sensitivity sensing responses to nitroaromatic explosives.