Tuning the Framework Topologies of CoII-Doped ZnII−Tetrazole-benzoate Coordination Polymers by Ligand Modifications: Structures and Spectral Studies

In our continuing efforts to explore the effects of ligand modifications on the structures and properties of their metal complexes, we studied the in situ [2 + 3] cycloaddition reactions of benzonitrile, o-phthalodinitrile, 3-cyanobenzoic acid, 4-cyanobenzoic acid with NaN3 in the presence of ZnII and/or CoII salts under hydrothermal conditions, and obtained four new CoII-doped ZnII-tetrazole-benzoate coordination polymers with the formula of [CoxZn1−x(Lm)y]n [5-phenyl-1H-tetrazole (HL1) for 1, 2-(1H-tetrazol-5-yl)benzoic acid (H2L2) for 2, 3-(1H-tetrazol-5-yl)benzoic acid (H2L3) for 3, and 4-(1H-tetrazol-5-yl)benzoic acid (H2L4) for 4]. The structure of 1 shows a classical diamondoid net, while 2 and 3, take 2D layer structure with (4.62)(4.6.4.6) topology and 3D SrAl2 topology, respectively. The structure of 4 exhibits a four-connected 3D network with rare non-diamondoid 66 topology. The coordination modes of the center metal and the ligands in the four complexes are almost the same, being tetrahedral or four-connected, but their topologies are quite different. Thus, the four structurally related ligands allow analysis of the effects of the disposition of a second functional carboxylate group on an aromatic ring and the twist angles of the carboxylate and tetrazoyl out of the plane of the aromatic ring on the overall structural topology of their complexes. Interestingly, the CoII ions were doped into the ZnII complexes, as confirmed by their macroscopical colors, inductively coupled plasma (ICP) analysis and UV−visible spectra. In addition, the photoluminescence of the four complexes in the solid state at room temperature was briefly studied.