Two 2D Cd(II) coordination polymers based on asymmetrical Schiff-base ligand: Synthesis, crystal structures and luminescent properties

Abstract

Two new two-dimensional coordination polymers [Cd3L2(SCN)6]n (1) and [CdLI2]n (2) have been synthesized and characterized by IR spectroscopy, elemental analysis, TG technique, XRPD and complete single crystal structure analysis, where L is 4-(pyridine-2-yl)methyleneamino-1,2,4-trizaole. Asymmetrical Schiff-base ligand L with five- and six-membered N-containing heterocyclic rings acts as a tridentate bridging ligand to bind two Cd(II) centers through one terminal Ntriazolyl and one pyridylimine chelate unit in 1 and 2. For polymer 1, tridentate bridging ligands link Cd-(1,3-μ-SCN−) 1D inorganic chains to form a 2D layer network. The existence of CH⋯π and ππ stacking interactions between 2D hybrid layers further gives rise to a 3D supramolecular network. In comparison with 1, polymer 2 shows a 2D layer network containing hexanuclear macrometallacyclic units. The 2D layers are staggered together through the combination of CH⋯π and ππ stacking interactions and forming a 3D supramolecular structure. The luminescent properties of the polymers 1 and 2 were investigated in the solid state at room temperature.