New CuII and CdII Metal-organic Coordination Polymers with 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole Ligands: Syntheses, Structures and Luminescent Properties

Three new complexes {[Cu(L-1)(2)(NO3)(2)]center dot H2O}(infinity) (1), {[Cu-4(L-2)(2)(OAc)(8)]center dot CH3CH2OH}(infinity) (2) and [Cd-2(L-3)(3)(NO3)(4)(H2O)(2)](infinity) (3) (L-1 = 4-phenyl-7-(pyridine-3-yl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole, L-2 = 4-(pyridine-3-yl)-7-phenyl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole, and L-3 = 4-(pyridine-4-yl)-7-phenyl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole) have been synthesized and characterized by elemental analyses, IR spectra and single crystal X-ray diffraction. The structural analyses reveal that complex 1 is a neutral 2-D network structure with a 4(4) topology, 2 has a 1-D neutral coordination chain with a [Cu-2(CH3COO)(4)] dinuclear structural unit bridged by four acetate ions, and 3 is a neutral rhombohedral grid structure. All the complexes are air stable at room temperature. Furthermore, the fluorescent properties of complex 3 and corresponding ligand L-3 have been investigated and discussed.