Auxiliary ligand-assisted structural diversities of three metal-organic frameworks with potassium 1H-1,2,3-triazole-4,5-dicarboxylic acid: syntheses, crystal structures and luminescence properties

Three metal-organic frameworks (MOFs) with d(10) metal ions, namely, {[Zn-3(TDA)(2)(bpy)(3)]center dot(bpy)center dot 10.5H(2)O}(n) (1), {[Zn-3(TDA)(2)(azopy)(2.5)(H2O)]center dot 4H(2)O}(n) (2) and {[Cd2K3(TDA)(HTDA)(2)(H2O)(4)]}(n) (3) (KH(2)TDA = potassium 1H-1,2,3-triazole-4,5-dicarboxylic acid, bpy = 4,4'-bipridine, azopy = 4,4'-azobispridine), have been successfully synthesized from KH(2)TDA with the aid of three different length-controllable auxiliary ligands and characterized by infrared spectra, elemental analysis, thermogravimetric analysis, powder X-ray diffraction and single-crystal X-ray diffraction. MOF 1 shows an interesting three-dimensional (3D) (3,4,4,4)-connected KAVGAQ framework with a Schlafli symbol of {6(3)}(2){6(4)center dot 10(2)}-{6(4)center dot 8(2)}(2), which can be extended by 2D layers and bpy pillars. MOFs 2 and 3 also display 3D framework structures, corresponding to a 6-connected {4(4)center dot 6(11)} net and a (6,12)-connected {3(12)center dot 4(30)center dot 5(20)center dot 6(4)}-{3(6)center dot 4(8)center dot 5} net, respectively. Moreover, a novel coordination mode of H(3)TDA is observed in 3. The luminescence properties of 1-3 are investigated.