Four new metal-organic frameworks based on a rigid linear ligand: synthesis, optical properties and structural investigation

Four coordination polymers, namely, {[Cd(L)(BIP)]center dot 3H(2)O}(n) (1), {[Co(L)(BIBP)(H2O)(4)]center dot 4H(2)O}(n) (2), {[Ni(L)(BIBP)(H2O)(2)]center dot 2DMF}(n) (3), [Ni(L)(BIMB)(DMF)(H2O)](n) (4), have been synthesized based on a rigid linear carboxylate ligand (H2L = 2 ',5 '-dimethoxy-[1,1 ':4 ',1 ''-terphenyl]-4,4 ''-dicarboxylic acid) and different lengths of imidazole ligands (BIP = 1,4-di(1H-imidazol-1-yl) benzene; BIBP = 4,4 '-di(1H-imidazol-1-yl)1,1 '- biphenyl; BIMB = 4,4 '-bis((1H-imidazol-1-yl) methyl)-1,1 '-biphenyl). These complexes have been characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. Complex 1 is a 6-connected 3-fold interpenetrating pcu net with the point symbol {4(12)center dot 6(3)}, 2 is a 1D supramolecular chain-like structure, 3 and 4 can be simplified as 4-connected sql nets with the point symbol {4(4)center dot 6(2)}. In addition, UV-visible spectra and photoluminescent properties are also investigated in detail.