Four MOFs with 2,2′-dimethoxy-4,4′-biphenyldicarboxylic acid: syntheses, structures, topologies and properties

Four novel metal-organic frameworks, [MnL(DMF)](n) (1), [NiL(H2O)(2)(DMF)](n) (2), [Cu2L2(H2O)(2)]center dot 6H(2)O center dot 2DMF (3), and Na-2(Me2NH2)(4)[Cd7L10]center dot 9H(2)O center dot 17Me(2)NH center dot 2DMF (4), were successfully synthesized in solvothermal conditions using 2,2'-dimethoxy-4,4'-biphenyldicarboxylic acid (H2L) as the ligand. The X-ray crystallography analysis reveals that MOF 1 exhibits a 3D framework with sra topology, while MOF 2 shows a 2D network with sql topology though they possess a similar secondary building unit (SBU) [MO6] (M = Mn for 1 and Ni for 2). MOF 3 reveals an unprecedented 4-fold interpenetrated 3D framework with lvt topology constructed from only planar 4-connected nodes ([Cu-2(CO2)(4)] SBUs) with the rigid dicarboxylic acids. MOF 4 features an unique acentric 3D/3D hetero-interpenetrated framework built from two different nodes (4- and 8-connected), different chemical compositions [Cd(CO2)(4) and Cd-3(CO2)(8)], and different topology of networks (6(6) and 4(24)center dot 6(4)) and contains an inorganic 1D chain consisting of a Na+ and three Cd2+ ions. The solid state Cd-113 NMR spectrum indicates that 4 has three 6-, 7-, and 8-coordinated Cd2+ ions with chemical shifts at delta -25.3, -41.2 and -83 ppm, respectively. MOF 3 has two kinds of 1D channels with diameters of 11 angstrom and 7 angstrom and exhibits a selective gas adsorption for CO2-N-2 and CH4-N-2. MOF 4 shows a selective adsorption for cationic dyes and a nonlinear SHG activity (ca. 0.8 times that of urea).