Four Co(II) coordination polymers based on 4,4′-(1H-1,2,4-triazol-1-yl)methylenebis(benzoic acid): syntheses, structural diversity, magnetic properties, dye adsorption and photocatalytic properties

Four functional metal-organic frameworks constructed from 4,4'-(1H-1,2,4-triazol-1-yl)methylenebis.benzoic acid) (H(2)tmlb), namely: {[Co4(tmlb)(4)(H2O)]center dot 2CH(3)CN center dot 4H(2)O}(n) (1), {[Co(tmlb)(bbibp)]center dot 1.5CH(3)OH center dot 2H(2)O}(n) (2), {[Co-2(tmlb)(2)(bimmb)]center dot 6CH(3)CH(2)OH center dot 4H(2)O}(n) (3), and {[Co(tmlb)(bibp)(H2O)]center dot DMA}(n) (4) (bbibp = 4,4'-bis.benzoimidazo-1-yl) biphenyl, bimmb = 1,4-bis.imidazol-1-ylmethyl) benzene, bibp = 4,4'-bis.imidazolyl) biphenyl), have been synthesized under solvothermal conditions. Four Co complexes have been characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction, thermogravimetric (TG) analysis and powder X-ray diffraction (PXRD). The single-crystal X-ray diffraction analysis reveals that complex 1 shows a two-fold interpenetrating (3,6,6)-connected framework with a Schlafli symbol of (4 center dot 6(2))(2)(4(2)center dot 6(10)center dot 8(3)) topology; complex 2 shows a two-fold interpenetrating uninodal 4-connected cds topology with a point symbol of (6(5)center dot 8); complex 3 shows a 2D -> 3D supramolecular structure through weak interactions; complex 4 shows a (3,4,6)-connected network with a point symbol of (4 center dot 6(2))(2)(4(2)center dot 6(4)center dot 9(3)center dot 10(6))(6(4)center dot 9 center dot 10) topology. Furthermore, the variable temperature magnetic susceptibilities of complexes 1-4 have been discussed. Complex 4 can selectively adsorb sulfate-containing dyes by Lewis acid-base interactions. And the four complexes all exhibit excellent photocatalytic capability in degradation of MB/MV.