Various dicarboxylates induced six Zn(II)/Cd(II) coordination polymers containing a new benzoimidazolyl terpyridine ligand: syntheses, structural diversity, luminescence and gas adsorption properties

Abstract

Six Zn(II)/Cd(II) coordination polymers (CPs), namely, {[Zn2(bimphtpy)(p-bdc)1.5(OH)]·(H2O)0.5}n (1), [Zn2(bimphtpy)2(tdc)2]n (2), {[Zn(bimphtpy)(cpoa)]·4H2O}n (3), [Cd2(bimphtpy)(p-bdc)2(H2O)]n (4), {[Cd2(bimphtpy)(m-bdc)2(H2O)2]·(H2O)0.75}n (5), and {[Cd(bimphtpy)(qda)]·H2O}n (6), constructed from N-heterocyclic ligand 4'-(4-(benzimidazol-1-yl)phenyl)-4,2':6',4''-terpyridine (bimphtpy) and five dicarboxylic acids, (p-H2bdc = 1,4-benzenedicarboxylic acid, H2tdc = 2,5-thiophenedicarboxylic acid, H2cpoa =4-carboxyphenoxyacetatic acid, m-H2bdc = 1,3-benzenedicarboxylic acid, H2qda = hydroquinone-o,o'-diacetic acid), have been solvothermally synthesized and structurally characterized mainly by single-crystal X-ray diffraction along with elemental analysis, IR spectroscopy, PXRD and TG analysis. Complex 1 exhibits a 2D + 2D → 3D polycatenated framework with bilayers showing the uninodal 5-c (4,4)Ia topology if Zn2(CO2)(OH) SBU (secondary building unit) are considered. Complex 2 reveals a 2D → 2D polycatenane of two-fold interpenetrated network with rods threading loops showing 63-hcb topology. Complex 3 presents a highly undulated 2D 44-sql sheet with thickness of about 18.5 Å. Complex 4 displays a single 3D network constructed by binuclear Cd2(CO2)4O2 SBU showing the uninodal 6-c pcu topology. Complex 5 features a 2D + 2D → 3D polycatenated framework showing an unidentified topology with point symbol of {42·6·72·9}{42·6}{6·72}{64·8·10}. Complex 6 shows a single 3D network constructed by binuclear Cd2O4C2 SBU with 8-c cds topology. Moreover, the fluorescent properties of complexes 1–6 in the solid state at room temperature as well as the adsorption properties of complex 3 are also investigated, suggesting their potential applications as luminescence materials and gas adsorption selectivity materials.