Seven Coordination Polymers Derived from Semirigid Tetracarboxylic Acids and N-Donor Ligands: Topological Structures, Unusual Magnetic Properties, and Photoluminescences

Abstract

Seven new complexes based on H4L1 and H4L2, namely, [Cd2(L1)(H2O)5]n (1), {[Cu5(L1)2(μ3-OH)2(H2O)4]·2H2O}n (2), {[Cd2(L1)(4,4′-bipy)2(H2O)3]·2H2O}n (3), [Zn2(L1)(4,4′-bipy)(H2O)3]n (4), {[Ni7(L1)4(4,4′-bipy)12(H2O)12]·2H2O}n (5), {[Ni1.5(L2)(4,4′-bipy)1.5(H2O)4]·H2O}n (6), and {[Ni9(L2)6(dib)12(H2O)18]·18H2O}n (7) [(H4L1 = 4-(3′,5′-dicarboxylphenoxy)phthalic acid, H4L2 = 3-(3′,5′-dicarboxylphenoxy)phthalic acid, 4,4′-bipy = 4,4′-bipyridine, dib = 1,4-di(1H-imidazol-1-yl)benzene], have been synthesized by solvothermal reactions. Complex 1 possesses a 4-connected chiral three-dimensional (3D) structure with a Schläfli symbol of (4.63.82). Complex 2 presents a (4,6)-connected porous architecture based on a chair-shaped [Cu4(μ3-OH)2]6+ secondary building unit (SBU) with a Schläfli symbol of (43.63)2(46.66.83), revealing unusual ferromagnetic behavior. Complex 3 exhibits a 2D → 3D framework through H-bonding interactions, which is a (3,3,4)-connected 2-fold interpenetrated structure with a Schläfli symbol of (6.82)2(63.83). Complex 4 shows a (3,4,6)-connected (4.64.8)2(62.8)2(42.66.86.10) topology. Complex 5 displays a rare (3,4)-connected polycatenation structure, possessing identical topologies with a Schläfli symbol of (63)(65.8) and weakly ferromagnetic behavior. Complex 6 features a (3,4)-connected 3D framework with a Schläfli symbol of (4 × 102)2(42.103.12). Complex 7 can be regarded as a (4,4)-connected (63.83)2(85.10) topology. Moreover, diverse structural topologies have not been documented hitherto. The magnetic properties of 2 and 5 are discussed in detail. The fluorescence properties have also been analyzed with density functional theory calculations, indicating that the emissions can be ascribed to intraligand charge transfer for 1 and ligand-to-ligand charge transfer for 3–4.