Ligand-directed and solvent-controlled assembly of six novel functional supramolecular metal–organic frameworks

Six novel functional metal–organic frameworks, namely, [CdCl(IP)(Hpydc)(H2O)]·2H2O (1), [Cd(IP)(H2imdc)]Cl (2), [Cd(IP)2(H2O)2](1,5-nds)·2H2O (3), [Co(IP)(H2O)4](1,5-nds)·H2O (4), [Zn(IP)(μ2-SO4)(H2O)]·H2O (5), [Zn(IP)(SO4)(H2O)3] (6) (IP = 1-H-imidazo[4,5-f][1,10]-phenanthroline, H2pydc = pyridine-2,6-dicarboxylic acid, H3imdc = imidazole-4,5-dicarboxylic acid, 1,5-nds = 1,5-naphthanlenedisulfonate), were synthesized by controlling auxiliary ligands, metal centers and solvents. In compound 1, Cd(II) is chelated by IP and Hpydc ligands, forming 0D → 3D supramolecular structure. Compound 2 is a 1D chain with repeated [Cd(IP)]2+ units connected by H2imdc ligands. With different metal centers, compounds 3 and 4 possess different crystal structures. With solvents regulated, compounds 5 and 6 exhibit distinct structures. In compound 5, sulfate anions show μ2-bridging mode, which results in the formation of 1D chain. In compound 6, only one oxygen atom from sulfate anion coordinates to the metal center, resulting in discrete repeated units. The luminescent properties of 1, 2, 3, 5, 6 and thermal stabilities of all compounds were measured.