Synthesis, structure, and magnetic and catalytic properties of metal frameworks with 2,2′-dinitro-4,4′-biphenyldicarboxylate and imidazole-containing tripodal ligands

Based on 1,3,5-tris(1-imidazolyl)benzene (tib) and 2,2'-dinitro-4,4'-biphenyldicarboxylic acid (H(2)dnbpdc), four new metal-organic frameworks [M-3(tib)(dnbpdc)(3)(H2O)(2)] [M = Mn (1), Cd (2)], [Zn-3(tib)(2)(dnbpdc)(2.5)(Hdnbpdc)]center dot 4DEF (3), and [Cd(tib)(dnbpdc)(H2O)]center dot DMF center dot H2O (4) (DEF = N,N-diethylformamide, DMF = N,N-dimethylformamide) were successfully synthesized. Isomeric 1 and 2 were unusual 8-connected uninodal three-dimensional (3D) frameworks with a point symbol of {3(3).4(15).5(9).6}. Compound 3 was a (3,3,4,4)-connected 4-nodal 3D net with a point symbol of {4.6.8}(2){4.6(2)}{4.8(5)} {6(2).8(3).10}, whereas 4 was a one-dimensional (1D) chain, which was further linked with neighboring 1D chains by hydrogen bonding interactions to give a 3D framework. It is interesting that 1 displayed ferromagnetic and antiferromagnetic interactions within the trinuclear Mn(II) subunit. We also performed Knoevenagel condensation reactions catalyzed by activated 3 to demonstrate its heterogeneous catalytic property. Furthermore, the adsorption property of 3 was also investigated.