Construction of Three-Dimensional Cobalt(II)-Based Metal–Organic Frameworks by Synergy between Rigid and Semirigid Ligands

Solvothermal assembly of Co­(II) ion, a semirigid tetrahedral carboxylate ligand tetrakis­[(4-carboxyphenyl)­oxamethyl]­methane acid (H₄L), and rigid linear bidentate linker 1,4-di­(1<i>H</i>-imidazol-1-yl)­benzene (dib) or 4,4′-di­(1<i>H</i>-imidazol-1-yl)-1,1′-biphenyl (dibp) yields four novel metal–organic frameworks (<b>1</b>–<b>4</b>) with different topological connections. [Co₂(L)­(dib)]·3DMF (<b>1</b>) is a 2-fold interpenetrating <i>sqc</i>422 network and contains 3-dimensional interconnected channels along [100], [010], and [110] directions; [Co₄(L)₂(dib)₃(H₂O)₄]·4H₂O (<b>2</b>) is a three-dimensional 3,4,4-connected new topology with 5-fold interpenetration; [Co₂(L)­(dibp)]·5DMF (<b>3</b>) and Co₂(L)­(dibp)₂ (<b>4</b>) are formed in the presence of dibp linker; they feature three-dimensional novel topologies based on 4,6-connection and 4,4-connection, respectively, and no interpenetration is observed. It is demonstrated that interpenetration is accessible simply by changing auxiliary ligands and solvents. Magnetic studies reveal that complexes <b>1</b> and <b>3</b> exhibit antiferromagnetic behavior