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(1H-imidazol-1-yl)­benzene
(dib) or 4,4′-di­(1H-imidazol-1-yl)-1,1′-biphenyl
(dibp) yields four novel metal–organic frameworks (1–4) with different topological connections. [Co2(L)­(dib)]·3DMF (1) is a 2-fold interpenetrating sqc422 network and contains 3-dimensional interconnected
channels along [100], [010], and [110] directions; [Co4(L)2(dib)3(H2O)4]·4H2O (2) is a three-dimensional 3,4,4-connected
new topology with 5-fold interpenetration; [Co2(L)­(dibp)]·5DMF
(3) and Co2(L)­(dibp)2 (4) 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 1 and 3 exhibit
antiferromagnetic behavior.