Construction of Three-Dimensional Cobalt(II)-Based
Metal–Organic Frameworks by Synergy between Rigid and Semirigid
Ligands
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Abstract
Solvothermal assembly of Co(II) ion, a semirigid tetrahedral
carboxylate
ligand tetrakis[(4-carboxyphenyl)oxamethyl]methane acid (H<sub>4</sub>L), 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. [Co<sub>2</sub>(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; [Co<sub>4</sub>(L)<sub>2</sub>(dib)<sub>3</sub>(H<sub>2</sub>O)<sub>4</sub>]·4H<sub>2</sub>O (<b>2</b>) is a three-dimensional 3,4,4-connected
new topology with 5-fold interpenetration; [Co<sub>2</sub>(L)(dibp)]·5DMF
(<b>3</b>) and Co<sub>2</sub>(L)(dibp)<sub>2</sub> (<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