Two 3D Cobalt(II) Metal–Organic Frameworks with Micropores for Selective Dye Adsorption

Two porous coordination polymers, {[Co<sub>0.5</sub>(TBC)]·2DMF}<sub><i>n</i></sub> (<b>1</b>) and {[Co­(TBC)­Cl<sub>0.5</sub>(CH<sub>3</sub>OH)]·0.5Cl}<sub><i>n</i></sub> (<b>2</b>), were synthesized via the solvothermal reaction of cobalt­(II) salts and 3,5-bis­(1<i>H</i>-1,2,4-triazol-1-yl)­benzenecarboxylic acid. Single-crystal X-ray diffraction analyses exhibited that complex <b>1</b> contains rtl three-dimensional (3D) skeleton and one-dimensional channels with large apertures, while complex <b>2</b> displays a novel 2-nodal 3,6-linked 3D structure with a Schläfli sign of {4.8<sup>2</sup>}<sup>2</sup>{4<sup>6</sup>.8<sup>9</sup>} and contains micropores. Meanwhile, compound <b>2</b> shows selective adsorption properties of anionic methyl orange in a water solution. The dye adsorption studies of <b>1</b> and <b>2</b> revealed that the porous character and charge properties of metal–organic frameworks are two important factors heavily influencing dye adsorption.