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

Two porous coordination polymers, {[Co_0.5(TBC)]·2DMF}_n (1) and {[Co­(TBC)­Cl_0.5(CH₃OH)]·0.5Cl}_n (2), were synthesized via the solvothermal reaction of cobalt­(II) salts and 3,5-bis­(1H-1,2,4-triazol-1-yl)­benzenecarboxylic acid. Single-crystal X-ray diffraction analyses exhibited that complex 1 contains rtl three-dimensional (3D) skeleton and one-dimensional channels with large apertures, while complex 2 displays a novel 2-nodal 3,6-linked 3D structure with a Schläfli sign of {4.8²}²{4⁶.8⁹} and contains micropores. Meanwhile, compound 2 shows selective adsorption properties of anionic methyl orange in a water solution. The dye adsorption studies of 1 and 2 revealed that the porous character and charge properties of metal–organic frameworks are two important factors heavily influencing dye adsorption.