A Co-MOF with a (4,4)-connected binodal two-dimensional topology: synthesis, structure and photocatalytic properties

The Co-MOF poly[[diaqua{μ₄-1,1,2,2-tetrakis[4-(1H-1,2,4-triazol-1-yl)phenyl]ethylene-κ⁴N:N':N'':N'''}cobalt(II)] benzene-1,4-dicarboxylic acid benzene-1,4-dicarboxylate], {[Co(C₃₄H₂₄N₁₂)(H₂O)₂](C₈H₄O₄)·C₈H₆O₄}_n or {[Co(ttpe)(H₂O)₂](bdc)·(1,4-H₂bdc)}_n, (I), was synthesized by the hydrothermal method using 1,1,2,2-tetrakis[4-(1H-1,2,4-triazol-1-yl)phenyl]ethylene (ttpe), benzene-1,4-dicarboxylic acid (1,4-H₂bdc) and Co(NO₃)₂·6H₂O, and characterized by single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction (PXRD), luminescence, optical band gap and valence band X-ray photoelectron spectroscopy (VB XPS). Co-MOF (I) shows a (4,4)-connected binodal two-dimensional topology with a point symbol of {4⁴·6²}{4⁴·6²}. The two-dimensional networks capture free neutral 1,4-H₂bdc molecules and bdc^2- anions, and construct a three-dimensional supramolecular architecture via hydrogen-bond interactions. MOF (I) is a good photocatalyst for the degradation of methylene blue and rhodamine B under visible-light irradiation and can be reused at least five times.