New interpenetrated mixed (Co/Ni) metal-organic framework for dye removal under mild conditions

A new three-dimensional (3D) bimetallic metal-organic framework (MOF), [CoNi(mu(3)-tp)(2)(mu(2)-pyz)(2)] (1) (tp = terephthalic acid and pyz = pyrazine), was hydrothermally synthesized using mixed O- and N-donor ligands. The structure of 1 has been determined by single-crystal X-ray diffraction analysis and characterized by FT-IR, powder X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Crystal structure shows that the metal centers are equally occupied by Co2+ and Ni2+ ions that was also confirmed by ICP technique. Two different coordination modes of terephthalate linkers connect three metal centers (CoNi), forming a (4,4)-connected 2D layers, which are pillaring by pyrazine ligands to form an interlocked 3D structure. Topological studies show a uninodal twofold interpenetrated structure with 3(4(12) . 6(3)) topological network. The prepared bimetallic MOF was applied as catalyst for the removal of Bismarck brown as a diazo dye under mild conditions. The results showed that compound 1 had good activity and stability during the dye removal process and could be recovered and reused at least for three cycles without considerable loss of activity. (C) 2015 Elsevier B.V. All rights reserved.