Water-Driven Structural Transformation In Cobalt Trimesate Metal-Organic Frameworks

We report on the synthesis and the characterization of a novel cobalt trimesate metal-organic framework, designated as KCL-102. Powder X-ray diffraction pattern of KCL-102 is dominated by a reflection at 10.2 degrees (d-spacing = 8.7 angstrom), while diffuse reflectance UV-Vis spectroscopy indicates that the divalent cobalt centers are in two different coordination geometries: tetrahedral and octahedral. Further, the material shows low stability in humid air, and it transforms into the well-known phase of hydrous cobalt trimesate, Co-3(BTC)(2)center dot 12H(2)O. We associated this transition with the conversion of the tetrahedral cobalt to octahedral cobalt.