Synthesis and characterization of a new Cd-based metal-organic framework isostructural with MOF-74/CPO-27 materials

A new M-MOF-74 material, with M being cadmium, is described. The so-called Cd-MOF-74 material was prepared under solvothermal conditions using cadmium acetate as metal source. It was characterized by a variety of physico-chemical techniques including PXRD, TGA, N2 adsorption–desorption isotherms, SEM, IR and multinuclear solid-state NMR. Although the quality and/or the size of the afforded crystals did not allow us solving the structure by single-crystal X-ray diffraction, the information given by different characterization techniques is enough to confirm that the sample is indeed a Cd-based MOF-74-like material. Fingerprint-based PXRD and FTIR techniques showed a good matching between the Cd-MOF-74 and the well-known Zn-MOF-74 samples. Likewise, TGA and N2 adsorption–desorption at 196 °C gave expected values of Cd/linker ratio and textural properties, respectively. SEM certified the homogeneity of crystals and the absence of impurities. Among the divalent metal ions capable to produce MOF-74 materials, Cd2+ presents some singularities: (i) it is the first metal of the second transition metal row able to led to a M-MOF-74 material; (ii) due to reasonably good magnetic properties of the diamagnetic non-quadrupolar 113Cd and 111Cd nuclei, metal-adsorbate interactions can be studied from a metal point of view by means of NMR techniques.