Influence of the Oxidation State of the Metal Center on the Flexibility and Adsorption Properties of a Porous Metal Organic Framework: MIL-47(V)

An alternative activation method was developed to stabilize the Metal Organic Framework (MOF) MIL-47(V) material in the V-III oxidation state. This solid and the oxidized forms were investigated by in situ infrared and Raman spectroscopies, X-ray diffraction (XRD), and Complex Impedance Spectroscopy (CIS). Unlike MIL-47(V-IV), MIL-47(V-III) is a flexible structure which presents mu(2)-hydroxyl groups acting as preferential adsorption sites for H2O or CO2. The modulation of the oxidation state of the metal center of this porous material leads to new intermediate porous solids with mixed oxidation states V-III/V-IV. In these materials, the V-III and V-IV centers seem to occur in close vicinity. However, the presence of V-IV centers inhibits the flexibility to a large extent.