Probing reactive platinum sites in uio-67 zirconium metal-organic frameworks

We present three methods of the synthesis of zirconium metal–organic framework UiO-67 functionalized with platinum bipyridine coordination complexes (bpydcPtIICl2 and bpydcPtIVCl4) acting as linkers in the MOF framework. These Pt complexes can be reduced to bpydcPt0 under flow of H2 gas in the 600–700 K range, as probed by a sophisticated parametric refinement of in situ EXAFS data. IR spectroscopy testifies the high coordinative unsaturation of the reduced centers, able to form bpydcPt0(CO)2 dicarbonyl complexes upon CO adsorption. The large pore size of UiO-67 allows for ligand exchange between 2 Cl– and even bulky ligands such as toluene-3,4-dithiol. Framework bpydcPtIICl2 complexes can also be oxidized at room temperature to bpydcPtIVBr4 through oxidative addition of liquid Br2. XANES spectroscopy was used to monitor the changes in the Pt oxidation state along the observed reactions. Platinum bipyridine-functionalized UiO-67-Pt displays the same exceptional stability as the parent material as testified on both long and local range by in situ XRPD and Pt L3-edge EXAFS data