Insight into Metal-Organic Framework Reactivity: Chemical Water Oxidation Catalyzed by a [Ru(tpy)(dcbpy)(OH₂ )]²⁺...

Investigation of chemical water oxidation was conducted on [Ru(tpy)(dcbpy)(OH₂ )]²⁺ (tpy=2,2':6',2''-terpyridine, dcbpy=5,5'-dicarboxy-2,2'-bipyridine)-doped UiO-67 metal-organic framework (MOF). The MOF catalyst exhibited a single-site reaction pathway with kinetic behavior similar to that of a homogeneous Ru complex. The reaction was first order with respect to both the concentration of the Ru catalyst and ceric ammonium nitrate (CAN), with k_cat =3(±2)×10^-3  m^-1  s^-1 in HNO₃ (pH 0.5). The common degradation pathways of ligand dissociation and dimerization were precluded by MOF incorporation, which led to sustained catalysis and greater reusability as opposed to the molecular catalyst in homogeneous solution. Lastly, at the same loading (ca. 97 nmol mg^-1 ), samples of different particle sizes generated the same amount of oxygen (ca. 100 nmol), indicative of in-MOF reactivity. The results suggest that the rate of redox-hopping charge transport is sufficient to promote chemistry throughout the MOF particulates.