Identification of the Different Mechanisms of Activation of a [RuII(tpy)(bpy)(OH₂)]²⁺ Catalyst by Modified Ruthenium Sensitizers in Supramolecular Complexes

We report the synthesis and photophysical studies of two different complexes incorporating a chromophore and a catalyst within the same structure. The chromophores used are of the form [(bpy) 2 (phen)Ru II ] 2+ and [(COOEt) 2 bpy) 2 (phen)Ru II ] 2+ . The electron-withdrawing auxophores in the periphery of the bipyridine ligands convey the chromophores with different chemical and photophysical properties. The catalyst incorporated is [Ru II (tpy)(bpy)(OH 2 )] 2+ which has been shown to carry out the catalytic oxidation of water and organic substrates. We present the different mechanisms of light-driven activation observed for the catalyst. Depending on the electronic properties of the chromophores, these can act as antenna systems by activating the catalyst via energy transfer followed by electron transfer to an acceptor or as chromophores, in which case activation of the catalyst is done by direct electron transfer from the photo-oxidized sensitizer. The oxidized form of the catalyst formed by either mechanism is stable on a time scale of milliseconds.