A donor–chromophore complex containing the polyazine bridging ligand 2,3-bis(2-pyridyl)pyrazine

The complex [(PTZpbpy)2Ru(dpp)](PF6)2 coupling a phenothiazine derived electron donor to a ruthenium complex with a polyazine bridging ligand dpp (PTZpbpy = 4-methyl-4′-(4-(N-phenothiazinato)pentyl)-2,2′-bipyridine, dpp = 2,3-bis(2-pyridyl)pyrazine) has been synthesized and the redox, spectroscopic, and excited state properties elucidated. In the coupled electron donor system, the emission intensity from the Ru(dπ) → dpp(π∗) 3MLCT state is quenched by 94% of that of the analogous system [(bpy)2Ru(dpp)](PF6)2 (bpy = 2,2′-bipyridine) which lacks a coupled electron donor. Coupling a donor–chromophore unit to a bridging ligand will allow the expansion of the molecular architecture to form complex molecular assemblies which contain covalently attached electron donors.

Graphical abstractThe electrochemical and photochemical properties of the complex [(PTZpbpy)2Ru(dpp)](PF6)2 (PTZpbpy = 4-methyl-4′-(4-(N-phenothiazinato)pentyl)-2,2′-bipyridine, dpp = 2,3-bis(2-pyridyl)pyrazine) which couples a donor–chromophore unit to a bridging ligand is reported. This complex displays weak emission from the Ru(dπ) → dpp(π∗) 3MLCT state compared to the analogous system [(bpy)2Ru(dpp)](PF6)2 (bpy = 2,2′-bipyridine) indicative of intramolecular electron transfer from the coupled electron donor. The title complex will allow the construction and study of complex photochemical molecular devices with coupled electron donors.Figure optionsDownload full-size imageDownload as PowerPoint slide