Novel RuII Complexes with Bispidine-Based Bridging Ligands: Luminescence Sensing and Photocatalytic Properties

New ligands with a bidentate bipyridyl (bpy) and a tetradentate bispidine (bisp) subunit (bipyridyl = 2,2'-bipyridine derivative, bispidine = 3,7-diazabicyclo[3.3.1]nonane derivative, and their heterodinuclear {[Ru(bpy)(3)(2+)-[M(bisp)](2+)} complexes (M = Cu2+, Fe2+) were prepared and characterized. The luminescence of the mononuclear Ru-II complexes (metal-free bisp subunit) is efficiently quenched in presence of Cu-II. An EPR spectroscopic study reveals that visible light irradiation does not alter the oxidation states of the two metal ions in {[Ru(bpy)(3)](2+)-[Cu(bisp)](2+)}, i.e. there is energy rather than electron transfer. The heterodinuclear {[Ru(bpy)(3)](2+)-[Cu(bisp)](2+)} complex shows a significant photocatalytic activity in the aziridination of styrene.