Aqueous solutions of [Ru(bpy)3]Cl2 are orange due to a strong MLCT absorption at 452 ± 3 nm (extinction coefficient of 14,600 M−1cm−1).

Thus, the photochemical properties of [Ru(bpy)3]2+ are reminiscent of the photosynthetic assembly, which also involves separation of an electron and a hole.

This species transfers an electron, located on one bpy ligand, to a sacrificial oxidant such as peroxodisulfate (S2O82−).

[10][11] Such complexes are widely discussed for applications in biodiagnostics, photovoltaics and organic light-emitting diode, but no derivative has been commercialized.

Application of [Ru(bpy)3]2+ and its derivatives to fabrication of optical chemical sensors is arguably one of the most successful areas so far.

[13] [14][15][16] Metal bipyridine as well as related phenanthroline complexes are generally bioactive, as they can act as intercalating agents.