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). Further absorption bands are found at 285 nm corresponding to ligand centered π*← π transitions and a weak transition around 350 nm (d-d transition). Light absorption results in formation of an excited state have a relatively long lifetime of 890 ns in acetonitrile  and 650 ns in water.
Aqueous solutions of [Ru(bpy)3]Cl2 display a characteristic orange color resulting from strong MLCT absorption at 452 ± 3 nm, accompanied by weaker bands for ligand-centered π*← π transitions and d-d transitions around 350 nm. The light-induced formation of an excited state exhibits relatively long lifetimes of 890 ns in acetonitrile and 650 ns in water.