Photochemistry and Photophysics of Coordination Compounds: Ruthenium

Ruthenium compound, particularly Ru(II) polypyridine complexes, are the class of transition metal complexes which has been most deeply investigated by a photochemical viewpoint. The reason for such a great interest stems from a unique combination of chemical stability, redox properties, excited state reactivity, luminescence emission, and excited state lifetime. Ruthenium polypyridine complexes are indeed good visible absorbers, feature relatively intense and long-lived luminescence, and can undergo reversible redox processes both in the ground and excited states. This chapter presents some general concepts on the photochemical properties of Ru(II)-polypyridine complexes and reports an overview of various research topics involving ruthenium photochemistry which have emerged in the last 15 years. In particular, aspects connected to supramolecular photochemistry and photophysics are discussed, such as multicomponent systems for light harvesting and photoinduced charge separation, systems for photoinduced multielectron/hole storage and photocatalytic processes based on supramolecular Ru(II)-polypyridine species. Interaction with biological systems and dye-sensitized photoelectrochemical cells are alsobriefly discussed.