Seeking to expand light response into the visible range, we turned our attention towards ruthenium (Ru) polypyridyl complexes, which continue to gain new and unique ground in the world of photochemistry . These compounds are highly photoactive and undergo covalent bond breakage upon visible light irradiation, with quantum yields of photodissociation many times greater than current organic chromophores and reaching 0.1 -0.6 in many cases .