Photostability of luminescent ruthenium(II) complexes in polymers and in solution.

The effects of oxygen on the photochemical properties of ruthenium(II) complexes in solution and in polymers are reported. In solution, the complex is actually protected from decomposition by the presence of oxygen as a result of deactivation of the complex by oxygen quenching before it can undergo ligand loss by monomolecular dissociation; however, in polymers, the presence of oxygen increases photochemical decomposition. Singlet molecular oxygen, a product of the oxygen quenching process, may attack the ground state complex or triplet oxygen may directly attack the excited state of the complex. Both mechanisms may be involved in the photodestruction of the complex. The role of oxygen in the photodecomposition was examined by monitoring the photochemical decomposition of various complexes of different singlet oxygen reactivity, as well as absorption and mass spectroscopy studies. It is suggested that in polymers, unlike in solutions, the newly formed reactive singlet oxygen is not able to diffuse away fr...