Singlet Oxygen as a Reactive Intermediate in the Photodegradation of Phenylenevinylene Oligomers

Singlet molecular oxygen (a 1 Δ g ) is shown to be the principal reactive intermediate in the photoinduced oxygen-dependent decomposition of a series of phenylenevinylene oligomers. The reaction rate between singlet oxygen and the oligomer decreases (1) with a decrease in the extent of phenylenevinylene conjugation (i.e., oligomer chain length) and (2) upon the incorporation of electron-withdrawing substituents on the oligomer. The reaction rate, however, does not appear to depend solely on the electron density of the oligomer π system, as calculated using ab initio methods. For oligomers with vinyl-substituted cyano group(s), the reaction with singlet oxygen is very slow, thus making such compounds good candidates for the production of stable electroluminescent materials.