Emission Intensity Enhancement for Iridium(III) Complex in Dimethyl Sulfoxide under Photoirradiation.

We found emission intensity enhancement for fac-Ir(ppy)3 (ppy = 2-(2'-phenyl)pyridine) in aerated dimethyl sulfoxide (DMSO) during photoirradiation for the first time. This phenomenon was concluded to be responsible for the consumption of 3O2 dissolved in DMSO through dimethyl sulfone production by photosensitized reaction using fac-Ir(ppy)3. A 3O2 adduct of DMSO molecule was detected by UV absorption measurement and theoretical calculation. We proposed a mechanism for the emission enhancement reaction including 1,3O2 molecules and 1,3O2-DMSO adducts and validated it through a simulation of emission intensity change using an ordinary differential equation solver.