My group explores functions of excited-state molecules. Prime interest is to control and utilize processes involving spin flip during electronic transition (e.g., phosphorescence) or in the excited state (e.g., intersystem crossing) of complexes having late transition metals. Specifically, wedevelope novel classes of molecular emitters, triplet sensitizers, photoredox catalysts, and bioprobes, with combined use of quantum chemistry, organic/organometallic/polymer synthesis techniques, and photophysical and electrochemical methods.
One of our key advances was a novel molecular mechanism which enabled very high quantum yields for photoelectrochemical functionalization of drugs through cycling of both photon and electron. We also investigated molecular origin for short operation time of blue-phosphorescent organic light-emitting devices. Our mechanistic study revealed that reactive radical ion species could be generated even under balanced carrier injection, and that exciton-mediated intermolecular electron transfer between a host and a dopant was responsible for the generation of such species. Finally, we extend our understanding of excited-state molecules to biological applications. Probes for use in metalloneurochemistry have been developed. In addition, biological utility of photosensitizers that generate singlet oxygen (1O2) has been successfully demonstrated.