Tuning the Electrochemical and Photophysical Properties of Osmium-Based Photoredox Catalysts

Abstract The use of low-energy deep-red (DR) and near-infrared (NIR) light to excite chromophores enables catalysis to ensue across barriers such as materials and tissues. Herein, we report the detailed photophysical characterization of a library of OsII polypyridyl photosensitizers that absorb low-energy light. By tuning ligand scaffold and electron density, we access a range of synthetically useful excited state energies and redox potentials. 1 Introduction 1.1 Scope 1.2 Measuring Ground-State Redox Potentials 1.3 Measuring Photophysical Properties 1.4 Synthesis of Osmium Complexes 2 Properties of Osmium Complexes 2.1 Redox Potentials of Os(L)2-Type Complexes 2.2 Redox Potentials of Os(L)3-Type Complexes 2.3 UV/Vis Absorption and Emission Spectroscopy 3 Conclusions