Low quantum efficiency of μ-oxo iron bisporphyrin photoacatalysts explained with femtosecond M-edge XANES

Abstract

Bridged μ-oxo iron bisporphyrins serve as photocatalysts for oxidative organic transformations, but suffer from low quantum efficiency. We use femtosecond optical and M2,3-edge XANES spectroscopy to investigate the early photodynamics of the μ-oxo iron bisporphyrin, (TPPFe)2O, providing evidence for the preferential formation of an TPPFe(III)+/TPPFe(III)-O- ion pair state instead of the desired TPPFe(II)/TPPFe(IV)=O.