Controlling Excited-State Reactivity of Iron(III) photosensitizers

Troian-Gautier, Ludovic [UCL]

Due to its high abundance, low cost and low toxicity, photosensitizers based on iron have long been considered as the holy grail for photochemical applications. Unfortunately, with a few exceptions,[1-3] these photosensitizers suffer from extremely short, sub-nanosecond, excited-state lifetimes that limit diffusional reactivity. We have determined key parameters that have allowed to circumvent these limitations and achieve efficient excited-state electron transfer with large cage-escape yields using green light irradiation.[4,5] Dehalogenation reactions operated with large yields and a clear view of the mechanistic pathway with the associated rate constants was obtained by a combination of time-resolved spectroscopic methods, such as femtosecond and nanosecond transient absorption or infrared spectroscopy (TRIR).