Benzene in the excited state: A playground for photochemical transformations

Abstract: Benzene, in the excited state, is a remarkably reactive chemical motif. The year 2025 marks the 200-year anniversary of Faraday’s discovery of benzene, and in this talk I will explore how its excited-state behavior offers a unique platform for photochemical transformations. The talk begins with a quick introduction to Baird’s rule, the reversal of the Hückel electron-counting rule for aromaticity and antiaromaticity in the lowest ππ* states of annulenes. I will then highlight computational explorations from our group over the past decade on how relief of excited-state antiaromaticity in benzene derivatives and heteroarenes can drive diverse photochemical transformations, including proton transfer, electron transfer, π-bond activation, tunable Lewis interactions, and photo-HF elimination.