Unlocking Nitroaromatic Radicals: Formation & Reactivity

Invited talk given at the International Conference on Electron Spin Resonance (ICESR-2026) in Bengaluru, India, 21-24 March 2026.

Abstract:

Organic radicals—metal-free molecules with unpaired electrons—exhibit unique magnetic and reactivity properties, enabling applications ranging from qubit implementations¹ to valuable chemical transformations.² However, their reactive nature and the synthetic challenges associated with their preparation impose strict structural and electronic constraints, limiting broader exploitation. Developing general strategies for radical formation under mild conditions, using readily available and inexpensive reagents, and applicable to a broad range of molecule, remains a key challenge.

Here, we present our efforts to establish nitroaromatic compounds as a versatile platform for radical formation, enabled by a single-electron transfer (SET) process from a wide range of anionic organo bases. Building on proof-of-concept studies of nitrobenzene,³ and combining continuous wave X-band EPR spectroscopy, quantum chemical calculations, and synthetic approaches, we demonstrate that this SET-induced mechanism operates across a broad set of commonly used nitroaromatic compounds, including FDA-approved drugs – these findings suggest a previously overlooked prevalence of nitroaromatic radical species. We further show how this framework resolves contested reaction mechanisms⁴ and enables the rational exploitation of SET-derived radical pairs to access valuable chemical transformations more efficiently.

Overall, our work highlights the untapped potential of SET-driven radical formation in nitroaromatic compounds and opens the door to extending radical properties to other Lewis acids.

Keywords: Organic Radicals, Single Electron Transfer, Lewis pairs, Nitroaromatics, Regioselectivity.

Bibliography

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2. Lu, Z., Ju, M., Wang, Y. et al. Regioselective aliphatic C–H functionalization using frustrated radical pairs. Nature, 2023, 619, 514–520.
3. S. A. Balahoju, N. Bhattacharjee, L. Lezama, et al., ACS Omega, 2025, 10, 22, 23798–23807
4. Zhang, Z., Yue, S., Jin, B. et al. Para-selective nitrobenzene amination lead by C(sp²)-H/N-H oxidative cross-coupling through aminyl radical. Nat Commun, 2024, 15, 4186.