Excited-state proton transfer relieves antiaromaticity in molecules

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 116; no. 41; pp. 20303 - 20308
• Main Authors: Wu, Chia-Hua, Karas, Lucas José, Ottosson, Henrik, Wu, Judy I-Chia
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 08.10.2019
• Subjects: antiaromaticity; Aromatic compounds; aromaticity; Baird's rule; Bonding strength; Chemical bonds; Electrons; Excitation; excited-state proton transfer; Hydrogen; Hydrogen bonding; Hydrogen bonds; Hydroxyquinolines - chemistry; Light effects; Models, Molecular; Molecular Structure; Organic chemistry; Organic compounds; Photoexcitation; Physical Sciences; Protons; Quantum Theory; Salicylic acid; Salicylic Acid - chemistry; Substrates; Tautomers; antiaromaticity; hydrogen bonding; Baird’s rule; excited-state proton transfer; aromaticity

Baird’s rule explains why and when excited-state proton transfer (ESPT) reactions happen in organic compounds. Bifunctional compounds that are [4n + 2] π-aromatic in the ground state, become [4n + 2] π-antiaromatic in the first ¹ππ* states, and proton transfer (either inter- or intramolecularly) hel...