Catching aromaticity in the act: Direct real-time tracking of how 'excited-state aromaticity' drives molecular shape changes

Scientists have achieved the first real-time visualization of how 'excited-state aromaticity' emerges within just hundreds of femtoseconds and then triggers a molecule to change from bent to planar structure in a few picoseconds. By combining ultrafast electronic and vibrational spectroscopies, the team captured these fleeting structural changes at the molecular level and showed that aromaticity appears before -- and then drives -- the structural planarization. Their findings lay the groundwork for designing more efficient photoactive materials, such as sensors and light-driven molecular switches, by leveraging the power of aromaticity in excited states.

source https://www.sciencedaily.com/releases/2025/03/250312134632.htm