Our paper on excited state Jahn–Teller distortion in an Al(III) complex has been published in Journal of the American Chemical Society.

Our research group has elucidated the relationship between excited-state structural dynamics and photophysical properties in a highly symmetric Al(III) binuclear triple-helical complex. These findings have been published in the Journal of the American Chemical Society (JACS).

Molecular symmetry  is a critical factor in determining the performance of photofunctional materials. While symmetry breaking in the excited state and its influence on photophysical behavior have been widely explored in d-block metal complexes, such phenomena remain largely unexplored in main-group element complexes.

In this study, we investigated an Al(III) dinuclear triple-helical complex that combines a twisted π-conjugated framework with high symmetry. Using femtosecond transient absorption spectroscopy with 10 fs pump pulse, we observed coherent nuclear wavepacket motion in the excited state. In particular, we identified a ligand twisting mode with a vibrational dephasing time of 410 fs that strongly couples to a Jahn–Teller distortion. This coupling induces symmetry breaking and flattening of one of the three ligands.

Our results reveal that this excited-state symmetry breaking and its coupling to vibrational modes that modulate π-conjugation are responsible for the large Stokes shift and high photoluminescence quantum yield observed in the Al(III) complex. This study provides a new design strategy for next-generation photofunctional materials based on earth-abundant elements and demonstrates the potential of symmetry-controlled excited-state dynamics in molecular design.

“Dynamic Excited-State Localization Induced by Jahn–Teller Distortion Observed by Coherent Vibrational Spectroscopy”
Takumi Ehara, Yusuke Yoneda, Tatsuya Yoshida, Tomohiro Ogawa, Yuto Konishi, Toshikazu Ono, Atsuya Muranaka, Hikaru Kuramochi*, Kiyoshi Miyata* and Ken Onda*
J. Am. Chem. Soc. in press, 2025