Photophysics and spectroscopy of 1,2-Benzazulene

The electronic spectroscopy and photophysics of 1,2-benzazulene (BzAz) have been examined in solution and in thin solid films, with the objective of comparing its intramolecular and intermolecular excited state decay processes with those of azulene. Unlike azulene, the S-2 - S-0 absorption and fluorescence spectra exhibit a clear mirror image relationship dominated by a single strong Franck-Condon active progression. Picosecond transient absorption spectra and non-linear S-2 fluorescence upconversion experiments reveal lifetimes that follow a well established energy gap law correlation, indicative of a dominant S-2 - S-1 decay route. Mechanistic interpretations, including the possibility of S-2 singlet fission in aggregates, are discussed.

Automated summary

The electronic spectroscopy and photophysics of 1,2-benzazulene have been studied in solution and thin solid films to compare its excited state decay processes with that of azulene. Results show a unique mirror image relationship in the absorption and fluorescence spectra, with lifetimes following an energy gap law correlation. Discussions include the possibility of singlet fission in aggregates.