A long-lived fluorenyl cation: Efficiency booster for uncaging and photobase properties

Chahinez Abdellaoui, Volker Hermanns, Matiss Reinfelds, Maximilian Scheurer, Andreas Dreuw, Alexander Heckel, Josef Wachtveitl*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The photochemistry of fluorenols has been of special interest for many years. This is because both the fluorenol and the fluorenyl cation are antiaromatic in the ground state due to their 4n π-electrons according to the Hückel rule. The photolysis reaction of various fluorene derivatives takes place via a cation intermediate and is preferred due to its excited state aromaticity. Here we present an extremely long-lived fluorenyl cation and its effects on the uncaging of various leaving groups. We analyze the relationship between uncaging quantum yields of fluorene-based cages and the longevity of their fluorenyl cations with different spectroscopic methods in the steady state and on an ultrafast time scale and find that the uncaging quantum yield rises with the stability of the cation. In contrast to previous reports, the cation can be observed on a time scale of minutes, even in moderately protic solvents as methanol and ethanol. The stability of this cation depends on the dimethylamino-substituents on the fluorene scaffold and the properties of the solvent. In addition, with bis-dimethylamino fluorenol, a photobase is introduced that expands the small group of known photoinduced hydroxide emitters.

Original languageEnglish
Pages (from-to)5294-5300
Number of pages7
JournalPhysical Chemistry, Chemical Physics
Issue number9
Publication statusPublished - 7 Mar 2022

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry


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