An S-shaped double helicene showing both multi-resonance thermally activated delayed fluorescence and circularly polarized luminescence

John Dos Santos, Dianming Sun, Juan Naranjo, David Hall, Francesco Zinna, Seán Ryan, Wenda Shi, Tomas Matulaitis, David Bradford Cordes, Alexandra Martha Zoya Slawin, David Beljonne, Stuart Warriner, Yoann Olivier, Matthew Fuchter, Eli Zysman-Colman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)
3 Downloads (Pure)

Abstract

We present the first example of a multi-resonant thermally activated delayed fluorescent (MR-TADF) extended helicene, Hel-DiDiKTa. This S-shaped double helicene exhibits sky-blue emission, a singlet-triplet energy gap, ΔEST, of 0.15 eV and narrow emission at a peak maximum of 473 nm with a full-width at half-maximum of 44 nm in toluene. The MR-TADF character is confirmed by the small degree of positive solvatochromism and temperature-dependent increase in intensity of the delayed emission. The chiroptical properties of the separated enantiomers are similar to other large helicenes with comparable dissymmetry values, but with the added benefit of MR-TADF. (P)-Hel-DiDiKTa is stable towards enantiomerization, with a Gibbs free energy of activation for enantiomerization (ΔGe) of 31± 2 kcal mol-1 at 298 K, a value similar to other reported double helicenes. (P)-Hel-DiDiKTa is also thermally stable, with a 5% weight loss at 399 oC revealed by thermogravimetric analysis (TGA). Thus, this study further strengthens the burgeoning area of chiral TADF emitters for use in cutting-edge optoelectronic and photocatalytic molecules and materials.
Original languageEnglish
Pages (from-to)4861-4870
JournalJournal of Materials Chemistry C
Volume10
Issue number12
Early online date27 Jan 2022
DOIs
Publication statusPublished - 28 Mar 2022

Keywords

  • Chirality
  • Circular dichroism
  • Circularly polarized luminescence
  • Helical structure
  • Helicene
  • Multi-resonant thermally activated delayed fluorescence
  • Narrow emission
  • TADF

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