An S-shaped double helicene showing both multi-resonance thermally activated delayed fluorescence and circularly polarized luminescence
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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.
Dos Santos , J , Sun , D , Naranjo , J , Hall , D , Zinna , F , Ryan , S , Shi , W , Matulaitis , T , Cordes , D B , Slawin , A M Z , Beljonne , D , Warriner , S , Olivier , Y , Fuchter , M & Zysman-Colman , E 2022 , ' An S-shaped double helicene showing both multi-resonance thermally activated delayed fluorescence and circularly polarized luminescence ' , Journal of Materials Chemistry C , vol. 10 , no. 12 , pp. 4861-4870 . https://doi.org/10.1039/D2TC00198E
Journal of Materials Chemistry C
Copyright © 2022 The Author(s). Open Access Article. This article is licensed under aCreative Commons Attribution 3.0 Unported Licence.
DescriptionFunding: Scottish Funding Council (SFC/AN/08/020), Leverhulme Trust (RPG-2016-047), H2020 Marie Skłodowska-Curie Actions (838009, 859752), UK Engineering and Physical Sciences Research Council (EP/P010482/1, EP/R00188X/1), Royal Society (SRF\R1\201089), Fonds De La Recherche Scientifique - FNRS (2.5020.11, F.4534.21), Università di Pisa (PRA 2020_21).
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