Chen, Xi and Sun, Lei and Sukhanov, Andrey A. and Doria, Sandra and Bussotti, Laura and Zhao, Jianzhang and Xu, Haijun and Dick, Bernhard and Voronkova, Violeta K. and Di Donato, Mariangela (2024) Photophysics and photochemistry of thermally activated delayed fluorescence emitters based on the multiple resonance effect: transient optical and electron paramagnetic resonance studies. CHEMICAL SCIENCE, 15 (28). pp. 10867-10881. ISSN 2041-6520, 2041-6539
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The photochemistry of two representative thermally activated delayed fluorescence (TADF) emitters based on the multiple resonance effect (MRE) (DABNA-1 and DtBuCzB) was studied. No significant TADF was observed in fluid solution, although the compounds have a long-lived triplet state (ca. 30 mu s). We found that these planar boron molecules bind with Lewis bases, e.g., 4-dimethylaminopyridine (DMAP) or an N-heterocyclic carbene (NHC). A new blue-shifted absorption band centered at 368 nm was observed for DtBuCzB upon formation of the adduct; however, the fluorescence of the adduct is the same as that of the free DtBuCzB. We propose that photo-dissociation occurs for the DtBuCzB-DMAP adduct, which is confirmed by femtosecond transient absorption spectra, implying that fluorescence originates from DtBuCzB produced by photo-dissociation; the subsequent in situ re-binding was observed with nanosecdon transient absorption spectroscopy. No photo-dissociation was observed for the NHC adduct. Time-resolved electron paramagnetic resonance (TREPR) spectra show that the triplet states of DABNA-1 and DtBuCzB have similar zero field splitting (ZFS) parameters (D = 1450 MHz). Theoretical studies show that the slow ISC is due to small SOC and weak Herzberg-Teller coupling, although the S1/T1 energy gap is small (0.14 eV), which rationalizes the lack of TADF. The photophysics of thermally activated delayed fluorescence emitters based on the multiple resonance effect was studied.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | LIGHT-EMITTING-DIODES; CHARGE-TRANSFER; TRANSFER STATE; GOLD(III) COMPLEXES; ACCEPTOR; PHOSPHORESCENCE; SEPARATION; ENERGY; LIGAND; TADF; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry III - Physical Chemistry (Molecular Spectroscopy and Photochemistry) > Prof. Dr. Bernhard Dick |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 17 Nov 2025 13:25 |
| Last Modified: | 17 Nov 2025 13:25 |
| URI: | https://pred.uni-regensburg.de/id/eprint/65202 |
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