Donor influence on the optoelectronic properties of N-substituted tetraphenylimidazole derivatives

Tomas Matulaitis, Paloma L dos Santos, Youichi Tsuchiya, David B. Cordes, Alexandra M. Z. Slawin, Chihaya Adachi, Ifor D. W. Samuel*, Eli Zysman-Colman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Three new 1,2,4,5-tetraphenylimidazole derivatives, 9,9-dimethyl-10-(4-(2,4,5-triphenyl-1H-imidazol-1-yl)phenyl)-9,10-dihydroacridine (DMAC-TPI), 10-(4-(2,4,5-triphenyl-1H-imidazol-1-yl)phenyl)-10H-phenoxazine (PXZ-TPI), and 10-(4-(2,4,5-triphenyl-1H-imidazol-1-yl)phenyl)-10H-phenothiazine (PTZ-TPI), bearing different electron donors at the N1 position of the imidazole were synthesised and characterised. DMAC-TPI and PXZ-TPI showed narrow emission at λPL of 388 and 418 nm in toluene, and in doped films in Zeonex polymer (1 wt.%) at λPL 381 and 407 nm, respectively, with a full width at half maximum (FWHM) ranging 0.42-0.44 eV. DMAC-TPI and PXZ-TPI are predicted to show very low oscillator strength for the low-energy transitions, which aligns to the observed low photoluminescence quantum yields. Both molecules showed a singlet-triplet energy gap (ΔEST of around 1.2 eV) that is much too large to enable reverse intersystem crossing and thermally activated delayed fluorescence. Connecting a donor group to TPI at the N1 position can lead to room temperature phosphorescence (RTP), as the example of PTZ-TPI showed.
Original languageEnglish
Article numbere202300274
Number of pages10
Issue number9
Early online date28 Feb 2023
Publication statusPublished - 6 Mar 2023


  • Bipolar
  • Charge transfer
  • DFT
  • Photophysics
  • Weak acceptor


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