Issue 18, 2023

A binaphthalimide motif as a chiral scaffold for thermally activated delayed fluorescence with circularly polarized luminescence activity

Abstract

This work describes the synthesis, photophysical and chiroptical properties of a new carbazole-naphthalimide donor–acceptor pair designed to induce circularly polarized thermally activated delayed fluorescence (CP-TADF). A monomeric achiral variant is compared to the dimeric target designed with a binaphthalimide core. TD-DFT calculations performed with the TPSSh basis set suggested that while the monomeric form should be purely fluorescent, dimerization is expected to trigger the emergence of TADF. Time-dependent and temperature-dependent spectroscopic analyses proved that while the monomeric species did not display any delayed emission because of a wide singlet-triplet (ΔEST) energy gap of 0.46 eV, the dimerization had a tremendous effect reducing the ΔEST to 0.1 eV enabling TADF emission with a 31% photoluminescence quantum yield in toluene. The enantiomers exhibited high performance CPL at room and low temperature with a dissymmetry factor up to 6 × 10−3 for TADF at room temperature and 5.2 × 10−2 for phosphorescence at 77 K. The chiral target displays various solid-state packings from the yellow phase (YP), including crystals, aggregates and gels, to an orange/red phase (OP). The transition from YP to OP can be achieved by applying mechanical stress.

Graphical abstract: A binaphthalimide motif as a chiral scaffold for thermally activated delayed fluorescence with circularly polarized luminescence activity

Supplementary files

Article information

Article type
Paper
Submitted
25 Jan 2023
Accepted
21 Mar 2023
First published
12 Apr 2023

J. Mater. Chem. C, 2023,11, 5968-5978

A binaphthalimide motif as a chiral scaffold for thermally activated delayed fluorescence with circularly polarized luminescence activity

Y. Tsuji, N. Kanno, C. Goto, S. Katao, Y. Okajima, P. Reine, P. Imbrasas, S. Reineke, K. Shizu, T. Nakashima, H. Kaji, T. Kawai and M. Louis, J. Mater. Chem. C, 2023, 11, 5968 DOI: 10.1039/D3TC00316G

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