Issue 30, 2019

Revealing resonance effects and intramolecular dipole interactions in the positional isomers of benzonitrile-core thermally activated delayed fluorescence materials

Abstract

We report on the properties of the three positional isomers of (2,7-di-tert-butyl-9,9-dimethylacridin-10(9H)-yl)benzonitrile, which are found to have comparable donor steric environments and donor–acceptor dihedral angles. An unexpected intramolecular dipole interaction imparts a unique molecular geometry to the ortho-linked isomer, while comparison of the meta- and para-isomers uncovers how positional differences in acceptor strengths (a consequence of differences in aromatic π-system electron density) lead to very different triplet harvesting and emission properties. These positional-isomer effects on TADF follow the well-known aromatic directing rules from organic synthesis, in keeping with their common origin arising from contributions of multiple electronic resonance structures. Understanding these positional effects and methods of dihedral control is critical to the future design of efficient TADF emitters.

Graphical abstract: Revealing resonance effects and intramolecular dipole interactions in the positional isomers of benzonitrile-core thermally activated delayed fluorescence materials

Supplementary files

Article information

Article type
Paper
Submitted
22 may 2019
Accepted
28 iyn 2019
First published
12 iyl 2019
This article is Open Access
Creative Commons BY license

J. Mater. Chem. C, 2019,7, 9184-9194

Revealing resonance effects and intramolecular dipole interactions in the positional isomers of benzonitrile-core thermally activated delayed fluorescence materials

N. A. Kukhta, H. F. Higginbotham, T. Matulaitis, A. Danos, A. N. Bismillah, N. Haase, M. K. Etherington, D. S. Yufit, P. R. McGonigal, J. V. Gražulevičius and A. P. Monkman, J. Mater. Chem. C, 2019, 7, 9184 DOI: 10.1039/C9TC02742D

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