Issue 36, 2023

Triplet conformation in chromophore-fused cyclooctatetraene dyes

Abstract

Cyclooctatetraene (COT) has a tub-shaped conformation in its ground non-aromatic state, while it is predicted to have a planar aromatic triplet state. However, COT possesses a non-vertical triplet state and therefore its detection has remained elusive through direct photoexcitation. Recently, fluorescent dyes synthesized by fusing COT with anthracene and phenazine “wings” have shown a large Stokes shift implying a significant conformational change in their excited singlet manifold. Here, using broadband transient absorption spectroscopy supported with electronic structure calculations, we demonstrate that intersystem crossing occurs in the planar COT conformation in these flapping dyes. We confirm that such a planar conformation in the triplet state does not impart aromaticity to the COT backbone, as previously predicted. Our work therefore provides the basis for the requisite structural design principles that would allow for triplet formation from excited singlet states in COT-based functional molecules.

Graphical abstract: Triplet conformation in chromophore-fused cyclooctatetraene dyes

  • This article is part of the themed collection: #MyFirstJMCC

Supplementary files

Article information

Article type
Paper
Submitted
19 Kho 2023
Accepted
08 Mha 2023
First published
08 Mha 2023

J. Mater. Chem. C, 2023,11, 12243-12253

Author version available

Triplet conformation in chromophore-fused cyclooctatetraene dyes

S. Paul, H. Kitakado, K. Suga, R. Kotani, N. Dey, R. Venkatramani, E. Matito, S. Saito and J. Dasgupta, J. Mater. Chem. C, 2023, 11, 12243 DOI: 10.1039/D3TC02151C

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