Issue 23, 2023

Rational design of anti-Kasha photoemission from a biazulene core embedded in an antiaromatic/aromatic hybrid

Abstract

The violation of the Kasha photoemission rule in organic molecules has intrigued chemists since their discovery, being always of relevance given its connection with unique electronic properties of molecules. However, an understanding of the molecular structure–anti-Kasha property relationship in organic materials has not been well-established, possibly because of the few existing cases available, limiting their prospective exploration and ad hoc design. Here we introduce a novel strategy to design organic emitters from high excited states combining intramolecular J-coupling of anti-Kasha chromophores with the hindering of vibrationally-induced non-radiative decay channels by enforcing molecular rigidity. We apply our approach to the integration of two antiparallel azulene units bridged with one heptalene all inserted into a polycyclic conjugated hydrocarbon (PCH). With the help of quantum chemistry calculations, we identify a suitable PCH embedding structure and predict its anti-Kasha emission from the third high energy excited singlet state. Finally, steady fluorescence and transient absorption spectroscopy studies corroborate the photophysical properties in a recently synthesized chemical derivative with this pre-designed structure.

Graphical abstract: Rational design of anti-Kasha photoemission from a biazulene core embedded in an antiaromatic/aromatic hybrid

Supplementary files

Article information

Article type
Edge Article
Submitted
24 Jan 2023
Accepted
22 May 2023
First published
22 May 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2023,14, 6420-6429

Rational design of anti-Kasha photoemission from a biazulene core embedded in an antiaromatic/aromatic hybrid

A. Diaz-Andres, J. Marín-Beloqui, J. Wang, J. Liu, J. Casado and D. Casanova, Chem. Sci., 2023, 14, 6420 DOI: 10.1039/D3SC00405H

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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