Issue 8, 2023

Exceptionally flexible quinodimethanes with multiple conformations: polymorph-dependent colour tone and emission of crystals

Abstract

Tetraarylated quinodimethanes, which are one of the overcrowded ethylenes, can adopt multiple conformations, such as folded, twisted, and other forms. However, it is difficult to obtain all of these conformations due to energy differences among them. To tackle this issue, we designed flexible polyaryl-substituted tetraazaanthraquinodimethanes (N4AQDs), in which a steric hindrance in the overcrowded fjord region was moderately reduced. As a result, X-ray analyses revealed that N4AQDs could adopt not only folded and twisted forms but also intermediate structures, e.g., planar and twisted-folded forms, in pseudopolymorphs. Since there is a large difference in the electronic configuration among conformers, the colour tone of crystals varied from yellow to red depending on the conformation of overcrowded N4AQDs. Notably, red to near-infrared emission was observed for the crystal containing twisted conformers. This is the first example of exceptionally flexible quinodimethanes with tunable photophysical properties and multi-chromic behaviour based on multiple conformations.

Graphical abstract: Exceptionally flexible quinodimethanes with multiple conformations: polymorph-dependent colour tone and emission of crystals

Supplementary files

Article information

Article type
Research Article
Submitted
21 Nov 2022
Accepted
04 Feb 2023
First published
08 Feb 2023
This article is Open Access
Creative Commons BY license

Mater. Chem. Front., 2023,7, 1591-1598

Exceptionally flexible quinodimethanes with multiple conformations: polymorph-dependent colour tone and emission of crystals

K. Sugawara, T. Ono, Y. Yano, T. Suzuki and Y. Ishigaki, Mater. Chem. Front., 2023, 7, 1591 DOI: 10.1039/D2QM01199A

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