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Dynamic covalent properties of a novel indolo[3,2-b]carbazole diradical

Badia-Dominguez, I., Pena-Alvarez, M., Wang, D., Peres Guardiola, A., Vida, Y., Rodriguez Gonzalez, S., Lopez Navarette, J. T., Hernadez Jolin, V., Sancho Garcia, J. C., Garcia Baonza, V., Nash, R., Hartl, F., Li, H. and Ruiz Delgado, M. C. (2021) Dynamic covalent properties of a novel indolo[3,2-b]carbazole diradical. Chemistry- A European Journal, 27 (17). pp. 5509-5520. ISSN 1521-3765

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To link to this item DOI: 10.1002/chem.202005211


This work describes the synthesis and properties of adicyanomethylene-substituted indolo[3,2-b]carbazole diradical ICz-CN. This quinoidal system dimerises almost completely to (ICz-CN)2,which contains two long C(sp3)@ C(sp3) s-bonds between the dicyanomethylene units. The minor open-shell ICz-CN component in the solid-state mixture was identified by EPR spectroscopy.Cyclic voltammetry and UV–visible spectroelectrochemical data, as well as comparison with reference monomerICz-Br reveal that the nature of the one-electronoxidation of (ICz-CN)2 at ambient temperature and ICz-CN at elevated temperature is very similar in all these compounds due to the prevailing localization of their HOMO on the ICz backbone. The peculiar cathodic behaviour reflects the co-existence of (ICz-CN)2 and ICz-CN. The involvement of the dicyanomethylene groupsstabilizes the close-lying LUMO and LUMO+1of(ICz-CN)2 and especially ICz-CN comparedtoICz-Br,resulting in ad istinctive cathodic response at low overpotentials. Differently from neutralICz-CN, its radicalanion and dianion are remarkably stable under ambient conditions. The UV/Vis(–NIR) electronic transitions in parent (ICz-CN)2 and ICz-CN and their different redox forms have been assigned convincingly with the aid of TD-DFT calculations. The s-bond in neutral(ICz-CN)2 is cleaved in solution and in the solid-state upon soft external stimuli (temperature, pressure), showing astrong chromism from light yellow to blue–green. Notably,inthe solid state, the monomeric diradical species is predominantly formed under high hydrostatic pressure (>1GPa).

Item Type:Article
Divisions:Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
ID Code:97653


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