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Dynamic Covalent Properties of a Novel Indolo[3,2‐b]carbazole Diradical.

Authors :
Badía‐Domínguez, Irene
Peña‐Álvarez, Miriam
Wang, Deliang
Pérez Guardiola, Andrés
Vida, Yolanda
Rodríguez González, Sandra
López Navarrete, Juan T.
Hernández Jolín, Víctor
Sancho García, Juan C.
García Baonza, Valentín
Nash, Rosie
Hartl, František
Li, Hongxiang
Ruiz Delgado, M. Carmen
Source :
Chemistry - A European Journal; 3/22/2021, Vol. 27 Issue 17, p5509-5520, 12p
Publication Year :
2021

Abstract

This work describes the synthesis and properties of a dicyanomethylene‐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) σ‐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 monomer ICz‐Br reveal that the nature of the one‐electron oxidation 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 groups stabilizes the close‐lying LUMO and LUMO+1 of (ICz‐CN)2 and especially ICz‐CN compared to ICz‐Br, resulting in a distinctive cathodic response at low overpotentials. Differently from neutral ICz‐CN, its radical anion 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 σ‐bond in neutral (ICz‐CN)2 is cleaved in solution and in the solid‐state upon soft external stimuli (temperature, pressure), showing a strong chromism from light yellow to blue–green. Notably, in the solid state, the monomeric diradical species is predominantly formed under high hydrostatic pressure (>1 GPa). [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
09476539
Volume :
27
Issue :
17
Database :
Complementary Index
Journal :
Chemistry - A European Journal
Publication Type :
Academic Journal
Accession number :
149412076
Full Text :
https://doi.org/10.1002/chem.202005211