Boron-nitrogen-doped nanographenes: a synthetic tale from borazine precursors

Dosso, Jacopo ORCID: https://orcid.org/0000-0003-4173-3430, Battisti, Tommaso, Ward, Benjamin D. ORCID: https://orcid.org/0000-0003-1406-5940, Demitri, Nicola, Hughes, Colan E., Williams, P. Andrew, Harris, Kenneth D. M. ORCID: https://orcid.org/0000-0001-7855-8598 and Bonifazi, Davide ORCID: https://orcid.org/0000-0001-5717-0121 2020. Boron-nitrogen-doped nanographenes: a synthetic tale from borazine precursors. Chemistry - A European Journal 26 (29) , pp. 6608-6621. 10.1002/chem.201905794

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Abstract

In this paper we report a comprehensive account of our synthetic efforts to prepare borazino-doped hexabenzocoronenes using the Friedel-Crafts-type electrophilic aromatic substitution. We showed that hexafluoro-functionalized aryl-borazines, bearing an ortho fluoride leaving group on each N- and B-aryl rings, could lead to cascade-type electrophilic aromatic substitution events in the stepwise C-C bond formation giving higher yields of borazinocoronenes than those obtained with borazine precursors bearing fluoride leaving groups at the ortho positions of the B-aryl substituents. It is with this pathway that an unprecedented boroxadizine-doped PAH featuring a gulf-type periphery could be isolated, and its structure proved through single crystal X-ray diffraction analysis. Mechanistic studies on the stepwise Friedel-Crafts-type cyclisation suggest that the mechanism of the planarization reaction proceeds through extension of the π system. To appraise the doping effect of the boroxadizine unit on the optoelectronic properties of topology-equivalent molecular graphenes, the all-carbon and pyrylium PAH analogues, all featuring a gulf-type periphery, were also prepared. As already shown for the borazino-doped hexabenzocoronene, the replacement of the central benzene ring by its B3N2O congener widens the HOMO-LUMO gap and it dramatically enhances the fluorescence quantum yield.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Advanced Research Computing @ Cardiff (ARCCA) Chemistry
Additional Information:	Published in - Special Issue: Chemical Functionalization of 2D Materials
Publisher:	Wiley
ISSN:	1521-3765
Date of First Compliant Deposit:	13 February 2020
Date of Acceptance:	5 February 2020
Last Modified:	11 Nov 2024 09:45
URI:	https://orca.cardiff.ac.uk/id/eprint/129637

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