Issue 9, 2023

Saddle-shaped aza-nanographene with multiple odd-membered rings

Abstract

A saddle-shaped aza-nanographene containing a central 1,4-dihydropyrrolo[3,2-b]pyrrole (DHPP) has been prepared via a rationally designed four-step synthetic pathway encompassing intramolecular direct arylation, the Scholl reaction, and finally photo-induced radical cyclization. The target non-alternant, nitrogen-embedded polycyclic aromatic hydrocarbon (PAH) incorporates two abutting pentagons between four adjacent heptagons forming unique 7−7−5−5−7−7 topology. Such a combination of odd-membered-ring defects entails a negative Gaussian curvature within its surface with a significant distortion from planarity (saddle height ≈ 4.3 Å). Its absorption and fluorescence maxima are located in the orange-red region, with weak emission originating from the intramolecular charge-transfer character of a low-energy absorption band. Cyclic voltammetry measurements revealed that this stable under ambient conditions aza-nanographene underwent three fully reversible oxidation steps (two one-electron followed by one two-electron) with an exceptionally low first oxidation potential of Eox1 = −0.38 V (vs. Fc/Fc+).

Graphical abstract: Saddle-shaped aza-nanographene with multiple odd-membered rings

Supplementary files

Article information

Article type
Edge Article
Submitted
23 okt 2022
Accepted
03 jan 2023
First published
03 jan 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-NC license

Chem. Sci., 2023,14, 2353-2360

Saddle-shaped aza-nanographene with multiple odd-membered rings

M. Krzeszewski, Ł. Dobrzycki, A. L. Sobolewski, M. K. Cyrański and D. T. Gryko, Chem. Sci., 2023, 14, 2353 DOI: 10.1039/D2SC05858H

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