Cyclopenta-fused polyaromatic hydrocarbons: synthesis and characterisation of a stable, carbon-centred helical radical. Issue 14 (22nd March 2022)

• Record Type: Journal Article
• Authors: Herzog, Stefan; Hinz, Alexander; Breher, Frank; Podlech, Joachim
• Is Part Of: Organic & biomolecular chemistry. Volume 20:Issue 14(2022)
• Page Start: 2873
• Page End: 2880
• Publication Date: 2022-03-22
• Subjects: Chemistry, Organic -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1039/d2ob00172a
• Languages: English
• ISSNs: 1477-0520

Abstract

Abstract : An air- and moisture-stable helical radical with seven six- and five-membered rings arranged alternately was synthesized by cyclizations in a suitably ortho, ortho ′-substituted terphenyl and re-establishment of its conjugation. Abstract : An air- and moisture-stable helical radical with seven six- and five-membered rings arranged alternately was synthesized by cyclizations in a suitably ortho, ortho ′-substituted terphenyl and re-establishment of its conjugation. Mesityl groups at the five-membered rings prevent radical reactions. This cyclopenta-fused polyaromatic hydrocarbon (CP-PAH) was characterized by X-ray crystallographic analysis, EPR and UV/Vis spectroscopy, and by cyclic voltammetry. Further properties and spectra were determined by quantum chemical calculation (spin densities, orbital energies, UV/Vis/NIR and ECD spectra). It turned out that this radical is best described with its radical centre being in the outer five-membered rings, which allows for the largest number of fully intact benzene rings. Its triradical character is rather small and can be neglected. The five-membered rings show significant antiaromatic character, which is highest in the central ring.