biostudies-literatureKrzeszewski MFundacja na rzecz Nauki PolskiejNarodowe Centrum Nauki2353-2360https://www.ebi.ac.uk/biostudies/studies/S-EPMC9977460biostudies-literatureUnknown14(9)A saddle-shaped aza-nanographene containing a central 1,4-dihydropyrrolo[3,2-<i>b</i>]pyrrole (DHPP) has been prepared <i>via</i> 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 <i>E</i> _ox1 = -0.38 V (<i>vs.</i> Fc/Fc⁺).Chemical scienceSaddle-shaped aza-nanographene with multiple odd-membered rings.PMC9977460START scholarship no. 039.2017TEAM POIR.04.04.00-00-3CF4/16-00HARMONIA 2018/30/M/ST5/00460Dobrzycki LGryko DTKrzeszewski MSobolewski ALCyranski MKfalseSaddle-shaped aza-nanographene with multiple odd-membered rings.A saddle-shaped aza-nanographene containing a central 1,4-dihydropyrrolo[3,2-<i>b</i>]pyrrole (DHPP) has been prepared <i>via</i> 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 <i>E</i> _ox1 = -0.38 V (<i>vs.</i> Fc/Fc⁺).2023-01-01T00:00:00Z2023 Mar2026-03-17T16:00:07.788Z2025-02-19T02:21:37.721ZS-EPMC99774603687385010.1039/d2sc05858h