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Superoctazethrene: An Open-Shell Graphene-like Molecule Possessing Large Diradical Character but Still with Reasonable Stability
Laterally extended zethrenes can be regarded as Z-shaped nanographenes with four zigzag edges, but their synthesis is very challenging. Herein, we report the successful synthesis of by far the largest zethrene molecule, a superoctazethrene (SOZ) derivative SOZ-Cl, in crystalline form. Although the p...
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Published in: | Journal of the American Chemical Society 2018-10, Vol.140 (43), p.14054-14058 |
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Main Authors: | , , , , , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Laterally extended zethrenes can be regarded as Z-shaped nanographenes with four zigzag edges, but their synthesis is very challenging. Herein, we report the successful synthesis of by far the largest zethrene molecule, a superoctazethrene (SOZ) derivative SOZ-Cl, in crystalline form. Although the parent SOZ is calculated to have a very large diradical character (y 0 = 81.0%), SOZ-Cl shows reasonable stability (t 1/2 = 64 h under ambient conditions) and can be purified by silica gel column chromatography. It exhibits a small electrochemical energy gap (E g = 1.01 eV) and characteristics for open-shell singlet diradicaloids. Compared with a previously reported octazethrene derivative (OZ-TIPS), SOZ-Cl shows much larger diradical character (y 0 = 76.3% vs 43.4%) and smaller singlet–triplet gap (ΔE S‑T = −2.30 kcal/mol vs −3.87 kcal/mol). Calculations also demonstrate global aromatic character of SOZ, but the smaller size octazethrene shows local aromaticity. |
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ISSN: | 0002-7863 1520-5126 |
DOI: | 10.1021/jacs.8b09075 |