Helical Nanographenes Containing an Azulene Unit: Synthesis, Crystal Structures, and Properties
Research output: Contribution to journal › Research article › Contributed › peer-review
Contributors
Abstract
Three unprecedented helical nanographenes (1, 2, and 3) containing an azulene unit are synthesized. The resultant helical structures are unambiguously confirmed by X-ray crystallographic analysis. The embedded azulene unit in 2 possesses a record-high twisting degree (16.1°) as a result of the contiguous steric repulsion at the helical inner rim. Structural analysis in combination with theoretical calculations reveals that these helical nanographenes manifest a global aromatic structure, while the inner azulene unit exhibits weak antiaromatic character. Furthermore, UV/Vis-spectral measurements reveal that superhelicenes 2 and 3 possess narrow energy gaps (2: 1.88 eV; 3: 2.03 eV), as corroborated by cyclic voltammetry and supported by density functional theory (DFT) calculations. The stable oxidized and reduced states of 2 and 3 are characterized by in-situ EPR/Vis–NIR spectroelectrochemistry. Our study provides a novel synthetic strategy for helical nanographenes containing azulene units as well as their associated structures and physical properties.
Details
Original language | English |
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Pages (from-to) | 5686-5691 |
Journal | Angewandte Chemie |
Volume | 132 |
Issue number | 14 |
Publication status | Published - 1 Mar 2020 |
Peer-reviewed | Yes |
External IDs
ORCID | /0000-0001-7323-7816/work/142257436 |
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