Helical Nanographenes Containing an Azulene Unit: Synthesis, Crystal Structures, and Properties

Ma J, Fu Y, Dmitrieva E, Liu F, Komber H, Hennersdorf F, Popov AA, Weigand JJ, Liu J, Feng X (2020)

Publication Type: Journal article

Publication year: 2020

Journal

Angewandte Chemie International Edition Wiley

Book Volume: 59

Pages Range: 5637-5642

Journal Issue: 14

DOI: 10.1002/anie.201914716

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.

Involved external institutions

Technische Universität Dresden DE Germany (DE) Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e.V. (IFW) / Leibniz Institute for Solid State and Materials Research Dresden DE Germany (DE) Leibniz-Institut für Polymerforschung Dresden e. V. DE Germany (DE) University of Hong Kong (HKU) / 香港大學 HK Hong Kong (HK)

How to cite

APA:

Ma, J., Fu, Y., Dmitrieva, E., Liu, F., Komber, H., Hennersdorf, F.,... Feng, X. (2020). Helical Nanographenes Containing an Azulene Unit: Synthesis, Crystal Structures, and Properties. Angewandte Chemie International Edition, 59(14), 5637-5642. https://doi.org/10.1002/anie.201914716

MLA:

Ma, Ji, et al. "Helical Nanographenes Containing an Azulene Unit: Synthesis, Crystal Structures, and Properties." Angewandte Chemie International Edition 59.14 (2020): 5637-5642.

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