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Resonance-enhanced charge delocalization in carbazole-oligoyne-oxadiazole conjugates

Zieleniewska, A; Zhao, X.; Bauroth, S.; Wang, C.; Batsanov, A.S.; Calderson, C.K.; Kahnt, A.; Clark, T.; Bryce, M.R.; Guldi, D.M.

Resonance-enhanced charge delocalization in carbazole-oligoyne-oxadiazole conjugates Thumbnail


Authors

A Zieleniewska

X. Zhao

S. Bauroth

C. Wang

C.K. Calderson

A. Kahnt

T. Clark

D.M. Guldi



Abstract

There are notably few literature reports of electron donor-acceptor oligoynes although they offer unique opportunities for studying charge transport through ‘all-carbon’ molecular bridges. In this context, the current study focuses on a series of carbazole–(C≡C)n-2,5-diphenyl-1,3,4-oxadiazoles (n = 1-4) as conjugated π-systems, in general, and explores their photophysical properties, in particular. Contrary to the behavior of typical electron donor-acceptor systems, for these oligoynes the rates of charge recombination after photoexcitation increase with increasing electron donoracceptor distance. To elucidate this unusual performance, detailed photophysical and time-dependent density functional theory investigations were conducted. Significant delocalization of the electron density along the bridge indicates that the bridging states come into resonance with either the electron donor or acceptor, thereby accelerating the charge transfer. Moreover, the calculated bond lengths reveal a reduction in bond length alternation upon photoexcitation, indicating significant cumulenic character of the bridge in the excited state. In short, strong vibronic coupling between the electrondonating N-arylcarbazoles and the electron-accepting 1,3,4-oxadiazoles accelerates the charge recombination as the oligoyne becomes longer.

Citation

Zieleniewska, A., Zhao, X., Bauroth, S., Wang, C., Batsanov, A., Calderson, C., …Guldi, D. (2020). Resonance-enhanced charge delocalization in carbazole-oligoyne-oxadiazole conjugates. Journal of the American Chemical Society, 142(44), 18769-18781. https://doi.org/10.1021/jacs.0c04003

Journal Article Type Article
Online Publication Date Oct 21, 2020
Publication Date Nov 4, 2020
Deposit Date Oct 8, 2020
Publicly Available Date Oct 21, 2021
Journal Journal of the American Chemical Society
Print ISSN 0002-7863
Electronic ISSN 1520-5126
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 142
Issue 44
Pages 18769-18781
DOI https://doi.org/10.1021/jacs.0c04003
Publisher URL https:/doi.org/10.1021/jacs.0c04003

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Copyright Statement
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https:/doi.org/10.1021/jacs.0c04003





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