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Toward cove-edged low band gap graphene nanoribbons.


ABSTRACT: Graphene nanoribbons (GNRs), defined as nanometer-wide strips of graphene, have attracted increasing attention as promising candidates for next-generation semiconductors. Here, we demonstrate a bottom-up strategy toward novel low band gap GNRs (Eg = 1.70 eV) with a well-defined cove-type periphery both in solution and on a solid substrate surface with chrysene as the key monomer. Corresponding cyclized chrysene-based oligomers consisting of the dimer and tetramer are obtained via an Ullmann coupling followed by oxidative intramolecular cyclodehydrogenation in solution, and much higher GNR homologues via on-surface synthesis. These oligomers adopt nonplanar structures due to the steric repulsion between the two C-H bonds at the inner cove position. Characterizations by single crystal X-ray analysis, UV-vis absorption spectroscopy, NMR spectroscopy, and scanning tunneling microscopy (STM) are described. The interpretation is assisted by density functional theory (DFT) calculations.

SUBMITTER: Liu J 

PROVIDER: S-EPMC4456008 | biostudies-other | 2015 May

REPOSITORIES: biostudies-other

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Toward cove-edged low band gap graphene nanoribbons.

Liu Junzhi J   Li Bo-Wei BW   Tan Yuan-Zhi YZ   Giannakopoulos Angelos A   Sanchez-Sanchez Carlos C   Beljonne David D   Ruffieux Pascal P   Fasel Roman R   Feng Xinliang X   Müllen Klaus K  

Journal of the American Chemical Society 20150504 18


Graphene nanoribbons (GNRs), defined as nanometer-wide strips of graphene, have attracted increasing attention as promising candidates for next-generation semiconductors. Here, we demonstrate a bottom-up strategy toward novel low band gap GNRs (Eg = 1.70 eV) with a well-defined cove-type periphery both in solution and on a solid substrate surface with chrysene as the key monomer. Corresponding cyclized chrysene-based oligomers consisting of the dimer and tetramer are obtained via an Ullmann coup  ...[more]