Solution Synthesis and Characterization of a Long and Curved Graphene Nanoribbon with Hybrid Cove–Armchair–Gulf Edge Structures. Issue 19 (24th March 2022) - Yang, Lin
Abstract: Curved graphene nanoribbons (GNRs) with hybrid edge structures have recently attracted increasing attention due to their unique band structures and electronic properties as a result of their nonplanar conformation. This work reports the solution synthesis of a long and curved multi‐edged GNR (cMGNR ) with unprecedented cove–armchair–gulf edge structures. The synthesis involves an efficient A2 B2 ‐type Diels–Alder polymerization between a diethynyl‐substituted prefused bichrysene monomer (3b ) and a dicyclopenta[ e, l ]pyrene‐5, 11‐dione derivative (6 ) followed by FeCl3 ‐mediated Scholl oxidative cyclodehydrogenation of the obtained polyarylenes (P1 ). Model compounds 1a and 1b are first synthesized to examine the suitability and efficiency of the corresponding polymers for the Scholl reaction. The successful formation of cMGNR from polymer P1 bearing prefused bichrysene units is confirmed by FTIR, Raman, and solid‐state NMR analyses. The cove‐edge structure of the cMGNR imparts the ribbon with a unique nonplanar conformation as revealed by density functional theory (DFT) simulation, which effectively enhances its dispersibility in solution. The cMGNR has a narrow optical bandgap of 1.61 eV, as estimated from the UV–vis absorption spectrum, which is among the family of low‐bandgap solution‐synthesized GNRs. Moreover, the cMGNR exhibits a carrier mobility of ≈2 cm 2 V −1 s −1 inferred from contact‐free terahertz spectroscopy. Abstract : A curved multi‐edged graphene nanoribbon (cMGNR) with an unprecedented cove–armchair–gulf edge topology is synthesized through the efficient A2 B2 ‐type Diels–Alder polymerization followed by the Scholl reaction. The resultant cMGNR possesses an average length of sub‐hundred nanometer and a narrow optical bandgap, making it a promising candidate for the fabrication of single GNR‐based nanoelectronic devices.