Structure Formation and Coupling Reactions of Hexaphenylbenzene and Its Brominated Analog. Issue 17 (18th July 2021)

• Record Type: Journal Article
• Authors: Teeter, Jacob D.; Costa, Paulo S.; Dobner, Christoph; Sarker, Mamun; Sinitskii, Alexander; Enders, Axel
• Is Part Of: Chemphyschem. Volume 22:Issue 17(2021)
• Page Start: 1769
• Page End: 1773
• Publication Date: 2021-07-18
• Subjects: graphene nanoribbons -- on-surface synthesis -- scanning tunneling microscopy -- self-assembly -- carbon nanostructure; Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.202100049
• Languages: English
• ISSNs: 1439-4235

Abstract

Abstract: The on‐surface coupling of the prototypical precursor molecule for graphene nanoribbon synthesis, 6, 11‐dibromo‐1, 2, 3, 4‐tetraphenyltriphenylene (C42 Br2 H26, TPTP), and its non‐brominated analog hexaphenylbenzene (C42 H30, HPB), was investigated on coinage metal substrates as a function of thermal treatment. For HPB, which forms non‐covalent 2D monolayers at room temperature, a thermally induced transition of the monolayer's structure could be achieved by moderate annealing, which is likely driven by π‐bond formation. It is found that the dibrominated carbon positions of TPTP do not guide the coupling if the growth occurs on a substrate at temperatures that are sufficient to initiate C−H bond activation. Instead, similar one‐dimensional molecular structures are obtained for both types of precursors, HPB and TPTP. Abstract : Annealing and substrate control self‐assembly : The precursor molecule 6, 11‐dibromo‐1, 2, 3, 4‐tetraphenyltriphenylene, C42 Br2 H26, is commonly used to fabricate chevron‐type graphene nanoribbons (top) via precursor polymerization that is guided by the two Br substituents. Under certain conditions, which include the substrate choice and the annealing conditions, the self‐assembly is not guided by the Br substituents, and alternative nanostructures (center and bottom) are observed. Such structurers are also observed when the non‐brominated analog hexaphenylbenzene (C42 H30 ) is used.