title: Molecules-oligomers-nanowires-graphene nanoribbons: a bottom-up stepwise on-surface covalent synthesis preserving long-range order.
abstract: We report on a stepwise on-surface polymerization reaction leading to oriented graphene nanoribbons on Au(111) as the final product. Starting from the precursor 4,4″-dibromo-p-terphenyl and using the Ullmann coupling reaction followed by dehydrogenation and C-C coupling, we have developed a fine-tuned, annealing-triggered on-surface polymerization that allows us to obtain an oriented nanomesh of graphene nanoribbons via two well-defined intermediate products, namely, p-phenylene oligomers with reduced length dispersion and ordered submicrometric molecular wires of poly(p-phenylene). A fine balance involving gold catalytic activity in the Ullmann coupling, appropriate on-surface molecular mobility, and favorable topochemical conditions provided by the used precursor leads to a high degree of long-range order that characterizes each step of the synthesis and is rarely observed for surface organic frameworks obtained via Ullmann coupling.
authors.affiliation: Dipartimento di Scienze Chimiche, Università degli Studi di Padova and Consorzio INSTM , Via Marzolo 1, 35131 Padova, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Basagni
authors.forename: Francesco
authors.initials: F
authors.lastname: Sedona
authors.forename: Carlo A
authors.initials: CA
authors.lastname: Pignedoli
authors.forename: Mattia
authors.initials: M
authors.lastname: Cattelan
authors.forename: Louis
authors.initials: L
authors.lastname: Nicolas
authors.forename: Maurizio
authors.initials: M
authors.lastname: Casarin
authors.forename: Mauro
authors.initials: M
authors.lastname: Sambi