title: Homo-coupling of terminal alkynes on a noble metal surface.
abstract: The covalent linking of acetylenes presents an important route for the fabrication of novel carbon-based scaffolds and two-dimensional materials distinct from graphene. To date few attempts have been reported to implement this strategy at well-defined interfaces or monolayer templates. Here we demonstrate through real space direct visualization and manipulation in combination with X-ray photoelectron spectroscopy and density functional theory calculations the Ag surface-mediated terminal alkyne C(sp)-H bond activation and concomitant homo-coupling in a process formally reminiscent of the classical Glaser-Hay type reaction. The alkyne homo-coupling takes place on the Ag(111) noble metal surface in ultrahigh vacuum under soft conditions in the absence of conventionally used transition metal catalysts and with volatile H(2) as the only by-product. With the employed multitopic ethynyl species, we demonstrate a hierarchic reaction pathway that affords discrete compounds or polymeric networks featuring a conjugated backbone. This presents a new approach towards on-surface covalent chemistry and the realization of two-dimensional carbon-rich or all-carbon polymers.
authors.affiliation: Physik Department E20, Technische Universität München, 85748 Garching, Germany.
authors.forename: Yi-Qi
authors.initials: YQ
authors.lastname: Zhang
authors.forename: Nenad
authors.initials: N
authors.lastname: Kepčija
authors.forename: Martin
authors.initials: M
authors.lastname: Kleinschrodt
authors.forename: Katharina
authors.initials: K
authors.lastname: Diller
authors.forename: Sybille
authors.initials: S
authors.lastname: Fischer
authors.forename: Anthoula C
authors.initials: AC
authors.lastname: Papageorgiou
authors.forename: Francesco
authors.initials: F
authors.lastname: Allegretti
authors.forename: Jonas
authors.initials: J
authors.lastname: Björk
authors.forename: Svetlana
authors.initials: S
authors.lastname: Klyatskaya
authors.forename: Florian
authors.initials: F
authors.lastname: Klappenberger
authors.forename: Mario
authors.initials: M
authors.lastname: Ruben
authors.forename: Johannes V
authors.initials: JV
authors.lastname: Barth