title: Stereoselective photopolymerization of tetraphenylporphyrin derivatives on Ag(110) at the sub-monolayer level.
abstract: We explore a photochemical approach to achieve an ordered polymeric structure at the sub-monolayer level on a metal substrate. In particular, a tetraphenylporphyrin derivative carrying para-amino-phenyl functional groups is used to obtain extended and highly ordered molecular wires on Ag(110). Scanning tunneling microscopy and density functional theory calculations reveal that porphyrin building blocks are joined through azo bridges, mainly as cis isomers. The observed highly stereoselective growth is the result of adsorbate/surface interactions, as indicated by X-ray photoelectron spectroscopy. At variance with previous studies, we tailor the formation of long-range ordered structures by the separate control of the surface molecular diffusion through sample heating, and of the reaction initiation through light absorption. This previously unreported approach shows that the photo-induced covalent stabilization of self-assembled molecular monolayers to obtain highly ordered surface covalent organic frameworks is viable by a careful choice of the precursors and reaction conditions.
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Padova, Via Marzolo 1, 35131, Padova (Italy). andrea.basagni@studenti.unipd.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Basagni
authors.forename: Luciano
authors.initials: L
authors.lastname: Colazzo
authors.forename: Francesco
authors.initials: F
authors.lastname: Sedona
authors.forename: Marco
authors.initials: M
authors.lastname: DiMarino
authors.forename: Tommaso
authors.initials: T
authors.lastname: Carofiglio
authors.forename: Elisa
authors.initials: E
authors.lastname: Lubian
authors.forename: Daniel
authors.initials: D
authors.lastname: Forrer
authors.forename: Andrea
authors.initials: A
authors.lastname: Vittadini
authors.forename: Maurizio
authors.initials: M
authors.lastname: Casarin
authors.forename: Alberto
authors.initials: A
authors.lastname: Verdini
authors.forename: Albano
authors.initials: A
authors.lastname: Cossaro
authors.forename: Luca
authors.initials: L
authors.lastname: Floreano
authors.forename: Mauro
authors.initials: M
authors.lastname: Sambi
keywords: covalent organic frameworks; on-surface synthesis; porphyrins; scanning tunneling microscopy (STM); surface photochemistry; surface polymerization