Hierarchical on-surface assembly of nanoribbons through concurrent hydrogen- and chalcogen-bonding interactions

Abstract

Secondary Bonding Interactions (SBIs), particularly chalcogen bonding interactions (ChBIs), offer powerful opportunities to direct the assembly of functional organic materials on surfaces. Here we combine Te-based ChBIs with F···H hydrogen bonds (HBs) to drive the hierarchical engineering of supramolecular nanoribbons on Au(111) using a chalcogenazolo-pyridine derivative. Low-temperature scanning tunnelling microscopy imaging reveals that the molecules first undergo directional Te···N chalcogen-bonded dimerisation, followed by HB-mediated polymerisation into robust nanoribbon architectures. Density functional theory calculations confirm the adsorption geometries and intermolecular binding modes. The Au(111) herringbone reconstruction templates the nanoribbon orientation and maximum attainable length, with the face-centred cubic regions being the preferred adsorption sites. Scanning tunnelling spectroscopy reveals two intrinsic electronic fingerprints at +0.6 V and +1.8 V, corresponding to the LUMO and LUMO+1 of the dimeric repeat unit, respectively. The dI/dV mapping visualises their distinct spatial distributions along the ribbon backbone and edges. Control experiments with a non-pyridyl congener that cannot engage in Te···N ChBIs yield only simple linear assemblies, confirming the pivotal role of ChBIs in enabling hierarchical ordering.