On-surface synthesis of aligned functional nanoribbons monitored by scanning tunnelling microscopy and vibrational spectroscopy

Abstract

In the blooming field of on-surface synthesis, molecular building blocks are designed to self-assemble and covalently couple directly on a well-defined surface, thus allowing the exploration of unusual reaction pathways and the production of specific compounds in mild conditions. Here we report on the creation of functionalized organic nanoribbons on the Ag(110) surface. C–H bond activation and homo-coupling of the precursors is achieved upon thermal activation. The anisotropic substrate acts as an efficient template fostering the alignment of the nanoribbons, up to the full monolayer regime. The length of the nanoribbons can be sequentially increased by controlling the annealing temperature, from dimers to a maximum length of about 10 nm, limited by epitaxial stress. The different structures are characterized by room-temperature scanning tunnelling microscopy. Distinct signatures of the covalent coupling are measured with high-resolution electron energy loss spectroscopy, as supported by density functional theory calculations.

The Orientation of Silver Surfaces Drives the Reactivity and the Selectivity in Homo‐Coupling Reactions

“…Upon annealing at 300 °C, linear dimers 4 or trimers alike are formed, strictly aligned along the [001]‐direction of the substrate (Figure b). The reaction can be extended further for an annealing temperature of 350 °C, leading to the formation of linear nanoribbons up to ∼10 nm long (inset Figure b), as we previously showed . On this surface, strict selectivity of the reaction type is thus observed, and also the reaction advancement can be finely controlled by the temperature.…”

“…We used the symmetrical precursor s ‐indacene‐1,3,5,7(2 H ,6 H )‐tetrone (INDO 4 , 1 , Figure ) to allow the formation of extended polymers . Also, an original reaction pathway, i. e. an oxidative coupling (see Figure ), has been recently observed with this molecule . We studied the adsorption of INDO 4 on silver surfaces in ultrahigh vacuum environment (UHV) using several complementary surface sensitive techniques such as room‐temperature STM, high resolution electron energy loss spectroscopy (HREELS) and X‐ray photoemission spectroscopy (XPS), in order to provide a comprehensive picture of the different mechanisms involved ,,…”

Functionalized Graphdiyne Nanowires: On‐Surface Synthesis and Assessment of Band Structure, Flexibility, and Information Storage Potential

“…However, the intricate coupling mechanism and the occurrence of cross‐linking side reactions prevented so far the production of high‐quality 2D architectures. With the help of substrate templating mechanisms, which proved efficient for increasing regio‐ and chemoselectivity, so‐called extended graphdiyne (GDY) nanowires were realized on a vicinal surface . Since the unit cell contained three phenyl and two alkyne moieties, the specific nanowire is designated a 3‐2 GDY nanowire.…”

Materials informatics for self-assembly of functionalized organic precursors on metal surfaces

“…While the importance of hydrogen bonding for forming 2D tilings in is well-known 1 , 2 , 14 – 18 , the other connections between functional group properties and island shape elucidated above appear new and may be helpful for bottom-up fabrication of low-dimensional nanomaterials from functionalized bianthracene precursors on Cu(111). We stress that the dendrogram is only intended to connect island shapes with functional group properties, and is not meant to identify the physical mechanisms that lead to a particular island shape.…”