Self-Assembly Following the Photothermal On-Surface Synthesis of 3-Methoxy-fluorenol from 3-Methoxy-diazofluorene on a Ag(111) Surface

Abstract

The self-assembly of adsorbates on surfaces drives significant nanoscale ordering through noncovalent interactions. Here, we delve into the impact of on-surface synthesis on self-assembly by strategically introducing specific side groups. The reactant 3-methoxy-diazofluorene self-assembles into extended chains, while the product, 3-methoxy-fluorenol, formed via the intermediate 3-methoxy-fluorenylidene self-assembles into dimers. Both assemblies rely on robust weak hydrogen bonding between the methoxy groups or containing water hydrogen bonding within the methoxy groups. We employ high-resolution, low-temperature scanning tunneling microscopy, X-ray photoemission spectroscopy, and density functional theory calculations to follow each step of the reaction process. The methoxy groups in both the reactant and the intermediate are accurately identified through inelastic electron tunneling manipulation and density functional theory computations. Methoxy is revealed in the self-assembled product using a specially modified scanning tunneling microscopy tip. Our study demonstrates the reestablishment of hydrogen-bonding motifs present in the reactant, which play a crucial role in the self-assembly of the final products.