In the pursuit of applications-targeted materials, the reaction of small molecular precursors on a surface is emerging as an attractive route towards designing 1D and 2D materials with well-defined chemical and structural properties. For example, the use of extended molecular scaffolds has led to unprecedented control over the growth of graphene nanoribbons on surfaces.[1] In this same vein, we have been systematically studying the use of small, single-ring aromatic precursor molecules as candidates for on-surface materials synthesis. Ironically, these simple molecules exhibit surprisingly complex behaviour under reaction conditions on metal surfaces. Here, I will discuss what we have learned by studying a range of di- and tri-carboxylated pyridine and benzene-based molecules on copper and silver single crystals. Through thermal annealing, we initiate first deprotonation, then decarboxylation of the molecules. We find that the adsorption geometry of the molecules changes significantly as they undergo successive reactions,[2] that molecules in different chemical states can assemble into complex structural motifs,[3] and that maintaining the pyridine ring integrity during decarboxylation may be difficult.[4] We have studied these systems using a range of surface science techniques including photoelectron spectroscopy, near-edge x-ray absorption fine structure and scanning tunnelling microscopy. When combined with density functional theory calculations, these measurements give us well-rounded insight into the challenges inherent in predictive control of on-surface synthesis using small precursor molecules.<br/><br/>

Assemblies and reactions of small carboxylated molecules on metal surfaces: diverse chemical and structural outcomes from simple precursor molecules

2019 Spring National Meeting

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