Elucidating the Role of NaCl in the on-Surface Synthesis of Conjugated Azaacene Polymers on Au(111)

Kratky, Tim and Liu, Xunshan and Guenther, Sebastian and Mutombo, Pingo and Schio, Luca and Floreano, Luca and Decurtins, Silvio and Repp, Jascha and Jelinek, Pavel and Liu, Shi-Xia and Patera, Laerte L. (2025) Elucidating the Role of NaCl in the on-Surface Synthesis of Conjugated Azaacene Polymers on Au(111). CHEMISTRY-A EUROPEAN JOURNAL, 31 (69). ISSN 0947-6539, 1521-3765

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Abstract

On-surface synthesis (OSS) offers unique opportunities for fabricating carbon-based nanostructures that are unattainable by conventional wet-chemical synthesis. Despite OSS being extremely successful, the use of coadsorbates to promote reactions remains largely unexplored. In this study, we investigate the role of sodium chloride (NaCl) in promoting the Scholl reaction (oxidative aryl-aryl coupling) of hexaazatriphenylene (HAT) molecules on Au(111), leading to the growth of conjugated azaacene oligomers. Using scanning tunneling microscopy (STM), synchrotron-based X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations, we shed light on the reaction mechanism and the intermediates involved. Upon codeposition on Au(111), NaCl decomposes on the surface, releasing Na atoms that form thermally stable metal-organic complexes, enhancing precursor stability against desorption. This stabilizing effect allows HAT molecules to undergo regioselective intermolecular coupling for polymerization at elevated temperatures. This study highlights the role of alkali metals in on-surface chemical reactions and outlines a strategy for overcoming the precursor-desorption issue.

Item Type: Article
Uncontrolled Keywords: METAL-ORGANIC NANOSTRUCTURES; CROSS-SECTIONS; ALKALI-METALS; PHOTOIONIZATION; ADSORPTION; density functional theory; on-surface synthesis; scanning tunneling microscopy; surface chemistry; X-ray photoemission spectroscopy
Subjects: 500 Science > 530 Physics
500 Science > 540 Chemistry & allied sciences
Divisions: Physics > Institute of Experimental and Applied Physics > Group Jascha Repp
Depositing User: Dr. Gernot Deinzer
Date Deposited: 07 May 2026 04:53
Last Modified: 07 May 2026 04:53
URI: https://pred.uni-regensburg.de/id/eprint/67466

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