Surface-bound reactions are a powerful method to develop nanoarchitecture through bottom-up as-sembly. The Ullmann-like coupling reaction has come to represent one of the most useful methods to form two-dimensional structures through covalent couplings of aromatic molecules following the dissociation of aryl carbon-halide bond. The leaving halogen atoms are proven to remain adsorbed on the surface and can be deleterious to the fabrication of larger conjugated superstructures. However, on Au(100) we have found the leaving halogen atoms generate a new adsorbate surface that leads to geo-metric isomer selectivity compared to the unmodified metal surface. The covalent coupling of 3,6-dibromo-phenanthrenequinone (DBPQ) was stud-ied. The bromine adlayer was found to modify the reconstruction of Au(100) and subsequently yield 100% selectivity of a radical trans dimer, while only cis dimers were observed on the undecorated Au surface. This selectivity on the new halogen surface ultimately resulted in larger conjugated polymers, a trait necessary for catalytic applications, bypassing the early termination of the reaction process due to steric hindrance.

Direct observation of the geometric isomer selectivity via scanning tunneling microscopy and tip-enhanced Raman spectroscopy

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.