On‐Surface Driven Formal Michael Addition Produces m‐Polyaniline Oligomers on Pt(111)
Martin-Gago J.A., Ruiz del Árbol N., Sánchez-Sánchez C., Otero-Irurueta G., Martínez J.I., de Andrés P.L., Gómez-Herrero A.C., Merino P., Piantek M., Serrate D., Lacovig P., Lizzit S., Alemán J., El
On‐surface synthesis is emerging as a highly rational bottom‐up methodology for the synthesis of molecular structures that are unattainable or complex to obtain by wet chemistry. Here, oligomers of meta‐ polyaniline, a known ferromagnetic polymer, were synthesized from para ‐aminophenol building‐blocks via an unexpected and highly specific on‐surface formal 1,4 Michael‐type addition at the meta position, driven by the reduction of the aminophenol molecule. We rationalize this dehydrogenation and coupling reaction mechanism with a combination of in‐situ scanning tunnelling and non‐contact atomic force microscopies, high‐resolution synchrotron‐based X‐ray photoemission spectroscopy and first‐principles calculations. This study demonstrates the capability of surfaces to selectively modify local molecular conditions to redirect well‐established synthetic routes, such as Michael coupling, towards the rational synthesis of new covalent nanostructures.
Pictorial view of the initial (IS), transition (TS), and final (FS) states for the two most favourable dimerization couplings of two different initial configurations of the precursors via the same attacking meta-site. This situation corresponds to the first step towards the formation of m-PANI.