On-surface synthesis and atomic-scale characterization of porphyrin-based nanostructures

Resumen del póster presentado a la XXXVIII Reunión Bienal de la Real Sociedad Española de Química, celebrada en el Palacio de Congresos de Granada, del 27 de junio al 30 de junio de 2022.Porphyrins (Pors) are tetrapyrrolic macrocycles that offer a palette of highly attractive features for applications in materials science. In particular, π-extended Pors have gained considerable attention in the field of organic semiconductors and molecular electronics due to their low HOMO-LUMO gaps. Furthermore, Pors can chelate transition metal ions in their inner cavity, which allows the construction of magnetically-active nanostructures, such as organic spin filters. However, the synthesis of such π-extended Pors typically suffers severe limitations, arising from lengthy synthetic schemes, low yields, poor solubility and significant stability issues. In this context, on-surface synthesis under ultra-high vacuum (UHV) conditions has emerged as an appealing alternative for the fabrication of such poorly soluble and inherently unstable structures. In addition to the synthetic benefits, the resulting on-surface synthesized nanostructures can directly be accessed by local-probe techniques such as scanning probe microscopy, allowing for an “in situ” structural and electronic characterization with sub-molecular resolution. In this communication, we present our recent progress in the on-surface preparation of Por-based nanostructures. A special focus will be laid on the electronic effects of the π-extension of the Por core, either with graphene nanoribbon (GNR) fragments or with open-shell polyaromatic hydrocarbons (PAHs), which in some cases leads to the appearance of an open-shell character as well as new and exciting reactive sites. Furthermore, the inherent open-shell structure of some of these structures can be combined with magnetically active transition metal ions, which opens the path towards complex and intriguing nanostructures.Peer reviewe