COVER PAGE IN CHEMISTRY OF MATERIALS

Our paper reporting on-surface formation of gold porphyrins has been selected for cover page of Chemistry of Materials, vol. 31.  

In the manuscript, we report the formation of gold porphyrin derivatives via thermally induced chemical transformations of a fluorinated free-base porphyrin, 2H-4FTPP, on a Au(111) surface, which can rarely be accessed via standard solution chemistry protocols. We also provide an accurate description of the mechanisms of on-surface reactions and self-assembly processes, including structural and electronic characterization of intermediates and products using high-resolution scanning probe microscopy with a CO tip supported by a computational study. An initial annealing step at 500 K induces planarization of the adsorbed free base via dehydrogenation and ring-closing reactions that preserve the integrity of the C–F bonds. A second annealing step at 575 K enables metalation, producing unprecedented surface-supported gold-coordinated planarized porphyrins. A final annealing step at 625 K induces C–F and C–H activation, leading to intermolecular C–C coupling between phenyl termini to form planarized porphyrin oligomers. These results open new avenues for engineering in a stepwise manner thermally sensitive on-surface chemical reactions and metal–organic compounds that cannot be accessed in solution chemistry.

B. Cirera, B. de la Torre, D. Moreno, M. Ondráček, R. Zbořil, R. Miranda, P. Jelínek, D. Écija 
On-Surface Synthesis of Gold Porphyrin Derivatives via a Cascade of Chemical Interactions: Planarization, Self-Metalation, and Intermolecular Coupling 
Chem. Mater. 31 (2019) 3248 - 3256.