Mechanochemistry: Fundamentals, applications and future

From molecules in solution to molecules on surfaces – using supramolecular dyads to form functional self-assembled networks on graphene Quentin Fernez a , Shiva Moradmand b , Michele Mattera a , William Djampa-Tapi c , Céline Fiorini-Debuisschert c , Fabrice Charra c , David Kreher d , Fabrice Mathevet ab , Imad Arfaoui b and Lydia Sosa Vargas a * a Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire (IPCM), France, b Sorbonne Université, CNRS, Laboratoire de la Molécule aux Nano-Objets : Réactivité, France, c Université Paris-Saclay, CEA-CNRS, France, d Université Versailles St-Quentin-en-Yvelines, France Using supramolecular chemistry to functionalise graphene for photonic applications is a challenging issue due to graphene’s capacity to quench any emission from molecules adsorbed on its surface. To overcome this problem, we propose the use of molecular dyads to form ordered self-assemblies on graphene-like substrates. These dyads are designed to reduce surface quenching by positioning the emissive component out-of-the plane of the substrate. We use a zinc porphyrin and a phthalocyanine as molecular pedestals to immobilise the dyads onto the graphene thanks to a nanoporous network; and a perylenetetracarboxylic diimide, as the emissive component. In order to obtain reproducible, functional, 2D self-assemblies on graphene from two different sets of molecules, we need to identify and characterise precisely the species present in the solution. So, we studied the formation of these dyads by absorbance, fluorescence and NMR spectroscopy in solution. We then analysed their self- assembling properties by scanning tunnelling microscopy; after drop-casting the dyad solutions on a nanoporous template. In solution, we demonstrate that these components can form two types of dyads, depending on the supramolecular interactions that dominate the equilibrium in the solution. A metal-ligand association was observed between the perylene and the porphyrin pedestal, whilst the phthalocyanine led to a dyad formed via π-π interactions. Finally, from STM observations, we conclude that the same dyads present in the solution are present on the surface. References 1. A. K. Geim and K. S. Novoselov, Nature Materials, 2007, 6, 183–191. 2. N. Petrone, C. R. Dean, I. Meric, A. M. van der Zande, P. Y. Huang, L. Wang, D. Muller, K. L. Shepard and J. Hone, NanoLett., 2012, 12, 2751–2756. 3. C. Anichini and P. Samorì, Small, 2021, 17, 2100514. 4. V. Georgakilas, M. Otyepka, A. B. Bourlinos, V. Chandra, N. Kim, K. C. Kemp, P. Hobza, R. Zboril and K. S. Kim, Chem. Rev., 2012, 112, 6156–6214. 5. S. Le Liepvre, P. Du, D. Kreher, F. Mathevet, A.-J. Attias, C. Fiorini-Debuisschert, L. Douillard and F. Charra, ACS Photonics, 2016, 3, 2291–2296. 6. L. Sosa-Vargas, E. Kim and A.-J. Attias, Mater. Horiz., DOI:10.1039/C7MH00127D 7. F. Würthner, C. R. Saha-Möller, B. Fimmel, S. Ogi, P. Leowanawat and D. Schmidt, Chem. Rev., 2016, 116, 962–1052. 8. C. Arrigoni, G. Schull, D. Bléger, L. Douillard, C. Fiorini-Debuisschert, F. Mathevet, D. Kreher, A.-J. Attias and F. Charra, J. Phys. Chem. Lett., 2010, 1, 190–194. 9. Q Fernez, S. Moradmand, M. Mattera, W. Djampa-Tapi, C. Fiorini-Debuisschert, F. Charra, D. Kreher, F. Mathevet, I. Arfaoui and L. Sosa Vargas, unpublished results, submitted recently to J. Mat. Chem. C, 2022.

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