Graphene; 1,3,4-oxadiazole; non-covalent interactions; supramolecular interactions; spectroscopy.

In this work, we investigated the interaction between graphene films and pyridyl derivatives of the 1,3,4-oxadiazole (2-(4-(dodecyloxy)phenyl)-5-(pyridin-3-yl)-1,3,4-oxadiazole (Oxa3py) and 2-(4-(dodecyloxy)phenyl)-5-(pyridin-4-yl)-1,3,4-oxadiazole (Oxa4py)), as well as the influence of this interaction on the properties of the molecules. The systems are formed by the adsorption of the molecules onto the films at a solid-liquid interface. Results of electronic absorption and emission spectroscopy showed that the molecule preserved its photophysical properties after adsorption onto the films, and their desorption processes confirmed the nature of physisorption interactions. We analyzed the solvent's influence on mechanically exfoliated graphene substrate and found that it interacts with the graphene sheet, potentially competing for adsorption sites with the molecules. Density functional theory (DFT) calculations were performed to investigate the adsorption behavior of the oxadiazole derivatives on graphene. The results indicated the molecules adsorb in a parallel configuration relative to the graphene plane, approximately 3.2 to 3.5 Å above the surface, without the formation of conventional chemical bonds. The adsorption of Oxa4py was found to be more stable, exhibiting more negative adsorption energies than Oxa3py, 1.33 and 1.07 eV, respectively. There is a small charge transfer, approximately 0.019 e, from graphene to the molecules, resulting in p-type doping. This low value should be insuficiente to significantly alter the properties of the molecules, which is consistent with the preservation of their photophysical properties.