Engineering perfluoroarene-arene interactions in coumarin-1,2,3-triazole-arene hybrid molecules

Abstract

In this work, we describe the synthesis and characterization of five hybrid molecules combining coumarin, 1,2,3-triazole, and arene or perfluoroarene units (compounds 5a, 5b, 6a, 6b, and 7). Crystallization conditions of these compounds were explored, and single crystals of compounds 5b and 7 (as a dioxane solvate, 7^.DIOX) were obtained. X-ray diffraction analysis revealed the presence of perfluoroarene–arene (ArF···Ar) interactions that govern the solid-state packing of both structures, leading to rod-like stacking in 5b and layered arrays in 7·DIOX. The ArF···Ar contacts were associated with centroid-to-centroid distances between 3.8 and 4.1 Å. Thermal analysis (TGA-DSC) confirmed that all compounds maintain structural integrity at high temperatures; 7·DIOX retained its crystallinity up to 150 °C before solvent loss. Powder X-ray diffraction confirmed the formation of pure crystalline phases under the employed recrystallization conditions. Additionally, preliminary solid-state fluorescence studies showed modest emission for all coumarin-containing compounds (5a, 5b, and 7·DIOX), with red-shifted maxima and variable quantum yields potentially influenced by non-covalent interactions in their molecular packing. These results underscore the utility of perfluoroarene–arene interactions in directing solid-state organization in fluorinated hybrid molecules.