Luminescent supramolecular assemblies based on hydrogenbonded complexes of stilbenecarboxylic acids and dithieno[3,2b:2′,3′d]thiophene2carboxylic acids with a tris(imidazoline) base

The synthesis of a number of stilbenecarboxylic acids, tetrazolylstilbenes and dithieno[3,2-b:2′,3′-d]thiophene-2-carboxylic acids is reported. These organic acids form non-covalent complexes with an imidazoline base, 1,3,5-tris(4,5-dihydroimidazol-2-yl)benzene 13. Two X-ray crystal structures confirm hydrogen bonds between carboxylate ligands and meta-positioned protonated imidazoline groups. The complexes possess a surprisingly flat disk-like shape with various close contacts between adjacent molecules. Most stilbene and dithieno[3,2-b:2′,3′-d]thiophene derivatives show strong blue or blue–green photoluminescence in solution, whereas fluorescence in the solid state is almost completely quenched.