Luminescent supramolecular assemblies based on hydrogen-bonded complexes of stilbenecarboxylic acids and dithieno[3,2-b : 2 ',3 '-d]thiophene-2-carboxylic 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-t ris(4,5-dihydroimidazol-2-yl)benzene 13. Two X-ray crystal structures confi rm hydrogen bonds between carboxylate ligands and meta-positioned protonate d imidazoline groups. The complexes possess a surprisingly flat disk-like s hape with various close contacts between adjacent molecules. Most stilbene and dithieno[3,2-b:2',3'-d]thiophene derivatives show strong blue or blue-g reen photoluminescence in solution, whereas fluorescence in the solid state is almost completely quenched.