Synthesis and Luminescence Properties of Dumbbell-Shaped Molecules Combined with Rod and Disc-Like Mesogens

A novel series of dumbbell-shaped molecules containing 1,3,4-oxadiazole moieties (OXDn: n=1, 2, and 3) was designed and synthesized. The molecular structures of these 1,3,4-oxadiazole derivatives were confirmed by FT-IR, 1H-NMR spectroscopy and elemental analyzer. The electron excitation and luminescence properties of these compounds were investigated by UV-vis absorption spectroscopy and photoluminescence spectroscopy both in CHCl3 solution and in solid state. The absorption peaks were found at 336nm-351nm, and the photoluminescent peaks at 410nm-450nm. The thermal properties were investigated by DSC method. Their melting temperatures were in the range of 81-95 degrees C depending on the structure. Especially, OXD1 could show a discotic columnar mesophase at 75 degrees C monotropically.