Multiresponsive luminescent dicyanodistyrylbenzenes and their photochemistry in solution and in bulk

Multiresponsive luminescent materials with dicyanodistyrylbenzene chromophores incorporated into bent-core and rod-like molecules have been prepared and characterized. Rod-like compounds exhibit nematic or smectic liquid crystal phases, whereas bent-core compounds melt directly to the isotropic liquid at high temperatures. Fluorescence properties are very sensitive to external stimuli such as heat, light, pressure and solvent vapors. All compounds undergo Z/E photoisomerization in solution under UV irradiation. In addition, photochemical activity in bulk has been investigated. Whereas the crystal phases are stable under UV irradiation, the liquid crystal phases are unstable giving rise to Z/E photoisomerization and [2+2]-photocycloaddition products. As a consequence, photoinduced phase changes are observed. This study shows the versatilty of dicyanodistyrylbenzene-based liquid crystals as novel types of photoreactive materials.