Two novel π-conjugated fluorophores for dye-doped LC on-off photo-luminescence switching

Among various classes of photoluminescent (PL) compounds, soft-matter based materials in which chromophores are embedded in a liquid-crystal (LC) host polymer prove to be very attractive in the production of flexible panels and on-off temperature switches. Actually, the obtainment of low cost, easily synthesizable, and stable organic molecules soluble in the LC matrix is a challenge for both scholars and technologists. Here we describe the synthesis of two new emissive dyes based on a dicyano-phenylenevinylene and on a bis-azobenzene core whose PL properties were investigated as neat solids, in solution, and in particular in a dye-doped LC nematic polymer often employed in PDLC applications.1H NMR and13C NMR spectroscopy allow the characterization of all compounds Their thermotropic liq-uid-crystalline (LC) properties were examined by differential scanning calorimetry and polarizing optical microscopy. Photoluminescence properties were characterized by fluorescence spectra.