Novel blue luminescent twin molecules containing fluorene, carbazole or phenothiazine units

Three new twin molecules F, C and P that were bridged with a hexamethylene chain and contained fluorene, carbazole or phenothiazine units, respectively, were synthesized by Heck coupling. They were readily soluble in common organic solvents and showed a satisfactory thermal stability and relatively low glass transition temperatures. They absorbed at 302–373 nm with optical band gap of 2.72–3.01 eV. F and C emitted blue light (428–449 nm) both in solution and thin film, while P emitted blue-greenish light (489–503 nm). The highest photoluminescence (PL) quantum yield in THF solution was obtained for F (0.60). The PL emission maximum in thin film was slightly red shifted relative to solution, thus suggesting a low tendency of molecules to aggregate. This was attributed to structural characteristics of the twin molecules.