Novel liquid crystals with high fluorescence: Synthesis, mesomorphic and photophysical properties of cholesterol-triazine-BODIPY trimers

By step-by-step etherification on cyanuric chloride with BODIPY unit and cholesterol units, two novel cholesterol-triazine-BODIPY trimers (compounds 6 and 7 with one and two cholesterol unit, respectively) were designed and synthesized in high yields. The investigation on mesomorphic properties suggested that compound 6 with one cholesterol unit was a nematic liquid crystal but compound 7 with two cholesterol units was a hexagonal columnar liquid crystal. Both compounds 6 and 7 exhibited the strong fluorescence with high quantum yields and larger Stokes shifts than their precursors. The cholesterol-triazine moiety played crucial role for producing liquid crystalline property and enhancing fluorescence.