Tetraphenylethylene-rufigallol-tetraphenylethylene trimers: Novel fluorescence liquid crystals in aggregated states

This work reported two novel liquid crystals with good fluorescence in aggregated states. Two tetraphenylethylene-rufigallol-tetraphenylethylene trimers (compounds 6a and 6b) were prepared in simple procedure. The columnar liquid crystalline behaviors of 6a and 6b were confirmed by the analysis of differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction. Compound 6b exhibited an ordered hexagonal columnar mesophase. They possessed excellent AIE fluorescence properties in THF-H2O solution, solid film and mesophase. The fluorescence quantum yields of compounds 6a and 6b were 12% and 22% in solid films, 14% and 24% in mesophase, respectively. The experimental results showed that the liquid crystalline properties and fluorescence properties were tuned by the lengths of the terminal alkyl chains.