Cholesterol decorated thiophene-vinylnitrile derivatives: Synthesis, mesophase and circularly polarized luminescence

This paper reported two novel AIE fluorescence liquid crystals with good CPL emission based on cholesterol-decorated thiophene-vinylnitrile derivatives. Thiophene-vinylnitrile Schiff-base derivatives 7 with one cholesterol unit and 8 with two cholesterol units were prepared in yields of 82% and 85%, respectively. The smectic phase was proposed for compound 7 from 95.9 to 153.8 ? and for compound 8 from 103.5 to 178.1 ?. They exhibited high aggregate-induced emission in THF-H2O system, solid film and mesophase. The absolute fluorescence quantum yields were 0.29 for sample 7 and 0.39 for sample 8 in solid films. They displayed excellent circularly polarized luminescence based on chiral transfer and chiroptical amplification based on the orderly molecular stacking in mesophase. The more cholesterol units resulted in the better CPL properties. The |g(lum)| value of sample 8 in mesophase was as high as 2.5 x 10(-3).