Circularly polarized luminescence based on cholesterol-tetraphenylethylene-perylene liquid crystal

Abstract

Perylene derivative with circularly polarized luminescence (CPL) at aggregated state was seldom reported due to the strong ACQ (aggregation-caused quench) effect at aggregation. In this work, a novel cholesterol-tetraphenylethylene-perylene derivative (TPE-P) was designed and synthesized in moderate yield. It exhibited liquid crystalline behavior with orderly hexagonal columnar mesophase and good fluorescence emission at long wavelength (600-700 nm) not only in solution but also at aggregated states based on the AIE (aggregation-induced emission)-FRET (fluorescence resonance energy transfer) effect between tetraphenylethylene unit and perylene moiety. Moreover, the circular dichroism (CD) and CPL studies suggested the effective chiral transfer from cholesterol unit to tetraphenylethylene unit and perylene skeleton due to the spiral liquid crystalline self-assembly. The CD and CPL signals showed the order of THF < THF-hexane < solid film < meosphase, indicating that the higher spiral orderly degree resulted in the stronger chiral transfer. The largest |glum| value for mesophase excited at 320 nm was as high as 1.5×10−2 based on the combining effect of AIE-FRET and chiral transfer. This research not only reported a novel CPL perylene derivative at aggregated state, but also confirmed that the combination of AIE-FRET effect and chiral transfer of liquid crytalline phase was an effective method to construct normal dye with excellent CPL property in aggregated state.