Simultaneous optical tuning of reflection and fluorescence in a self-organized simple 3D cubic structure by α-cyanodiarylethene-based chiral fluorescence photoswitches

Abstract

The simultaneous phototuning of reflection and fluorescence in blue-phase liquid crystals (BPLCs) based on chiral fluorescence photoswitches was demonstrated. First, two novel α-cyanodiarylethene-based chiral fluorescence photoswitches with excellent photoresponsive performances and chiral induction abilities were synthesized, including switch 1 featuring a central (S)-binaphthyl chiral group linked to a one-sided α-cyanoethene moiety and switch 2 possessing a two-sided α-cyanoethene structure. BPLC systems were then constructed by doping switch 1 and switch 2 into the chiral LCs, thus, the BP temperature ranges were broadened in both the systems. Furthermore, a fast, reversible, and large-shift tuning of the photonic bandgap (PBG) of BPII with a self-organized simple 3D cubic structure can be achieved in the switch 1-doped BPLC system upon light irradiation, accompanied by significant changes in fluorescence intensity. Finally, high contrast reflectance-fluorescence dual-mode patterns in the BPLCs were obtained.