Induced Red Circularly Polarized Luminescence Emission Promoted by Intermolecular Förster Resonance Energy Transfer through a Cholesteric Liquid Crystal Medium.

In this paper, planar chiral helicenes based on [2.2]paracyclophane PCPH5 acted as both chiral inducers and energy donors to construct the circularly polarized luminescence (CPL)-active ternary cholesteric liquid crystals (T-N*-LCs) in a commercial nematic liquid crystal (SLC1717, N-LCs) medium. Induced red CPL emission based on the energy acceptor of the achiral polymer DTBTF8 could be successfully promoted by the intermolecular Förster resonance energy transfer mechanism. The resulting T-N*-LCs can generate intensive CPL signals with up to +0.70/-0.67. Interestingly, this kind of "on-off" CPL switching of T-N*-LCs can be manipulated by the applied direct current electric field.