A Highly Efficient Luminescent Liquid Crystal with Aggregation Induced Energy Transfer.

A luminescent liquid crystal molecule (TPEMes) with efficient solid-state emission is rationally constructed via the chemically conjugation of blue-emitting tetraphenylethene cores and luminescent mesogenic tolane moieties, which are both featured with aggregation-induced emission properties. As for this fluorophore, aggregation induced energy transfer from the emissive tolane mesogens to the lighting-up tetraphenylethene units endows the molecule pure blue emission in the suspension and bulk state. Combining DSC, POM and 1D XRD experiments, TPEMes is deduced to adapt thermodynamically more stable layered crystalline phase, and can be "frozen" into a monotropic smectic mesophase due to kinetic reasons. As a result of more densely packing of TPEMes in the crystalline phase indicated by 1D XRD, the luminescence of TPEMes in crystalline phase has blue-shifted with 17 nm relative to the metastable mesophase.