Circularly polarized luminescence and controllable helical self-assembly of an aggregation-induced emission luminogen

A new chiral tetraphenylethene derivative with two l-leucine-containing attachments, TPE-DLEU, has been designed and synthesized by Cu(I)-catalyzed azide-alkyne cycloaddition “click” reaction. It emits faintly and gives weak circular dichroism (CD) signals in solutions, but shows strong fluorescence and Cotton effects in the aggregated state, showing aggregation-induced emission (AIE) and CD (AICD) characteristics. Furthermore, its film displays circularly polarized luminescence (CPL) with an emission dissymmetry factor of +3.2 × 10−3. Interestingly, TPE-DLEU exhibits controllable helical self-assembly behaviours. It could readily assemble into right-handed helical nanofibers upon the evaporation of its 1,2-dichloroethane (DCE) solution, but form left-handed helical nanofibers by the addition of hexane to its DCE solution.