Pillar[5]arenes: A new class of: AIE gen macrocycles used for luminescence sensing of Fe³⁺ ions

Herein, we report on an unusual light-emitting behavior of the homo- and copillar[5]arenes (MeP5, EtP5, PrP5, BuP5, DBuP5 and DBP5) with combinations of alkoxy functionalities. Our investigations revealed that the emission of these pillar[5]arenes was highly enhanced in the aggregate state. This turn-on fluorescence could be ascribed to the well-known aggregation-induced-emission (AIE) mechanism, which was confirmed by SEM imaging and the dynamic light scattering (DLS) technique. The current work may open another avenue to the chemistry of pillararenes as new AIEgen macrocycles for luminescence sensing of guest species including organic molecules, and metal ions as herein tested for Fe(iii).