Multiring-induced multicolour emission: Hyperbranched polysiloxane with silicon bridge for data encryption

Multicolour emissive nonconventional macromolecular luminogens with aggregation-induced emission have drawn great attention due to their potential application in a wide range of areas. However, the exploration of efficient synthetic strategies and emission mechanisms still remains a challenge. Herein, we report a facile route to the synthesis of hyperbranched polysiloxane (P1) with adjacent -CO and -CC groups. Surprisingly, it not only showed blue emission under white light excitation, but also exhibited multicolour luminescence under different excitation wavelengths. Especially, multiple through-space conjugation rings can be found between the first generation P1 molecules via DFT calculation; based on its remarkable luminescence properties, we proposed a new luminescence mechanism namely "multiring-induced multicolour emission" (MIE). In addition, the stimuli-responsive behaviour of P1 as well as its application in data encryption based on the quenching effect of Fe³⁺ was studied. This work provides guidance to design and synthesise nonconventional macromolecular AIEgens with multicolour luminescence.