Water-soluble fluorescent supramolecular polymer network with sustainable “Fluorescence on” based on AIEgen-containing host-guest interactions

Abstract

Inspired by miraculous bioluminescence phenomena, many synthetic water-soluble fluorescent supramolecular polymer networks (WFSPNs) have attracted wide attention. Up to now, WFSPNs could be divided into two categories on a basis of aggregation-caused quenching (ACQ) effect or aggregation-induced emission (AIE) effect, respectively. However, these two kinds of WFSPNs could only be emissive at partial crosslinking degrees. Herein, we constructed WFSPNs with sustainable “fluorescence on” property. Firstly, cyanostilbene molecule ZPP with AIE property and cyanostilbene-based polymer 4APEG-ZPP were synthesized. Then γ-CD was added into the aqueous solution of 4APEG-ZPP to self-assemble into WFSPNs. This self-assembled process was based on host-guest interactions driven by the hydrophobic interactions. Upon adding γ-CD into the aqueous solution of 4APEG-ZPP, yellow fluorescence was emitted on account of cyanostilbene groups in 4APEG-ZPP tending to form a “dimer” through intermolecular interactions, like π-π stacking and CN∙∙∙π. Moreover, green fluorescence emitted by WFSPNs could be seen with the larger amount of γ-CD being mixed into the 4APEG-ZPP aqueous solution on account of the increase of crosslinking degrees. Obviously, the fluorescence wassustainable with the concentration of γ-CD increasing. Therefore, this system realized the sustainable “fluorescence on” property during the transformation from polymers to networks.

Keywords

• Water-soluble
• Supramolecular polymer networks
• Sustainable “fluorescence on”
• Host-guest interactions
• Self-assembly