Pillar[5]arene-Based AIE Supramolecular Polymer Networks Exhibiting Various Fluorescence to Achieve Visible Surveillance

Supramolecular polymer networks (SPNs) based on pillar[n]arene are widely studied and it is known that evolution from linear polymers to SPNs occurs as a progressive process, which is of importance to monitor the detailed morphology throughout the process. Yet, the current reports related to that distinction by employing fluorescence approach have realized confined success, it still remains a challenge to distinguish the various states visually. Herein, a fluorescent group of the pyrene benzohydrazonate-based (PBHZ-based) derivative is introduced into the pillar[5]arene based SPNs gained from host-guest recognition, enabling the visual monitoring during the formation of SPNs. The whole visual detection was based on the fluorescence color transition ranging from blue to green relying on the gradual aggregated PBHZ molecules upon the increasing cross-linking degree. Besides, the stimuli-responsiveness of this SPNs was confirmed that increasing the temperature or adding a reducing agent would reduce the cross-linking degree.