Host–Guest Interactions Induce Supramolecular Assembly and Inhibit Electron Transfer to Enhance the Fluorescence Emission of Supramolecular Polymers

Abstract

Three different monomers, A 2 B 2 , C 2 , and D 2 , were synthesized. The monomers A 2 B 2 + C 2 could self-assemble to form a linear supramolecular polymer (SLP) by crown ether-based host−guest interactions at high concentrations. The electrospun nanofibers could be prepared from the SLP solution. When adding monomer D 2 to the SLP solution, the SLP transformed into a cross-linked supramolecular polymer (SCP) through the pillar[5]arene (P5)-based host−guest interaction. The SCP exhibited enhanced fluorescence emission compared to D 2 due to the inhibition of electron transfer between the P5 group and the borondipyrromethene (BODIPY) group on D 2 . When the concentration of monomer A 2 B 2 exceeded 85 mM, the SCP turned into a SP gel and emitted green fluorescence. The gel exhibited multiple stimuli-responsiveness such as K + and temperature responsiveness. The reversible transition of sol−gel could be achieved by K + or temperature control, accompanied by a change of the fluorescence intensity. Additionally, the SCP gel had good self-repairing ability and thermal stability.