Supramolecular hydrogel-based AIEgen: Construction and dual-channel recognition of negative charged dyes

Abstract It is noteworthy that highly selective molecular recognition endows host-guest gels, especially hydrogel, with valuable properties. Therefore, in pure water, a supramolecular hydrogel (SH-α - CD) was constructed by using benzimidazolium-based positive charged guest molecule (J2) assembled with cyclodextrin (α-CD) through host-guest interaction, and accompanied an aggregation-induced emission (AIE). The self-assemble process of the hydrogel-based AIEgen was investigated using 1 H NMR titration, 2D NOESY, XRD and SEM. In particular, the hydrogel-based AIEgen was investigated as a good candidate for fluorescent quenching and gel state destruction dual-channel recognizing negative charged dye molecule methyl orange (MO). The competitive inclusion interaction triggered the dissolution of aggregate, which induced the gel to transform into sol, with disappearance of the AIE of SH-α-CD. However, the addition of the competitive dye molecules methylene blue (MB) and xylenol orange (XO) only made the fluorescence quenching of hydrogel-based AIEgen. Meanwhile, the hydrogel-based AIEgen also exhibited an excellent thermal responsiveness under temperature transition. Such a performance is highly beneficial for potential applications in probe material for organic dye molecules.