Fabrication of fluorescent supramolecular organic frameworks through host–guest interactions and their application in ratiometric detection of I ⁻

The construction of fluorescent supramolecular organic frameworks (SOFs) through host-guest interactions not only enables the construction of functional aggregates with diverse structures, but also effectively regulates the luminescence properties of the molecules. Herein, we synthesized a chalcone based fluorescent amphiphilic molecule (molecule 1). Molecule 1 could aggregate into nanospheres, with the emission color changing from yellow to green. After co-assembly with γ-cyclodextrin (γ-CD) through host-guest interactions, three-dimensional cube-like SOF structures were obtained. The emission color could be regulated from green to blue by adjusting the concentration of the complex. More importantly, the supramolecular complex suppressed the aggregation-caused quenching (ACQ) nature of molecule 1, and therefore, the bright luminescence can be sustained both in the solid state and in solution. Based on the stable emission properties of 1/γ-CD, we developed a ratiometric fluorescence platform for detection of I^- using the 1/γ-CD complex as a reference signal combined with orange luminescent gold nanoclusters (AuNCs). The redox reaction between I^- and AuNCs induces fluorescence quenching of AuNCs and no change to the fluorescence intensity of the 1/γ-CD complex, resulting in a low detection limit of 0.042 μM.