A novel approach to supramolecular Aggregation-Induced emission using tetracationic tetraphenylethylene and sulfated β-Cyclodextrin

Abstract

The combination of aggregation-induced emission-based luminogens (AIEgens) with supramolecular chemistry has gained significant attention due to its ability to produce intense emission even at low concentrations. In this study, we report a supramolecular arrangement characterized by aggregation-induced emission through the integration of tetracationic tetraphenylethylene with a macrocyclic polyanionic derivative of β-cyclodextrin. Despite the exploration of ionic derivatives of cyclodextrins in pharmaceutical and host–guest supramolecular chemistry, the phenomenon of supramolecular aggregation-induced emission based on non-covalent interactions between the ionic derivative of β-cyclodextrin and derivatives of tetraphenylethyelene, a class of AIEgens, has received limited investigation. Our work explores AIE shown by the allylimidazolium derivative of tetracationic tetraphenylethyelene (ALITPE) induced by complexation with polyanionic sulfated β-cyclodextrin (SCD). The effectiveness of the emission intensity of this supramolecular assembly based on AIE is confirmed by steady-state and time-resolved fluorescence measurements, which are supported by ground-state absorption measurements. We also investigate the effect of changes in external environment, such as temperature, pH, and ionic strength, on the supramolecular assembly. Moreover, the aggregation behavior of ALITPE with SCD is comparatively studied with neutral native β-cyclodextrin, highlighting the contribution of high negative charge density on the surface of SCD for efficient aggregation with ALITPE molecules. Additionally, Molecular Docking calculations are employed to provide insights into the aggregation behavior of ALITPE molecules induced by SCD. Overall, our findings demonstrate the potential applicability of the ALITPE/SCD supramolecular assembly as a potential fluorescent sensing probe for various biological applications.