Sulfated prism[6]arene as a water-soluble host for molecular recognition of dye pollutants in aqueous environments

The contamination of urban groundwater by synthetic organic compounds represents a growing environmental concern; therefore, the development of supramolecular systems capable of selectively recognizing pollutants in aqueous environments is increasingly important, both for detection and remediation purposes. Herein, we report the synthesis of a water-soluble prism[6]arene extensively functionalized with sulfate groups at both rims. This host exhibits remarkable binding affinities toward organic dyes, specifically rhodamine B and methylene blue. The binding properties with these guests were investigated via UV-vis, fluorescence, NMR, DLS, DOSY, and ITC. Notably, in the presence of rhodamine B, the sulfated prism[6]arene forms both 1:1 endo-cavity and 1:2 capsular complexes, as evidenced by multi-technique characterization. Furthermore, in silico calculations suggest that two macrocycle units assemble into a water-bridged supramolecular capsule that encapsulates one molecule of rhodamine B. In contrast, methylene blue exclusively forms 1:1 endo-cavity complexes. These findings establish sulfated prism[6]arene as a promising water-soluble macrocycle paving the way for applications in environmental remediation.