A Water‐Soluble Cycloparaphenylene: Supramolecular Receptor with Visible Fluorescence

Abstract We report the first synthesis of a water‐soluble [9]cycloparaphenylene derivative containing three hydrindacene (1,2,3,5,6,7‐hexahydro‐ s ‐indacene) units with four carboxylates at the 2,6‐positions via a macrocyclic gold complex. This crown‐shaped macrocyclic compound exhibits remarkable water solubility, of up to 16 mmol L −1 (2.6 g/100 mL), as well as strong visible fluorescence in water (λ em =447 nm, ϕ F =0.64, brightness (ϵ×ϕ F )=5.1×10 4 ). This molecule effectively encapsulates cationic guest compounds, such as methyl viologen dichloride, as indicated by a change in visible fluorescence.