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 (λem=447 nm, ϕF=0.64, brightness (ϵ×ϕF)=5.1×104). This molecule effectively encapsulates cationic guest compounds, such as methyl viologen dichloride, as indicated by a change in visible fluorescence.