A Doubly Alkynylpyrene‐Threaded 4Rotaxane That Exhibits Strong Circularly Polarized Luminescence from the Spatially Restricted Excimer

The Sonogashira coupling of γ-CD-encapsulated alkynylpyrenes with terphenyl-type stopper molecules gave a doubly alkynylpyrene-threaded 4rotaxane. The rotaxane showed only excimer emission, with a high fluorescence quantum yield of Φf =0.37, arising from the spatially restricted excimer within the cavity of the γ-CD. The excimer emission suffered little from self-quenching up to a concentration of 1.5×10(-5) M and was circularly polarized with a high glum value of -1.5×10(-2) . The strong circularly polarized luminescence may result from the two stacked pyrenes existing in the rotaxane in an asymmetrically twisted manner.