Light-Harvesting Fluorescent Supramolecular Block Copolymers Based on Cyanostilbene Derivatives and Cucurbit[8]urils in Aqueous Solution

A novel system of light-harvesting supramolecular block copolymers (SBCPs) in water is demonstrated. To realize cucurbit[8] uril (CB[8])-based SBCPs generating artificial light-harvesting in water, finely color-tuned supramolecular homopolymers (SHPs) comprising CB[8] host and different cyanostilbene guests (named as B, G, Y, and R) emitting blue, green, yellow, and red fluorescence are first synthesized and characterized, respectively. Light-harvesting SBCPs with mixed guest emitters are then simply produced by mixing blue and red-emitting SHPs according to the dynamic host-guest exchange interaction. The light-harvesting SBCPs show highly efficient energy transfer from B (donor D) to R (acceptor A) attributed to the D/A proximity and parallel orientation of their transition dipoles secured in the block copolymer structure. It is comprehensively shown that cyanostilbene/CB[8]-based fluorescent SBCPs represent a novel and fascinating class of eco-friendly artificial light-harvesting system.