No abstract

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.

Water-soluble, highly fluorescent host-guest chromophore-cucurbit[8]uril supramolecular polymer bundles are investigated by polarized time-resolved photoluminescence spectroscopy, structural methods, and quantum chemistry to fully reveal structural organization and heterogeneity but, in particular, energy-transfer dynamics, being of crucial importance for the design of supramolecular artificial light-harvesting systems.

Tolylacridine-viologen dyads show distinct fluorescence emission changes in the presence of double-strand DNA (dsDNA) and single-strand DNA (ssDNA) depending on the position of the linkage. The para isomer shows fluorescence quenching in the presence of both dsDNA and ssDNA, while the ortho isomer interacts selectively with ssDNA with enhancement in fluorescence intensity.