Soft Nanotubes Acting as a Light-Harvesting Antenna System

Amphiphilic monomers, which were quantitatively synthesized from a dehydration reaction between a glycolipid and naphthalene-boronic acids, self-assembled in organic solvents to selectively form tape-like structures (nanotape) and tubular structures (nanotube) depending on the bond position of the boron atom in the naphthalene ring. The nanotube has a strong narrow fluorescence band attributable to the monomer species of the naphthalene group, whereas the nanotape has a weak broad fluorescence band at a relative longer wavelength region based on the excimer species of the naphthalene group. Light energy adsorbed by the naphthalene groups densely and regularly organized in the bilayer membrane wall of the nanotube was transferred, with high quantum efficiency, into anthracene as an acceptor encapsulated in the nanochannel. The supramolecular nanotube proved to be able to act as a light-harvesting antenna.