Self-assembly of naphthalene diimides into cylindrical microstructures

We have designed two rod-shaped compounds each incorporating a naphthalene diimide core and two terminal carboxylic acids. Both molecules aggregate in aqueous solution and spontaneously organize into cylindrical microstructures on the surface of solid substrates. Presumably, hydrogen bonds between the carboxylic acid termini and hydrophobic contacts between the naphthalene diimide cores are mainly responsible for the formation of these supramolecular arrays. Indeed, extended stacks of molecules self-assemble with close contacts between their aromatic cores in single crystals grown from polar solvents.