Terminal Peptide Directed Assembly of Naphthalene-Bisimides

The self-assembly of two naphthalene-bisimide based nonionic bolaamphiphiles containing two terminal tripeptide moieties has been investigated. The bisimide 1 containing a core of adjacent aromatic rings and two termini of folded tripeptide moieties (-Tyr-Aib-Leu-OMe) adopts a dumbbell shape conformation, and it self-assembles through noncovalent interactions to fabricate microspheres. In contrast, the bisimide 2 containing two termini of extended tripeptide moieties (-Phe-Phe-Tyr-OMe) adopts a wrist band shape structure, and it self-assembles to produce elongated fibrils. The X-ray crystallography reveals that the bisimide 1 adopts a dumbbell shape with two terminal β-turns, and it self-associates to form a rhombus-like structure in higher order packing. Moreover, the conductivity of the bisimide 2 is 2 orders of magnitude higher than that of the bisimide 1 in room light. The secondary structures of the terminal tripeptides of bisimide systems and the peptide–peptide interactions are the driving forces f...