Self-assembled monolayer and multilayer films based on l-lysine functionalized perylene bisimide

Abstract

L-Lysine functionalized tetrachloroperylene bisimide (Lys-4ClPBI-Lys) was synthesized, and its aqueous self-assembly behaviours were investigated at different pH values. The zwitterionic-type Lys-4ClPBI-Lys amphiphile spontaneously self-assembled into a uniform monolayer film in water at pH ranging from 9 to 1, whereas it did not formed any ordered aggregates in solution with pH above 10. Formation of the monolayer film was believed due to synergistic interaction of directional π–π interactions and intermolecular hydrogen bonding. In contrast, the addition of copper(II) ions induced the formation of multilayer films due to inter-film ligation between Cu²⁺ and the α-amino acid moiety. The corresponding self-assembly behaviours and assemblies' structures were characterized using UV-vis absorption and fluorescence emission spectroscopy, cryogenic transmission electron microscopy, atomic force microscopy, and X-ray diffraction.