Supramolecular self-assembly of naphthalene diimide bolaamphiphile with biologically important amines: Cyclam, spermine and melamine

Abstract

A rigid bolaamphiphile molecule (NDI-1) was synthesized consisting of a naphthalenediimide unit with glutamic acid head groups. Co-assembly of NDI-1 with cyclam, spermine and melamine bearing amine functional groups is studied herein giving significantly different microstructures. NDI-1 was designed to induce geometrically favourable hydrogen bonding with its counterpart molecules in the co-assembly to trigger supramolecular micro- and nano-architectures formation. The interaction between the bolaamphiphile NDI-1 and biologically important amines such as cyclam, spermine and melamine was investigated by UV–vis and fluorescence emission spectroscopy and the nanostructure morphology was studied using scanning electron microscopy. It was found that the co-assembly of NDI-1 with cyclam resulted in fractal-like morphology. Co-assembly of NDI-1 with spermine yielded a crystalline microstructure based on an α-helix molecular arrangement changed into a quasicrystal structure. Self-assembly of NDI-1 in the presence of melamine resulted in a highly crystalline needle-like morphology. The nucleation and growth of the nanostructures were tuned by analytes into distinct classes. Such changes in morphology are significant to the fabrication of various nanomaterials via non-covalent interactions with distinct properties.