Self-Assembly of Nanocubes from Small-Molecule Amphiphiles

Abstract

Directing the self-assembly of small organic molecules into anisotropic nanoparticles without relying on metal coordination remains a fundamental challenge. Here, we show that controlled evaporation of aqueous solutions of a small-molecule amphiphile composed of a π-conjugated aromatic core functionalized with oligo(ethylene glycol) (OEG) side chains drives the formation of nanocubes (∼300 nm edge length). Spectroscopic and microscopic characterizations suggest that these nanocubes are crystalline assemblies comprising π-stacked aromatic domains interspersed with OEG-rich regions and exhibit compliant mechanical properties comparable to those of soft polymers and biological tissues, with Young’s moduli in the range of 1.6–7.0 MPa. This work establishes structural and experimental factors responsible for the emergence of the metal-free formation of soft, shape-defined nanostructures from small-molecule amphiphiles.