Globular Aggregates Stemming from the Self-Assembly of an Amphiphilic N-Annulated Perylene Bisimide in Aqueous Media

Abstract

Herein, we describe the synthesis of highly emissive amphiphilic N-annulated PBI 1 decorated with oligo ethylene glycol (OEG) side chains. These polar side chains allow the straightforward solubility of 1 in solvents of different polarity such as water, iPrOH, dioxane, or chloroform. Compound 1 self-assembles in aqueous media by π-stacking of the aromatic units and van der Waals interactions, favored by the hydrophobic effect. The hypo- and hypsochromic effect observed in the UV-Vis spectra of 1 in water in comparison to chloroform is diagnostic of H-type aggregation. Solvent denaturation experiments allow deriving the free Gibbs energy for the self-assembly process in aqueous media and the factor m that is indicative of the influence exerted by a good solvent in the stability of the final aggregates. The ability of compound 1 to self-assemble in water yields globular aggregates that have been visualized by TEM imaging.