Solvent- and concentration-induced self-assembly of an amphiphilic perylene dye

A new amphiphilic perylene dye bearing two carboxylic and two amidic chains (PDA-CA) has been synthesized and the ability to form pi-pi driven aggregates or folded structures has been investigated in aqueous or organic solvents at different concentrations, by means of NMR spectroscopy, theoretical calculations and optical characterization. The H-1 NMR data showed the coexistence of supramolecular aggregates due to a synergetic effect of pi-pi stacking, hydrogen bonding and hydrophobic/hydrophilic interactions. The ratio between these species has been evaluated by concentration- and temperature-dependent H-1 NMR experiments and also by the effect of aqueous or organic solvents. UV-Vis measurements are in agreement with NMR data evidencing the presence of more organized structures in organic solvents and aggregated species in aqueous solution. The pi-stacking ability and the role intermolecular hydrogen bonds in the formation of different aggregated structures, was also estimated by density functional theory.