Photophysical characterization and the self-assembly properties of mono- and bis-pyrene derivatives for cell imaging applications

Abstract

A series of fluorescent mono- (1–4) and bis-pyrene derivatives (5–7) were synthesized and their photophysical and self-aggregation properties in solution were fully investigated by UV-vis and fluorescence spectroscopies and dynamic light scattering (DLS). While in dilute DMSO mono-pyrene derivatives 1–4 show the characteristic features of monomer emission, bis-pyrene derivatives 5–7 display both monomer and excimer emissions, the latter attributable to a dynamic process. The gelation behaviour of these compounds was also studied, and only mono-pyrene leucine derivative 1 was found to display efficient gelation in aromatic solvents, such as toluene and p-xylene, and in a polar solvent mixture, water/DMSO (4 : 1 v/v). Finally, mono-pyrenes 1–4 showed no apparent cytotoxic impact on A549 and RD cell lines; derivatives 1–5 showed accumulation within both live and fixed cells, and macropinocytosis was found to be the main pathway for 5 to enter into the cells.