Self-assembled photoresponsive amphiphilic diphenylaminofluorene-C60 conjugate vesicles in aqueous solution

Water-soluble oligo(ethylene glycolated) derivatives of two-photon absorptive diphenylaminofluoreno-carbonyl-methano[60]fullerene, denoted as C-60(> DPAF-EG(6)), were synthesized with their molecular self-assembly characteristics in H2O studied. The formation of nano- to submicron-sized spherical hollow vesicles with a shell width of 15-20 nm was observed by transmission electron microscopy (TEM) micrographs. This shell width fits approximately with the length of a disordered bilayer-like molecular packing of C-60(> DPAF-EG(6)), arising from strong intermolecular hydrophobic interactions of fullerene cages. Photoinduced intramolecular charge separation followed by charge recombination on the nanosecond time scale, from the DPAF moiety to the C-60 cage in the vesicle structure, was detected via transient spectroscopic measurements.