Photofunctional self-assembled nanostructures formed by perylene diimide-gold nanoparticle hybrids

We report on the synthesis of organic dye-metal nanoparticle hybrids from two thiol-derivatized perylenediimide (PDI) ligands and 1.5 nm gold nanoparticles. The hybrids form spherical nanostructures when cast from 40% methanol/chloroform solution and toluene. The spherical aggregates are in the size range 50-230 nm in 40% MeOH/CHCl(3) mixture and 100-400 nm in toluene solution, as evidenced by transmission electron microscopy (TEM). Scanning electron microscopy (SEM) measurements show that these spherical aggregates are vesicles with a hollow interior. The π-π interactions of the perylenediimides are the predominant driving force leading to the aggregation of the hybrids, whereby the sizes of the nanospheres can be regulated via the PDI linker moiety and solvent choice. Femtosecond transient absorption studies of the hybrids reveal complex photophysical behavior involving electron transfer from the gold nanoparticles to the PDI moieties. This study shows that the formation of well-defined hybrid nanostructures as well as tuning their sizes can be achieved through employing a combination of the capping ligand choice and regulating the solvophobic interactions between the ligands.