Preparation and Fluorescence Properties of Perylenediimide Nanodispersions Having a One-Dimensional π-Stacked Structure.

We prepared stable nanodispersions of a fluorescent perylenediimide (PDI) derivative having long alkyl chains by nanosecond laser fragmentation of its microcrystalline powder in acetonitrile (ACN). The nanoparticles had cube-like or rod shapes with a mean size of 100 nm, and they dispersed stably for longer than 1 month. The prepared nanobricks exhibited absorption and fluorescence spectra characteristic of one-dimensional aggregates with cofacial stacking of PDI planes. Single-particle fluorescence measurements demonstrated that nanobricks had a well-aligned structure of one-dimensional columns of PDI. The aqueous dispersions were also fabricated by redispersing the prepared nanobricks, utilizing lipophilic interactions of surfactants having long alkyl chains. We examined the fluorescence properties of nanoparticles dispersed in ACN and in water, and observed amplified fluorescence quenching by the surface-adsorbed dye.