Nanosized crystallites of charge-transfer complex of 9-methylanthracene and 1,2,4,5-tetracyanobenzene for bright and optically anisotropic fluorescent probes

Nanocrystallites of charge-transfer (CT) complexes with an average size of 20-40 nm were synthesized from ethyl acetate solutions of 9-methylanthracene and 1,2,4,5-tetracyanobenzene by means of spin coating. The optical properties of nanocrystallites were investigated by dark-field and fluorescence imagings. No blinking behavior was observed. Fluorescence brightness and photostability comparable to a standard dye-doped polystyrene sphere were confirmed. We found a pronounced dependence of fluorescence intensity on the polarization of excitation light due to optical anisotropy of the nanocrystallites. The results indicate that the CT nanocrystallite is a promising tool for the observation of rotational motion of nanoobjects in nanofluidics.