Fluorescent Organic Nanoparticles of 3-Styrylindoles: Synthesis and Characterization

Nanoparticles of 3-styrylindoles viz. 3-styryl-1H-indole (1), 3-(4-nitrostyryl)-1H-indole (2), 3-(4-nitrostyryl)-5-methoxy-1H-indole (3) and 3-(4-nitrostyryl)-5-bromo-1H-indole (4) have been synthesized by re-precipitation method. The nanoparticles are formed in the shape of a sphere with mean diameter of about 20–30 nm. The size of nanoparticles is controlled mainly by the fraction of added water and final concentration of the nanoparticles dispersion. The nanoparticles of 1, 2 and 4 showed little change in their fluorescence spectra as compared to the fluorescence spectra of the corresponding isolated molecules in THF. However, nanoparticles of 3 show enhanced fluorescence emission. This is attributed to the presence of methoxy and nitro groups in 3, which may be effective in reducing face-to-face intermolecular interaction in the nanoparticles of 3, inducing formation of J-type morphology responsible for enhanced fluorescence emission. Over a period of time, the nanoparticles progressively tend to clump in to bigger sizes, and become less fluorescent.