Organic styryl dye nanoparticles: synthesis and unique spectroscopic properties.

We report the synthesis and unique spectroscopic properties of organic styryl dye nanoparticles. Aqueous-phase ion association between a cationic styryl dye 2-(4-(dimethylamino)styryl)-1-ethylpyridinium (DASPE), possessing both electron donor and acceptor groups in its molecule, and tetraphenylborate (TPB) or tetrakis(4-fluorophenyl)borate (TFPB) anion, in the presence of poly(vinylpyrrolidone), produces the ion-based dye (DASPE) nanoparticles of approximately 30-100 nm in diameter. Absorption spectra of the DASPE nanoparticles show a large bathochromic shift in comparison with that of the dye monomer in water.