Cetyltrimethylammonium bromide stabilized perylene nanoparticles for fluorimetric estimation of bicarbonate (HCO3−) anion: spectroscopic approach
Fluorescent perylene nanoparticles were prepared by a reprecipitation method in the presence of cetyltrimethylammonium bromide (CTAB) as a stabilizer. The formation of perylene nanoparticles was confirmed by dynamic light scattering , UV-visible absorption spectroscopy, fluorescence spectroscopy and excited state life time measurements. The observation of a significant large Stoke's shift (24 546 cm−1) of perylene nanoparticles in aqueous suspension as compared with that of a dilute solution of perylene in acetone (14 250 cm−1) indicated aggregation of molecules in their ground state by lateral π-stacking. A highly intense, single band fluorescence peak at 565 nm is attributed to the direct excitation of perylene nanoparticles (λex = 380 nm) due to aggregation induced enhanced emission (AIEE) and is quenched appreciably by HCO3− anions. A positive surface charge is created by the CTAB cage on the nanoparticles and binding interactions result in quenching of fluorescence of perylene nanoparticles which is observed in the spectrum at 565 nm. The quenching of perylene nanoparticles emission is linear in the concentration range of 0–80 μM of HCO3− ion in solution. The quenching results obey the Stern–Volmer relation and the method after calibration can be applied successfully in the quantitative analysis of sodium bicarbonate in commercially available medicinal tablets.