Carbazole based nanoprobe for selective recognition of Fe ion in aqueous medium: Spectroscopic insight.

A simple carbazole based nanoprobe prepared by reprecipitation method shows selective sensing behavior for Fe ion in aqueous medium. The prepared SDS capped 9-phenyl carbazole nanoparticles (9-PCzNPs) has narrower particle size distribution with an average diameter 35nm and zeta potential of -34.3mV predicted a good stability with negative surface charge over the nanoparticles. The Field Emission Scanning Electron Microscopy (FE-SEM) image showed cubic shape morphology of nanoparticles. The aqueous suspension of SDS capped 9-phenyl carbazole nanoparticles exhibited aggregation induced enhanced red shifted intense emission in comparison with the emission arising from dilute solution of 9-phenyl carbazole in DCM. The cation recognition test based on fluorescence change shows Fe ion induce significant fluorescence quenching, however remaining cations responds negligibly. The obtained quenching data fit into Stern-Volmer relation in the concentration range of 0.0-1.0μg·mL of Fe ion solution and the detection limit is 0.0811μg·mL. The probable mechanism of fluorescence quenching of SDS capped 9-PCzNPs is because of adsorption of Fe ion over the negatively charged surface of NPs through electrostatic interaction. Thus the proposed method was successfully applied for the detection of Fe ion in environmental water sample.