Carbazole based nanoprobe for selective recognition of Fe³⁺ ion in aqueous medium: Spectroscopic insight

A simple carbazole based nanoprobe prepared by reprecipitation method shows selective sensing behavior for Fe³⁺ 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 Fe³⁺ 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^-1 of Fe³⁺ ion solution and the detection limit is 0.0811μg·mL^-1. The probable mechanism of fluorescence quenching of SDS capped 9-PCzNPs is because of adsorption of Fe³⁺ ion over the negatively charged surface of NPs through electrostatic interaction. Thus the proposed method was successfully applied for the detection of Fe³⁺ ion in environmental water sample.