A novel water-soluble chitosan linked fluorescent carbon dots and isophorone diisocyanate fluorescent material toward detection of chromium(vi)

Abstract

In this work, a NCO-capped intermediate was first prepared from fluorescent carbon dots (FCDs) and isophorone diisocyanate (IPDI) via an in situ method in the presence of dibutyltin dilaurate as the catalyst. Based on the fact that –NCO groups can react with the hydroxyl and amino groups in chitosan polymeric chains, a novel water-soluble chitosan linked fluorescent carbon dots and isophorone diisocyanate (FCDs–IPDI–CTS) fluorescent material was obtained from the NCO-capped intermediate and chitosan. The prepared FCDs–IPDI–CTS material shows blue fluorescence under UV exposure. The structure and morphology of the as-prepared FCDs–IPDI–CTS material were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The as-prepared FCDs–IPDI–CTS material exhibits excellent fluorescence properties and good stability. It could be quenched by chromium(VI) and has been further used as a novel fluorescent probe for selective detection of chromium(VI). The optimum conditions for sensing Cr(VI) were investigated. Based on the optimum conditions, a new sensitive method for sensing Cr(VI) was established. This method has been successfully applied to detect Cr(VI) in water and soil samples with satisfactory results.