Carbon dot-based molecular receptor for the colorimetric sensing of Cr(VI) from aqueous solutions

A novel molecular probe was fabricated by the integration of a smart carbon dot and a Schiff's base viz 4-amino -N-[(2-hydroxyphenyl)methylidene] benzoic acid. The synthesised carbon dot composite was well characterised, and a colorimetric molecular probe derived from ecologically sound carbon dot composite materials was explored for the colorimetric sensing of Cr (VI) in aqueous solutions. The results demonstrated that the developed colorimetric sensor can effectively sense Cr (VI) in aqueous solutions even below the picomolar concentration range. Also, the method's practical applicability was checked by the recovery of Cr(VI) from real tap water samples by the standard addition method and was found to be in the range of 99–109%. Highlights Chromium (VI) is considered as a severe environmental pollutant, due to its highly toxic and carcinogenic properties. Low cost, highly sensitive sensors for the determination of Cr(VI) are highly demanded. We have demonstrated a colorimetric molecular probe for detecting Cr(VI) based on the inner filter effect (IFE). This CD-based nano sensor provides obvious advantages of simplicity, convenience, rapid response, high selectivity, and sensitivity, which have potential application for the detection of Cr(VI) in the environmental industry. The developed colorimetric sensor can be effectively adopted for the sensing of Cr(VI) in aqueous solutions even below the picomolar concentration range. Based on the colorimetric observation we can qualitatively determine the presence of Cr(VI) without the aid of any sophisticated analytical instruments. GRAPHICAL ABSTRACT