A rhodamine based fluorescent and colorimetric chemosensor for the detection of Cr3+ ions and its utility in a molecular logic gate

A new rhodamine based fluorescent and colorimetric chemosensor S1 was synthesized for the selective recognition of Cr3+, a trivalent metal ion. The interaction of S1 toward different metal ions has been studied via fluorescence and UV-visible spectroscopy. The studies revealed that the fluorescence and colorimetric changes of chemosensor S1 are prominent for Cr3+ over other competitive metal ions. Moreover, the chemosensor S1 exhibits 1 : 1 complex formation with Cr3+ as apparent from the Job's plot and the Benesi-Hildebrand (B-H) plot. Density functional theory (DFT) studies also revealed that the Cr3+ ion is coordinated to three atoms of S1, which validates the formation of a complex between S1 and Cr3+. The limit of detection (LOD) of chemosensor S1 for Cr3+ was 0.21 mu M. Furthermore, to explore the recyclability of S1, ethylenediaminetetraacetic acid (EDTA) was added to the S1-Cr3+ solution. On the addition of EDTA to the solution of S1-Cr3+, the reversibility of the complex was observed, and a colorimetric variation was also observed on the addition of Cr3+ and EDTA to S1 which mimics the INHIBIT molecular logic gate. Chemosensor S1 also demonstrated practical utility through detection of Cr3+ in the solid state.

Automated summary

A new rhodamine based chemosensor S1 was synthesized for selective recognition of Cr3+. The interaction between S1 and different metal ions was studied using fluorescence and UV-visible spectroscopy. The results showed that S1 exhibited significant fluorescence and colorimetric changes for Cr3+ compared to other metal ions. The chemosensor S1 formed a 1 : 1 complex with Cr3+ as confirmed by Job's plot and Benesi-Hildebrand (B-H) plot. Density functional theory (DFT) studies confirmed the coordination of Cr3+ ion to three atoms of S1. The chemosensor S1 had a limit of detection (LOD) of 0.21 μM for Cr3+. Additionally, S1 showed reversibility and colorimetric variation when ethylenediaminetetraacetic acid (EDTA) was added to the S1-Cr3+ solution, mimicking the INHIBIT molecular logic gate. The practical utility of S1 was demonstrated for the detection of Cr3+ in the solid state.