Development of a Rhodamine‐Based Chemosensor for Cd 2+ Ions: A Combined Approach of Colorimetric, Fluorescent Detection, and Computational Modelling

This paper presents the design and synthesis of a new rhodamine‐based Schiff base chemosensor ( L ) with exceptional selectivity and sensitivity for Cd 2+ . An analysis of L was conducted using various spectroscopic techniques, thereby validating its structure and activity. The chemosensor exhibited a clear turn‐on fluorescence response and significant colour change with Cd 2+ ions in acetonitrile. Binding investigations confirmed that L interacts with Cd 2+ ions in a 1:1 ratio, as shown by Job's plot and Benesi‐Hildebrand (B‐H) analysis. The binding constant ( K a = 0.107 × 10 4 ) highlights the strong and specific interactions between L and Cd 2+ ions.The limit of detection was found to be (LOD = 2.01 nM) for Cd 2+ ions. DFT studies confirmed the stability of the L ‐Cd 2+ complex, indicating the coordination of Cd 2+ to the four atoms in L . The reversible properties of L in the presence of EDTA illustrate its potential as a reusable chemosensor and emphasise its INHIBIT molecular logic gate functionality. Molecular docking analyses of L with the human DNA‐binding protein 5VBN were performed to assess its binding affinity and interaction characteristics. The practical application was demonstrated by the effective detection of Cd 2+ in actual water, vegetable and fruit juice samples, solid‐state sensing tests and filter paper‐based assays, highlighting its potential for environmental monitoring.