Development of a Rhodamine-Based Chemosensor for Cd²⁺ Ions: A Combined Approach of Colorimetric, Fluorescent...

Area of Science:

• Analytical Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Cadmium (Cd2+) is a toxic heavy metal pollutant.
• Development of selective and sensitive chemosensors is crucial for environmental monitoring.
• Rhodamine-based Schiff bases offer promising platforms for fluorescent chemosensor design.

Purpose of the Study:

• To design and synthesize a novel rhodamine-based Schiff base chemosensor (L) for selective and sensitive detection of Cd2+.
• To investigate the sensing mechanism, binding properties, and reusability of the chemosensor.
• To evaluate the practical applicability of the chemosensor in real-world samples.

Main Methods:

• Synthesis and characterization of the rhodamine-based Schiff base chemosensor (L).
• Spectroscopic studies (UV-Vis, fluorescence) to determine sensing behavior towards Cd2+.
• Job's plot and Benesi-Hildebrand analysis for binding stoichiometry and constant determination.
• Density Functional Theory (DFT) and molecular docking studies for theoretical validation.
• Reversibility studies using EDTA and application in real samples (water, juices).

Main Results:

• The chemosensor (L) exhibited a selective 'turn-on' fluorescence response and color change upon binding with Cd2+ ions.
• A 1:1 binding ratio and a high binding constant (Ka = 0.107 × 10^4) were determined.
• A low limit of detection (LOD = 2.01 nM) for Cd2+ was achieved.
• DFT studies confirmed the stability of the L-Cd2+ complex, and molecular docking indicated interactions with DNA-binding proteins.
• The sensor demonstrated reversibility and effective Cd2+ detection in various real samples, including solid-state and filter paper assays.

Conclusions:

• The developed rhodamine-based Schiff base chemosensor (L) is highly selective and sensitive for Cd2+ detection.
• Its reversible nature and successful application in real samples highlight its potential as a reusable tool for environmental monitoring.
• The study showcases the utility of Schiff base derivatives in designing advanced chemosensors for toxic metal ion detection.