Isophthaloyl-Based Selective Fluorescence Receptor for Zn (II) Ion in Semi-Aqueous Medium

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Analytical Chemistry

Background:

• Development of selective chemosensors for metal ion detection is crucial in environmental and biological monitoring.
• Isophthaloyl-based hydrazide receptors offer potential for sensitive and selective ion recognition.

Purpose of the Study:

• To synthesize and characterize a novel Isophthaloyl-based symmetrical receptor for selective Zn(II) ion detection.
• To investigate the fluorescence response and binding properties of the receptor towards various metal ions.
• To determine the binding stoichiometry, mechanism, and electrochemical behavior of the receptor-Zn(II) complex.

Main Methods:

• Synthesis and spectroscopic characterization (NMR, IR, Mass Spectrometry) of the receptor.
• Fluorescence spectroscopy for metal ion sensing in a CH3CN:H2O medium.
• Job's plot, Benesi-Hildebrand, Scatchard, and Connor's plots for binding studies.
• Density Functional Theory (DFT) for structural calculations.
• Electrochemical analysis (cyclic voltammetry) for complex confirmation.

Main Results:

• The synthesized receptor exhibited selective fluorescence enhancement for Zn(II) ions over other metal ions.
• A 1:2 binding stoichiometry between the receptor and Zn(II) was confirmed.
• High binding constants (Ka ≈ 1.00 × 10^4 M⁻¹) and low limits of detection (LOD = 0.292 μM) and quantification (LOQ = 0.974 μM) were achieved.
• Photo-induced electron transfer (PET) mechanism and coordination with the hydroxyl group were identified as the binding modes.
• DFT calculations supported the proposed complex structure, and electrochemical studies confirmed complex formation.

Conclusions:

• The novel Isophthaloyl-based receptor is a highly selective and sensitive fluorescent chemosensor for Zn(II) ions.
• The study provides insights into the binding mechanism and structural properties of the receptor-Zn(II) complex.
• The developed sensor holds promise for practical applications in detecting zinc ions in various samples.