Synthesis and Characterization of a Pyrazoline-Based Fluorescence Turn-Off Sensor for Selective Fe³⁺ Detection in...

Area of Science:

• Chemical Sensing
• Fluorescent Probes
• Coordination Chemistry

Background:

• Development of selective and sensitive fluorescent sensors is crucial for environmental monitoring and biological analysis.
• Heavy metal ion detection remains a significant challenge due to potential toxicity and environmental impact.

Purpose of the Study:

• To synthesize and characterize a novel pyrazoline-based fluorescent sensor (PZ).
• To investigate the sensing capabilities of PZ for various heavy metal ions.
• To determine the sensing mechanism and performance for the target analyte.

Main Methods:

• Synthesis of pyrazoline ligand (PZ) and characterization using spectroscopic techniques (UV-Vis, FT-IR, NMR, ESIMS).
• Fluorescence and absorbance studies upon interaction with various metal ions (Fe³⁺, Al³⁺, Co²⁺, etc.).
• Determination of detection limit, limit of quantification, binding constant, and complex stoichiometry using fluorescent titration and DFT calculations.

Main Results:

• The synthesized pyrazoline ligand (PZ) exhibited fluorescence quenching in the presence of Fe³⁺ ions.
• PZ demonstrated high selectivity for Fe³⁺ with a low detection limit (0.30 µM) and limit of quantification (1.004 µM) within a 0-5 µM range.
• Fluorescent titration revealed a 1:1 complex formation between PZ and Fe³⁺, with a high association constant (1.25 × 10³ M⁻¹).

Conclusions:

• The synthesized pyrazoline ligand (PZ) functions as an effective "turn-off" fluorescent sensor for Fe³⁺ detection.
• PZ offers a sensitive and selective method for quantifying Fe³⁺ ions.
• The study provides insights into the coordination chemistry and sensing mechanism of the PZ-Fe³⁺ complex.