Highly Selective and Sensitive Visual Detection of Fe³⁺ using a Simple Quinazoline-Based Colorimetric Sensor

Area of Science:

• Analytical Chemistry
• Materials Science
• Environmental Science

Background:

• Iron(III) (Fe3+) is crucial for cellular functions but toxic when imbalanced.
• Fe3+ contamination in industrial wastewater poses environmental risks.
• Selective Fe3+ chemosensors are vital for monitoring and remediation.

Purpose of the Study:

• To synthesize and characterize a novel colorimetric sensor, BQ (6-(6-bromopyridin-2-yl)benzo[4,5]imidazo[1,2-c]quinazoline).
• To evaluate BQ's selectivity and sensitivity for Fe3+ detection in aqueous media.
• To investigate the optimal conditions for BQ-based Fe3+ sensing.

Main Methods:

• Synthesis and characterization of BQ using NMR, IR, and mass spectrometry.
• Colorimetric and UV-vis spectroscopic analysis of BQ's response to various cations.
• pH stability studies and Job's plot analysis for binding stoichiometry.

Main Results:

• BQ demonstrated excellent selectivity and sensitivity towards Fe3+.
• Visual color change (colorless to yellow) allows naked-eye Fe3+ detection.
• Optimal sensing stability observed between pH 5-10.
• A 1:1 binding ratio between BQ and Fe3+ was confirmed.
• A linear relationship for Fe3+ concentration (58-114 μM) with a detection limit of 53.39 nM was established.

Conclusions:

• BQ is a highly selective and sensitive colorimetric sensor for Fe3+ detection.
• The sensor's visual detection capability and stability make it suitable for practical applications.
• BQ offers a promising tool for monitoring Fe3+ in biological and environmental samples.