Mononuclear Zn(II) Complex Based on N2O Ligand Compartment: First Case to Detect Nitro Explosives

Area of Science:

• Coordination Chemistry
• Materials Science
• Analytical Chemistry

Background:

• Schiff base complexes are crucial in developing chemical sensors.
• Hypersensitive fluorescent probes are needed for detecting hazardous materials like nitro explosives.
• Anti-trafficking measures require rapid and reliable detection methods for explosives.

Purpose of the Study:

• To synthesize and characterize a novel Zn(II) Schiff base complex.
• To evaluate the complex's potential as a fluorescent sensor for nitro explosives.
• To develop a visual detection method for forensic applications.

Main Methods:

• One-pot synthesis of a Zn(II) Schiff base complex.
• Characterization using spectroscopic tools and single crystal X-ray diffraction.
• Fluorescence quenching studies for nitro aromatic detection in acetonitrile solution.
• Density Functional Theory (DFT) calculations for mechanism elucidation.
• Development of a paper sensor strip for visual detection.

Main Results:

• A new square pyramidal Zn(II) complex with a Schiff base ligand was successfully synthesized and characterized.
• The complex exhibits fluorescence quenching in the presence of nitro aromatics, acting as a "turn-off" sensor.
• High sensitivity was achieved with a detection limit of 7.6×10^-7 M for NO₂ and a binding constant of 1.1021×10⁸ M^-1.
• DFT calculations supported the proposed fluorescence quenching mechanism.
• A visual paper sensor strip was successfully developed for detecting nitro explosive residues.

Conclusions:

• The synthesized Zn(II) Schiff base complex is a highly sensitive and selective fluorescent probe for nitro explosives.
• The developed sensor offers a low-cost, rapid, and visual detection method suitable for forensic investigations and security applications.
• This research contributes to the advancement of chemical sensing technologies for homeland security and anti-trafficking initiatives.