A Benzophenanthrazine Schiff Base Fluorescent Probe for Selective Detection of Cu²

Area of Science:

• Analytical Chemistry
• Environmental Science
• Materials Science

Background:

• Copper ions (Cu²⁺) are essential but toxic at high concentrations.
• Developing selective fluorescent probes for Cu²⁺ is crucial for monitoring.
• Existing probes may lack selectivity, speed, or a wide pH range.

Purpose of the Study:

• To develop a benzophenanthrazine Schiff base fluorescent probe (D1) for Cu²⁺ detection.
• To achieve high selectivity, sensitivity, and rapid response for Cu²⁺ sensing.
• To evaluate the probe's performance across a broad pH range and in real samples.

Main Methods:

• Synthesis of the benzophenanthrazine Schiff base probe (D1).
• Fluorescence spectroscopy for Cu²⁺ detection and characterization.
• Job's plot and fluorescence titration for binding stoichiometry and affinity.
• Selectivity tests with various metal ions and pH range studies.
• FT-IR, quantum yield, and DFT calculations for mechanism elucidation.

Main Results:

• Probe D1 showed fluorescence quenching at 517 nm upon Cu²⁺ addition.
• Achieved a low detection limit of 0.53 µM with a response time under 20 s.
• Confirmed 1:1 binding stoichiometry with an association constant of 5.0 × 10⁵ M⁻¹.
• Demonstrated excellent selectivity for Cu²⁺ over other metal ions in THF/H₂O (9:1, v/v).
• Probe D1 functioned effectively across a wide pH range (4-11) and in real water samples.

Conclusions:

• The developed probe D1 is highly selective and sensitive for Cu²⁺ detection.
• Its rapid response and broad pH applicability make it suitable for environmental monitoring.
• Coordination between Cu²⁺ and the phenolic O and imine N atoms governs the fluorescence quenching mechanism.