Novel Dual-Mode Fluorescent Sensor for Detecting Chlorpyrifos and Cu(II).

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Materials Science

Background:

• Hazardous chemicals, including pesticides like chlorpyrifos (CP) and heavy metals like copper ions (Cu2+), pose significant risks to ecosystems and human health.
• Industrial and agricultural activities are major sources of environmental contamination by these toxic substances.
• Sensitive and selective detection methods are essential for monitoring and mitigating the impact of hazardous chemicals.

Purpose of the Study:

• To develop a novel, dual-analyte fluorescent sensor for the simultaneous and selective detection of chlorpyrifos (CP) and Cu2+.
• To characterize the sensor's performance, including sensitivity, selectivity, and detection limits under various conditions.
• To elucidate the binding mechanisms and stoichiometric ratios involved in the detection processes.

Main Methods:

• Synthesis of an oxime-functionalized carbazole-based fluorescent sensor (PK).
• Fluorescence spectroscopy was employed to detect CP and Cu2+.
• Job's plot analysis, infrared spectroscopy, mass spectrometry, 1H nuclear magnetic resonance (NMR), and density functional theory (DFT) calculations were used to confirm binding stoichiometry and mechanisms.

Main Results:

• The developed sensor (PK) exhibited fluorescence quenching upon interaction with both CP and Cu2+.
• PK demonstrated high selectivity for CP over other organophosphates in a basic buffer, with a detection limit of 0.485 ppm.
• PK selectively detected Cu2+ in an aqueous organic solution with a detection limit of 15.19 ppb, distinguishing it from interfering metal ions.
• Binding studies confirmed a 1:1 stoichiometric ratio for both CP and Cu2+ interactions with PK.

Conclusions:

• The synthesized oxime-functionalized carbazole (PK) serves as an effective dual-analyte fluorescent sensor for CP and Cu2+.
• The sensor offers high sensitivity and selectivity, making it suitable for environmental monitoring applications.
• The detailed mechanistic studies provide valuable insights into the sensor's operation and potential for further development.