Copper-based metal-organic framework for sensitive sensing of Cr₂O₇^2- in aqueous solution

Area of Science:

• Environmental Chemistry
• Materials Science
• Nanotechnology

Background:

• Dichromate ions (Cr2O72-) are toxic and carcinogenic pollutants in wastewater.
• Accurate and rapid monitoring of Cr2O72- is crucial for environmental safety.

Purpose of the Study:

• To develop a water-stable copper-based metal-organic framework (Cu-OCH3 MOF) as a fluorescent sensor.
• To detect Cr2O72- in aqueous media with high sensitivity and rapid response.

Main Methods:

• Synthesis of a water-stable Cu-OCH3 MOF with mixed oxidation states of copper.
• Characterization of MOF photoluminescence properties (excitation/emission spectra, quantum yield, fluorescence lifetime).
• Evaluation of the MOF sensor's performance for Cr2O72- detection in aqueous solutions.

Main Results:

• The Cu-OCH3 MOF exhibited fluorescence with excitation/emission maxima at 310 nm/393 nm.
• The sensor achieved ~95% quenching efficiency for Cr2O72- at 1 mM.
• Achieved a low detection limit of 6.27 × 10^-6 M with a wide linear range (0.0209-1 mM).

Conclusions:

• The developed Cu-OCH3 MOF is a promising fluorescent sensor for Cr2O72- detection.
• Sensing mechanism involves inner filter effect (IFE) and dynamic quenching effect (DQE).
• This MOF offers a sensitive, rapid, and effective method for monitoring dichromate pollution.