An efficient and sensitive fluorescent pH sensor based on amino functional metal-organic frameworks in aqueous...

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) offer tunable properties for sensing applications.
• Luminescent MOFs are promising for developing optical sensors.
• Developing stable and sensitive pH sensors for aqueous environments remains a challenge.

Purpose of the Study:

• To synthesize and characterize a novel luminescent MOF, Al-MIL-101-NH2, for fluorescent pH sensing.
• To evaluate the stability, sensitivity, and accuracy of Al-MIL-101-NH2 as a pH sensor in aqueous solutions.
• To investigate the sensing mechanism and practical applicability of the developed MOF sensor.

Main Methods:

• Fabrication of Al-MIL-101-NH2 via reaction of Al(III) salt and 2-aminoterephthalic acid.
• Characterization of luminescence properties and structural stability in aqueous media.
• Quantitative analysis of fluorescence intensity response to pH variations (4.0-7.7).
• Incorporation of Fe3O4 nanoparticles for easy sample isolation.

Main Results:

• Al-MIL-101-NH2 exhibits good luminescence and structural integrity in aqueous solutions (pH 4.0-7.7).
• A strong linear correlation (R(2) = 0.99688) between fluorescence intensity and pH was observed (I = 2.33 pH + 26.04).
• The sensor demonstrated accuracy and reusability through error analysis and cycling experiments.
• Effective pH sensing was achieved in practical samples like PBS and lake water.

Conclusions:

• Al-MIL-101-NH2 is a highly stable and sensitive luminescent MOF for fluorescent pH sensing in aqueous solutions.
• The developed sensor offers a reliable and accurate method for pH monitoring with a clear linear response.
• This work presents an integrated pH sensing system based on luminescent MOFs, highlighting their potential in environmental and biological applications.