Multipurpose made colorimetric materials for amines, pH change and metal ion detection

Area of Science:

• Materials Science
• Analytical Chemistry
• Organic Electronics

Background:

• Multipurpose sensors are challenging due to stability and functional design limitations.
• Existing sensors often lack broad applicability across different phases (solution and gas).

Purpose of the Study:

• To develop novel organic materials for multipurpose sensing applications.
• To demonstrate the materials' response to pH, metal ions, and amine vapors.
• To validate sensing capabilities using analytical and computational methods.

Main Methods:

• Spectrophotometric titrations with trifluoroacetic acid (TFA) and triethyl amine (TEA) for acid-base response.
• Metal ion binding studies with Zn(II) and Cu(II) using UV-Vis spectroscopy and X-ray crystallography.
• Fabrication of paper-based sensors for amine vapor detection.
• Analysis using CIE L*a*b* color space for quantitative color change assessment.

Main Results:

• Organic materials exhibited significant spectral shifts (up to 100 nm) and color changes in response to pH and solvent polarity.
• Excellent reversibility in acid-base titrations, with higher sensitivity to bases.
• Stable complexes formed with Zn(II) and Cu(II); Cu(II) detected as low as 2.5 × 10⁻⁶ M with signal suppression.
• Paper-based sensors detected amine vapors at 1 ppm concentration.
• CIE L*a*b* color space provided objective quantification of color changes, enabling sensitive and specific analyte detection.

Conclusions:

• Developed stable, multipurpose organic sensors for solution and gas-phase analytes.
• Demonstrated effective sensing of pH, metal ions (Zn(II), Cu(II)), and amine vapors.
• Validated the utility of CIE L*a*b* color space for quantitative and specific sensing.