Fluorescence turn on amine detection in a cationic covalent organic framework

Area of Science:

• Materials Science
• Analytical Chemistry
• Supramolecular Chemistry

Background:

• Ionic covalent organic frameworks (iCOFs) are emerging porous materials with tunable properties.
• Functionalized iCOFs can act as chemosensors by altering luminescence upon guest molecule interaction.
• Ammonia and primary amines are important analytes in environmental and food safety monitoring.

Purpose of the Study:

• To develop a novel luminescence sensor based on iCOFs for the detection of ammonia and primary aliphatic amines.
• To investigate the sensing mechanism involving intramolecular charge transfer (ICT) suppression.
• To demonstrate the practical application of the sensor in monitoring biogenic amines in food products.

Main Methods:

• Synthesis of an ionic covalent organic framework (TGH+•PD) incorporating guanidinium and phenanthroline moieties.
• Luminescence spectroscopy to study the fluorescence response to various analytes.
• Evaluation of detection limits and selectivity for ammonia and primary amines.
• Testing the sensor's performance in detecting biogenic amines from decomposing meat products.

Main Results:

• TGH+•PD exhibits strong fluorescence emission enhancement upon interaction with primary amines, attributed to ICT suppression.
• Achieved an ultra-low detection limit of 1.2 × 10⁻⁷ M for ammonia.
• Demonstrated size selectivity due to ordered pore walls.
• Successfully monitored biogenic amine vapors released from improperly stored meat products.

Conclusions:

• The developed iCOF (TGH+•PD) serves as an effective and sensitive luminescence sensor for ammonia and primary aliphatic amines.
• The sensor's water dispersibility and fluorescence-based detection mechanism offer practical advantages.
• This technology holds promise for real-time monitoring of food decomposition and related safety concerns.