Constructing Highly Emissive Covalent Organic Frameworks for Fe³⁺ Ion Detection via Wall Function

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) are crystalline porous polymers with tunable structures.
• COFs are promising for light-emitting applications but suffer from aggregation-caused quenching (ACQ).
• ACQ in COFs arises from strong inter-layer interactions, hindering luminescence.

Purpose of the Study:

• To develop COFs with improved luminescence by suppressing ACQ.
• To engineer COFs for sensitive and selective metal ion detection.

Main Methods:

• Synthesized TM-OMe-EBTHz-COF using building units with three methoxy groups.
• Investigated the luminescence properties of the synthesized COF in the solid state.
• Evaluated the COF's performance as a sensor for metal ions, particularly Fe3+.

Main Results:

• TM-OMe-EBTHz-COF exhibits yellow-green luminescence with a high absolute quantum yield of 21.1%.
• The methoxy groups and hydrazine linkage provide three coordination sites for metal ion sensing.
• The COF demonstrated high sensitivity and selectivity for Fe3+ ions, with a detection limit below 150 nM.

Conclusions:

• The methoxy-functionalized COF effectively suppresses ACQ, leading to enhanced solid-state luminescence.
• TM-OMe-EBTHz-COF shows excellent potential as a highly sensitive and selective sensor for Fe3+ ions.