Modular Construction of Vinylene-Linked Covalent Organic Frameworks with Tunable Emission for Tumor Visualization

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) with ordered π structures are promising for porous light-emitting materials.
• Existing COFs often suffer from poor luminescence or lack of water stability.

Purpose of the Study:

• To construct a series of isostructural donor-acceptor (D-A) vinylene-linked COFs with enhanced properties.
• To investigate the relationship between molecular structure and luminescence properties.
• To explore the application of these COFs in bioimaging.

Main Methods:

• Synthesis of isostructural D-A vinylene-linked COFs using a new D2h symmetric linker (TMTA).
• Characterization of COFs for crystallinity, surface area, chemical, and thermal stability.
• Density Functional Theory (DFT) calculations to establish structure-property relationships.

Main Results:

• The constructed COFs exhibit high crystallinity, high surface area, and excellent stability.
• Luminescence properties (adsorption and emission wavelength) are tunable based on the π-system density in the electron-donating group.
• DFT calculations confirmed the link between luminescence and donor electronic structure.

Conclusions:

• The developed vinylene-linked COFs provide a foundation for molecular engineering of luminescent properties.
• FZU-203, a representative COF, demonstrates potential for bioimaging applications.
• These findings offer strategic guidance for using COFs as fluorescent nanoprobes in medical diagnosis and tumor therapy.