CFA-4 - a fluorinated metal-organic framework with exchangeable interchannel cations.

Area of Science:

• Materials Science
• Crystallography
• Coordination Chemistry

Background:

• Development of novel porous materials is crucial for applications like gas storage and separation.
• Metal-organic frameworks (MOFs) offer tunable structures and high surface areas.
• Fluorinated ligands can impart unique properties to MOFs.

Purpose of the Study:

• To synthesize and characterize a new fluorinated linker, 1,4-bis(3,5-bis(trifluoromethyl)-1H-pyrazole-4-yl)benzene (H2-tfpb).
• To construct and investigate a novel family of metal-organic frameworks, M[CFA-4], based on the H2-tfpb linker.
• To explore the structural, thermal, and gas sorption properties of the synthesized MOFs.

Main Methods:

• Single crystal X-ray diffraction for ligand and MOF structure determination.
• Spectroscopic techniques (photoluminescence, NMR, IR) and mass spectrometry for ligand characterization.
• Synchrotron X-ray diffraction, thermogravimetric analysis, variable temperature powder X-ray diffraction, and gas sorption measurements for MOF analysis.

Main Results:

• The fluorinated linker H2-tfpb was successfully synthesized and characterized.
• A new family of MOFs, M[CFA-4] (M = Cu(I), K, Cs, Ca(0.5)), was discovered.
• The copper(I)-containing MOF, Cu(I)[CFA-4], crystallizes in a chiral hexagonal system with a 3D porous structure built from pentanuclear copper(I) units.
• Cu(I)[CFA-4] and K[CFA-4] were analyzed for thermal stability and gas sorption properties.

Conclusions:

• The synthesized H2-tfpb linker enables the formation of novel M[CFA-4] metal-organic frameworks.
• Cu(I)[CFA-4] exhibits a chiral, porous structure with potential for gas sorption applications.
• Comparative analysis of thermal stability and gas sorption properties provides insights into framework behavior.