Mixed Metal-Organic Framework Stationary Phases for Liquid Chromatography

Area of Science:

• Materials Science
• Analytical Chemistry
• Separation Science

Background:

• Strategic design of stationary phases is critical for advancing liquid chromatography (LC) separations.
• Metal-organic frameworks (MOFs) present a versatile platform for creating tunable stationary phases due to their structural modifiability.

Purpose of the Study:

• To propose and investigate a novel design approach for LC stationary phases using mixed metal-organic frameworks (MOFs).
• To explore the tunability of MOF pore sizes and their impact on retention behavior by systematically varying organic ligands.

Main Methods:

• Synthesized three isostructural MOFs with systematically varied pore sizes using 1,4-benzenedicarboxylate (bdc), 1,4-naphthalenedicarboxylate (ndc), and 9,10-anthracenedicarboxylate (adc) ligands.
• Prepared packed LC columns using pure MOF particles, binary mixtures of MOF particles, and mixed-linker solid-solution MOFs.
• Evaluated the retention capability of polyethylene glycol (PEG) on these MOF-packed columns.

Main Results:

• Columns packed with binary MOF particle mixtures allowed for controlled retention based on mixing ratios.
• Columns packed with mixed-linker solid-solution MOFs exhibited a significant multicomponent effect on retention.
• Specifically, bdc/ndc mixed-linker solid-solution MOFs demonstrated retention superior to their individual parent MOFs.

Conclusions:

• Mixed-linker solid-solution MOFs offer a powerful strategy for designing advanced LC stationary phases.
• The enhanced retention in solid-solution MOFs is attributed to their unique nanostructures influencing substrate affinity and adsorption kinetics.
• MOFs provide a promising and highly tunable recognition medium for next-generation LC applications.