High-Precision Separation and Refinement of Fatty Acid Derivatives by Metal-Organic Frameworks.

High-precision separation of fatty acid (FA) derivatives is essential for differentiating between structural variations such as E/Z isomerism and unsaturated bond (C═C) positions, which determine their properties and physiological functions. However, current separation and purification methods lack the necessary resolution, efficiency, and scalability. Herein, we report that metal-organic frameworks (MOFs) with configured nanopores enable the precise separation of long-chain FA derivatives. Two pillared-layer-type isoreticular MOFs featuring sub-nanometer channels were employed as adsorbents and stationary phases in liquid chromatography (LC). The MOF-packed LC columns demonstrated high-resolution separation of C18 fatty acid methyl esters (FAMEs), effectively distinguishing E/Z isomers and C═C positional isomers through a nanopore insertion-based recognition mechanism. Thermodynamic analysis and molecular dynamics simulations revealed an unprecedented recognition mechanism for C═C positional isomers, driven by specific multi-site interactions between the functional groups on the FAME chains and the regularly arranged organic ligands within the MOF nanopores. Moreover, MOFs enable the purification of fats and oils (triacylglycerols) by effectively separating them from associated process contaminants that may pose carcinogenic risks to humans. This approach facilitates the scalable and efficient refinement of edible oils, achieving contaminant elimination efficiencies exceeding 99%.