Synthesis\nof the Fluorine-Edged Macrocycle for Promoting\nHigh-Resolution Gas Chromatographic Separation

Herein, we report that the introduction of fluorine binding\nsites\nto macrocycles achieves high-resolution gas chromatographic separation\nof aromatic hydrocarbons, cycloolefins, and cycloparaffins. The tetrafluoroterphen[3]arene\n(<b>4FTP3</b>) macrocycle, containing 12 fluorines on its skeleton\nedge, was synthesized in a 52% yield via a one-pot approach and then\ncoated onto a capillary column as a gas chromatographic stationary\nphase. The resulting column permitted the high-resolution separation\nof cyclohexane/cyclohexene/benzene, cycloheptane/cycloheptene, and\ntetrahydronaphthalene/naphthalene mixtures, with a retention capacity\ndecreasing in the order of aromatic hydrocarbons > cycloolefins\n>\ncycloparaffins. Single-crystal structural analysis revealed that <b>4FTP3</b> assembled into a three-dimensional superstructure with\nmultiple internal cavities and external voids by multiple intermolecular\nC–H···F interactions and contributed to the\nseparation. Significantly, the distinction of C–H···F\ninteractions between macrocycle <b>4FTP3</b> and analytes resulted\nin different binding affinities, association enthalpies, and retention\ntimes for the various analytes and therefore plays a key role in such\nhigh-resolution separation. The simple preparation, high yield, and\nclear separation mechanism associated with <b>4FTP3</b> render\nit a cost-effective separation material for use in further applications.\nThe design of macrocycles with specific binding sites provides new\ninsights into high-resolution gas chromatographic separation.