A chiral metal-organic cage used as the stationary phase for gas chromatography separations

Chiral metal-organic cages (MOCs) are a new type of porous materials with unique molecular recognition ability, which have received research attention as a chiral stationary phase (CSP) for gas chromatography (GC). Herein, we report the detailed investigation of a chiral MOC ([Cu₁₂(L_PA)₁₂(H₂O)₁₂], PA = L-phenylalanine, MOC-PA) as a novel stationary phase for GC separations. The MOC-PA capillary column exhibited a high-resolution performance for a wide range of analytes, including n-alkanes, n-alcohols, esters, aromatic compounds and the Grob mixture, positional isomers and racemates. In particular, MOC-PA coated column displayed good resolution and performance for amino acid derivatives. Moreover, the MOC-PA column showed excellent separation repeatability and reproducibility. The relative standard deviation (RSD) values for the retention times were in the range of 0.16-0.30% for run to run (n = 3), 0.31-0.77% for day-to-day (n = 3), and 3.6-4.7% for column-to-column (n = 3), respectively. The experimental results showed that MOC-PA had great potential as a GC stationary phase.