A chiral emissive porous organic cage used for high-resolution gas chromatography separations

Abstract

Herein, we report a chiral and porous tubular organic molecular cage (3P-1) that was obtained through a [3+6] imine condensation reaction between ETTBA (4,4′,4′′,4′′′-(ethene-1,1,2,2-tetrayl)-tetrabenzaldehyde) and (R, R)-CHDA ((R, R)-diaminocyclohexane), as the stationary phase for preparing a 3P-1-coated capillary column by the static coating method. Because the chirality of (R, R)-CHDA was transferred from the point to the chiral face of TPE (tetraphenylethylene) during the formation of the 3P-1 cage, it provides a chiral and porous environment within it. The prepared 3P-1 chiral porous cage is verified by a variety of characterizations. Achiral mixtures, including halogenated benzenes, alkylbenzenes, esters, n-alcohols, n-alkanes, Grob reagent and isomers, have been separated on the 3P-1-coated column. In addition, the separation performance for various racemates, including ethers, esters, alcohols, epoxides, and amino acid derivatives, on the 3P-1-coated column was evaluated. Nine racemates including butyl glycidyl ether, γ-heptalactone, 2-hexanol, 2,3-butanediol, epichlorohydrin, epibromohydrin, 3-buten-2-ol, DL-threonine, and DL-isoleucine have been resolved on this column, and it showed good chiral resolution capacity for them. The 3P-1-coated column exhibited good enantioseparation complementarity for separating some racemates compared with the β-DEX 120 commercial column, and it could even separate some racemates that the β-DEX 120 commercial column could not separate well. Furthermore, the prepared 3P-1-coated column presents good reproducibility after multiple injections of the same analytes and good thermal stability. In summary, all of the studies in this work demonstrate the good application potential of the 3P-1-coated capillary for GC separations.