Investigation on five novel substituted β-cyclodextrins used as GC stationary phases

Five β-cyclodextrin derivatives, heptakis[2,6-di-O-pentyl-3-O-(4- nitrobenzyl))-β-CD (CD-I), heptakis [2,6-di-O-pentyl-3-O-(5-hexenyl)]- β- CD(CD-II), heptakis-(2, 6-di-O-cinnamyl-3-O-methyl)-β-CD(CD-III), heptakis- (2, 6-di-O-cinnamyl-3-O-acetyl)-β-CD (CD-IV) and heptakis (2, 6-di-O- cinnamyl-3-O-trifluoroacetyl)-β-CD(CD-V), were synthesized and coated on fused-silica capillary columns. Their chromatographic characteristics were tested and compared with heptakis (2,3,6-tri-O-pentyl)-β-CD (CD-VI) and heptakis (2,6-di-O-pentyl-3-O-trifluoroacetyl)-β-CD(CD-VII). It was found that the size, polarity, and aromatic property of the substituted group at the 3-position of heptakis (2,6-di-O-pentyl)-β-cyclodextrins greatly influenced their chromatographic properties and separation ability. The introduction of aromatic group or a group containing a double-bond may bring π-π interactions between the host and guest molecules, and therefore increased the separation ability of the β-CDs for substituted benzene isomers. Introduction of cinnamyl groups in to the 2,6-3-position of β-CD has a significant effect on the chromatographic properties of the stationary phases(CD-III-CD-V).