Separation properties of bis(β-diketonato)-copper(II) complexes in capillary gas chromatography

The bis[1-4'-(octyloxybiphenyl-4-yl)-3-(l'-methylpropyl)-1,3-dionato]- and bis[1-4'-(nonyloxybiphenyl-4-yl)-3-(l'methylpropyl)-1,3-dionatol- copper(II) complexes were synthesized and successfully coated onto a fused- silica capillary column. The results obtained from differential scanning calorimetry and the melting point apparatus equipped with a polarization microscopy showed that they present a nematic phase and have a very limited liquid crystalline temperature range under cooling conditions. The chromatographic experiments show that these metal complexes possess good separation abilities for many different kinds of di- and tri-substituted benzene isomers, polycyclic aromatic hydrocarbons and constituents of volatile oils. In order to illustrate the influence of the presence of copper in the molecules of the stationary phase, the selectivities of 1,3-diones were compared with their corresponding bis(β-diketonato)-copper(II) complexes.