The Synthesis And Separation Property Research Of β-cyclodextrin Derivatives

Chiral compounds,which have unique structure of chiral,have aroused widely attentions of the researchers in some fields such as spices,medicine and pesticide.For gas chromatography（GC）or high performance liquid chromatography（HPLC）,the stationary phase of capillary is mainly used to separate chiral analyte.Thus,the research and development of new chromatographic stationary phase have been a hot research topic in the field of chromatography.The purpose of this paper is to synthesize novel β-cyclodextrin（β-CD）derivatives and g-C₃N₄ nanosheets which were characterized and evaluated by the comprehensive analysis methods.Then both of them were used as a stationary phase,coated on capillary chromatographic column,and explored its gas chromatographic separation performance.In this paper,the key research content is as follows:1.A novel β-cyclodextrin（β-CD）derivatives,per（6-Valine-methylester-2,3-phenylcarbamoyla-ted）-β-CD,were synthesized through four-steps reaction: iodination,azidation,esterification and stauding reaction in turn.And the derivatives were characterized by Fourier transform infrared spectroscopy（FT-IR）,Element analysis and Hydrogen nuclear magnetic spectroscopy（1HNMR）to characterise its molecular structure.The result shows that the per（6-Valine-methylester-2,3-phenylcarbamoylated）-β-CD was successfully prepared.Then the thermogravimetric analysis（TGA）shows that the derivatives begin to be decomposed at about 210 ℃ and could be used as a stationary phase in GC.2.The g-C₃N₄ nanosheets were synthesized via direct pyrolysis of melamine followed by two-step calcining method（therml aggregation,thermal exfoliation）.After calcining,a kind of few-layer g-C₃N₄ nanosheets was obtained,which possess thinner layer structure and higher surface areas by comparing with the previous bulk g-C₃N₄.This will result in the more adsorption sites and superior performance.The crystal structure,surface valence bond structure,functional group and morphology were explored by comprehensive characterisation methods such as X-ray diffraction（XRD）,X-ray photoelectron spectrometer（XPS）,Fourier transform infrared spectroscopy（FT-IR）,Scanning electron microscope（SEM）,Transmission electron microscopy（TEM）.3.Both of novel β-CD derivatives and g-C₃N₄ nanosheets have larger specific surface area and better adsorption performance,which are suitable for the preparation of capillary column as stationary phase.Therefore three columns based on novel β-CD derivatives,g-C₃N₄ nanosheets and the mixture of them respectively were prepared by static method and explored their chromatographic separation performance.The results exhibit that the novel β-CD derivatives column not only can separate achiral compounds（such as: Grob reagents,C9-C15 straight-chain alkanes,ethylbenzene-xylene and nitrotoluene）,but also can be a very good candidate separation material for chiral compounds（such as limonene,lactic acid methyl ester and methyl valine and camphor）.The g-C₃N₄ nanosheets column has better separation efficiency for isooctane-heptane-octane mixture.The column based on the mixture of β-CD derivatives and g-C₃N₄ nanosheets shows the merits of the two kinds of stationary phases.The mixture column offered higher separation performance for the Grob reagents,C9-C15 straight-chain alkanes,nitrotoluene,isooctane-heptane-octane mixture and aliphatic alcohol C3-C5-OH,especially alkanes and aliphatic alcohols.