Biomimetic Mineralization At A Dilute Concentration And Application Of Silica In Enantioseparation

Biomineralization is a common phenomenon in nature,as a kind of biological mineral,silica shows great application prospects in medicine,food,chromatographic separation and so on.Cyclodextrin derivatives,amino acid derivatives and polysaccharides are three typical stationary phases of gas chromatography for enantioseparation,while silica as an inorganic material for gas chromatography stationary phase can separate organic matter,which can avoid the loss of stationary phase,and can be reused by calcining at high temperature to remove pollutants when the stationary phase is seriously polluted.Therefore,it has great significance to develop chromatographic stationary phase of the chiral inorganic silica materials,which greatly widens the selection range of the stationary phase for enantioseparation.In this paper,the chiral materials are prepared and used as the stationary phase of capillary gas chromatography for enantioseparation.The main research work is shown as following:Firstly,inorganic chiral silica material was successfully prepared and its application in enantioseparation was achieved.Specifically,two kinds of chiral silica materials are applied,one is the silica material prepared by biomimetic mineralization under tetraethoxysilane(TEOS)/L-18Phe6 Py Br(2:1,w/w)using the self-assemblies of an L-phenylalanine derivative(L-18Phe6 Py Br)at a concentration of 0.30 m M,which realized the seperation of 1-phenyl-1-propanol,1-(4-chlorophenyl)ethanol and2-methylpentanoic acid enantiomers,and also exhibits good selectivity for the separation of linear alkanes and aromatic hydrocarbon mixtures.The other is single-handed helical silica nanotubes which obtained through the sol-gel process by using the self-assemblies of an LL-12Ala11 Py Cl O4 as template and TEOS as the silicon source,which realized the seperation of 1-phenylethanol and 2-methylpentanoic acid enantiomers.The results indicate that these two kinds of inorganic silica materials show chiral recognition ability as stationary phase gas chromatography,and chiral supramolecular imprinting is proposed to drive this enantioseparation ability of silicas.Secondly,the assembly of dipeptide sodium salts with long alkyl chains derivedfrom L-alanine(C15H31CO-L-Ala-L-Ala-ONa)in tetrahydrofuran is used as the stationary phase of packed column gas chromatography for enantioseparation.The results show that enantiomers can not be separated by this statinoary phase,but shows excellent separation ability for linear alkanes,alcohols,and aromatic hydrocarbon mixtures.