Preparation And Evaluation Of The Molecularly Imprinted Monoliths Based On Metal Ion Pivot And Ionic Liquid

Molecular imprinting is one of new techniques for synthesizing material of molecular recognition with the ability of pre-selectivity.Monolithic columns are a new type of chromatographic stationary.Because of combining the molecular recognition of molecular imprinting and merits of monolithic columns,molecularly imprinted monolithic column?MIMC?becomes a tendency.Porogen plays a very important role in the preparation of molecularly imprinted polymers?MIPs?.First,porogen effects the formation of large pores,which make sure of good flow-through properties of the resultant MIPs.Second,the porogenic solvent also controls the strength of non-covalent interactions and influences the morphology of polymers.Ionic liquid has been used as solvent or porogen to prepare MIPs and shown to be able to accelerate the polymerization and improve the effect of imprinting.Recently,it has been demonstrated in our lab that the adoption of metallic pivot for self-assembly could effectively produce highly specific imprinted polymers.However,a new system of porogen is stilled needed to prepare molecularly imprinting monolithic columns for the insolubility of metal ion in ionic liquid.In this study,a new ternary porogen based on ionic liquid[BMIM]BF₄,dimethyl sulfoxide and dimethyl formamide is adopted to obtain desired separation,which can resolve metal ion,increase the permeability and specific recognition of the obtained monolithic column.The results are follows:1.An effective way of synthesis of molecular imprinting monolithic columns based on ionic liquid for chiral separation was developed.The results demonstrate that the strategy of metal ions as pivot in combination of ionic liquid is an effective method to prepare MIP monolithic column with high permeability and column efficiency for chiral separation.Baseline separation is achieved and the resolution of rac-mandelic acid reaches 1.871.An imprinted monolithic column was synthesized using a mixture of R-mandelic acid?R-MAN,template?,4-vinylpyridine?4-VP?,ethylene glycol dimethacrylate?EDMA?,2,2'-Azobis?2-isobutyrontrile??AIBN?,cobalt acetate,dimethyl sulfoxide?DMSO?,dimethyl formamide?DMF?and[BMIM]BF₄.The influence of polymerization parameters such as the nature of metal ions,the ratio of template to metal ion and the template to functional monomer,and the degree of crosslinking on permeability,morpholophy and chiral separation effect of R-Mandelic acid-imprinted monolith were systematically investigated.2.Gallic acid imprinted monolithic column was synthesized using a mixture of gallic acid?GAL,template?,4-vinylpyridine?4-VP?,ethylene glycol dimethacrylate?EDMA?,2,2'-Azobis?2-isobutyrontrile??AIBN?,cobalt acetate,dimethyl sulfoxide?DMSO?,dimethyl formamide?DMF?and[BMIM]BF₄.The separation of GAL and its analogues can be achieved and RS reached 4.038.The preparation conditions of monolithic column system were investigated,such as the proportion of template and functional monomer,the ratio of porogen,functional monomer and cross-linking agent ratio.With the analysis of scanning electron microscopy,mercury intrusion and experiments of high performance liquid chromatography,the preparation of monolithic column and the chromatographic conditions were optimized.