High-efficiency Recognition Of Poly(ionic Liquid) For Amino Acids And The Preparation And Application Of The Polymer Network Supported Catalyst Based On This Foundation

Ionic liquids can enable specific detection of certain substances because of its own structure and the atomic groups.Besides,Ionic liquids not only promote the reaction rate,but also increase the selectivity of the reaction.Therefore,ionic liquids have developed rapidly in asymmetric synthesis reactions in recent years.Poly(ionic liquid)have the same properties both ionic liquids and polymers.Compared to small-molecule ionic liquids,polymer backbones and side chains can be more efficiently tuned for their structure and more conducive to the construction of highly efficient identification systems and supported catalytic systems.Through experimental studies,it has been found that PIL can detect three basic amino acids(Asp,Lys,His)with high sensitivity and selectivity in water,and a strong non-covalent interaction force can be formed between the poly(ionic liquid)and L-proline.Based on this idea,we designed and synthesized a polymer network system suppored with a chiral catalyst L-proline.The details are as follows:(1)The naked eye detection of amino acids(AA)in water is importance in bioanalytical applications.In this paper,we prepared novel poly(ionic liquid)chemical sensors with different chain lengths by reversible addition-fragmentation chain transfer polymerization(RAFT polymerization)to study the interaction with various amino acids in water and ethanol.The AA recognition performance of PILs with different alkyl chain lengths and molecular weights was evaluated by naked-eye color change and ultraviolet-visible(UV–vis)spectral studies.These PILs were successfully used for highly sensitive and selective detection of Arg,Lys,and His in water.And the recognition performance was improved effectively with increased molecular weight of PILs.Through this we realized the recognition effect of poly(ionic liquid)in water mainly depends on the aggregation and polarization effects,and this recognition is achieved through the interaction with carboxyl groups.(2)Based on the above experiments,a new heterogeneous proline catalyst system was prepared based on strong noncovalent interactions between polymer ionic liquid(PIL)and L-proline and made its apply to symmetrical catalysis.First,PIL complex with L-proline monomer by noncovalent interaction.The polymer network supported chiral catalyst was then obtained by further free radical polymerization.At the same time,we have prepared a series of polymer network systems with different surface structures by adjusting the ratio of chiral monomers and polymer ionic liquids.The synthesized catalysts were characterized by thermogravimetry,scanning electron microscope and elemental analysis.Then the catalyst system be used to directly catalyze asymmetric Aldol reactions and multi-component reactions.Compared to organic small-molecule catalysts,This immobilized chiral catalysts system has a higher catalytic efficiency and was able to be reused and recycled five times with no discernible loss in catalytic activity and enantioselectivity.