Synthesis Of Cyclodextrin Porous Liquid And Its Chiral Recognition,Separation And Induction Performance

As a kind of liquid with permanent porosity,porous liquid material is a new type of multifunctional material in recent years.Because of its combination of the porosity of solid material and the fluidity of the liquid,porous liquid has shown great application potential in the fields of gas adsorption,gas separation and homogeneous catalysis.The porous liquid materials which prepared are mainly focused on organic cages,hollow nanoparticles,metal organic framework materials,molecular sieves and other materials in current research.However,there are few reports on porous liquid materials based on cyclodextrin which composed of a variable cavity and abundant hydroxyl groups in surface.This paper designed and synthesized a new type of cyclodextrin porous liquid material,and studied its application on chiral recognition and separartion toward 2′-deoxypyrimidine nucleosides and chiral induction toward two-dimensional planar conjugated molecules by taking advantage of chiral cavity.This paper aims to provide new ideas and new preparation method for porous liquid materials and explore the potential application value of porous liquid materials in the fields of chiral recognition,chiral separation and chiral induction,which has important theoretical and practical significance.In this paper,different cyclodextrins were reacted with imidazole-1-acetyl chloride respectively to introduce the imidazole group on the cyclodextrins and obtained the cyclodextrin esterification products（CD-IMs）.The esterification products were further reacted with dimethyl phosphite to obtain a cyclodextrin porous liquid material（CDPL）in a liquid state at room temperature.Finally,the prepared materials were characterized and identified by FT-IR,UV-vis,NMR,MALDI-TOF MS,CD,conductivity and other characterization methods.The conductivity of the CDPL was 100-500 times as great as that of dimethyl phosphite at 25°C.It was proved that cyclodextrin porous liquid,which belongs to the Type I porous liquid,was successfully synthesized.Based on the synthesis of a series of cyclodextrin porous liquid materials,the chiral recognition ability of the cyclodextrin porous liquid materials toward 2′-deoxypyrimidine nucleosides was investigated.The effects of the typse of cyclodextrin porous liquid materials,the p H and temperature of the solution on the chiral recognition effect were studied.The results showed that under the same conditions,the order of the chiral recognition ability ofα-CDPL,β-CDPL andγ-CDPL toward 2’-deoxycytidine and 2’-deoxythymidine is:γ-CDPL>α-CDPL>β-CDPL.It was shown that the p H of the solution plays an important role in the chiral recognition ofγ-CDPL toward 2′-deoxypyrimidine nucleosides.When the p H of the solution is 8,γ-CDPL shows high enantioselectivity to D-2’-deoxycytidine（D-d C）at 25 ^oC;when the p H of the solution is 10,γ-CDPL shows high enantioselectivity to L-2′-deoxythymidine（L-d T）at 25 ^oC.On the basis of the above results,the chiral separation ability ofγ-CDPL to 2′-deoxypyrimidine nucleosides was investigated and the effect of the solution p H,temperature and concentration of deoxynucleoside on the chiral separation was investigated.The results were shown that when the temperature is 25 ^oC and the deoxynucleoside concentration is 8×10^-5 mol·L^-1,the p H of the solution is 8,the enantiomeric excess value（ee）of the chiral separation ofγ-CDPL to（L+D）-d C（racemate of L-d C and D-d C）is 84.81%;the p H of the solution is 10,the ee of the chiral separation ofγ-CDPL to（L+D）-d T（racemate of L-d T and D-d T）is 66.26%.By comparing the chiral recognition and separation ability ofγ-CDPL withγ-cyclodextrin quaternary ammonium salt compound（γ-CD-HPTA）,γ-CD-IM,γ-CD andβ-CD to 2′-deoxypyrimidine nucleosides,it was concluded that the chiral recognition and separation ability of 5 kinds of cyclodextrin materials to 2′-deoxycytidine and 2′-deoxythymidine is in the order ofγ-CDPL>γ-CD-HPTA>γ-CD-IM>γ-CD>β-CD.Combined with molecular dynamics simulations,a recognition mechanism based on the different strengths of van der Waals interactions and hydrogen bonds betweenγ-CDPL and enantiomers was proposed.In the field of chirality research,chiral recognition is closely related to chiral induction.Based on the above results that cyclodextrin porous liquid materials have good chiral recognition ability,the chiral induction ability of cyclodextrin porous liquid has been continuously studied.Based on the chiral cavity of the cyclodextrin porous liquid material,which could include achiral molecules into its cavity,the chiral induction performance of the cyclodextrin porous liquid material and the silver nanoparticles modified by the cyclodextrin porous liquid material toward the two-dimensional planar conjugated molecules was investigated.It was found that the achiral nitroso red salt,alizarin red S,methylene blue and sodium indigo disulfonate cannot be induced to yield chirality byα-CDPL.In addition,α-CDPL,β-CDPL andγ-CDPL modified silver nanoparticles all have chirality,andβ-CDPL modified silver nanoparticles can induce the chirality of methylene blue and sodium indigo disulfonate.In order to achieve the chiral induction of methylene blue and indigo sodium disulfonate byα-CDPL,azobenzene-modified silver nanoparticles（Azo-Ag NPs）were designed and synthesized.Then,Azo-Ag NPs,α-CDPL and dye molecules were mixed and obtained a supramolecular chiral induction system.The chiral induction properties of the system toward methylene blue and indigo sodium disulfonate were investigated.It was shown that when Azo-Ag NPs,α-CDPL and methylene blue were added together at the same time,or when Azo-Ag NPs andα-CDPL were mixed in advance and then methylene blue was added,the system can induce methylene blue to yield chirality.Under different p H conditions,Azo-Ag NPs andα-CDPL could induce the chirality of methylene blue or indigo sodium disulfonate differently.When the p H is 7.5 to 10,Azo-Ag NPs andα-CDPL induce methylene blue to yield chirality;when the p H of the system is 6.5-7.5,Azo-Ag NPs andα-CDPL could induce sodium indigo disulfonate yield chirality at 25 ^oC.Azo-Ag NPs andα-CDPL have stronger chiral induction ability to methylene blue or sodium indigo disulfonate when the ionic strength is low,.