Construction And Enantiomeric Resolution Of Chiral Sensing Interface Based On Ferrocene Derivatives

Electrochemical analysis technology with the advantages of fast response speed and high sensitivity has been widely used in chiral recognition.At the same time,the detection of samples by electrochemical analysis has certain restrictions.Common analytes include tyrosine,tryptophan,cysteine,dopa,et al.It is hard to detect the non-electroactive chiral compounds.Herein,in this thesis,to enlarge the detection range of electrochemical methods,different kinds of supramolecular systems were developed for chial electroanalysis of the non-electroactive chiral compounds.Specific research contents are as follows:1.Chiral recognition of nonelectroactive enantiomers by supramolecular interaction based on ferrocene derivatives: The main molecule is a cyclic tetravalent bipyridine salt loaded on the surface of the working electrode;The guest molecules are combined by the supramolecular interaction between chiral selectors and ferrocene derivatives to form ferrocene modified enantiomeric electroactive molecules.Through π-electron attraction and π-π stacking between host and guest,Once the guest binds to non-electroactive amino acid isomers with different configurations,the electron transfer rate between the guest molecule and the host molecule will be limited,and the peak current difference will be given by cyclic voltammetry,which may be affected by the interaction between amino acid isomers and chiral selectors.At the same time,the change of peak current was discussed under the action of metal ion coordination,and the formation of copper ion modified molecular self-assembly and its supramolecular interaction with L/D-threonine were confirmed by density functional theory.2.Research on chiral recognition of nonelectroactive amino acids by polymeric ferrocene derivatives: The self-assembly system contains chiral imine/quaternary ammonium salt as binding site and ferrocene as electroactive unit.The branched chain of chiral polymer has two functional groups(phenyl and ferrocene),and one of its advantages is that its shape is similar to pliers to provide sufficient steric hindrance.Chiral polymers were modified on the working electrode(glassy carbon electrode)as electrochemical chiral sensors.When amino acid isomers interact with the three-dimensional center of chiral polymer,the electron transport of ferrocene is affected.When cyclic voltammetry is used to detect non-electroactive amino acids such as proline,threonine and alanine,the peak current responses to L/D-isomers are obviously distinguished at different p H values.Furthermore,the recognition mechanism of amino acid isomers by chiral polymers was confirmed by density functional theory.3.Electrochemical chiral recognition of amino acid enantiomers based on ferrocene modified silica microspheres: Achiral ferrocene derivatives were directly bridged to the surface of silica microspheres,and electrochemical signals were given by ferrocene.Then the synthesized silica microspheres were mixed with excessive β-cyclodextrin to mask the electrochemical activity of ferrocene.The self-assembled system was characterized by IR,TG and X-ray photoelectron spectroscopy.When the system is immobilized on the surface of carbon working electrode as a chiral sensor,amino acids(phenylalanine,histidine,glutamic acid and threonine)can enter the cavity of β-cyclodextrin to compete with ferrocene,and then release ferrocene,which leads to signal enhancement.Because of the different inclusion constants between the enantiomers and β-cyclodextrin,L-amino acids and D-amino acids have different enantioselectivity for electrochemical signals.