Selective Recognition Of Amino Acid Enantiomers By Electrochemical Sensors Based On Chiral MOFs

The enantioselective recognition and quantitative detection of amino acids and chiral drug molecules have a very important impact on pharmaceutical chemistry,life science and human health.It is of great significance to develop a fast,economical,highly sensitive and highly selective method for amino acid recognition and detection.Here,the Chiral metal-organic framework(c MOFs)was designed and synthesized to explore the electrochemical identification ability of c MOFs for amino acid enantiomers.These studies extended the application of c MOFs in electrochemical chiral identification.It also opens up a new way for the design and synthesis of chiral sensing materials.The research content of this paper mainly includes the following two chapters:(1)Two kinds of 3D chiral coordination polymers Cu-TBPBe/Cu-TBPBa were constructed with the same chiral ligand--double substituted linear phenylproline derivatives ligand and Cu(Ⅱ)under the condition of different auxiliary ligand--bpee/bpea by solvethermal synthesis method.They are two isomorphic 3D isomorphic coordination polymers.The crystal structure and purity were characterized by X-ray single crystal diffraction,PXRD and IR.Cyclic voltammetry(CV)and differential pulse voltammetry(DPV)were used to evaluate the recognition efficiency of tryptophan enantiomers by c MOFs,and it was found that Cu-TBPBe/Cu-TBPBa had completely different enantiomer recognition performance.Cu-TBPBe has good enantioselectivity and high sensitivity for the electrochemical recognition of L-Trp,and the detection limit is 3.16 n M.The peak current ratio of DPV to L-Trp/D-Trp is up to53,which is much higher than that reported by previous electrochemical sensors.In contrast,Cu-TBPBa cannot distinguish between L-and D-Trp.The mechanism of action was fully analyzed through structural analysis,water contact angle test,ultraviolet,infrared,circular dichroism and other spectral characterization methods,and the synergistic mode of enantioselective adsorption of chiral groups and chiral auxiliary ligands was explored.In addition,we explore the best recognition conditions of CuTBPBe modified electrode for Trp chiral recognition.Verify its repeatability,stability and specificity as a sensor;The quantitative detection of any configuration in the racemic mixture of tryptophan;The anti-interference performance of tryptophan in mixed complex biological systems(such as urine)was also evaluated.The feasibility and advantages of this method compared with traditional HPLC-UV method for tryptophan enantiomer recognition were evaluated.This work also highlights the important role of achiral ligands in enantiomer recognition and provides new ideas for the synthesis of chiral sensing materials.(2)Using Layer synthesis method,a 3D chiral coordination polymer Cu-TMSBa was constructed from the principal ligand(chiral terephthalic acid mono-substituted serine derivative),the auxiliary ligand(bpea)and the transition metal Cu(Ⅱ)through diffusion process at room temperature,and its structure was characterized and the electrochemical recognition of enantiomers was determined.Firstly,the conductive properties of the modified electrode were investigated by CV and EIS methods.Through the identification of natural amino acids,it was found that Cu-TMSBa modified electrode had a strong recognition efficiency for aspartic acid(Asp)isomer,and also had a certain recognition ability for glutamic acid(Glu)isomer.The interaction between L-isomer and Cu-TMSBa was discussed by means of spectral characterization,and the mechanism of enantioselectivity was clearly explained.In addition,we found that Cu-TMSBa also exhibited chiral recognition of UDCA,CDCA and Allo-UDCA.In conclusion,the synthesis method of c MOF/GCE(glassy carbon electrode)sensor is simple,low cost,good chemical stability and repeatability.However,there are still few electrochemical sensors directly used by c MOF as chiral sensing materials so far,and the recognition efficiency is low.Therefore,it is of great significance to develop c MOF sensing materials with high selectivity and sensitivity.