A Chiral Sensor Based On Surface Enhanced Raman Scattering And Its Mechanism Research

Chiral compounds are widely used in a variety of fields such as catalytic chemistry,food science,pharmaceutical engineering.However,it is significantly different in the efficacy of the chiral compounds;most traditional identification techniques are time-consuming,costly and dependent on large-scale instruments.In recent years,chiral sensors have been developed rapidly in chiral recognition due to their advantages such as the efficience and convenience.The surface-enhanced Raman scattering spectra(SERS)have been widely used in various fields of science chemistry.However,the application of surface-enhanced Raman for chiral recognition remains a challenge.Herein,we present,for the first time,a reliable and simple method for enantioselective discrimination by SERS spectroscopy.The first part is a review of the progress of surface-enhanced Raman spectroscopy and its applications in chiral recognition.The second chapter prepared the SERS AuNPs sustrate througth electrostatic interaction.Firstly,the gold nanoparticles were prepared by sodium citrate reduction method and characterized by UV-vis and SEM.We also investigated the SERS effects of the different time in the assembly process.The results show that AuNPs substrate with different particle coverage can be obtained along different assembly times.At the same time,the performance of the substrate was investigated by the SERS Mapping.The results show that the AuNPs substrate has good stability,uniformity and repeatability.In the third chapter,we established a new Schiff base surface based on the self-assemblied AuNPs substrate throug covalent modification for chiral recognition.In the process of constructing functionalized Schiff base nanofilm,Different characterizations such as X-ray photoelectron spectroscopy(XPS).Contact angle(CA),Atomic force microscop(AFM),Quartz crystal microbalance(QCM)were used to study it in detail.Finally,it was more hydrophilic compared to the same condition when the Schiff base surface was rinsed in D-mandelic acid solution.Besides,the SERS enantioselective discrimination behavior of the adsorbed Schiff base molecule should be related to hydrogen bonding interactions when immersed in different enantiomers.This causes an orientation difference between the two complexes of the two enantiomers and Schiff base relative to the gold surface,which could result in a distinct difference in the SERS spectra.In conclusion,we constructed a novel functional Schiff base surface for chiral recognition based on Surface-enhanced Raman scattering.In the fourth chapter,the mechanism of recognition was studied by computer simulation,the interaction between Schiff base and malic acid enantiomer was simulated by Auto Dock Vina;At the same time,its orbital energy level of the receptor schiff base and malic acid was analyzed by Gaussian09.The results indicate that the complex through hydrogen bonding led to the formation of different CT states of the receptor Schiff base and malic acid complex,which was consistent with the results in the third chapter.