The Surface Enhanced Raman Spectroscopy Characteristics of Cyromazine Molecule Based on Density Function Theory
Cyromazine is a white crystalline powder insecticide used in the agricultural production of various melons and fruits,solanaceous fruits,beans,and leafy vegetables.It is widely used in agriculture and other fields.However,the massive use of Cyromazine will be extremely destructive to the ecological environment and will endanger human health.Therefore,there is an urgent need for rapid detection technology of Cyromazine pesticide residues in the process of vegetable agricultural production.Surface-enhanced Raman spectroscopy(SERS)has the advantages of high sensitivity,high accuracy and simple sample preparation and has become a hot research technology in the field of pesticide residue detection.Density function theory(DFT)can be used for theoretical simulation of molecular structure and properties and calculation of Raman spectra.The surface-enhanced Raman spectra of Cyromazine molecule introduced into gold nanoclusters are calculated based on the density functional theory;the software of Multiwfn and VMD are used to explore the surface electrostatic potential distribution of herbicidal strong molecules.Based on the B3LYP/6-31++G(d,p)basis set,the structure optimization and Surface Enhanced Raman spectroscopy calculation of the Cyromazine-gold nanoclusters complex formed by combining 4Au atomic clusters are studied.The 6-31++G(d,p)basis set is used for the atoms in the Cyromazine molecule that may coordinate with the Au nanoclusters,and the LANL2DZ pseudo basis set is used for the Au Atomic Clusters.The Raman spectra and the surface-enhanced Raman Spectra of Cyromazine are obtained,and the characteristic peaks are identified and compared.According to the molecular electrostatic potential distribution,Au nanoclusters may form coordination with N1,N3 and N5 atoms in the C6H10N6 molecule and form C6H10N6-4Au nanoclusters.The Raman spectra of C6H10N6-4Au coordinated by N1,N3 and N5 atoms are calculated and analyzed,the maximum Raman spectral enhancement of C6H10N6-4Au molecules coordinated by Au clusters and N1,N3 and N5 is 4.0 times,1.4 times and 3.2 times,respectively,and the position of the spectral peak has a certain degree of red shift or blue shift.The research results lay a theoretical foundation for the rapid detection of pesticide residues on the surface of vegetables by SERS technology.
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