黄曲霉素B1在银团簇表面吸附的表面增强拉曼光谱

摘要

采用密度泛函理论(DFT)的B3LYP方法和6-311g(d,p)(C,H,O)/LanL2DZ(Ag)基组,优化得到黄曲霉素分子AFB.与Ag小团簇形成的复合物AFB1-Agn(n=2,4,6)的稳定结构,并计算了三种复合物的表而增强拉曼光谱(SERS)和预共振拉曼光谱(SERRS):与实验结果相一致.计算结果显示:三种复合物表面增强拉曼光谱中C=O伸缩振动模的增强因子约为102-103,足由于极化率改变引起的静化学增强.根据含时密度泛函理论(TDDFT)方法计算得到的吸收光谱,分别选择407.5、446.2和411.2 nm作为入射光,计算三种复合物的共振拉曼光谱,发现在SERRS光谱中,Ag—O伸缩振动的增强因子达到104量级,主要是由电荷转移产生的共振增强引起的.%The structures, surface-enhanced Raman scattering (SERS), and pre-resonance Raman spectra (SERRS) of Aflatoxin B1 (AFB1)-Agn (n=2, 4, 6) complexes were calculated using density functional theory (DFT) with the B3LYP/6-311G(d, p) (C, H, O)/LanL2DZ (Ag) basis set. The results show that the SERS enhancement factors were about 102-103 for the AFB1-Agn (n=2, 4, 6) complexes, respectively. This is due to the C = O stretch of the pyran ring and the larger static polarizability of the three complexes. The SERS spectra were consistent with the experimental results. The SERRS spectra of the three complexes were obtained by excitation at 407.5, 446.2, and 411.2 nm, which were close to the electronic excitation energy of absorption spectra as determined by time-dependent density functional theory (TDDFT). The SERRS enhancement factors caused by the charge-transfer excitation resonance were about 104, which corresponds to the Ag —O stretching.