磺胺甲恶唑的振动光谱和密度泛函理论研究

Vibrational spectroscopy and density functional theory study of sulfamethoxazole

磺胺甲恶唑(Sulfamethoxazole,SMX)是一种磺胺类广谱抗生素.基于密度泛函理论(DFT)的B3LYP方法,在B3LYP/6-311++G(d,p)基组水平上对SMX初始构型进行结构优化,得出该分子最稳定结构构型.同时,给出了SMX的键长、键角和二面角等空间结构参数值,确定该分子空间构型为非平面结构.相同基组水平下进行频率计算,通过频率校正因子0.9630修正并绘制了SMX分子的红外光谱和拉曼光谱图.发现光谱谱段主要分布在3600-2800 cm-1和1700-300 cm-1频率段,并且理论计算值和实验测定值有较好吻合,表明DFT计算方法是可取和可信的.借助GaussView 6.0软件和计算得到的势能分布结果对频率范围内每一个振动模式进行了指认归属.此外,采用Multiwfn和VMD程序计算并分析SMX分子的静电势和前线分子轨道,预测了该分子的反应活性位点.该结果为SMX分子的振动光谱检测提供基础数据,为其结构鉴定提供技术参考.

Sulfamethoxazole(SMX)is a broad-spectrum sulfonamide antibiotic.In this study,the B3LYP method of density functional theory(DFT)was used to optimize the initial configuration at the level of the B3LYP/6-311++G(d,p)basis set,and the most stable molecular structure was obtained.The bond length,bond angle and dihedral angle patameter values of SMX were given,and the molecule exhibited a non-planar structure.The frequency calculation was conducted at the same basis set level,and the infrared and Raman spectra of SMX were corrected and plotted using a frequency correction factor of 0.9630.The spectral bands were found to be mainly distributed in the frequency bands of 3600-2800 cm-1 and 1700-300 cm-1,and there are good agreement between the theoretically calculated and experimentally measured values,indicating that the DFT calculation method is desirable and credible.The GaussView 6.0 software package and the calculated potential energy distribution were used to assign each vibration mode within the frequency range.In addition,the electrostatic potential and frontline molecular orbitals of the SMX molecule were calculated and analyzed using the Multiwfn and VMD programs to predict the reactive sites of the molecule.These results provide basic data for detecting the vibration spectrum of SMX and are technical reference for its structural identification.