外场作用下C_(12)H_4Cl_4O_2的分子结构和电子光谱研究  

Molecular structure and electronic spectrum of C_(12)H_4Cl_4O_2 under external electric field

作　　者：杜建宾[1] 冯志芳[2] 韩丽君[1] 唐延林 武德起 Du Jian-Bin;Feng Zhi-Fang;Han Li-Jun;Tang Yan-Lin;Wu De-Qi(College of Physics and Electrical Information,Langfang Normal University,Langfang 065000,China;College of Mathematics and Information Science,Langfang Normal University,Langfang 065000,China;College of Physics,Guizhou University,Guiyang 550025,China;College of Information Engineering,Henan Mechanical and Electrical Vocational College,Zhengzhou 451191,China)

机构地区：[1]廊坊师范学院物理与电子信息学院,廊坊065000 [2]廊坊师范学院数学与信息科学学院,廊坊065000 [3]贵州大学物理学院,贵阳550025 [4]河南机电职业学院信息工程学院,郑州451191

出　　处：《物理学报》2018年第22期173-179,共7页Acta Physica Sinica

基　　金：河北省教育厅青年基金项目(批准号:QN2015219);廊坊师范学院自然基金(批准号:LSZQ201105)资助的课题~~

摘　　要：各种环境毒物危害着人类的生产生活,二噁英更是严重危害人类的健康. C_(12)H_4Cl_4O_2(2, 3, 7, 8-tetrachlorodibenzo-p-dioxin, TCDD)是二噁英中毒性最强的化合物,也是目前已知毒性最强的污染物.为研究TCDD外场效应,采用密度泛函理论方法优化了不同静电场0—0.025 a.u.(0—1.2856×10^(10)V/m)作用下TCDD分子的基态几何结构,得到了分子总能量;在此基础上,采用含时密度泛函理论方法对TCDD分子的紫外-可见(UV-Vis)吸收光谱在不同外电场下的变化进行了研究.结果表明:分子几何构型与电场大小呈现强烈的依赖关系,分子总能量随着外电场的增强而减小;伴随着外电场的增强,分子激发态的摩尔吸收系数逐渐减小, UV-Vis吸收峰显著红移.Various environmental poisons have caused damage to human production and life, and dioxin has seriously harmed human health. The C12H4Cl4O2（2, 3, 7, 8-tetrachlorodibenzo-p-dioxin, TCDD） is currently the most toxic compound. In order to study the influence of external electrical field on molecular structure and spectrum, herein the density functional theory（DFT） at a B3 LYP/6-31＋g（d,p） level is employed to calculate the geometrical parameters of the ground state of TCDD molecule under external electric fields ranging from 0 to 0.025 a.u.（0–1.2856×10^10 V/m）. Based on the optimized structure, time-dependent DFT at the same level as the above is adopted to calculate the absorption wavelengths and the molar absorption coefficients for the first twenty-six excited states of TCDD molecule under external electric fields. The results show that the most absorption band located at 221 nm with a molar absorption coefficient of 54064 L·mol^-1·cm^-1 in the UV-Vis absorption spectrum appears in the E belt, which originates from the benzene electronic transition fromπ to π＊. In addition, a shoulder peak at 296 nm appears in the B belt, which is the characteristic absorption of aromatic compounds＇ electron transition from π to π＊. Compared with the data in the literature, the wavelength of the shoulder is blue-shifted only 9 nm. The molecular geometry parameters are strongly dependent on the external field intensity, and the total energy decreases with external field intensity increasing. With the enhancement of external electric field, the electrons in the molecule have an overall transfer, which makes the big bond of benzene ring weakened, the energy of the transition decreases, and the wavelength of the transition increases, that is, the absorption peak is red-shifted. When the external electric field increases to 0.02 a.u., the electron cloud migration phenomenon of occupied and transition orbits of TCDD molecule are obvious, and the absorption peak red shift phenomenon is also very significa

关 键 词：C12H4Cl4O2 外电场 密度泛函理论 紫外-可见光谱 

分 类 号：O621.13[理学—有机化学]