邻苯二甲酸二丁酯(dibutyl phthalate,DBP)是增塑剂的主要成分之一.为研究外电场对环境毒物增塑剂类化合物的分子结构和光谱产生的影响,本文采用密度泛函(density functional theory,DFT)B3LYP方法在6-311++G(d,p)基组水平上优化了不同静电场(0—0.020 a.u.)作用下DBP分子的基态几何结构,在此基础上利用同样的方法计算了DBP分子的电偶极矩、分子总能量和红外(infrared,IR)光谱,最后利用含时密度泛函(time-dependent density functional theory,TDDFT)在同一基组下研究了不同外电场对DBP分子紫外-可见(UV-Vis)吸收光谱产生的影响,并与实验测得的光谱图进行了比较.结果表明,在外电场的作用下,分子结构变化剧烈,电偶极矩增大,分子总能量减小,红外光谱吸收峰出现红移或蓝移,分子的摩尔吸收系数重新分配,振动斯塔克效应(vibrational stark effect,VSE)明显;随着外电场的增强,分子UV-Vis光谱的吸收峰红移显著,振子强度剧烈下降.
Quantum chemical calculations are performed to study the reactions of OH and ozone with- out and with water to estimate whether the single water molecule can decrease the energy barrier of the OH radical reaction with ozone. The calculated results demonstrate that the single water molecule can reduce the activated barrier of the naked OH＋Oa reaction with the value of about 4.18 kJ/mol. In addition, the transition state theory is carried out to determine whether the single water molecule could enhance the rate constant of the OH＋O3 reaction. The computed kinetic data indicate that the rate of the ozone reaction with the formed complexes between OH and water is much slower than that of the OH＋O3 reaction, whereas the rate constant of OH reaction with the formed H20---Oa complex is 2 times greater than that of the naked OH radical with ozone reaction. However, these processes in the atmosphere are not important because the reactions can not compete well with the naked reaction of OH with ozone under atmospheric condition.
