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多溴代芴化合物是一类潜在的化学污染物,其热力学性质数据对于进一步研究这些化合物的其它物理、化学性质以及它们在环境中的形成、分布及迁移转化机制有重要价值,但这些热力学性质数据极其缺乏。本文采用密度泛函理论在B3LYP/6-311G~(**)水平上优化135个多溴代芴分子的几何结构,并获得它们在理想气态的一些热力学性质的数值,研究这些性质与取代的溴原子数目和位置的关系,根据各异构体的相对标准生成Gibbs自由能的大小,得它们热力学稳定性的顺序。结果表明:多溴代芴分子的几何构型,取决于溴原子的取代位置。多溴代芴最稳定及最不稳定异构体的△_fH~(?)及△_fG~(?),都随Br原子数目增加而逐渐增加。溴原子数目相同的多溴代芴异构体的△_fH~(?)和△_fG~(?)与溴原子的取代位置有很大的关系,其相对稳定性看离域π键和Br…Br核排斥作用的强弱而决定。
Polybrominated fluorene compounds are a group of potential chemical contaminants whose thermodynamic properties are of great value to further study of other physical and chemical properties of these compounds as well as their formation, distribution and migration mechanisms in the environment. However, these thermodynamic properties Extreme lack of data. In this paper, the geometrical structures of 135 polybrominated fluorene molecules are optimized at B3LYP / 6-311G ~ (**) level by using density functional theory, and their thermodynamic properties in the ideal gas state are obtained. The properties and substitutions of The relationship between the number of bromine atoms and the position of the Gibbs free energy according to the relative standard of the isomers generated their order of thermodynamic stability. The results show that the geometry of polybromofluorene molecule depends on the substitution position of bromine atoms. The most stable and the most unstable isomers of polybromofluorenes △ _fH ~ (?) And △ _fG ~ (?), With the increase of the number of Br atoms gradually increased. △ _fH ~ (?) And △ _fG ~ (?) Of polybromofluorene isomers with the same number of bromine atoms have a great relationship with the substitution position of bromine atoms, and the relative stability of them can be seen from the delocalized π bond and Br ... Br nuclear rejection of the strength of the decision.