运用密度泛函活性理论的信息论方法研究苯并富烯衍生物的芳香性（英文）

Aromaticity Study of Benzene-Fused Fulvene Derivatives Using the Information-Theoretic Approach in Density Functional Reactivity Theory

文献中已有越来越多的芳香性体系被发现,同时也有越来越多的芳香性指标被提出来,但是如何解释芳香化合物稳定性的起源以及理解芳香性的本质仍然是当今理论化学中一个悬而未决的难题。运用我们新近提出的密度泛函活性理论信息论方法,不久前我们曾对一系列富烯衍生物进行了系统研究并得到了一个全新的认识。本文进一步探讨苯并富烯衍生物的芳香性行为,目的在于考察一个或多个苯环与富烯连接之后其芳香性发生变化的情况。运用香农熵,费舍尔信息,Ghosh-Berkowitz-Parr熵,Onicescu信息能,信息增益,以及相对Rényi熵六个信息量,和四种芳香指标,ASE,HOMA,FLU和NICS,我们系统地研究了信息量和芳香性指标在单、双、三苯并富烯衍生物中的相关性。我们发现,不管是否有苯环与富烯相连,芳香指标和信息量的交叉相关性都是一样的。这表明,虽然苯环本身具有芳香性,但苯环与富烯相连并不能改变富烯的芳香性与反芳香性本质。苯并富烯衍生物与富烯衍生物的芳香性和反芳香性一致。苯并富烯衍生物的芳香性和反芳香性完全取决于富烯本身的芳香性和反芳香性。这些结果为认识和理解复杂体系芳香性和反芳香性起源和本质将提供有益的启示。

Although a large variety of aromatic systems have been unveiled in the literature, justifying their origin of stability and understanding their nature of aromaticity is still an unaccomplished task. In this work, using tools recently developed by us within the density functional reactivity theory framework, where we employ simple density functionals to quantify molecular structural and reactivity properties, we examine the aromaticity concept from a different perspective. Using six quantities from the information-theoretic approach, namely, the Shannon entropy, Fisher information, Ghosh-Berkowitz-Parr entropy, Onicescu information energy, information gain, and relative Renyi entropy, and four aromaticity descriptors, namely, the aromatic stabilization energy （ASE） index, the harmonic oscillator model of aromaticity （HOMA） index, the aromatic fluctuation （FLU） index, and the nucleus-independent chemical shift （NICS） index, we systematically examined the correlations between substituted fulvene derivatives fused with one, two, and three benzene rings. Among the 14 benzofulvene derivatives studied in this work, there were seven single-fused, four double-fused, and three triple-fused benzofulvene derivatives. Our results show that the aromaticity indexes are often well correlated with one another. The same is true for information-theoretic quantities. Moreover, these correlations are valid across all series of benzofulvene derivatives with different ring structures. The cross-correlations between information-theoretic quantities and aromaticity indexes were usually strong. However, two completely opposite patterns were observed; as a consequence, these correlations are not valid across all series of benzofulvene derivatives. The nature of these correlations depends on the nature of the ring structure. The two groups of systems, each obeying the same cross-correlation patterns, have a total number of 4n ＋ 2 and 4n rr electrons, respectively, which are in agreement with HJckel＇s rule of aromaticity and antiaromaticity. Compared with the results obtained for systems without a benzene fused ring, the correlation patterns of these quantities were always found to be the same, both with and without fused benzene rings. This suggests that, despite benzene＇s aromaticity, its fusion with a fulvene moiety does not modify the aromaticity and antiaromaticity of the fulvene ring. These results confirm that the fusion of benzene rings with a fulvene moiety has no influence on the aromatic nature of the fulvene moiety. Thus, the aromaticity and antiaromaticity of benzene-fused fulvene derivatives are solely determined by the fulvene moiety. These results should provide a new understanding of the origin and nature of aromaticity and antiaromaticity.