物理化学学报

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运用概念密度泛函理论和信息论方法定量描述胺类分子的分子碱度

肖雪珠1, 曹小芳1, 赵东波2, 荣春英1, 刘述斌3   

  1. 1 湖南师范大学化学化工学院, 长沙 410081;
    2 南京大学化学化工学院, 南京 210023;
    3 北卡罗莱纳大学大学教堂山校区超级计算中心, 北卡罗莱纳州 27599-3420, 美国
  • 收稿日期:2019-06-06 修回日期:2019-07-01 录用日期:2019-07-12 发布日期:2019-07-17
  • 通讯作者: 荣春英, 刘述斌 E-mail:rongchunying@aliyun.com;shubin@email.unc.edu
  • 基金资助:
    国家自然科学基金(21503076)和湖南省国家自然科学基金(2017JJ3201)资助项目

Quantification of Molecular Basicity for Amines: a Combined Conceptual Density Functional Theory and Information-Theoretic Approach Study

Xuezhu Xiao1, Xiaofang Cao1, Dongbo Zhao2, Chunying Rong1, Shubin Liu3   

  1. 1 College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, P. R. China;
    2 School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China;
    3 Research Computing Center, University of North Carolina, Chapel Hill, NC 27599-3420, USA
  • Received:2019-06-06 Revised:2019-07-01 Accepted:2019-07-12 Published:2019-07-17
  • Contact: Chunying Rong, Shubin Liu E-mail:rongchunying@aliyun.com;shubin@email.unc.edu
  • Supported by:
    The project was supported by the National Natural Science Foundation of China (21503076) and the Hunan Provincial Natural Science Foundation of China (2017JJ3201).

摘要: 分子酸碱性是一对在化学、生物和其他学科中广泛运用的化学概念。如何从理论和计算的角度定量描述分子酸碱度仍然是一个尚未完全解决的难题。为此,我们早前从概念密度泛函的角度提出运用分子静电势和自然原子价轨道。随后,我们又提出运用信息理论中的香农熵、费舍尔信息、信息增益等量来定量测定亲电性、亲核性、区域和立体选择性,并成功运用于预测包括单和双取代苯甲酸、苯磺酸、苯亚硒酸、酚和烷基羧酸在内的五类分子酸性,系统地验证了信息论方法的适用性和有效性。作为该工作的延续,本文将概念密度泛函理论和信息论方法结合起来并推广运用至更多更广的体系。为此我们以伯胺、仲胺和叔胺三类胺类体系共179个分子为例,验证其普适性和有效性。运用分子静电势或者等价的自然价原子轨道能量,以及信息理论中香农熵、费舍尔信息、Ghosh-Berkowitz-Parr熵、信息增益、Onicescu信息能量、相对Rényi熵等信息量,发现均能有较地预测三类胺分子的碱性,与实验pKa值呈较好的相关性。而且,将这些量组合在一起能够得到更准确的预测模型。其原因在于这些描述符均为电子密度泛函。根据密度泛函理论的基本原理,它们包含有足够的信息来描述包括分子酸碱性在内的所有基态性质。我们的结果显示,该方法同样适用于其他体系。本文为有效预测分子酸碱性提供了一个有效途径。

关键词: pKa, 胺分子, 概念密度泛函理论, 信息论方法

Abstract: The pair of molecular acidity and basicity is one of the most widely used chemical concepts in chemistry, biology, and other related fields. Nevertheless, quantitative determination of these intrinsic physical properties from the perspective of theory and computation is still an unresolved task at present. Earlier, we proposed to utilize the molecular electrostatic potential and natural atomic orbital from conceptual density functional theory for this purpose. Later, we also proposed utilizing quantities from the information-theoretic approach in the density functional reactivity theory such as Shannon entropy, Fisher information, and information gain to quantify electrophilicity, nucleophilicity, regioselectivity, and stereoselectivity. The latter was successfully applied later to five series of molecular systems for determining the molecular acidity, including singly and doubly substituted benzoic acids, benzenesulfonic acids, benzeneseleninic acids, phenols, and alkyl carboxylic acids, whose validity and effectiveness have been sufficiently corroborated. As a continuation of our recent efforts along this line, in this work, we generalize our previous approaches by combining these two approaches together as a new set of descriptors to quantify the molecular basicity. The applicability and usefulness of our new approach are demonstrated hereby by three types of amines, namely, primary, secondary, and tertiary amines, with a total of 179 systems. We show that this new set of descriptors, including the molecular electrostatic potential or its equivalence, the natural valence atomic orbital energy, and quantities from information-theoretic approach such as Shannon entropy, Fisher information, Ghosh-Berkowitz-Parr entropy, information gain, Onicescu information energy, and relative Rényi entropy, is able to accurately predict the experimental pKa values for the three types of amines. Our findings confirm that each of these quantities possesses strong linear correlation with the experimental pKa value, though less significantly than expected. Moreover, when combined, these quantities can yield accurate and quantitative models for determining the molecular basicity of all the three types of amines. The reason behind this is that all these descriptors are simple electron density functionals. According to the basic theorem of density functional theory, they should contain adequate information for the determination of all the physio-chemical properties in the ground state of molecular systems, including molecular acidity and basicity. Our present results predict that this new approach should be readily applicable to many other molecular species, thereby providing an effective and robust approach to appreciate chemical concepts such as acidity and basicity.

Key words: pKa, Amine, Conceptual density functional theory, Information-theory approach

MSC2000: 

  • O641