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Quantitative electrophilicity Measures

物理化学学报 2018年第6期34卷 662-674页

作者： GONZáLEZ Marco Martínez CáRDENAS Carlos RODRíGUEZ Juan I. LIU Shubin HEIDAR-ZADEH Farnaz MIRANDA-QUINTANA Ramón Alain AYERS Paul W. Laboratory of Computational and Theoretical Chemistry Faculty of Chemistry University of Havana Havana 10400 Cuba. Departamento de Quimica and Centro de Quimica Universidade de Coimbra 3004-535 Coimbra Portugal. Departamento de Fisica Fac

Quantitative correlation of several theoretical electrophilicity measures over different families of organic compounds are examined relative to the experimental values of Mayr et al.Notably,the ability to predict these values accurately will help to elucidate the reactivity and selectivity trends observed in charge-transfer reactions.A crucial advantage of this theoretical approach is that itprovides this information without the need of experiments,which are often demanding and time-consuming.Here,two different types of electrophilicity measures were analyzed.First,models derived from conceptual density functional theory(c-DFT),including Parr's original proposal and further generalizations of this index,are investigated.For instance,the approaches of Gázquez et al.and Chamorro et al.are considered,whereby it is possible to distinguish between processes in which a molecule gains or loses electrons.Further,we also explored two novel electrophilicity definitions.On one hand,the potential of environmental perturbations to affect electron incorporation into a system is analyzed in terms of recent developments in c-DFT.These studies highlight the importance of considering the molecular surroundings when a consistent description of chemical reactivity is needed.On the other hand,we test a new definition of electrophilicity that is free from inconsistencies(so-called thermodynamic electrophilicity).This approach is based on Parr's pioneering insights,though it corrects issues present in the standard working expression for the calculation of electrophilicity.Additionally,we use machine-learning tools(i.e.,symbolic regression) to identify the models that best fit the experimental values.In this way,the best possible description of the electrophilicity values in terms of different electronic structure quantities is obtained.Overall,this straightforward approach enables one to obtain good correlations between the theoretical and experimental quantities by using the simple,yet powerful,interpretative advantage of c-DFT method

关键词： electrophilicity Conceptual density functional theory Symbolic regression Genetic programming Grammatical evolution

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Cyclic(Amino)(Aryl)Nitrenium Cations with Lewis Acidity Controlled by Remote Substituents

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Chinese Journal of Chemistry 2022年第3期40卷 311-316页

作者： Wenqing Wang Xin Zheng Leran Zhang Shunjie Li Yue Zhao Xinping Wang College of Chemistry and Material Science Key Laboratory of Functional Molecular SolidsMinistry of EducationAnhui Laboratory of Molecule-Based MaterialsAnhui Normal UniversityWuhuAnhui 241002China State Key Laboratory of Coordination Chemistry School of Chemistry and Chemical EngineeringNanjing UniversityNanjingJiangsu 210023China College of Science Henan Agricultural UniversityZhengzhouHenan 450002China

N-Heterocyclic nitrogen Lewis acids are important in synthetic chemistry.Stable cyclic(amino)(aryl)nitrenium cations,cyc-1^(+)-cyc-3^(+),were synthesized by chemical oxidation of aryl azo compounds with different substituents,H and I,at the para positions of the phenyl group.The excited triplet states of cyc-1^(+)-cyc-3^(+) abstract H-atoms step by step to generate radical intermediates cyc-1H^(*+-)cyc-3H^(*+)traced by EPR spectroscopy and products cyc-1H^(2+)-cyc-3H^(2+) characterized by single crystal X-ray diffraction.The Lewis acidity of species cyc-1^(+)-cyc-3^(+) are remote substituent-dependent.Cyc-2^(+)-cyc-3^(+) have much higher acidity than those previously reported congeners based on energies of LUMOs.The electrophilicity enables them to form Lewis adducts with neutral Lewis base Me_(3)P,and to gain one-electron to produce neutral radicals cyc-1^(*)-cyc-3^(*).

关键词： Nitrenium cation Acidity Radicals Excited triplet state electrophilicity

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Density Functional Theory Study of Exohedral Carbon Atoms Effect on electrophilicity of Nicotine: Comparative Analysis

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Computational Chemistry 2016年第1期4卷 17-31页

作者： S. Dheivamalar L. Sugi K. Ambigai Department of Physics Government Arts College for Women (Autonomous) Pudukkottai India Department of Physics Bharath College of Science & Management Thanjavur India

In recent years, many studies have been done on the structure of fullerene as medicine nano carrier compounds. On this basis, Quantum mechanical calculations have been done and the effect of the nicotine compound in structure of Nanofullerene C12 was studied. Density Functional Theory (DFT) can be used to calculate an accurate electronic structure, HOMO and LUMO energies, Mulliken charge of atoms, energetic orbital levels, global hardness, chemical potential and electrophilicity of systems, and finally chemical, physical properties of fullerene and fullerene derivatives. Theoretical calculations such as Natural Bond Orbital (NBO) are very important to understand the pathways of electron transfer in assemblies. Consequently, the obtained results showed that energy orbital levels decreased considerably by linking structure of Nanofullerene to the structure of Nicotine. The intramolecular interaction is formed by the orbital overlap between C-C, C-N, C-H anti bonding orbital which results an intermolecular charge transfer (ICT) from a Lewis valence orbital (donor), with a decreasing of its occupancy, to a non-Lewis orbital (acceptor). The interacting effect is also discussed in terms of the change in the C-C bond lengths, net atomic charge distribution, total dipole moment. The obtained results indicate that the C-C distances are enlarged interaction. Furthermore, there is a complete change in the net atomic charge distribution, as well as a corresponding increase in the value of the total dipole moment. On the basis of fully optimized ground-state structure, TDDFT//B3LYP/3-21G* calculations have been performed to determine the low-lying excited states of nanofullerene interacting with nicotine (NFN).

关键词： DFT electrophilicity Chemical Hardness Chemical Potential Nano Fullerene Nicotine

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Research on Chemical Reactivity of Nitrotriazolam in Its Process of Preparation

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Chemical Research in Chinese Universities 2019年第4期35卷 680-685页

作者： YANG Bowen AN Qiufeng ZHAO Zhigang SHAO Kaiyuan HU Wenxiang Shaanxi Key Laboratory of Chemical Additives for Industry College of Chemistry and Chemical Engineering Shaanxi University of Science and Technology Xi'an 710021 P. R. China College of Chemistry and Environment Protection Engineering Southwest University for NationalitiesChengdu 610041P.R.China Jingdong Xianghu Microwave Chemistry Union Laboratory Beijing Excalibur Space Military Academy of Medical SciencesBeijing 101601P.R.China Aerospace Systems Division Strategic Support TroopsChinese People's Liberation ArmyBeijing 100101P. R.China

Chemical reaction possibility was described quantitatively for the case of nitrotriazolam preparation with 2-clonazepam by using the data of two quantum chemical reactivity indices: net electrophilicity index and Wiberg bond order. Furthennore, relevant reaction mechanism was derived from tlie aspect of quantum chemistry. The results show that the indices used can quantitatively explain the chemical reactivity and reaction mechanism of the nitrotriazolam preparation. To validate the universal applicability of the proposed approach, the authors continued to use the quantum chemical reactivity indices to describe some classic chemical reactions, expecting to predict major issues related to physical organic chemistry, such as new chemical reactions and their mechanisms.

关键词： Density functional tlieory Net electrophilicity index Wiberg bond order Chemical reactivity Reaction mechanism

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