Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science, South-Central Minzu University, Wuhan, 430074, China.
College of Pharmacy, University of Kentucky, Lexington, KY, 40536, USA.
J Mol Model. 2023 Mar 2;29(3):83. doi: 10.1007/s00894-023-05485-9.
Aromaticity is a fundamental chemical concept that has been widely used in explaining the reactivity, stability, structure, and magnetic properties of many molecules such as conjugated macrocycles, metal heterocyclic compounds, and certain metal clusters. Porphyrinoids (including porphyrin) are of particular interest in terms of diverse aromaticity. Various indices therefore have been used to predict the aromaticity of porphyrin-like macrocycles. However, the reliability of these indices for porphyinoids is always questionable. In order to assess the performance of the indices, we have selected six representative indices to predict the aromaticity of 35 porphyrinoids. The calculated values were then compared with the corresponding results obtained from experiments. Our studies suggest that the theoretical prediction by nucleus independent chemical shifts (NICS), topology of the induced magnetic field (TIMF), anisotropy of the induced current density (AICD), and gauge including magnetically induced current method (GIMIC) are essentially consistent with experimental evidence in all 35 cases and thus are preferred indices.
Based on density functional theory, the performance of the NICS, TIMF, AICD, GIMIC, harmonic oscillator model of aromaticity (HOMA), and multicenter bond order (MCBO) indices were evaluated theoretically. Molecular geometries were optimized at the M06-2X/6-311G** level. NMR calculations using GIAO or CGST method were performed at the M06-2X/6-311G** level. The above calculations were carried out using Gaussian16 suite. The TIMF, GIMIC, HOMA, and MCBO indices were obtained using the Multiwfn program. The AICD outputs were visualized using the POV-Ray software.
芳香性是一个基本的化学概念，已广泛应用于解释许多分子的反应性、稳定性、结构和磁性质，如共轭大环、金属杂环化合物和某些金属簇。卟啉类（包括卟啉）在多样性的芳香性方面特别有趣。因此，已经使用了各种指标来预测类似卟啉的大环的芳香性。然而，这些指标对于卟啉类的可靠性总是值得怀疑的。为了评估这些指标的性能，我们选择了六个有代表性的指标来预测 35 种卟啉类化合物的芳香性。然后将计算值与实验得到的相应结果进行比较。我们的研究表明，核独立化学位移（NICS）、感应磁场拓扑（TIMF）、感应电流密度各向异性（AICD）和包含磁诱导电流的规范方法（GIMIC）的理论预测在所有 35 种情况下与实验证据基本一致，因此是首选指标。
基于密度泛函理论，理论上评估了 NICS、TIMF、AICD、GIMIC、芳香性的谐振子模型（HOMA）和多中心键序（MCBO）指数的性能。分子几何形状在 M06-2X/6-311G水平上进行了优化。使用 GIAO 或 CGST 方法在 M06-2X/6-311G水平上进行了 NMR 计算。上述计算使用 Gaussian16 套件完成。使用 Multiwfn 程序获得了 TIMF、GIMIC、HOMA 和 MCBO 指数。使用 POV-Ray 软件可视化 AICD 输出。
