物理化学学报 >> 2009, Vol. 25 >> Issue (04): 694-700.doi: 10.3866/PKU.WHXB20090408

研究论文 上一篇    下一篇

A3型Corrole中位取代基对其β位1H-NMR的影响

刘海洋 冷科 胡军 应晓 徐志广 张启光   

  1. 华南理工大学化学系, 广州 510641; 香港科技大学化学系, 香港; 华南理工大学应用物理系, 广州 510641; 华南师范大学化学与环境学院, 广州 510631
  • 收稿日期:2008-11-11 修回日期:2009-01-10 发布日期:2009-03-31
  • 通讯作者: 刘海洋 张启光 E-mail:chhyliu@scut.edu.cn;chang@ust.hk

Effect of Meso-Substituents on β 1H-NMR of A3 Type Corrole

 LIU Hai-Yang, LENG Ke, HU Jun, YING Xiao, XU Zhi-Guang, CHANG Chi-Kwong   

  1. Department of Chemistry, South China University of Technology, Guangzhou 510641, P. R. China; Department of Chemistry, The Hong Kong University of Science and Technology, Hong Kong, P. R. China; Department of Applied Physics, South China University of Technology, Guangzhou 510641, P. R. China; School of Chemistry and Environment, South China Normal University, Guangzhou 510631, P. R. China
  • Received:2008-11-11 Revised:2009-01-10 Published:2009-03-31
  • Contact: LIU Hai-Yang, CHANG Chi-Kwong E-mail:chhyliu@scut.edu.cn;chang@ust.hk

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摘要：

采用密度泛函(DFT)方法对八个中位有不同取代基的A3型corrole进行了几何结构优化和核磁共振(NMR)理论计算. 几何优化结果显示5,10,15-三苯基corrole的两个环内NH异构体的中位苯环空间排布方向不同. 此外, 虽然A3型corrole两个环内NH异构体A和B的能量相差不大, 但A和B分子的Boltzman分布概率却有较大的不同, 且受取代基影响很大. 因而在计算NMR时必须对A和B异构体的理论化学位移做Boltzman统计平均处理. NMR计算结果表明, 在B3LYP/6-311+G(2d,p)//B3LYP/6-31G(d,p)水平下可以得到较为合理的corrole的1H-NMR化学位移结果. β-位氢的化学位移与取代基Hammett常数σ+P的大小成正比关系. 此外, 由于corrole大环的低对称性, 取代基对不同位置β-位氢的NMR影响程度不同, 其β-位氢化学位移的大小和顺序与中位取代基的电子效应和corrole的立体结构因素有关.

关键词: Corrole, 1H核磁共振, 规范不变原子轨道, 密度泛函理论

Abstract:

Geometries of eight A3-type corroles bearing different substituents were optimized and their nuclear magnetic resonance(NMR) propertieswere also calculated using density functional theory (DFT). Geometry optimization results showed that the NH tautomerization of 5,10,15-tris(phenyl)corrole is accompanied by the twisting of its phenyl groups. Although the total energies of both corrole NH tautomers are similar, the Boltzmann distribution probabilities of the A and B tautomers are significantly different. It is also dependent on the meso-substituents. Boltzman statistic averaging should thus be used to evaluate the 1H-NMR of corrole. NMR calculations performed at B3LYP/6-311+G (2d,p)//B3LYP/6-31G(d,p) level may give reasonable 1H-NMR chemical shifts for the corrole. β-H chemical shifts were proportional to the Hammett constants σ+P of the substituents. Furthermore, because of the low symmetry of corrole, the substituents exerted a different effect on the NMR of β-protons at different positions. The order of 1H-NMR chemical shifts for different β-H is quite sensitive to the nature of meso-substituents. β1H-NMR is determined by the electronic effect of substituents and the geometrical structure of the corrole.

Key words: Corrole, 1H-NMR, Gauge-independent atomic orbital, Density functional theory