Foroutan-Nejad Cina, Larsen Simon, Conradie Jeanet, Ghosh Abhik
CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, CZ - 62500, Brno, Czech Republic.
Department of Chemistry, UiT - The Arctic University of Norway, 9037, Tromsø, Norway.
Sci Rep. 2018 Aug 10;8(1):11952. doi: 10.1038/s41598-018-29819-3.
Density functional theory calculations of magnetically induced current densities have revealed high diatropic ring currents in unsubstituted isocorrole consistent with homoaromatic character. An examination of the Kohn-Sham molecular orbitals showed clear evidence of homoconjugative interactions in four occupied π-type molecular orbitals as well as in the LUMO. Remarkably, substituents at the saturated meso position were found to exert a dramatic influence on the overall current density pattern. Thus, whereas bis(trimethylsilyl)-substitution strongly enhanced the peripheral diatropic current (consistent with enhanced homoaromaticity), difluoro-substitution engendered a strong, net paratropic current (consistent with antihomoaromaticity). In this respect, isocorroles stand in sharp contrast to benzenoid aromatics, for which substituents typically exert a small influence on the current density distribution.
对磁感应电流密度的密度泛函理论计算表明，未取代的异方酸卟啉中存在高抗磁环电流，这与同芳香性特征相符。对Kohn-Sham分子轨道的研究表明，在四个占据的π型分子轨道以及最低未占分子轨道（LUMO）中存在明显的同共轭相互作用证据。值得注意的是，发现在饱和中位位置的取代基对整体电流密度模式有显著影响。因此，双（三甲基硅基）取代强烈增强了外围抗磁电流（与增强的同芳香性一致），而二氟取代产生了强烈的净顺磁电流（与反同芳香性一致）。在这方面，异方酸卟啉与苯型芳烃形成鲜明对比，对于苯型芳烃，取代基通常对电流密度分布影响较小。
