Bradley David, Jirásek Michael, Anderson Harry L, Peeks Martin D
School of Chemistry, University of New South Wales Sydney NSW 2052 Australia
School of Chemistry, University of Glasgow Glasgow G12 8QQ UK.
Chem Sci. 2023 Jan 16;14(7):1762-1768. doi: 10.1039/d2sc05923a. eCollection 2023 Feb 15.
Magnetic field-induced ring currents in aromatic and antiaromatic molecules cause characteristic shielding and deshielding effects in the molecules' NMR spectra. However, it is difficult to analyze (anti)aromaticity directly from experimental NMR data if a molecule has multiple ring current pathways. Here we present a method for using the Biot-Savart law to deconvolute the contributions of different ring currents to the experimental NMR spectra of polycyclic compounds. This method accurately quantifies local and global ring current susceptibilities in porphyrin nanorings, as well as in a bicyclic dithienothiophene-bridged [34]octaphyrin. There is excellent agreement between ring current susceptibilities derived from both experimental and computationally-predicted chemical shifts, and with ring currents calculated by the GIMIC method. Our method can be applied to any polycyclic system, with any number of ring currents, provided that appropriate NMR data are available.
芳香族和反芳香族分子中磁场诱导的环电流会在分子的核磁共振谱中产生特征性的屏蔽和去屏蔽效应。然而，如果一个分子有多个环电流路径，就很难直接从实验核磁共振数据中分析（反）芳香性。在此，我们提出一种利用毕奥-萨伐尔定律来解卷积不同环电流对多环化合物实验核磁共振谱贡献的方法。该方法能准确量化卟啉纳米环以及双环二噻吩并噻吩桥连的[34]八卟啉中的局部和全局环电流磁化率。从实验和计算预测的化学位移得出的环电流磁化率之间，以及与通过GIMIC方法计算的环电流之间，都有很好的一致性。只要有合适的核磁共振数据，我们的方法可应用于任何具有任意数量环电流的多环体系。
