Bortolussi Stephen D S, Zhou Carmen, Lynch Nicholas B, Peeks Martin D
School of Chemistry, University of New South Wales, NSW, 2052, Australia.
Chemistry. 2024 Aug 19;30(46):e202401741. doi: 10.1002/chem.202401741. Epub 2024 Jul 25.
Aromaticity and antiaromaticity are foundational principes in organic chemistry, regularly invoked to explain stability, structure, and magnetic and electronic properties. There are ongoing challenges in assigning molecules as aromatic or antiaromatic using optical spectroscopy. Here we report spectroelectrochemical and computational analyses of porphyrin (18π neutral, aromatic) and norcorrole (16π neutral, antiaromatic), and their oxidized (16π porphyrin dication) and reduced (norcorrole 18π dianion) forms. Our results show that while the visible spectra are characteristic of (anti)aromaticity consistent with Hückel's rules, the IR spectra are much less informative, owing to the relative rigidity of norcorrole. The results have implications for the assignment of (anti)aromaticity in both ground-state and time-resolved spectra.
芳香性和反芳香性是有机化学中的基础原理，常被用于解释稳定性、结构以及磁性和电子性质。使用光谱学方法将分子归类为芳香性或反芳香性分子仍面临诸多挑战。在此，我们报告了卟啉（18π中性，芳香性）和降卟啉（16π中性，反芳香性）及其氧化形式（16π卟啉二价阳离子）和还原形式（降卟啉18π二价阴离子）的光谱电化学和计算分析。我们的结果表明，虽然可见光谱具有符合休克尔规则的（反）芳香性特征，但由于降卟啉的相对刚性，红外光谱提供的信息要少得多。这些结果对于基态光谱和时间分辨光谱中（反）芳香性的归属具有重要意义。
