Systemic studies are lacking to derive an understanding from the limited number of individually imaged diverse structures from noncontact atomic force microscopy and relate them to the chemistry of a macroscopic ensemble of a heterogeneous petroleum mixture. This initial study intends to fill this gap by studying polycyclic aromatic hydrocarbons (PAHs) and understanding their aromaticity and bonding orders. Both alternant and nonalternant PAHs are present in petroleum molecules, and the significance of nonalternant hydrocarbons in disrupting electron distribution of aromatic hydrocarbons was revealed by quantifying local aromaticity using nucleus-independent chemical shift, complemented by the qualitative prediction with Clar’s sextet theory. We found that local aromaticity is maximized, resulting in a new understanding of large aromatic structures in petroleum. In addition, bond order analysis on PAHs from atomic force microscopy imaging revealed that partial double bond character is common in petroleum molecules and could reach a significant degree in certain sites in a structure, with important implications in a wide range of reactivities and properties. Overall, this preliminary study provides means and methodology to connect finite structures from single-molecule imaging with infinite diverse molecules in petroleum.

中文翻译：

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揭示了石油分子中的非交替芳香性和部分双键：通过非接触原子力显微镜获得的多环芳香烃的理论理解。

缺乏系统的研究不足以从非接触原子力显微镜的有限数量的单独成像的多样结构中获得理解，并将其与异质石油混合物的宏观整体化学联系起来。这项初步研究旨在通过研究多环芳烃（PAH）并了解其芳构性和键合顺序来填补这一空白。交替和非交替的PAHs都存在于石油分子中，非交替的碳氢化合物在破坏芳香烃的电子分布中的重要性通过使用不依赖于核的化学位移定量局部芳香性来揭示，并辅以Clar的六重定性理论进行定性预测。我们发现当地的芳香性得到了最大化，对石油中的大型芳香结构有了新的认识。此外，原子力显微镜成像对PAHs的键序分析表明，部分双键特征在石油分子中很常见，并且在结构中的某些部位可能达到很大程度，这对广泛的反应性和性质具有重要意义。总的来说，这项初步研究提供了将单分子成像中的有限结构与石油中的无限多种分子联系起来的手段和方法。