Solid state and Structural Chemistry Unit, Indian Institute of Science, Bangalore, India -560 012.
J Phys Chem A. 2010 May 13;114(18):5940-6. doi: 10.1021/jp102065g.
We have studied the nature of aromaticity in expanded porphyrinic analogues of thiophenes formed by four and six thiophenes. Using density functional theory (DFT) we have analyzed the aromaticity of both the macrocycle and individual molecular fragments. We find paramagnetic annulenic ring currents in the case of tetracyclic molecules and diamagnetic annulenic ring currents for hexacyclic molecules. We have also studied the effect of substitution of benzene rings within the macrocycle. We find that as the number of benzene rings is increased the aromaticity increases for tetracyclic systems and decreases for hexacyclic systems. All the results have been analyzed with various microscopic parameters, including geometry, excitation gap, and NMR criteria.
我们研究了由四个和六个噻吩组成的扩展卟啉类似物中噻吩的芳香性本质。使用密度泛函理论（DFT），我们分析了大环和单个分子片段的芳香性。我们发现四元环分子具有顺磁薁环电流，而六元环分子具有反磁薁环电流。我们还研究了大环中环苯取代的影响。我们发现，随着苯环数量的增加，四环体系的芳香性增加，而六环体系的芳香性降低。所有结果均使用各种微观参数进行了分析，包括几何形状、激发能隙和 NMR 标准。
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