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Understanding Aromaticity in [5]Helicene-Bridged Cyclophanes: A Comprehensive Study
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2024-01-18 , DOI: 10.1021/acs.joc.3c02485
Mesías Orozco-Ic 1 , Luis Soriano-Agueda 1 , Sílvia Escayola 1, 2 , Dage Sundholm 3 , Gabriel Merino 4 , Eduard Matito 1
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2024-01-18 , DOI: 10.1021/acs.joc.3c02485
Mesías Orozco-Ic 1 , Luis Soriano-Agueda 1 , Sílvia Escayola 1, 2 , Dage Sundholm 3 , Gabriel Merino 4 , Eduard Matito 1
Affiliation
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This study explores the aromaticity of doubly [5]helicene-bridged (1,4)cyclophane and triply [5]helicene-bridged (1,3,5)cyclophane via calculations of the magnetic response and of electronic aromaticity indices. The primary objective is to assess the π-electron delocalization to determine whether they sustain global ring currents associated with π aromaticity. The molecules show local ring currents in the presence of an external magnetic field. The ring currents flow diatropically in the stacked six-membered rings and in the helicene arms. However, these π currents are not interconnected due to the discontinuity of the π delocalization at the C–C single bonds connecting the central six-membered rings to the helicene arms. Electronic indices suggest that the helicene-arm systems have significantly smaller electron delocalization than benzene. The reduction in the delocalization does not compromise their ability to exhibit ring currents in the presence of an external magnetic field. The analysis provides further evidence that the magnetic criteria yield a different degree of aromaticity for the helicene arms than obtained in the calculation of the electronic aromaticity indices. However, both approaches confirm that the studied molecules are not globally aromatic.
中文翻译：
了解 [5] 螺烯桥环芳烃的芳香性：一项综合研究
本研究通过计算磁响应和电子芳香指数，探讨了双[5]螺烯桥联(1,4)环芳烷和三[5]螺烯桥联(1,3,5)环芳烷的芳香性。主要目标是评估 π 电子离域，以确定它们是否维持与 π 芳香性相关的全局环电流。在外部磁场存在的情况下，分子显示出局部环电流。环流在堆叠的六元环和螺旋烯臂中呈变向流动。然而，由于连接中心六元环和螺旋烯臂的 C-C 单键的 π 离域不连续，这些 π 电流并不相互连接。电子指数表明螺旋烯臂系统的电子离域比苯小得多。离域的减少不会损害它们在存在外部磁场的情况下表现出环电流的能力。该分析提供了进一步的证据，表明磁性标准产生的螺旋烯臂的芳香度与电子芳香度指数计算中获得的芳香度不同。然而，这两种方法都证实所研究的分子不是全局芳香族的。
更新日期：2024-01-18
中文翻译：
了解 [5] 螺烯桥环芳烃的芳香性：一项综合研究
本研究通过计算磁响应和电子芳香指数，探讨了双[5]螺烯桥联(1,4)环芳烷和三[5]螺烯桥联(1,3,5)环芳烷的芳香性。主要目标是评估 π 电子离域，以确定它们是否维持与 π 芳香性相关的全局环电流。在外部磁场存在的情况下，分子显示出局部环电流。环流在堆叠的六元环和螺旋烯臂中呈变向流动。然而，由于连接中心六元环和螺旋烯臂的 C-C 单键的 π 离域不连续，这些 π 电流并不相互连接。电子指数表明螺旋烯臂系统的电子离域比苯小得多。离域的减少不会损害它们在存在外部磁场的情况下表现出环电流的能力。该分析提供了进一步的证据，表明磁性标准产生的螺旋烯臂的芳香度与电子芳香度指数计算中获得的芳香度不同。然而，这两种方法都证实所研究的分子不是全局芳香族的。
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