Artigas Albert, Carissan Yannick, Hagebaum-Reignier Denis, Bock Harald, Durola Fabien, Coquerel Yoann
Facultat de Ciències, Universitat de Girona, Campus Montilivi, Carrer de Maria Aurèlia Capmany i Farnès 69, 17003, Girona, Catalunya, Spain.
Aix Marseille Univ, CNRS, Centrale Méditerranée, iSm2, Marseille, France.
Chemistry. 2024 Jun 20;30(35):e202401016. doi: 10.1002/chem.202401016. Epub 2024 May 24.
Electron delocalization and aromaticity was comparatively evaluated in recently synthesized figure-eight molecules made of two condensed U-shaped polycyclic aromatic hydrocarbon moieties connected either by two single bonds or by two para-phenylene groups. The selected examples include molecules that incorporate eight-membered and sixteen-membered rings, as well as a doubly [5]helicene-bridged (1,4)cyclophane. We probe whether some electron delocalization could occur through the stereogenic single bonds in these molecules: Is aromaticity purely (semi-)local, or possibly also global in these molecules? It was concluded that the situation can go from a purely (semi-)local character when the dihedral angle at the connecting single bonds is large, such as in biphenyl, to a predominantly (semi-)local character with a minor global contribution when the dihedral angle is small, such as in the para-phenylene connectors of the [5] helicene-bridged cyclophane.
对最近合成的由两个稠合的U形多环芳烃部分通过两个单键或两个对亚苯基连接而成的数字8分子中的电子离域和芳香性进行了比较评估。所选实例包括含有八元环和十六元环的分子，以及双[5]螺旋烯桥连的(1,4)环芳。我们探究了在这些分子中是否会通过手性单键发生一些电子离域：这些分子中的芳香性是纯粹（半）局域的，还是也可能是全局的？得出的结论是，当连接单键处的二面角较大时，情况可以从纯粹（半）局域的特征，如在联苯中，转变为当二面角较小时，主要是（半）局域特征且有较小的全局贡献，如在[5]螺旋烯桥连环芳的对亚苯基连接体中。
