In this paper, the heteroatom-bridged pillar[n]arene derivatives, namely bora-, aza-, and oxa-pillar[n]arenes (PnX, X = B, N, and O respectively, n = 4 − 6) are studied by quantum chemical calculations at the ωB97XD/6-311G(d,p) level of theory. The geometries, energetics, electronic structures, absorption spectra, solvent effects, and the inclusion complexation with paraquat dication are discussed in detail. The calculated results show the structures of pentamers (P5X) are more stable compared with tetramers (P4X) and hexamers (P6X) and the PnB have relatively loose and irregular geometry structures. The molecular cavities of PnX are electron-rich and capable of accommodating cationic guests. Absorption spectra of PnN and PnO are very similar to those of Pn with one intense peak (λmax) at around 260 nm, while PnB indicates another characteristic peak between 300 and 400 nm. P5X can form inclusion complexes of 1:1 stoichiometry with paraquat dication, and P5N exhibits strongest combination ability with paraquat dication among them. These thorough understanding of the structure and properties of heteropillar[n]arenes will broaden the designs, syntheses, and applications of pillararenes.

中文翻译：

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杂原子桥接柱[n]芳烃结构和夹杂物性质的理论预测

在本文中，杂原子桥接的柱[n]芳烃衍生物，即硼-、氮杂-和氧杂-柱[n]芳烃（PnX，分别为X = B、N和O，n = 4 − 6）是在 ωB97XD/6-311G(d,p) 理论水平通过量子化学计算进行研究。详细讨论了几何形状、能量学、电子结构、吸收光谱、溶剂效应以及与百草枯二甲基化的包合络合。计算结果表明，与四聚体（P4X）和六聚体（P6X）相比，五聚体（P5X）的结构更稳定，PnB具有相对松散和不规则的几何结构。PnX 的分子腔富含电子，能够容纳阳离子客体。PnN 和 PnO 的吸收光谱与 Pn 的吸收光谱非常相似，在 260 nm 附近有一个强峰 (λmax)，而 PnB 表示 300 到 400 nm 之间的另一个特征峰。P5X可与百草枯形成1:1化学计量的包合物，其中P5N与百草枯的结合能力最强。这些对杂柱芳烃结构和性质的透彻理解将拓宽柱芳烃的设计、合成和应用。