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<p><i>π</i>-Conjugated molecules with non-trivial topologies, such as catenanes and molecular knots, offer aromaticity and through-space electronic and magnetic interactions absent in traditional planar <i>π</i> systems. However, their synthesis remains challenging, with previous examples showing only localized aromaticity in individual benzenoid rings. Here we report the synthesis of a [2]catenane comprising 2 intertwined octaphyrinoid rings, each with 34 globally delocalized <i>π</i> electrons, achieved using a passive metal-template strategy with 2,2′-dipyrromethene as the directing ligand. X-ray crystallographic analysis reveals a nearly orthogonal spatial arrangement of the rings in neutral catenane, stabilized by multiple [NH···N] and [S···N] close contacts. These rings exhibit global aromaticity with entangled magnetic shielding interactions. Upon four-electron oxidation, the system converts to a tetracation with two globally antiaromatic (32<i>π</i>) rings, in which through-space bonding interactions diminish the antiaromatic destabilization. Notably, counterions also affect the (anti)aromaticity of the tetracations in the single-crystal state, highlighting a dynamic interplay between molecular topology, electronic structure and external interactions.</p><p></p>

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Aromaticity and through-space electronic coupling in [2]catenanes comprising two intertwined globally electron-delocalized octaphyrinoid rings

  • 期刊论文

  • 发表日期：

    2025年10月30日

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  • Yuguang Sui,
  • Zipeng Wang,
  • Jiahang Hao,
  • Shaofei Wu,
  • Longbin Ren,
  • Zebing Zeng,
  • Jishan Wu,
  • Yong Ni

摘要

π-Conjugated molecules with non-trivial topologies, such as catenanes and molecular knots, offer aromaticity and through-space electronic and magnetic interactions absent in traditional planar π systems. However, their synthesis remains challenging, with previous examples showing only localized aromaticity in individual benzenoid rings. Here we report the synthesis of a [2]catenane comprising 2 intertwined octaphyrinoid rings, each with 34 globally delocalized π electrons, achieved using a passive metal-template strategy with 2,2′-dipyrromethene as the directing ligand. X-ray crystallographic analysis reveals a nearly orthogonal spatial arrangement of the rings in neutral catenane, stabilized by multiple [NH···N] and [S···N] close contacts. These rings exhibit global aromaticity with entangled magnetic shielding interactions. Upon four-electron oxidation, the system converts to a tetracation with two globally antiaromatic (32π) rings, in which through-space bonding interactions diminish the antiaromatic destabilization. Notably, counterions also affect the (anti)aromaticity of the tetracations in the single-crystal state, highlighting a dynamic interplay between molecular topology, electronic structure and external interactions.