天津大学孙哲团队报道了过度拥挤的乙烯桥联纳米环二聚体的区域选择性合成、多组态电子态和全局Hückel/Mbius芳香性。相关研究成果于2021年11月24日发表在《美国化学会杂志》。

具有多种几何构型和电子构型分子系统的设计和制备是具有刺激响应行为多功能材料的基石。

该文中，研究人员描述了两种过度拥挤的乙烯桥联纳米环二聚体的区域选择性、简便合成，它们具有折叠和扭曲的几何结构以及封闭的壳层、双自由基和电子结构。应变纳米环结构对整个分子和电子构型有着深远的影响，导致了不稳定的双自由基态。

X射线晶体学分析揭示了中性物种的折叠分子几何结构和指示物种的扭曲几何结构。通过光谱和电化学方法揭示了溶液相独特的分子动力学、光学性质和动态氧化还原性质。此外，综合实验结果和理论分析，揭示了整体Hückel和Mbius芳香性。该研究有助于设计具有独特拓扑结构和功能的纳米环复合多结构材料。

附：英文原文

Title: Overcrowded Ethylene-Bridged Nanohoop Dimers: Regioselective Synthesis, Multiconfigurational Electronic States, and Global Hückel/Mbius Aromaticity

Author: Ke Li, Zhuofan Xu, Jun Xu, Taoyu Weng, Xing Chen, Sota Sato, Jishan Wu, Zhe Sun

Issue&Volume: November 24, 2021

Abstract: The design and preparation of molecular systems with multiple geometric and electronic configurations are the cornerstones for multifunctional materials with stimuli-responsive behaviors. We describe here the regioselective and facile synthesis of two types of overcrowded ethylene-bridged nanohoop dimers, with folded and twisted geometric structures as well as closed-shell, diradical and dication electronic structures. The strained nanohoop structures have a profound effect on the overall molecular and electronic configurations, which resulted in the destabilized diradical state. X-ray crystallographic analysis revealed the folded molecular geometry for the neutral species and twisted geometry for the dication species. The unique molecular dynamics, optical properties, and dynamic redox properties were disclosed in the solution phase by spectroscopic and electrochemical methods. Furthermore, the global Hückel and Mbius aromaticity were revealed by a combination of experimental and theoretical approaches. Our studies shed light on the design of nanohoop-incorporated multiconfigurational materials with unique topologies and functions.

DOI: 10.1021/jacs.1c10170

Source: https://pubs.acs.org/doi/10.1021/jacs.1c10170