标题： 合成与表征$π$-扩展的Clar高脚杯 显示英文标题

标题： Synthesis and characterization of a $π$-extended Clar's goblet

摘要： 隐藏的非凯库勒多苯结构烃没有亚晶格不平衡，但不能分配一个经典的凯库勒结构，导致形成开壳层基态，具有在有机自旋电子学中的潜在应用。 它们构成了可以构建的给定数量的苯环多苯结构烃总数中极其小的一部分，而且它们的合成仍然具有挑战性。 此类系统的原型是克拉尔的高脚杯（C$_{38}$H$_{18}$），这是1972年由埃里希·克拉尔提出的一种二自由基，并且最近在Au(111)表面上被合成出来。 在这里，我们报告了通过溶液相和表面合成相结合的方法合成了一种π扩展的克拉尔高脚杯（C$_{76}$H$_{26}$），这是一种四自由基隐藏的非凯库勒多苯结构烃。 通过低温扫描隧道显微镜和原子力显微镜，我们表征了吸附在Cu(111)表面上的单个分子。 我们通过平均场和多构型量子化学计算提供了对该难以捉摸的分子电子性质的见解，包括其基态和激发态的多体性质。 显示英文摘要

摘要： Concealed non-Kekul\'e polybenzenoid hydrocarbons have no sublattice imbalance yet cannot be assigned a classical Kekul\'e structure, leading to an open-shell ground state with potential application in organic spintronics. They constitute an exceedingly small fraction of the total number of polybenzenoid hydrocarbons that can be constructed for a given number of benzenoid rings, and their synthesis remains challenging. The archetype of such a system is Clar's goblet (C$_{38}$H$_{18}$), a diradical proposed by Erich Clar in 1972 and recently synthesized on a Au(111) surface. Here, we report the synthesis of a pi-extended Clar's goblet (C$_{76}$H$_{26}$), a tetraradical concealed non-Kekul\'e polybenzenoid hydrocarbon, by a combined in-solution and on-surface synthetic approach. By means of low-temperature scanning tunneling microscopy and atomic force microscopy, we characterized individual molecules adsorbed on a Cu(111) surface. We provide insights into the electronic properties of this elusive molecule, including the many-body nature of its ground and excited states, by mean-field and multiconfigurational quantum chemistry calculations.