A multistable molecular switching system based on an anthracene-extended bis-thiaxanthylidene with three individually addressable states that can be interconverted by electrochemical, thermal, and photochemical reactions is reported. Besides reversible switching between an open-shell diradical- and a closed-shell electronic configuration, our findings include a third dicationic state and control by multiple actuators. This dicationic state with an orthogonal conformation can be switched electrochemically with the neutral open-shell triplet state with orthogonal conformation, which was characterized by EPR. The remarkably stable diradical shows kinetic stability as a result of a significant activation barrier for isomerization to a more stable neutral closed-shell folded geometry. We ascribe this activation barrier of ΔG^⧧(293 K) = 25.7 kcal mol^–1 to steric hindrance in the fjord region of the overcrowded alkene structure. The folded closed-shell state can be converted back to the diradical state by irradiation with 385 nm. The folded state can also be oxidized to the dicationic state. These types of molecules with multiple switchable states and in particular stable diradicals show great potential in the design of new functional materials such as memory devices, logic gates, and OFETs.

中文翻译：

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具有高度稳定双自由基态的蒽扩展双噻吨亚基的三态转换

报道了一种基于蒽扩展双噻吨亚基的多稳态分子开关系统，该系统具有三种可单独寻址的状态，可以通过电化学、热和光化学反应相互转换。除了开壳双自由基和闭壳电子配置之间的可逆切换外，我们的研究结果还包括第三种阳离子状态和多个致动器的控制。这种具有正交构象的双阳离子态可以与具有正交构象的中性开壳三重态进行电化学转换，其特征在于 EPR。显着稳定的双自由基显示出动力学稳定性，这是由于显着的活化屏障异构化为更稳定的中性闭壳折叠几何形状。我们将这个激活屏障归因于ΔG^⧧ (293 K) = 25.7 kcal mol ^–1对过度拥挤烯烃结构的峡湾区域的空间位阻。折叠的闭壳状态可以通过 385 nm 的辐照转换回双自由基状态。折叠状态也可以被氧化成双阳离子状态。这些类型的分子具有多种可切换状态，尤其是稳定的双自由基，在设计新功能材料（如存储器件、逻辑门和 OFET）方面显示出巨大潜力。