Pedersen Viktor Bliksted Roug, Nielsen Mogens Brøndsted
Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen Ø, DK-2100, Denmark.
Chem Asian J. 2025 May 2;20(9):e202500356. doi: 10.1002/asia.202500356. Epub 2025 Apr 9.
Tetrathiafulvalene (TTF) and polycyclic aromatic hydrocarbons (PAHs) represent two distinct classes of redox-active chromophores. By merging these two classes in so-called extended tetrathiafulvalenes, new physico-chemical characteristics emerge. Here in this study, we summarize the properties of such PAH-extended TTFs for which the PAH core incorporates five-membered carbo-cyclic rings together with six-, seven-, and/or eight-membered rings. A key structural motif of these molecules is the planar 2-(1H-inden-1-ylidene)-1,3-dithiole unit. Fusing two such units directly together or via various one- or two-dimensional PAH scaffolds has during the past decade provided a large selection of planar, twisted, or curved extended TTFs. Strong associations of radical cations are in some cases obtained, corresponding to redox-controlled self-assembly in solution, and these associations have allowed for the ready generation of semi-conducting salts by electrocrystallization. Some molecules exhibit remarkable multiredox behavior and can reversibly reach high cationic states, and, in some cases, also anionic states. Several structural examples also reveal how closed-shell versus open-shell characters of the dication states can be controlled by the nature of the PAH core, particularly by the number of Clar sextets within the core.
四硫富瓦烯（TTF）和多环芳烃（PAHs）代表了两类不同的氧化还原活性发色团。通过在所谓的扩展四硫富瓦烯中融合这两类物质，新的物理化学特性得以显现。在本研究中，我们总结了此类PAH扩展TTF的性质，其中PAH核心包含五元碳环以及六元、七元和/或八元环。这些分子的一个关键结构基序是平面的2-(1H-茚-1-亚基)-1,3-二硫醇单元。在过去十年中，将两个这样的单元直接融合在一起或通过各种一维或二维PAH支架融合，提供了大量平面、扭曲或弯曲的扩展TTF。在某些情况下会得到自由基阳离子的强缔合，这对应于溶液中的氧化还原控制自组装，并且这些缔合使得通过电结晶容易生成半导体盐。一些分子表现出显著的多氧化还原行为，能够可逆地达到高阳离子态，并且在某些情况下还能达到阴离子态。几个结构实例还揭示了双阳离子态的闭壳层与开壳层特征如何受PAH核心的性质控制，特别是受核心内克莱尔六隅体数量的控制。
