Hasegawa Masashi, Nakamura Ken-Ichi, Tokunaga Saki, Baba Yumi, Shiba Ryota, Shirahata Takashi, Mazaki Yasuhiro, Misaki Yohji
Department of Chemistry, School of Science, Kitasato University, 1-15-1 Kitasato. Minami-ku, Sagamihara, Kanagawa, 252-0373, Japan.
Department of Applied Chemistry, Graduate School of Science of Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama Ehime, 790-8577, Japan.
Chemistry. 2016 Jul 11;22(29):10090-101. doi: 10.1002/chem.201601785. Epub 2016 Jun 10.
Understanding the details of the electronic structure in face-to-face arranged tetrathiafulvalenes (TTFs) is very important for the design of supramolecular functional materials and superior conductive organic materials. This article is a comprehensive study of the interactions among columnar stacked TTFs using trimeric (trimer) and tetrameric (tetramer) TTFs linked by alkylenedithio groups (-S(CH2 )n S-, n=1-4) as models of triple- and quadruple-decker TTF arrays. Single-crystal X-ray analyses of neutral trimeric TTFs revealed that the three TTF moieties are oriented in a zigzag arrangement. Cyclic voltammetry measurements (CV) reveal that the trimer and tetramer exhibited diverse reversible redox processes with multi-electron transfers, depending on the length of the -S(CH2 )n S- units and substituents. The electronic spectra of the radical cations, prepared by electrochemical oxidation, showed charge resonance (CR) bands in the NIR/IR region (1630-1850 nm), attributed to a mixed valence (MV) state of the triple- and quadruple-decker TTF arrays. In the trimeric systems, the dicationic state (+2; 0.66 cation per TTF unit) was found to be a stable state, whereas the monocationic state (+1) was not observed in the electronic spectra. In the tetrameric system, substituent-dependent redox processes were observed. Moreover, π-trimers and π-tetramers, which show a significant Davydov blueshift in the spectra, are formed in the tricationic (trimer) and tetracationic (tetramer) state. In addition, these attractive interactions are strongly dependent on the length of the linkage unit.
了解面对面排列的四硫富瓦烯（TTF）的电子结构细节对于超分子功能材料和优质导电有机材料的设计非常重要。本文以亚烷基二硫基（-S(CH2 )n S-，n = 1 - 4）连接的三聚体（trimer）和四聚体（tetramer）TTF作为三层和四层TTF阵列的模型，对柱状堆叠TTF之间的相互作用进行了全面研究。中性三聚体TTF的单晶X射线分析表明，三个TTF部分呈锯齿状排列。循环伏安法测量（CV）表明，三聚体和四聚体表现出不同的可逆氧化还原过程，伴有多电子转移，这取决于-S(CH2 )n S-单元的长度和取代基。通过电化学氧化制备的自由基阳离子的电子光谱在近红外/红外区域（1630 - 1850 nm）显示出电荷共振（CR）带，这归因于三层和四层TTF阵列的混合价（MV）状态。在三聚体系统中，发现双阳离子状态（+2；每个TTF单元0.66个阳离子）是稳定状态，而在电子光谱中未观察到单阳离子状态（+1）。在四聚体系统中，观察到了取代基依赖性的氧化还原过程。此外，在三阳离子（三聚体）和四阳离子（四聚体）状态下形成了在光谱中显示出显著的达维多夫蓝移的π-三聚体和π-四聚体。此外，这些有吸引力的相互作用强烈依赖于连接单元的长度。
