Watanabe Motonori, Doi Yasutaka, Hagiwara Hidehisa, Staykov Aleksandar Tsekov, Ida Shintaro, Matsumoto Taisuke, Shinmyozu Teruo, Ishihara Tatsumi
International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), ‡Graduated School of Integrated Frontier Science, Department of Automotive Science, §Faculty of Engineering, Department of Applied Chemistry, and ∥Institute for Materials Chemistry and Engineering, Kyushu University , 744 Motooka, Nishi-ku, Fukuoka 819-0395 Japan.
J Org Chem. 2015 Sep 18;80(18):9159-66. doi: 10.1021/acs.joc.5b01525. Epub 2015 Aug 28.
A series of syn/anti mixtures of anthradifuran (ADF) and substituent compounds were systematically synthesized, and the effect of substitution at the 5,11-positions on the neutral and radical states of ADF was investigated. All compounds were measured and analyzed by absorption and fluorescence spectroscopy, cyclic voltammetry, electrochemical absorption spectroscopy, and DFT calculations. The absorption spectra of 5,11-substituent compounds in their neutral state were red-shifted. In addition, the substituted compounds exhibited increased thermal stability with respect to the parent 1a because of elongation of the π-conjugation and an increased steric hindrance effect due to the bulky ethynyl substituent groups. The cyclic voltammograms of all of the compounds exhibited irreversible reduction potentials and irreversible oxidation potentials, except in the case of (trimethylsilyl)silylethynyl-substituted ADF. When the materials were subjected to oxidation/reduction potentials, the radical cation and anion species were generated. The absorption spectra of the radical-cation species of the compounds exhibited similar characteristics and similar absorption ranges (550-1400 nm), whereas the spectra of the radical anion species were blue-shifted (550-850 nm) compared than that of the parent 1a(•-) (550-1100 nm). The DFT computation results suggested that the radical states of lowest energy transitions occurred primarily from π to π(SOMO) or from π(SOMO) to π*.
系统合成了一系列蒽二呋喃（ADF）及其取代化合物的顺式/反式混合物，并研究了5,11位取代对ADF中性态和自由基态的影响。所有化合物均通过吸收光谱和荧光光谱、循环伏安法、电化学吸收光谱和密度泛函理论（DFT）计算进行测量和分析。5,11位取代化合物在中性态下的吸收光谱发生红移。此外，由于π共轭的延长以及庞大的乙炔基取代基导致的空间位阻效应增加，取代化合物相对于母体1a表现出更高的热稳定性。除了（三甲基硅基）硅乙炔基取代的ADF外，所有化合物的循环伏安图均显示出不可逆的还原电位和不可逆的氧化电位。当材料受到氧化/还原电位作用时，会产生自由基阳离子和阴离子物种。化合物的自由基阳离子物种的吸收光谱表现出相似的特征和相似的吸收范围（550 - 1400 nm），而自由基阴离子物种的光谱与母体1a(•-)（550 - 1100 nm）相比发生了蓝移（550 - 850 nm）。DFT计算结果表明，最低能量跃迁的自由基态主要发生在从π到π（单占据分子轨道）或从π（单占据分子轨道）到π*。
