摘要/Abstract

具有适中氧化还原电位和良好柔韧性的平面有机电子给体是有机分子材料和自组装化学的研究基础.本文以易得的原料和简便的操作方法合成了一系列含有亚乙二氧/硫基和邻苯二巯基的不对称四硫富瓦烯（TTF）衍生物.两种取代基团的引入明显增大了TTF的氧化还原半电位，进而提高了有机电子给体的光电稳定性.与刚性TTF不同本文所设计和合成出的TTF衍生物是一类具有一定柔韧性的有机电子给体.实验证明，通过在TTF外围引入C—S键可明显增强化合物的柔韧性.在复合物（TTF4）（C₆₀）中，TTF4的中心C₂S₄平面与外围C₂S₂平面之间的二面角比中性分子的增加了5.87°，这充分说明柔韧性有机电子给体能够在自组装化学中发挥独特的作用.
关键词: 有机电子给体, 四硫富瓦烯, 光电稳定性, 柔韧性, 自组装
Organic electron donors with planar configuration, moderate redox potential and favorable flexibility are the foundation of the molecular material science and self-assembly chemistry. A series of TTF derivatives (TTF1~TTF8) with well molecule flexibility have been synthesized employing a copper-mediated C—S coupling reaction of 1,2-diiodophenyl groups and a zinc-thiolate complex, (TBA)₂[Zn(DMIT)₂] (TBA=tetrabutyl ammonium, DMIT=1,3-dithiole-2-thione-4,5-dithiolate) as the key step. The physicochemical properties and crystal structures of these TTFs are fully investigated by UV/Vis absorption spectra, cyclic voltammetry, single crystal X-ray diffraction. The ethylenedioxy/ethylenedithio group and sulfur attached phenyl groups lead to unusual properties of TTFs. In comparison with TTF5~TTF8 containing ethylenedithio groups, TTF1~TTF4 substituted by ethylenedioxy groups exhibit stronger absorbance, due to the different electronegative of oxygen and sulfur atom. In addition the absorbance is reducing progressively as the electron donating ability of the respective aryl groups increasing. By introducing fused aryls, the first half redox potential (E_1/2¹) used to estimate the electrochemical stability of different organic electron donors of the TTF derivatives are much higher than that of BEDT-TTF and TTF itself. The aryls ensure the stability of TTF-core via dispersing its electrons. By hot recrystallization or slowly evaporating the solvent, single crystals of eight TTFs suitable for single-crystal X-ray diffraction measurement were obtained. All these TTF derivatives adopt boat conformation with various dihedral angles between the central C₂S₄ plane with the terminal C₂O₂ and C₂S₂ plane of the TTF framework. Complicated aryls leads to larger dihedral angles. TTF5~TTF8 with ethylenedithio groups have more dominant curving configuration with respect to TTF1~TTF4 functionalized by ethylenedioxy groups. Additionally, the stereo-hindrance effects due to the fused phenyl groups prolong the distance from one molecule to another. As a typical example of crystal structure of TTF4, the two methoxy groups make the distance much longer than that in TTF1. Furthermore, the flexible TTFs exhibit unique behavior on self-assembling when the C—S bond vibrate upon and down the TTF-skeleton plane. Single crystals of the complex (TTF4)(C₆₀) are obtained via slowly evaporating chlorobenzene at room temperature after the mixture was heated and refluxed for five minutes. The dihedral angles of TTF4 enlarges to some extent from 24.30° in monomer to 30.17° in complex. Two electron donor molecules produced a cavity and a C₆₀ molecule filled the cavity with C—C and C—S contacts.
Key words: organic electro donor, tetrathiafulvalene (TTF), photoelectric stability, flexibility, self-assembly


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