Design of Organic-Oraganometallic Hybrid Molecules with Mixed-valence Redox Activity

近年来，包含多个还原-氧化中心的分子的研究由于制备了具有应用价值的新型π共轭材料而引起了材料科学领域的广泛关注。此外，这种具有两个以上氧化还原活性金属中心的分子是通过这些多金属体系衍生的混合价态来研究多电子转移过程的一个极具吸引力的目标。另一方面，对利用含有16族元素的5π-和7π-电子骨架设计新型氧化还原活性有机中心的兴趣促使我们探索了含硫原子的新5元杂环的合成。因此，我们设计了由噻吩、二噻吩和噻吩桥接的二茂铁低聚衍生物，作为阴极和阳极多重氧化还原活性有机-有机金属杂化分子。通过与噻吩或低硫噻吩衍生物的交叉偶联反应，系统地、选择性地合成了二茂铁或二茂铁氯化锌。通过物理和光谱方法对分子进行了表征。含有噻吩和铁二烯片段的新型有机-有机金属杂化分子的循环伏安图显示出由异常稳定的5π噻吩自由基阳离子和7π噻吩自由基阴离子引起的明确可逆的阳极和阴极步骤。此外，这些分子表现出多个不同的可逆阳极步骤，这些步骤来自于由一个噻吩或一个寡噻吩相互分离的二茂铁阳离子。

In recent years, the study of molecules comprising multiple reduction-oxidation (redox) centers have attracted considerable research interest in the field of material science due to the preparation of new π-conjugated materials with application in material science. Moreover, this kind of molecule having more than two redox-active metal centers is a fundamentally attractive target for the study of multi-electron transfer processes via the mixed valence state derived from these multi-metallic systems. On the other hand, interest in the design of novel redox-active organic centers by the use of a 5π- and 7π- electron framework containing group 16 elements has led us to explore the synthesis of new 5-membered heterocycles containing sulfur atom (s). Therefore, we have designed oligo-ferrocene derivatives bridged by thiophene, bithiopehene, and terthiophene as both cathodic and anodic multiple-redox active organic-organometallic hybrid molecules. Each molecule has been systematically and selectively synthesized from heloferrocene or ferrocenylzinc chloride by cross-coupling reactions with thiophene or oligothiophene derivatives. Characterization of the molecules was performed by physical and spectroscopic means. The cyclic voltammograms of the novel organic-organometallic hybrid molecules containing both thiophene and ferrcene fragments showed well-defined reversible both anodic and cathodic steps derived from the unusually stable 5π thiophene radical cations, 7π thiophene radical anions. In addition, the molecules showed multiple distinct reversible anodic steps derived from ferrocenium cations separated from each other by a thiophene or an oligothiophene.