Astruc Didier, Ornelas Cátia, Ruiz Jaime
Institut des Sciences Moléculaires, UMR CNRS No 5255, Université Bordeaux 1, 33405 Talence, France.
Chemistry. 2009 Sep 14;15(36):8936-44. doi: 10.1002/chem.200901294.
In this Concept article, we summarize and discuss recent reports on dendritic molecular electrochromic batteries. Giant dendrimers containing 3(n+2) terminal tethers (n = generation number) and terminated by first-raw late-transition-metal metallocenes, permethyl metallocenes and other sandwich complexes were shown to be redox robust. Indeed, they can be oxidized and reduced without decomposition and exist under two stable oxidation states (Fe(III/II), Co(III/II)). Thus, a pre-determined number of electrons (up to 14,000) per dendrimer can be exchanged. Cyclic voltammetry showed a remarkable complete reversibility even up to 14,000 Fe and Co termini in metallodendrimers, indicating fast electron hoping among the redox sites and between dendrimers on a carbon surface covered by arylcarboxylate groups. The dendrimer sizes were measured by dynamic light scattering in solution and by AFM (subsequent to flattening in the condensed state also indicating that these metallodendrimers aggregate to form discrete nanoparticles of dendrimers, as atoms do). The metallodendrimer size varies considerably between the two redox forms due to tether extension of the cationic dendrimers upon oxidation, and a breathing mechanism was shown by atomic and electric force microscopy (AFM and EFM). When the redox potential is very negative, the reduced form is an electron-reservoir system that can deliver a large number of electrons per dendrimer to various reducible substrates. These systems are thus potential dendritic molecular batteries with two different colors for the two redox forms (electrochromic behavior).
在这篇概念文章中，我们总结并讨论了关于树枝状分子电致变色电池的近期报道。含有3(n + 2)个末端连接基（n为代数）且以第一排晚期过渡金属茂金属、全甲基茂金属及其他夹心配合物封端的巨型树枝状大分子显示出氧化还原稳定性。实际上，它们能够被氧化和还原而不分解，并以两种稳定的氧化态（Fe(III/II)、Co(III/II)）存在。因此，每个树枝状大分子可以交换预先确定数量的电子（多达14,000个）。循环伏安法显示，即使在金属树枝状大分子中有多达14,000个Fe和Co末端，仍具有显著的完全可逆性，这表明在被芳基羧酸盐基团覆盖的碳表面上，氧化还原位点之间以及树枝状大分子之间存在快速的电子跳跃。通过溶液中的动态光散射和原子力显微镜（在凝聚态扁平化后也表明这些金属树枝状大分子聚集形成离散的树枝状大分子纳米颗粒，就像原子那样）测量了树枝状大分子的尺寸。由于阳离子树枝状大分子在氧化时连接基的延伸，两种氧化还原形式之间的金属树枝状大分子尺寸有很大差异，并且原子力显微镜和电场力显微镜（AFM和EFM）显示出一种呼吸机制。当氧化还原电位非常负时，还原形式是一个电子储存系统，每个树枝状大分子可以向各种可还原底物提供大量电子。因此，这些系统是具有两种氧化还原形式（电致变色行为）且颜色不同的潜在树枝状分子电池。
