A molecular metal with ion-conducting channels
A molecular metal with ion-conducting channels
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DOI：
10.1038/28128
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发表时间：
1998-07-09
期刊：
影响因子：
64.8
通讯作者：
Friend, RH
中科院分区：
文献类型：
--
作者：
Nakamura, T;Akutagawa, T;Friend, RH
金属行为在电荷转移配合物中是众所周知的，这些配合物包含平面的、部分氧化的（或还原的）π共轭分子。电子传导发生在由分子间轨道重叠形成的部分占据的离域π带中，其中一些材料表现出超导性（1,2）。为了实现电荷中性而存在的反离子通常起被动作用，尽管在某些情况下它们与电子结构耦合，例如通过定向排序施加新的结构周期性（超晶格）(1)。能够同时支持电子和离子传输的分子固体的发展对几个领域都很重要，包括固态电池（3,4）、电致发光器件(5)和仿生系统（6,7）的发展。冠醚是这种系统中很有前途的成分，因为它们提供了离子运动可能发生的空腔。在这里，我们报道了电荷转移盐Li(0.6)（15-冠-5-醚）[Ni(dmit)(2)](2). h (2)O同时表现出电子和离子的导电性：镍配合物（dmit是一种有机分子）的堆叠提供了电子传导的途径，而冠醚的堆叠为锂离子的运动提供了通道。后者在250 K以上的证据由核磁共振和电导率研究提供。我们也看到了电子和离子运动耦合的证据。该化合物可作为开发其他杂化电子/离子导电材料的模型。
Metallic behaviour is well known in charge-transfer complexes that contain stacks of planar, partially oxidized (or reduced) pi-conjugated molecules. Electronic conduction occurs in the partially occupied, delocalized pi bands formed by intermolecular orbital overlap, and some of these materials exhibit superconductivity(1,2). Counter-ions, present to achieve charge neutrality, usually play a passive role, although in some cases they couple to the electronic structure, for example by imposing a new structural periodicity (a superlattice) by orientational ordering(1). The development of molecular solids that can simultaneously support the transport of both electrons and ions is important for several fields, including the development of solid-state batteries(3,4), electroluminescent devices(5) and biomimetic systems(6,7). Crown ethers are promising components for such systems, as they provide cavities through which ion motion might occur. Here we report that the charge-transfer salt Li(0.6)(15-crown-5-ether) [Ni(dmit)(2)](2).H(2)O exhibits both electron and ion conductivity: the stacks of the nickel complex (dmit is an organic molecule) provide a pathway for electron conduction, and stacks of the crown ethers provide channels for lithium-ion motion. Evidence for the latter above 250 K is provided by NMR and conductivity studies. We also see evidence for coupling of the electron and ion motions. This compound might serve as a model for the development of other hybrid electronic/ionic conducting materials.