Charge‐Transfer Mechanisms between Gold Clusters
Charge‐Transfer Mechanisms between Gold Clusters
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金簇之间的电荷转移机制
DOI：
10.1002/ejic.200390143
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发表时间：
2003
影响因子：
2.3
通讯作者：
G. Schmid
中科院分区：
文献类型：
--
作者：
V. Torma;O. Vidoni;U. Simon;G. Schmid
复杂化学中的电子转移过程通常用Taube的“外球”和“内球”机制来描述。这些电子转移机制在复杂的化学行为可以观察到的配体保护的Au 55纳米团簇之间的电荷转移传输。如果存在非共价键，则观察到簇-簇距离与电子转移活化能之间的线性关系;这种相互作用与共价键连接的簇中的距离无关。相反，活化能取决于连接分子的电子性质。二硫醇1，5-二硫代萘（1）、4，4 ′-硫代双（苯乙撑）（2）和2，8-二硫代-6-羟基嘌呤（3）已被用作双功能共价连接剂，它们要么以单体形式（2），要么在空气存在下通过S-S键二聚（1，2，3），导致簇之间的距离增加，并导致簇网络4 - 7。非共价簇网络由8和11中的具有单齿配体的簇的颗粒形成，仅通过货车德瓦尔斯力连接，或者通过使用通过离子吸引与簇相互作用的双官能间隔物（9，10）。活化能的研究清楚地表明，在非共价组织的纳米颗粒的情况下，即使使用如10中的共轭π-系统，也只有簇间距是相关的。这种行为对应于一个外层机制。相反，对于共价连接的簇，它们之间的距离不起明显的作用。活化能都低于非共价键的例子，团簇-团簇距离和活化能之间的关系并不明显。在这些情况下，这种关系表明了一种内球机制，其中间隔物的传输特性起着决定性的作用。这些发现可能有助于解释关于有机分子导电行为的相互矛盾的报道。（© Wiley-VCH Verlag GmbH & Co. KGaA，69451魏因海姆，德国，2003）
Electron-transfer processes in complex chemistry are usually described by Taube’s “outer sphere” and “inner sphere” mechanisms. A behaviour related to these electron-transfer mechanisms in complex chemistry can be observed for charge-transfer transport between ligand protected Au55 nanoclusters. A linear dependence between cluster-cluster distance and activation energy for electron transfer is observed if a noncovalent linkage exists; this interaction is independent of the distance in covalently linked clusters. Instead, the activation energy depends on the electronic nature of the linking molecules. The dithiols 1,5-dithionaphthaline (1), 4,4′-thiobis(benzenethiol) (2), and 2,8-dithio-6-hydroxypurine (3) have been used as bifunctional covalent linkers either in their monomeric form (2) or, in the presence of air, dimerized via S−S bonds (1, 2, 3), causing an increase in the distance between the clusters and leading to the cluster networks 4−7. Noncovalent cluster networks are formed either by pellets of clusters with monodentate ligands in 8 and 11, linked only by van der Waals forces, or by using bifunctional spacers that interact with the clusters by ion attractions (9, 10). A study of the activation energies clearly indicates that in the case of noncovalently organized nanoparticles only the cluster spacing is of relevance, even if conjugated π-systems like in 10 are used. This behaviour corresponds to an outer-sphere mechanism. On the contrary, for covalently linked clusters the distances between them does not play a visible role. The activation energies all lie below those of the noncovalent examples, and a relation between cluster-cluster distance and activation energy is not obvious. In those cases the relationship suggests an inner-sphere mechanism where the transport properties of the spacer play a decisive role. These findings possibly help to explain contradictory reports on the conductivity behaviour of organic molecules. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)