Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, California 95064, USA.
Nanoscale. 2012 Jul 21;4(14):4183-9. doi: 10.1039/c2nr30213f. Epub 2012 Mar 22.
Ruthenium nanoparticles (2.12 ± 0.72 nm in diameter) were stabilized by the self-assembly of alkyne molecules (from 1-hexyne to 1-hexadecyne) onto the Ru surface by virtue of the formation of Ru-vinylidene interfacial linkages. Infrared measurements depicted three vibrational bands at 2050 cm(-1), 1980 cm(-1) and 1950 cm(-1), which were ascribed to the vibrational stretches of the terminal triple bonds that were bound onto the nanoparticle surface. Thermogravimetric analysis showed that there were about 65 to 96 alkyne ligands per nanoparticle (depending on the ligand chainlength), corresponding to a molecular footprint of 20 to 15 Å(2). This suggests that the ligands likely adopted a head-on configuration on the nanoparticle surface, consistent with a vinylidene bonding linkage due to interfacial tautomeric rearrangements. With this conjugated interfacial bonding interaction, electronic conductivity measurements of the corresponding nanoparticle solid films showed that the nanoparticles all exhibited linear current-potential curves within the potential range of -0.8 V to +0.8 V at varied temperatures (200 to 300 K). The ohmic characters were partly ascribed to the spilling of core electrons into the organic capping layer that facilitated interparticle charge transfer. Furthermore, based on the temperature dependence of the nanoparticle electronic conductivity, the activation energy for interparticle charge transfer was estimated to be in the range of 70 to 90 meV and significantly, the coupling coefficient (β) was found to be 0.31 Å(-1) for nanoparticles stabilized by short-chain alkynes (1-hexyne, 1-octyne, and 1-decyne), and 1.44 Å(-1) for those with long alkynes such as 1-dodecyne, 1-tetradecyne, and 1-hexadecyne. This may be accounted for by the relative contributions of the conjugated metal-ligand interfacial bonding interactions versus the saturated aliphatic backbones of the alkyne ligands to the control of interparticle charge transfer.
钌纳米粒子（直径为 2.12 ± 0.72nm）通过炔烃分子（从 1-己炔到 1-十六炔）在 Ru 表面上的自组装稳定，这得益于 Ru-亚乙烯基界面键的形成。红外测量显示在 2050cm(-1)、1980cm(-1)和 1950cm(-1)处有三个振动带，它们归因于束缚在纳米粒子表面上的末端三键的振动伸展。热重分析表明，每个纳米粒子上约有 65 到 96 个炔烃配体（取决于配体链长），对应于 20 到 15Å(2)的分子足迹。这表明配体可能在纳米粒子表面上采用了头对头的构型，与界面互变异构重排引起的亚乙烯基键合连接一致。通过这种共轭界面键合相互作用，相应的纳米颗粒固体薄膜的电子传导性测量表明，在不同温度（200 至 300K）下，纳米颗粒在-0.8V 至+0.8V 的电位范围内均表现出线性电流-电位曲线。欧姆特性部分归因于核心电子溢出到有机盖帽层中，从而促进了颗粒间的电荷转移。此外，基于纳米颗粒电子传导性的温度依赖性，估计颗粒间电荷转移的活化能在 70 至 90meV 的范围内，并且显著地，对于由短链炔烃（1-己炔、1-辛炔和 1-癸炔）稳定的纳米颗粒，耦合系数（β）为 0.31Å(-1)，而对于长链炔烃（如 1-十二炔、1-十四炔和 1-十六炔）稳定的纳米颗粒，耦合系数为 1.44Å(-1)。这可以归因于共轭金属-配体界面键合相互作用与炔烃配体的饱和脂肪族骨架对控制颗粒间电荷转移的相对贡献。
