Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, California 95064, USA.
Langmuir. 2011 Oct 18;27(20):12636-41. doi: 10.1021/la202424q. Epub 2011 Sep 21.
Olefin metathesis reactions of carbene-stabilized ruthenium nanoparticles were exploited for the incorporation of multiple functional moieties onto the nanoparticle surface. When the nanoparticles were cofunctionalized with 4-vinylbenzo-18-crown-6 and 1-vinylpyrene, the resulting particles exhibited fluorescence characteristics that were consistent with dimeric pyrene with a conjugated chemical bridge, with three peaks observed in the emission spectra at 391, 410, and 485 nm. The behaviors were ascribed to intraparticle charge delocalization between the pyrene moieties afforded by the conjugated Ru═carbene interfacial linkages. Notably, upon the binding of metal ions in the crown ether cavity, the emission intensity of the nanoparticle fluorescence was found to diminish at 485 nm and concurrently increase at 391 and 410 nm rather markedly, with the most significant effects observed with K(+). This was accounted for by the selective binding of 18-crown-6 to potassium ions, where the positively charged ions led to the polarization of the nanoparticle core electrons that was facililated by the conjugated linkage to the metal surface and hence impeded intraparticle charge delocalization. Control experiments with a pyrene-crown ether conjugate (2) and with ruthenium nanoparticles cofunctionalized with 4-vinylbenzo-18-crown-6 and 1-allylpyrene suggested that the through-bond pathway played a predominant role in the manipulation of intraparticle electronic communication whereas the contributions from simple electrostatic interactions (i.e., through-space pathway) were minimal.
卡宾稳定的钌纳米粒子的烯烃复分解反应被用于将多种官能团引入纳米粒子表面。当纳米粒子与 4-乙烯基苯并-18-冠-6 和 1-乙烯基芘共功能化时，得到的颗粒表现出与共轭化学桥相连的二聚芘一致的荧光特性，在发射光谱中观察到三个峰，分别在 391、410 和 485nm 处。这些行为归因于共轭 Ru═卡宾界面键赋予的芘部分之间的粒子内电荷离域。值得注意的是，在冠醚腔中的金属离子结合后，发现纳米粒子荧光的发射强度在 485nm 处减弱，同时在 391 和 410nm 处显著增加，其中与 K(+) 观察到的效果最显著。这是由于 18-冠-6 对钾离子的选择性结合，其中带正电荷的离子导致纳米粒子核心电子的极化，这种极化通过与金属表面的共轭键得到促进，从而阻碍了粒子内电荷离域。与芘-冠醚轭合物（2）的控制实验以及与 4-乙烯基苯并-18-冠-6 和 1-烯丙基芘共功能化的钌纳米粒子的控制实验表明，通过键的途径在操纵粒子内电子通信中起着主要作用，而简单静电相互作用（即，通过空间途径）的贡献最小。
