Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, California 95064, USA.
Nanoscale. 2011 May;3(5):2294-300. doi: 10.1039/c1nr10158g. Epub 2011 Apr 15.
Carbene-stabilized ruthenium nanoparticles were functionalized with anthryl moieties by olefin metathesis reactions with 9-vinylanthracene, at a surface concentration of about 19.7%, as estimated by (1)H NMR spectroscopic measurements. Because of the conjugated metal-ligand interfacial bonding interactions, UV-vis measurements of the resulting nanoparticles showed a new broad absorption band centered at 612 nm, in addition to the peaks observed with monomeric vinylanthracene. FTIR measurements depicted apparent red-shifts of the aromatic vibrational stretches as compared to those of the monomeric vinylanthracene, suggestive of decreasing bonding order of the aromatic moieties as a result of extended conjugation between the particle-bound anthracene groups. Photoluminescence measurements confirmed the notion that effective intraparticle charge delocalization occurred by virtue of the conjugated metal-ligand interfacial bonding interactions, with apparent red-shifts of the excitation peaks and blue-shifts of the emission features, as compared to those of the monomeric vinylanthracene. The diminishment of the Stokes shift was, at least in part, attributed to the different chemical environments surrounding the anthryl moieties on the nanoparticle surface. Electronic conductivity measurements showed that because of the conjugated Ru[double bond, length as m-dash]C π bonds, the activation energy for interparticle charge transport was about one order of magnitude lower than that observed with particles passivated by alkanethiolates. Additionally, whereas the original carbene-stabilized nanoparticles exhibited a semiconductor-metal transition within the temperature range of 100 to 320 K, anthracene-functionalized nanoparticles displayed apparent semiconducting behaviors with the ensemble conductivity increasing monotonically with temperature, most likely due to the disordering within the nanoparticle solids that arose from the different structures of the carbene ligands and anthryl moieties. These studies indicate that anthracene functionalization may be exploited as an effective route towards the manipulation of nanoparticle optoelectronic properties.
通过烯烃复分解反应，用 9-乙烯基蒽与卡宾稳定的钌纳米颗粒反应，在表面浓度约为 19.7%，如（1）H NMR 光谱测量所估计的。由于共轭的金属-配体界面键合相互作用，所得纳米颗粒的紫外-可见测量显示出一个新的宽吸收带，中心在 612nm 处，除了观察到单体乙烯基蒽的峰之外。FTIR 测量显示出与单体乙烯基蒽相比，芳香振动伸展的明显红移，表明由于粒子结合的蒽基团之间的扩展共轭，芳香部分的键序降低。光致发光测量证实了由于共轭的金属-配体界面键合相互作用，有效粒子内电荷离域发生的观点，与单体乙烯基蒽相比，激发峰出现明显红移，发射特征出现蓝移。Stokes 位移的减小至少部分归因于纳米颗粒表面上蒽部分周围不同的化学环境。电子电导率测量表明，由于共轭的 Ru[双键，长度为 m-dash]C π 键，粒子间电荷输运的活化能比用烷硫醇封端的粒子观察到的要低一个数量级。此外，虽然原始的卡宾稳定的纳米颗粒在 100 到 320K 的温度范围内表现出半导体-金属转变，但蒽功能化的纳米颗粒表现出明显的半导体行为，整体电导率随温度单调增加，很可能是由于卡宾配体和蒽部分的不同结构引起的纳米颗粒固体中的无序。这些研究表明，蒽功能化可能被用作操纵纳米颗粒光电性质的有效途径。
