Shem Patrick M, Sardar Rajesh, Shumaker-Parry Jennifer S
Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, UT 84112, USA.
Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, 402 N. Blackford Street, Indianapolis, IN 46202-3274, USA.
J Colloid Interface Sci. 2014 Jul 15;426:107-16. doi: 10.1016/j.jcis.2014.03.059. Epub 2014 Apr 3.
The synthesis of gold nanoparticles (AuNPs) in organic solvents without addition of surfactant may be achieved without the use of strong capping agents in the presence of soft ligands from the starting materials. Through post synthesis surface modification with ligands having moderate or strong affinity, the soft ligands should be displaced, allowing for manipulation of the AuNP size, size distribution, as well as the interparticle spacing.
Synthesis of gold nanoparticles was undertaken using the reducing agent 9-borabicyclo[3.3.1]nonane without addition of stabilizing ligands. Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS) were used to characterize the NPs. The interparticle spacing in 2D assemblies of the NPs was correlated with localized surface plasmon resonance (LSPR) shifts exhibited by the NPs in solution.
Soft-ligand-stabilized AuNPs in a size range of 3-5 nm were generated at a slow rate. The soft ligands were found to be chloride (Cl(-)) ions and triethylphosphine (Et3P). Bipyridyl and thiol ligands displaced the weakly adsorbed soft ligands. Thiolate-stabilized AuNPs formed long range 2-D assemblies with regular interparticle spacing (edge-to-edge). UV-vis spectroscopy analysis shows the thiolated AuNPs exhibited an exponential localized wavelength (λmax) decay dependence on the alkylthiolate chain length, indicating an increase in the interparticle spacing.
在不添加表面活性剂的有机溶剂中合成金纳米颗粒（AuNP），在起始原料中存在软配体的情况下，无需使用强封端剂即可实现。通过用具有中等或强亲和力的配体进行合成后表面改性，软配体应被取代，从而可以控制AuNP的尺寸、尺寸分布以及颗粒间间距。
使用还原剂9-硼双环[3.3.1]壬烷在不添加稳定配体的情况下进行金纳米颗粒的合成。采用透射电子显微镜（TEM）和X射线光电子能谱（XPS）对纳米颗粒进行表征。纳米颗粒二维组装体中的颗粒间间距与溶液中纳米颗粒表现出的局域表面等离子体共振（LSPR）位移相关。
以缓慢的速率生成了尺寸范围为3-5nm的软配体稳定的AuNP。发现软配体为氯离子（Cl(-)）和三乙膦（Et3P）。联吡啶和硫醇配体取代了弱吸附的软配体。硫醇盐稳定的AuNP形成了具有规则颗粒间间距（边到边）的长程二维组装体。紫外可见光谱分析表明，硫醇化的AuNP表现出指数衰减的局域波长（λmax），其依赖于烷基硫醇盐链长，表明颗粒间间距增加。
