Controlled growth of gold nanoparticles during ligand exchange
Controlled growth of gold nanoparticles during ligand exchange
复制标题
DOI：
10.1021/ja983510q
复制
发表时间：
1999-02-03
影响因子：
15
通讯作者：
Hutchison, JE
中科院分区：
文献类型：
--
作者：
Brown, LO;Hutchison, JE
Metal nanocrystals have become a subject of intense interest in materials and physical chemistry. Their unique physical properties give rise to a wide variety of potential applications such as sensors, biochemical tagging reagents, optical switches, nanoelectronic devices, and catalysts. 1 Recently we reported the preparation of robust thiolate-stabilized gold nanoparticles by application of ligand exchange chemistry to the known species, Au55 (PPh3) 12Cl6. 2 A potential limitation of the ligand exchange approach is the inability to control the metal core size. Here we demonstrate that the use of a primary amine ligand3 such as 1-pentadecylamine (PDA) 4 in an exchange reaction leads to a nanocrystalline product with a highly reproducible, yet expanded core size. Growth of the core from 1.4 to 5 nm occurs in a controlled manner as observed by TEM and visible spectroscopy. Thus it is now possible to use ligand exchange methods to alter the physical size of the nanoparticle, as well as the ligand shell.The ligand exchange chemistry between triphenylphosphinestabilized gold nanoparticles (Au-TPP) 5 and PDA was investigated under a variety of conditions (see Table 1). Briefly, 6 Au-TPP is dissolved in CH2Cl2 (or CHCl3) and stirred in the presence of excess PDA at room temperature, typically for∼ 4 days. A golden precipitate of large insoluble nanocrystals may be observed when using CH2Cl2 as the solvent. This is usually excluded from the product mixture by filtration. 7 The remaining smaller nanocrystals are precipitated at reduced temperature and collected by filtration. Rinsing removes impurities to give the amine-stabilized nanocrystals (Au-PDA) as a golden film, soluble in CH2Cl2 or CHCl3. Further conversion from amine-passivation to thiolate-passivation is possible. 8
