Su Yen Hsun, Lai Wei Hao, Chang Shih-Hui, Hon Min Hsiung
Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan.
J Nanosci Nanotechnol. 2007 Sep;7(9):3146-51. doi: 10.1166/jnn.2007.682.
We prepared gold nanoparticles (Au NPs) by only using trisodium citrate as the stabilizer. The detailed reaction mechanisms of S(N)1 and E1 reactions are examined and evidenced in this study by FTIR data. Citric acid is a kind of tertiary substrate. In aqueous solution, the substitution nucleophile path 1 (S(N)1) reaction and Elimination path 1 (E1) reaction usually occur simultaneously. Chloride ions, the substitution nucleophile, play a very important role to launch the mechanisms of S(N)1 and E1 reactions. Controlling the concentration of the chloride ions with the addition of HCl(aq) according to Le Chatelier theory, the average particle size of Au NPs (5.5 nm) was achieved to overcome the minimum limited size (approximately 10 nm). Two stages of the photoinduced method, aggregation into triangular conglomerates and growth into triangular particles, were determined form TEM observations. This preparation of Au NPs has potential in tuning the size, shape, and mechanism of Au NP formation by using only environmentally friendly trisodium citrate and the photoinduced method.
我们仅使用柠檬酸三钠作为稳定剂制备了金纳米颗粒（Au NPs）。本研究通过傅里叶变换红外光谱（FTIR）数据对S(N)1和E1反应的详细反应机理进行了研究和验证。柠檬酸是一种叔底物。在水溶液中，取代亲核途径1（S(N)1）反应和消除途径1（E1）反应通常同时发生。氯离子作为取代亲核试剂，在引发S(N)1和E1反应机理中起着非常重要的作用。根据勒夏特列理论，通过添加盐酸（aq）控制氯离子浓度，实现了Au NPs的平均粒径（5.5 nm），以克服最小限制尺寸（约10 nm）。通过透射电子显微镜（TEM）观察确定了光诱导法的两个阶段，即聚集成三角形聚集体和生长成三角形颗粒。仅使用环境友好的柠檬酸三钠和光诱导法制备Au NPs在调节Au NPs的尺寸、形状和形成机理方面具有潜力。
