Digestive Ripening of Au Nanoparticles Using Multidentate Ligands

Abstract

The efficiency of multidentate ligands as digestive ripening (DR) agents for the preparation of monodisperse Au nanoparticles (NPs) was investigated. This systematic investigation was performed using ligands possessing one, two, or three thiol moieties as ligands/DR agents. Our results clearly establish that among the different ligands, monodentate ligands and the use of temperature in the range of 60-120 °C offer the best conditions for DR. In addition, when DR was carried out at lower temperatures (e.g., 60 °C), the NP size increased as the number of thiol groups per ligand increased. However, in the case of ligands possessing two and three thiol moieties, when they were heated with polydispersed particles at higher temperatures (120 or 180 °C), the etching process dominated, which affected the quality of the NPs in terms of their monodispersity. We conclude that the temperature-dependent strength of the interaction between the ligand headgroup and the NP surface plays a vital role in controlling the final particle sizes.

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“…Figure 3(c,d) also shows the effect of ligands addition in Au NPs solution. In the presence of ligands, dispersity as well as size of the Au NPs were decreased 54 . The crystal structure of the synthesised was also inspected with high-resolution transmission electron microscopy (HRTEM).…”

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“…We believe the different behavior for TPPS Au 0.9nm versus THPC Au 1.6nm is due to the Au NC size rather than the nature of the stabilizer. Au NCs have undergone digestive ripening by a high concentration of thiols in solutions of NCs, which involves their dissolution …”

“…Au NCs have undergone digestive ripening by a high concentration of thiols in solutions of NCs, which involves their dissolution. [58][59]…”

Digestive Ripening at Nanoscale and Its Application in the Preparation of Monodisperse Nanomaterials

“…硫醇的用量越大, 同 样条件下得到的纳米粒子体系的单分散程度越高 [35] , 但大大过量的硫醇有可能导致形成硫醇保护的金属原 子簇 [36] . 短烷基链硫醇保护的金纳米粒子在甲苯溶剂 中倾向于形成超晶格结构, 而长烷基链硫醇更容易形成 单分散的粒子 [37] , 这可能与硫醇分子在甲苯中的溶解 性有关; 硫醇的烷基链越长, 得到的金纳米颗粒的尺寸 越大 [38] ; 单巯基长链烷基配体与双巯基及三巯基长链 烷基配体的比较研究证明, 单巯基配体是更好的消化熟 化剂 [39] . 使用巯基聚乙二醇(PEG5000-SH)作为消化熟 化剂可以在水相中进行消化熟化, 直接得到聚乙二醇保 护的金纳米粒子 [40] .…”

“…2018 年, 高传博等 [21] [44] Figure 4 TEM images of Ag (a, d), Au (b, e) and Pd (c, f) nanoparticles after digestive ripening using dodecylthiol (a～c) and dodecylamine (d～ f), respectively [39] . 可以发 现, 随着温度的升高, 熟化后的纳米粒子的尺寸变大.…”