Fan Qikui, Yang Hao, Ge Juan, Zhang Shumeng, Liu Zhaojun, Lei Bo, Cheng Tao, Li Youyong, Yin Yadong, Gao Chuanbo
Frontier Institute of Science and Technology, State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710054, China.
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123, China.
Research (Wash D C). 2020 Jan 21;2020:2131806. doi: 10.34133/2020/2131806. eCollection 2020.
It is highly desirable, while still challenging, to obtain noble metal nanocrystals with custom capping ligands, because their colloidal synthesis relies on specific capping ligands for the shape control while conventional ligand exchange processes suffer from "the strong replaces the weak" limitation, which greatly hinders their applications. Herein, we report a general and effective ligand exchange approach that can replace the native capping ligands of noble metal nanocrystals with virtually any type of ligands, producing flexibly tailored surface properties. The key is to use diethylamine with conveniently switchable binding affinity to the metal surface as an intermediate ligand. As a strong ligand, it in its original form can effectively remove the native ligands; while protonated, it loses its binding affinity and facilitates the adsorption of new ligands, especially weak ones, onto the metal surface. By this means, the irreversible order in the conventional ligand exchange processes could be overcome. The efficacy of the strategy is demonstrated by mutual exchange of the capping ligands among cetyltrimethylammonium, citrate, polyvinylpyrrolidone, and oleylamine. This novel strategy significantly expands our ability to manipulate the surface property of noble metal nanocrystals and extends their applicability to a wide range of fields, particularly biomedical applications.
获得具有定制封端配体的贵金属纳米晶体是非常理想的，虽然具有挑战性，因为它们的胶体合成依赖于特定的封端配体来控制形状，而传统的配体交换过程存在“强者取代弱者”的限制，这极大地阻碍了它们的应用。在此，我们报告了一种通用且有效的配体交换方法，该方法可以用几乎任何类型的配体取代贵金属纳米晶体的天然封端配体，从而灵活地定制表面性质。关键是使用对金属表面具有方便可切换结合亲和力的二乙胺作为中间配体。作为一种强配体，它以原始形式可以有效地去除天然配体；而质子化后，它失去结合亲和力并促进新配体，尤其是弱配体，吸附到金属表面。通过这种方式，可以克服传统配体交换过程中的不可逆顺序。通过十六烷基三甲基铵、柠檬酸盐、聚乙烯吡咯烷酮和油胺之间的封端配体相互交换证明了该策略的有效性。这种新策略显著扩展了我们操纵贵金属纳米晶体表面性质的能力，并将其适用性扩展到广泛的领域，特别是生物医学应用。
