Yan Nan, Xia Nan, Wu Zhikun
Key Laboratory of Materials Physics, Anhui Key Laboratory of Nanomaterials and Nanotechnology, CAS Center for Excellence in Nanoscience, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China.
Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui, 230601, P. R. China.
Small. 2021 Jul;17(27):e2000609. doi: 10.1002/smll.202000609. Epub 2020 Jul 30.
Ligand exchange reactions have attracted extensive interest due to their utility in tailoring the properties and applications of metal nanoparticles, but these techniques are not well understood due to the unclearness of metal nanoparticles at an atomic level. The emerging ultrasmall metal nanoparticles (metal nanoclusters) provide excellent opportunities for investigating this challenging issue. Herein, it is revealed that structurally similar Au (SC H Ph) , Au Cd(SC H Ph) and Au Hg(SC H Ph) transform to Au (SCH Ph- Bu) , Au Cd(SCH Ph- Bu) and ≈5 nm gold nanoparticles after reacting with HSCH Ph- Bu, respectively. Based on this and some other facts, it is suggested that the intrinsic stability is one key factor that determines the ligand exchange direction, whether by mere ligand exchange or further structure transformation (including aggregation). Single crystal X-ray crystallography further reveals that the partial surface ligand configuration reverses after ligand exchange, providing structure evidence for the unimolecular nucleophilic substitution (S 1)-like mechanism.
配体交换反应因其在定制金属纳米颗粒的性质和应用方面的实用性而引起了广泛关注，但由于金属纳米颗粒在原子水平上的不清晰性，这些技术尚未得到充分理解。新兴的超小金属纳米颗粒（金属纳米团簇）为研究这一具有挑战性的问题提供了绝佳机会。在此揭示，结构相似的Au(SC₆H₄Ph)₂、Au₂Cd(SC₆H₄Ph)₄和Au₂Hg(SC₆H₄Ph)₄分别与HSCH₂Ph - Bu反应后，转变为Au(SCH₂Ph - Bu)₂、Au₂Cd(SCH₂Ph - Bu)₄和约5纳米的金纳米颗粒。基于此及其他一些事实，表明内在稳定性是决定配体交换方向的一个关键因素，无论是通过单纯的配体交换还是进一步的结构转变（包括聚集）。单晶X射线晶体学进一步揭示，配体交换后部分表面配体构型发生反转，为单分子亲核取代（S₁）样机制提供了结构证据。
