NSF's ChemMatCARS, University of Chicago, Chicago, Illinois 60637, United States.
James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States.
Nano Lett. 2021 Feb 24;21(4):1613-1619. doi: 10.1021/acs.nanolett.0c04147. Epub 2021 Feb 3.
Thiol ligands bound to the metallic core of nanoparticles determine their interactions with the environment and self-assembly. Recent studies suggest that equilibrium between bound and free thiols alters the ligand coverage of the core. Here, X-ray scattering and MD simulations investigate water-supported monolayers of gold-core nanoparticles as a function of the core-ligand coverage that is varied in experiments by adjusting the concentration of total thiols (sum of free and bound thiols). Simulations demonstrate that the presence of free thiols produces a nearly symmetrical coating of ligands on the core. X-ray measurements show that above a critical value of core-ligand coverage the nanoparticle core rises above the water surface, the edge-to-edge distance between neighboring nanoparticles increases, and the nanoparticle coverage of the surface decreases. These results demonstrate the important role of free thiols: they regulate the organization of bound thiols on the core and the interactions of nanoparticles with their surroundings.
硫醇配体与纳米颗粒的金属核心结合，决定了它们与环境的相互作用和自组装。最近的研究表明，结合态和游离态硫醇之间的平衡会改变核心的配体覆盖度。在这里，X 射线散射和 MD 模拟研究了水支撑的金核纳米颗粒单层作为核心-配体覆盖度的函数，通过调整总硫醇浓度（游离和结合硫醇之和）在实验中改变覆盖度。模拟表明，游离硫醇的存在会在核心上产生几乎对称的配体涂层。X 射线测量表明，在核心-配体覆盖度超过一个临界值时，纳米颗粒核心会上升到水面以上，相邻纳米颗粒之间的边缘到边缘距离增加，纳米颗粒对表面的覆盖度降低。这些结果表明了游离硫醇的重要作用：它们调节了核心上结合态硫醇的组织和纳米颗粒与周围环境的相互作用。
