State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada.
Angew Chem Int Ed Engl. 2022 Aug 26;61(35):e202202405. doi: 10.1002/anie.202202405. Epub 2022 Jul 21.
Metal nanoparticles (NPs) stabilized with thiol- (HS-) terminated polymers have applications in medicine, optoelectronics, and catalysis. It is assumed that upon exposure to oxidants or even air, these NPs lose colloidal stability, due to the oxidation of the HS-end-group and elimination of polymer ligands from the NP surface, however, this mechanism does not explain the unsuccessful recovery of the NP stability by adding fresh HS-terminated polymers. Here we propose the oxidation of the surface metal atoms as a mechanism for the oxidative elimination of polymer from the NP surface. Based on this mechanism, we reversed NP aggregation by reducing the oxidized metal surface and re-attaching HS-terminated polymer ligands. This mechanism is general for various metal NPs and different HS-terminated polymers. We show that oxidative elimination and reductive addition reactions can improve the colloidal stability of polymer-capped metal NPs and control their redox stimuli-responsive self-assembly.
金属纳米粒子（NPs）被巯基（HS）封端的聚合物稳定，在医学、光电子学和催化中有应用。据假设，这些 NPs 暴露于氧化剂甚至空气中时，由于 HS 端基的氧化和聚合物配体从 NP 表面的消除，它们会失去胶体稳定性，然而，这种机制并不能解释通过添加新鲜的 HS 封端聚合物来恢复 NP 稳定性的失败。在这里，我们提出表面金属原子的氧化是 NP 表面聚合物氧化消除的一种机制。基于这一机制，我们通过还原氧化的金属表面并重新连接 HS 封端的聚合物配体来逆转 NP 的聚集。这种机制适用于各种金属 NPs 和不同的 HS 封端聚合物。我们表明，氧化消除和还原加成反应可以改善聚合物包覆的金属 NPs 的胶体稳定性，并控制它们的氧化还原刺激响应自组装。
