Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China.
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian 116023, China.
J Am Chem Soc. 2016 Mar 16;138(10):3278-81. doi: 10.1021/jacs.5b12730. Epub 2016 Mar 7.
Metal nanoclusters whose surface ligands are removable while keeping their metal framework structures intact are an ideal system for investigating the influence of surface ligands on catalysis of metal nanoparticles. We report in this work an intermetallic nanocluster containing 62 metal atoms, Au34Ag28(PhC≡C)34, and its use as a model catalyst to explore the importance of surface ligands in promoting catalysis. As revealed by single-crystal diffraction, the 62 metal atoms in the cluster are arranged as a four-concentric-shell Ag@Au17@Ag27@Au17 structure. All phenylalkynyl (PA) ligands are linearly coordinated to the surface Au atoms with staple "PhC≡C-Au-C≡CPh" motif. Compared with reported thiolated metal nanoclusters, the surface PA ligands on Au34Ag28(PhC≡C)34 are readily removed at relatively low temperatures, while the metal core remains intact. The clusters before and after removal of surface ligands are used as catalysts for the hydrolytic oxidation of organosilanes to silanols. It is, for the first time, demonstrated that the organic-capped metal nanoclusters work as active catalysts much better than those with surface ligands partially or completely removed.
表面配体可去除而金属骨架结构保持完整的金属纳米团簇是研究表面配体对金属纳米粒子催化作用影响的理想体系。我们在此工作中报道了一种含有 62 个金属原子的金属间纳米团簇，Au34Ag28(PhC≡C)34，并将其用作模型催化剂来探索表面配体在促进催化中的重要性。单晶衍射表明，该簇中的 62 个金属原子排列为四同心壳 Ag@Au17@Ag27@Au17 结构。所有的苯乙炔基（PA）配体都以直线形式与表面 Au 原子配位，具有典型的“PhC≡C-Au-C≡CPh”结构。与报道的硫醇化金属纳米团簇相比，Au34Ag28(PhC≡C)34 表面的 PA 配体在相对较低的温度下很容易被去除，而金属核保持完整。在去除表面配体前后的团簇都被用作有机硅烷水解氧化为硅醇的催化剂。首次证明，有机封端的金属纳米团簇作为活性催化剂的效果比部分或完全去除表面配体的催化剂要好得多。
