Wan Xian-Kai, Wang Jia-Qi, Nan Zi-Ang, Wang Quan-Ming
Department of Chemistry, Tsinghua University, Beijing 10084, P. R. China.
Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Fujian 361005, P. R. China.
Sci Adv. 2017 Oct 6;3(10):e1701823. doi: 10.1126/sciadv.1701823. eCollection 2017 Oct.
Atomically precise gold nanoclusters are ideal model catalysts with well-defined compositions and tunable structures. Determination of the ligand effect on catalysis requires the use of gold nanoclusters with protecting ligands as the only variable. Two isostructural Au nanoclusters, [Au(L)(PhP)] (L = alkynyl or thiolate), have been synthesized by a direct reduction method, and they have an unprecedented face-centered cubic (fcc)-type Au kernel surrounded by 4 AuL staple motifs, 4 PhP, and 12 bridging L ligands. The Au kernel can be derived from the fusion of two fcc-type Au via sharing a Au face. Catalytic performance was studied with these two nanoclusters supported on TiO (1/TiO and 2/TiO) as catalysts. The alkynyl-protected Au are very active (>97%) in the semihydrogenation of alkynes (including terminal and internal ones) to alkenes, whereas the thiolated Au showed a very low conversion (<2%). This fact suggests that the protecting ligands play an important role in H activation. This work presents a clear demonstration that catalytic performance of gold nanoclusters can be modulated by the controlled construction of ligand spheres.
原子精确的金纳米团簇是具有明确组成和可调结构的理想模型催化剂。确定配体对催化的影响需要使用以保护配体为唯一变量的金纳米团簇。通过直接还原法合成了两种同构的金纳米团簇[Au(L)(PhP)]（L = 炔基或硫醇盐），它们具有前所未有的面心立方（fcc）型金核，被4个AuL钉状结构单元、4个PhP和12个桥连L配体包围。金核可由两个fcc型金通过共享一个金面融合而成。以负载在TiO（1/TiO和2/TiO）上的这两种纳米团簇作为催化剂研究了催化性能。炔基保护的金在炔烃（包括末端和内端炔烃）半加氢生成烯烃反应中非常活跃（>97%），而硫醇盐保护的金转化率非常低（<2%）。这一事实表明保护配体在氢活化中起重要作用。这项工作清楚地证明了金纳米团簇的催化性能可以通过配体球的可控构建来调节。
