Wang He, Liu Xiaokang, Zhao Yulong, Sun Zhihu, Lin Yue, Yao Tao, Jiang Hai-Long
Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.
Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
Natl Sci Rev. 2024 Jul 23;11(10):nwae252. doi: 10.1093/nsr/nwae252. eCollection 2024 Oct.
While atomically precise metal nanoclusters (NCs) with unique structures and reactivity are very promising in catalysis, the spatial resistance caused by the surface ligands and structural instability poses significant challenges. In this work, Au(Cys) NCs are encapsulated in multivariate metal-organic frameworks (MOFs) to afford Au@M-MOF-74 (M = Zn, Ni, Co, Mg). By the MOF confinement, the Au NCs showcase highly enhanced activity and stability in the intramolecular cascade reaction of 2-nitrobenzonitrile. Notably, the interaction between the metal nodes in M-MOF-74 and Au(Cys) is able to suppress the free vibration of the surface ligands on the Au NCs and thereby improve the accessibility of Au sites; meanwhile, the stronger interactions lead to higher electron density and core expansion within Au(Cys). As a result, the activity exhibits the trend of Au@Ni-MOF-74 > Au@Co-MOF-74 > Au@Zn-MOF-74 > Au@Mg-MOF-74, highlighting the crucial roles of microenvironment modulation around the Au NCs by interaction between the surface ligands and MOF hosts.
尽管具有独特结构和反应活性的原子精确金属纳米团簇（NCs）在催化领域极具潜力，但表面配体引起的空间阻力和结构不稳定性带来了重大挑战。在这项工作中，Au（Cys）NCs被封装在多元金属有机框架（MOFs）中，得到Au@M-MOF-74（M = Zn、Ni、Co、Mg）。通过MOF的限域作用，Au NCs在2-硝基苯甲腈的分子内级联反应中展现出高度增强的活性和稳定性。值得注意的是，M-MOF-74中的金属节点与Au（Cys）之间的相互作用能够抑制Au NCs表面配体的自由振动，从而提高Au位点的可及性；同时，更强的相互作用导致Au（Cys）内更高的电子密度和核心膨胀。结果，活性呈现出Au@Ni-MOF-74 > Au@Co-MOF-74 > Au@Zn-MOF-74 > Au@Mg-MOF-74的趋势，突出了通过表面配体与MOF主体之间的相互作用对Au NCs周围微环境进行调控的关键作用。
