Wang Zhi, Gupta Rakesh Kumar, Alkan Fahri, Han Bao-Liang, Feng Lei, Huang Xian-Qiang, Gao Zhi-Yong, Tung Chen-Ho, Sun Di
School of Chemistry and Chemical Engineering, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, People's Republic of China.
Department of Nanotechnology Engineering, Abdullah Gül University, Kayseri, 38080, Turkey.
J Am Chem Soc. 2023 Sep 13;145(36):19523-19532. doi: 10.1021/jacs.3c01119. Epub 2023 Aug 30.
Structural transformation of metal nanoclusters (NCs) is of great ongoing interest regarding their synthesis, stability, and reactivity. Although sporadic examples of cluster transformations have been reported, neither the underlying transformation mechanism nor the intermediates are unambiguous. Herein, we have synthesized a flexible 54-nuclei silver cluster () by combining soft (BuC≡C) and hard (PrCOO) ligands. The existence of weakly coordinated PrCOO enhances the reactivity of , thus facilitating the dicarboxylic acid to induce structural transformation. X-ray structural analyses reveal that transforms to Ag cluster-based 2D networks ( and ) induced by Hsuc (succinic acid) and Hglu (glutaric acid), whereas with Hpda (2,2'-(1,2-phenylene)diacetic acid), a discrete Ag cluster () is isolated. The key intermediate that emerges during the self-dissociation of was isolated by using cryogenic recrystallization and characterized by X-ray crystallography. The "tandem transformation" mechanism for the structure evolution from to is established by time-dependent electrospray ionization mass spectrometry (ESI-MS) and UV-vis spectroscopy. In addition, the catalytic activity in the 4-nitrophenol reduction follows the sequence > > > due to more bare silver sites on the surface of the Ag cluster unit. Our findings not only open new avenues to the synthesis of silver NCs but also shed light on a better understanding of the structural transformation mechanism from one cluster to another or cluster-based metal-organic networks induced by dicarboxylates.
金属纳米团簇（NCs）的结构转变在其合成、稳定性和反应性方面一直备受关注。尽管已经报道了一些团簇转变的零星例子，但潜在的转变机制和中间体都不明确。在此，我们通过结合软配体（BuC≡C）和硬配体（PrCOO）合成了一种柔性的54核银团簇（）。弱配位的PrCOO的存在增强了的反应性，从而促进二羧酸诱导结构转变。X射线结构分析表明，由琥珀酸（Hsuc）和戊二酸（Hglu）诱导转变为基于银团簇的二维网络（和），而使用2,2'-（1,2-亚苯基）二乙酸（Hpda）时，分离出了离散的银团簇（）。通过低温重结晶分离出了在自解离过程中出现的关键中间体，并通过X射线晶体学对其进行了表征。通过时间分辨电喷雾电离质谱（ESI-MS）和紫外可见光谱确定了从到的结构演化的“串联转变”机制。此外，由于银团簇单元表面有更多裸露的银位点，在4-硝基苯酚还原反应中的催化活性遵循>> >的顺序。我们的发现不仅为银纳米团簇的合成开辟了新途径，也有助于更好地理解二羧酸盐诱导的从一种团簇到另一种团簇或基于团簇的金属有机网络的结构转变机制。
