Shen Hui, Tang Xiongkai, Wu Qingyuan, Zhang Yuhao, Ma Chuxin, Xu Zhen, Teo Boon K, Zheng Nanfeng
State Key Laboratory for Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, and National & Local Joint Engineering Research Center for Preparation Technology of Nanomaterials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen 361005, China.
ACS Nanosci Au. 2022 Aug 9;2(6):520-526. doi: 10.1021/acsnanoscienceau.2c00026. eCollection 2022 Dec 21.
Optimizing the synthesis of atomically precise metal nanoclusters by virtue of molecular tools is highly desirable but quite challenging. Herein we report how F NMR spectroscopy can be used to guide the high-yield synthesis of N-heterocyclic carbene (NHC)-stabilized gold nanoclusters. In spite of little difference, F NMR signals of fluoro-incorporated NHCs (NHC) are highly sensitive to the tiny change in their surrounding chemical environments with different N-substituents, metals, or anions, thus providing a convenient strategy to discriminate species in reaction mixtures. By using F NMR, we first disclosed that the one-pot reduction of NHC-Au-X (X is halide) yields multiple compounds, including cluster compounds and also a large amount of highly stable [Au(NHC)] byproduct. The detailed quantitative F NMR analyses over the reductive synthesis of NHC-stabilized Au nanoclusters reveal that the formation of the di-NHC complex is deleterious to the high-yield synthesis of NHC-stabilized Au nanoclusters. With the understanding, the reaction kinetic was then slowed by controlling the reduction rate to achieve the high yield of a [Au(NHC)XH] nanocluster with a unique structure. The strategy demonstrated in this work is expected to provide an effective tool to guide the high-yield synthesis of organic ligand-stabilized metal nanoclusters.
借助分子工具优化原子精确的金属纳米团簇的合成是非常理想的，但颇具挑战性。在此，我们报告了如何利用氟核磁共振光谱来指导N-杂环卡宾（NHC）稳定的金纳米团簇的高产率合成。尽管差异不大，但含氟NHC（NHC）的氟核磁共振信号对其周围化学环境中不同的N-取代基、金属或阴离子的微小变化高度敏感，从而提供了一种辨别反应混合物中物种的便捷策略。通过使用氟核磁共振，我们首次揭示了NHC-Au-X（X为卤化物）的一锅还原会产生多种化合物，包括团簇化合物以及大量高度稳定的[Au（NHC）]副产物。对NHC稳定的金纳米团簇还原合成过程进行的详细定量氟核磁共振分析表明，二-NHC配合物的形成对NHC稳定的金纳米团簇的高产率合成不利。基于这一认识，随后通过控制还原速率来减缓反应动力学，以实现具有独特结构的[Au（NHC）XH]纳米团簇的高产率。这项工作中展示的策略有望为指导有机配体稳定的金属纳米团簇的高产率合成提供一种有效工具。
