Synthesis and Structural Determination of Multidentate 2,3-Dithiol-Stabilized Au Clusters

详细信息    查看全文

• 作者：Zhenghua Tang ; Bin Xu ; Baohua Wu ; Markus W. Germann ; Gangli Wang
• 刊名：Journal of the American Chemical Society
• 出版年：2010
• 出版时间：March 17, 2010
• 年：2010
• 卷：132
• 期：10
• 页码：3367-3374
• 全文大小：299K
• 年卷期：v.132,no.10(March 17, 2010)
• ISSN：1520-5126

文摘

Interface bond structure, in addition to the well-known size and shape quantum confinement effects, is another factor that affects the properties of nanomaterials that is less known and studied. Inspired by the thiol-bridging “staple” motif (RS−Au−SR, Jadzinsky; et al. Science 2007, 318, 430.) discovered from monothiol-stabilized gold nanoclusters, dithiol ligand 2,3-dimercaptopropanesulfonic (DMPS) acid has been employed to synthesize dithiol-protected Au clusters (DTCs). The structure and property of the Au DTCs are studied to probe two effects: the entropy gain of dithiol over monothiol ligand protection and the constraint to the formation of the thiol bridging surface bonding. The hydrodynamic sizes of Au DTCs were estimated by diffusion nuclear magnetic resonance (NMR). The size distribution, Au core plus ligands on solid support, was confirmed by atomic force microscope (AFM) imaging. Size-dependent optical properties were observed. Au₄ clusters at high purity, characterized by mass spectrometry and organic−metal ratio confirmed by thermogravimetric analysis (TGA), display a characteristic absorbance band at 282 nm. The proton chemical environments as well as Au−S bond information of the Au₄ cluster were fully elucidated by ¹³C−¹H heteronuclear single-quantum coherence (HSQC) in conjunction with other two-dimensional (2D) NMR techniques. The Au−S bonding was further studied in thiol stretching by infrared and Au(4f) and S(2p) electrons by X-ray photoelectron spectroscopy (XPS). One possible structure of the Au₄ cluster has been proposed that needs further theoretical studies or single-crystal confirmation.