Sensitivity of Structural and Electronic Properties of Gold–Thiolate Nanoclusters to the Atomic Composition: A Comparative X‑ray Study of Au19(SR)13 and Au25(SR)18

• Published in: Journal of physical chemistry. C Vol. 116; no. 47; pp. 25137 - 25142
• Main Authors: Chevrier, Daniel M, MacDonald, Mark A, Chatt, Amares, Zhang, Peng, Wu, Zhikun, Jin, Rongchao
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 04.03.2013
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic structure of nanoscale materials : clusters, nanoparticles, nanotubes, and nanocrystals; Exact sciences and technology; Materials science; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Physics; Structure of solids and liquids; crystallography; Nanocluster; Gold; Electronic properties; Thiolate; X-ray absorption; Fine structure; Local structure; Electronic structure; Property structure relationship; Ab initio calculations; Atomic structure; Comparative study; X-ray photoelectron spectra; Crystal structure
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp309283y

With the recent successful synthesis of an increasing number of atomically precise thiolate–gold nanoclusters (NCs), there are growing demands for a better understanding of their atomic structures and structure–property relationships in response to composition change. Herein, we present X-ray experimental results on structural and electronic properties of a recently synthesized gold–thiolate nanocluster, Au19(SR)13, in comparison with the structurally well-known Au25(SR)18 reference. The atomic structure of Au19(SR)13 was first probed with extended X-ray absorption fine structure (EXAFS). A multishell EXAFS fitting method (consisting of one Au–S and three Au–Au shells) allowed for a detailed structural comparison of the two nanoclusters, which revealed a sizable increase of the bond distances between the surface–surface and surface–staple Au atoms upon the decrease of Au atoms in the nanocluster. X-ray photoemission experiments and ab initio calculations further demonstrated the sensitive change of electronic properties of the nanoclusters when the cluster composition was varied, that is, the Au19(SR)13 nanocluster has a differently shaped and positively shifted Au 5d band relative to Au25(SR)18. These experimental findings highlight the sensitivity of the local structure and electronic properties of thiolate-gold nanoclusters to even a small change of the metal core from Au13 to Au11.