467605 Structure-Dependent Stability of Magic-Number Thiolated Metal Nanoparticles

Wednesday, November 16, 2016: 2:12 PM
Golden Gate 5 (Hilton San Francisco Union Square)
Michael G. Taylor and Giannis Mpourmpakis, Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA

Magic numbers in the stability of Mn(SR)m nanoparticles (NPs) in Brust-Schiffrin-type syntheses have been recently identified with advancements in synthesis and characterization techniques.1 The atomically-precise nature of these particles makes them attractive candidates for understanding the thermodynamic and colloidal stability of NPs in solution. Traditionally, this magic stability has been explained by electron shell closure methods such as the “superatom model”.2 However, this model has not held in rationalizing the stability of several recently-identified NP structures, such as the Au20SR16 and the Au36SR­24.3 Herein, we introduce a theory developed using density functional theory calculations relating the exceptional stability of thiolated-metal NPs to structure-dependent, thermodynamic descriptors. Using the identified descriptors we rationalize the stability of various monometallic and multimetallic atomically-precise nanoparticles both for charged and neutral systems. Our theory is able to capture a series of experimentally observed stability trends in nanoscale thiolate-protected metal NPs. The thermodynamic implications of our findings help rationalize the observed structures of NPs and help to inform thiolate ligand selection in NP synthesis. Our findings aid in accelerating the discovery of atomically precise, stable metal nanoparticles.

1. Jin, R. Atomically precise metal nanoclusters: stable sizes and optical properties. Nanoscale 15, 1549–1565 (2015).

2. Walter, M. et al. A unified view of ligand-protected gold clusters as superatom complexes. Proc. Natl. Acad. Sci. U. S. A. 105, 9157–9162 (2008).

3. Zeng, C., Liu, C., Chen, Y., Rosi, N. L. & Jin, R. Gold-Thiolate Ring as a Protecting Motif in the Au20(SR)16 Nanocluster and Implications. J. Am. Chem. Soc. 20, 16–19 (2014).

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