Hidden Components in Aqueous “Gold-144” Fractionated by PAGE: High-Resolution Orbitrap ESI-MS Identifies the Gold-102 and Higher All-Aromatic Au-pMBA Cluster Compounds

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• 作者：Marcos M. Alvarez ; Jenny Chen ; Germán Plascencia-Villa ; David M. Black ; Wendell P. Griffith ; Ignacio L. Garzón ; Miguel José-Yacamán ; Borries Demeler ; Robert L. Whetten
• 刊名：Journal of Physical Chemistry B
• 出版年：2016
• 出版时间：July 7, 2016
• 年：2016
• 卷：120
• 期：26
• 页码：6430-6438
• 全文大小：554K
• 年卷期：0
• ISSN：1520-5207

文摘

Experimental and theoretical evidence reveals the resilience and stability of the larger aqueous gold clusters protected with p-mercaptobenzoic acid ligands (pMBA) of composition Au_n(pMBA)_p or (n, p). The Au₁₄₄(pMBA)₆₀, (144, 60), or gold-144 aqueous gold cluster is considered special because of its high symmetry, abundance, and icosahedral structure as well as its many potential uses in material and biological sciences. Yet, to this date, direct confirmation of its precise composition and total structure remains elusive. Results presented here from characterization via high-resolution electrospray ionization mass spectrometry on an Orbitrap instrument confirm Au₁₀₂(pMBA)₄₄ at isotopic resolution. Further, what usually appears as a single band for (144, 60) in electrophoresis (PAGE) is shown to also contain the (130, 50), recently determined to have a truncated-decahedral structure, and a (137, 56) component in addition to the dominant (144, 60) compound of chiral-icosahedral structure. This finding is significant in that it reveals the existence of structures never before observed in all-aromatic water-soluble species while pointing out the path toward elucidation of the thermodynamic control of protected gold nanocrystal formation.