title: Chromatographic isolation of "missing" Au55 clusters protected by alkanethiolates.
abstract: We report on the first synthesis of alkanethiolate-protected Au55 (11 kDa), which has been a "missing" counterpart of Schmid's Au55(PR3)12Cl6. Au:SCx clusters (x = 12, 18) were prepared by the reaction of alkanethiol (CxSH) with polymer-stabilized Au clusters ( approximately 1.3 nm) and subsequently incubated in neat CxSH. The resulting clusters were successfully fractionated by recycling gel permeation chromatography into Au approximately 38:SCx and Au approximately 55:SCx and identified by laser-desorption ionization mass spectrometry. The Au approximately 55:SCx clusters exhibited structured optical spectra, suggesting molecular-like properties. The thiolate monolayers were found to be liquid-like on the basis of the IR spectrum and the monolayer thickness, which was estimated from the hydrodynamic diameter.
authors: Research Center for Molecular-Scale Nanoscience, Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan.
authors: Hironori
authors: H
authors: Tsunoyama
authors: Yuichi
authors: Y
authors: Negishi
authors: Tatsuya
authors: T
authors: Tsukuda