Au-329(SR)(84) Nanomolecules: Compositional Assignment of the 76.3 kDa Plasmonic Faradaurates

作者：Kumara Chanaka; Dass Amala^*

来源：Analytical Chemistry, 2014, 86(9): 4227-4232.

DOI：10.1021/ac403851s

The purpose of this work is to determine the chemical composition of the previously reported faradaurates, which is a large 76.3 kDa thiolated gold nanomolecule. Electrospray ionization quadrupole-time-of-flight (ESI Q-TOF) mass spectrometry of the title compound using three different, thiols yield the 329:84 gold to thiol compositional assignment. The purity of the title compound was checked by matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry. Positive and negative mode ESI-MS spectra show identical peaks denoting that there are no counterions, further reinforcing the accuracy of the assigned composition. We intentionally added Cs+ ions to show that the Au-329(SR)(84) is the base molecular ion, with several Cs+ adducts. A comprehensive investigation including analysis of the title compound with three ligands, in positive and negative mode and Cs+ adduction, leads to a conclusive composition of Au-329(SR)(84). This formula determination will facilitate the fundamental understanding of emergence of surface plasmon resonance in Au-329(SR)(84) with 245 free electrons.

• 出版日期2014-5-6