Au329(SR)84 nanomolecules: compositional assignment of the 76.3 kDa plasmonic faradaurates.
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 Au329(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 Au329(SR)84. This formula determination will facilitate the fundamental understanding of emergence of surface plasmon resonance in Au329(SR)84 with 245 free electrons.
Department of Chemistry and Biochemistry, University of Mississippi , University, Mississippi 38677, United States.
Chanaka
C
Kumara
Amala
A
Dass