Can NMR calculations be used as fingerprints for the determination of structural features in Monolayer Protected Clusters (MPCs)? The effect of the chiral 2-methyl-1-butanethiol (SMeBu) ligand on the inherently achiral Au25 nanocluster system Au25(SMeBu)180, is being studied. To explain the unique features found in the 1H NMR spectra as a function of decreasing enantiomeric excess (e.e.) percentage, we are using computational spectroscopic characterization. One of the unique features to this cluster is that when the e.e. of the ligand is systematically changed the 1H NMR peak for the α-methylene protons evolves by splitting and broadening. We are currently investigating the origin of such splitting. Computational methods involving quantum chemistry may be able to answer these questions. Currently, our results agree with experiment in terms of the maximum peak for the a-methylene protons for 100% S enantiomer. Our hypothesis is that as the e.e. is changed, steric constraints create two populations of ligand conformations.

Computational NMR characterization of chiral Au25(SMeBu)180

256th National Meeting (2018)

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