How does a localized unpaired electron spin delocalize along an organic ligand that is chemically bound to the host of the former is not only a key fundamental question in the newly emerging field of molecular spintronics, but also of challenge to characterize it. Using paramagnetic Au25(SR)180 (R = pentyl, hexyl, and octyl) as a model system of molecular spinterfaces, we report herein that routine high-resolution solution 13C can be used to address this question in a straightforward fashion. Specifically, the carbon-position dependent 13C NMR shifts reveal interestingly different electron-spin delocalization characteristics. Between the two types of thiolate ligands on Au25, the out-ligands (ones that bind to two surface Au atoms) delocalize electron spin much farther than the in-ligands (ones that bind to a core and a surface Au atom respectively) do, although the latter have higher spin density to begin with. This highlights the controlling nature of the metal-ligand bonding at the molecular spinterfaces. On the other hand, the proportionality between the experimentally determined 13C NMR shift changes caused by the unpaired electron spin and the DFT calculated spin density suggests strongly that the electron-spin delocalization is dominantly through bonds.

Electron-spin delocalization along the stabilizing ligands in paramagnetic atomic-precise neutral Au25(SR)18 clusters as measured by high-resolution solution 13C-NMR spectroscopy

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.