Single-Molecule Magnets on Molecular Nanoparticles of δ-Bi₂O₃

ChristiAnna L. Brantley,*^a Elly Daniels,^a Michael Schulze^b,c, Khalil A. Abboud,^a Wolfgang Wernsdorfer^b,c, and George Christou^a

aDepartment of Chemistry, University of Florida, Gainesville, FL 32611, USA
bKarlsruher Institut für Technologie (KIT), Physikalisches Institut, Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
cInstitute of Quantum Materials and Technologies (IQMT), Hermann-von-Helmholtz-Platz 1, Gebäude 640, 76344 Eggenstein-Leopoldshafen, Germany

Molecular chemistry brings powerful advantages to the study of nanoscale materials of different kinds, and in recent years research in this area has been rapidly growing. In the field of molecular nanomagnetism these advantages have been crucial in the study and understanding of single-molecule magnets (SMMs) and have led to the discovery of new quantum physics phenomena important to 21^st century technologies. More recently, our group has utilized a molecular bottom-up approach to attain a versatile and growing library of truly monodispersed (single-sized) metal-oxo clusters with the same structure as the corresponding bulk oxides, which we call ‘molecular metal-oxide nanoparticles’ (MNP’s). MNP’s possess a monolayer shell of organic ligands, imparting solubility and crystallinity and allowing structural characterization to atomic resolution by single-crystal X-ray crystallography. The synthesis of MNPs in the ultra-small size regime is important to understanding the size-dependent properties generally exhibited by nanoparticles. Our efforts began in cerium dioxide (CeO₂) chemistry, which is important for a variety of applications in industrial, environmental, and bio-medical catalysis. To date, our group has synthesized the largest Ce/O MNP, with a nuclearity of 100, exhibiting the fluorite structure of CeO₂. Since then our efforts have been extended to bismuth(III), iron(III), and Mn(III,IV) oxides, and also mixed-metal oxides. Specifically, Bi/O- based materials are interesting as bismuth is a non-toxic heavy metal that has been investigated in materials for multiferroics, photocatalysts, and electrolytes for fuel cells. Bismuth trioxide (Bi₂O₃) is a semiconducting material relevant to photocatalysis and solid oxide fuel cells. Recently, we have begun investigating MNPs with magnetic units on their surface as molecular analogues of magnetic units on surfaces. This allows the binding of the SMM to the surface and any magnetic interactions between the SMM units to be determined. The syntheses, structures, and magnetic properties of SMMs bound to MNPs of δ-Bi₂O₃ will be described.