High-frequency ESR and frequency domain magnetic resonance spectroscopic studies of single molecule magnets in frozen solution

Abstract

Frozen solutions of the single molecule magnet ${\mathrm{Mn}}_{12}\mathrm{Piv}$ ($\mathrm{Piv}=\text{pivalate}$ or trimethylacetate) are studied by magnetization and magnetic resonance investigations. ac magnetic susceptibility measurements show that the system is stable in solution. Interestingly, the barrier and prefactor for the thermally activated magnetization relaxation are the same as in the solid state. This means that this system is not influenced by its surroundings, in contrast to other ${\mathrm{Mn}}_{12}$ derivatives. The zero-field-splitting spin Hamiltonian parameters of ${\mathrm{Mn}}_{12}\mathrm{Piv}$ in solution are determined by magnetic resonance spectroscopy methods to be very similar to those in the solid state. By these methods, it is also possible to distinguish between truly dissolved and precipitated species, which is not possible by magnetization measurements.