Reversible Pressure-Magnetic Modulation in a Tetrathiafulvalene-Based Dyad Piezochromic Dysprosium Single-Molecule Magnet.

The extreme sensitivity of trivalent lanthanide ions to crystal field variations led to the emergence of single-molecule magnetic switching under various stimuli. The use of pressure as an external stimulus instead of classic light irradiation, oxidation or any chemical reactions allows a fine tuning of the magnetic modulation. Here the well-known pure isotopically enriched [162Dy(tta)3(L)]⋅C6H14 ( 162Dy) Single-Molecule Magnet (SMM) (tta- = 2-2-thenoyltrifluoroacetonate and L = 4,5-bis(propylthio)-tetrathiafulvalene-2-(2-pyridyl)benzimidazole-methyl-2-pyridine) was experimentally investigated by single-crystal diffraction and squid magnetometry under high applied pressures. Both reversible piezochromic properties and pressure modulation of the SMM behavior were demonstrated and supported by ab initio calculations. The magnetic study of the diluted sample [162Dy0.05Y0.95(tta)3(L)]⋅C6H14 ( 162Dy@Y) indicated that variations in the electronic structure have both intra- and inter-molecular origins. Quantitative magnetic interpretation concludes to a deterioration of the Orbach process for the benefit of both Raman and QTM mechanisms under applied pressure.