Seven μ-Oacylhydrazone-bridged Ln3 clusters were synthesized. Cluster 3 displayed magnetic refrigeration properties, whereas cluster 5 showed slow magnetic relaxation. The solid-state fluorescence properties of 2, 4 and 5 were also studied.
A possible relation between the value of the axial Zero Field Splitting and the occurrence of field-induced slow magnetic relaxation has been established for a new gadolinium(iii) compound.
Dinuclear [M(H3L1,2,4)]2 (M = Dy, Dy2; M = Ho, Ho2) complexes were isolated from an heptadentate aminophenol ligand. The crystal structures of Dy2·2THF, and the pyridine adducts Dy2·2Py and Ho2·2Py,...
A series of mononuclear Co(II) complexes showing slow magnetic relaxation is assessed from the point of view of relaxation mechanisms. In certain cases, the reciprocating thermal behavior is detected: On cooling, the slow relaxation time is prolonged until a certain limit and then, unexpectedly, is accelerated. The low-temperature magnetic data can be successfully fitted by assuming Raman and/or phonon bottleneck mechanisms of the slow magnetic relaxation for the high-frequency relaxation channel. An additional term with the negative temperature exponent is capable of reproducing the whole experimental dataset.
The conformations of the title compounds were determined in solution (NMR and UV-Vis spectroscopy) and in the solid state (FT-IR and XRD), complemented with density functional theory (DFT) in the gas phase. The nonequivalence of the amide protons of these compounds due to the hindered rotation of the C(O)–NH2 single bond resulted in two distinct resonances of different chemical shift values in the aromatic region of their 1H-NMR spectra. Intramolecular hydrogen bonding interactions between the carbonyl oxygen and the sulfonamide hydrogen atom were observed in the solution phase and solid state. XRD confirmed the ability of the amide moiety of this class of compounds to function as a hydrogen bond acceptor to form a six-membered hydrogen bonded ring and a donor simultaneously to form intermolecular hydrogen bonded complexes of the type N–H···O=S. The distorted tetrahedral geometry of the sulfur atom resulted in a deviation of the sulfonamide moiety from co-planarity of the anthranilamide scaffold, and this geometry enabled oxygen atoms to form hydrogen bonds in higher dimensions.
Reciprocating Thermal Behavior in Multichannel Relaxation of Cobalt(II) Based Single Ion Magnets