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We report the synthesis, ab initio calculations, magnetic and optical characterization of a DyIII-based dimeric compound named DyAZO. The dimers self-organize into a supramolecular chain decorated with photo-isomerizable azobenzene ligands. DyAZO displays single-molecule magnet (SMM) behavior. However, ab initio calculations highlight a quite strong admixture of MJ states of the 6H15/2 level of DyIII ions, the presence of low-lying excited MJ states and antiferromagnetic Dy–Dy dipolar coupling. This favors zero-field fast tunneling. Accordingly the Dy-doped analogue YDyAZO (5.5% Dy doping) displays enhanced magnetic relaxation with a hysteresis that is observed at 0.5 K. The influence of the cis- to trans-isomerization of the decorating azobenzene ligand on magnetic properties has been tested for both solid samples and solutions of DyAZO and YDyAZO. This provides hints for the synthesis of future Dy-based photo-isomerizable molecules. [ABSTRACT FROM AUTHOR]

Single‐molecule magnet (SMM) behavior of dysprosium‐based dimers was optimized by substitution of a DyIII ancillary ligand (hfac– in the previously reported DyPyNO and tta– in Dy). A clear hysteresis opening is visible at 0.5 K for Dy that allows for the determination of an antiferromagnetic (AF) coupling of –2.92 cm–1 (S = 1/2, gz = 19.58) which was confirmed by ab initio calculations. Comparison with the results of DyPyNO shows that stronger AF coupling correlates with better SMM behavior. This is further demonstrated by diamagnetic substitution, and a Y–Dy species (YDy) highlights that the strong AF magnetic interaction in Dy significantly enhances magnetic relaxation at low temperature. This coupling is also expected to be at the origin of the unexpectedly weak isotopic effect observed for the isotopically pure parents of Dy, namely 161Dy and 164Dy. [ABSTRACT FROM AUTHOR]

Herein, we provide some structural evidence of the complexation color-change of murexide solutions in presence of lanthanide, which has been used for decades in complexometric studies. For Ln=Sm to Lu and Y, the compounds crystallize as monomeric [Ln(Murex)3] ⋅11 H2O with an N3O6 tricapped square-antiprism environment, which are stable up to 250 °C. Single-ion magnet (SIM) behavior is then observed on the YbIII derivative in an original nine-coordinated environment. In-field slow relaxation (Δ=(15.6±1) K; τ0=2.73×10−6 s) is observed with a very narrow distribution of the relaxation time ( αmax=0.09). Magnetic and photophysical properties can be correlated. On one hand the analysis of NIR emission spectrum permits to have access to crystal field parameters and to compare them with those extracted from dc measurements. On the other hand, magnetic measurements permit to identify the nature of the MJ states involved in the 2F5/2→2F7/2 luminescence spectrum. The gap between the low-lying states is in agreement with the energy barrier obtained from magnetic slow-relaxation measurement. [ABSTRACT FROM AUTHOR]

The reaction of isonicotinic acid N-oxide and Dy(NO)3 ·6H2O under aerobic conditions leads to the formation of a porous lanthanide, a cubane-based 3D edifice of the formula [Dy4(μ3-OH)3(μ3-O)(NOPyCOO)6(OH)(H2O)3 ·(DMF)3(H2O)12]∞ (NOPyCOO = pyridine-4-carboxylate N-oxide). Crystal structure investigations show that the [Dy4(μ3-OH)3(μ3-O)] cubane cores are interconnected by organic ligands to form an extended porous structure. Thermogravimetric analyses and temperature-dependent X-ray diffraction analyses evidence that the compound is stable upon dehydration/desolvatation up to 200 °C. Calculations for the N2 kinetic radius afford a void volume of 3603 Å3 per unit cell (33.8 %) and a potential porosity of 1400 m2 g-1. The large pores can potentially host molecules with a projected surface area as large as 20 Å2 into a large pore volume (600 Å3). Moreover, the onset of a slow magnetic relaxation has been observed and rationalized by a comparison with closely related 0D and 2D compounds. [ABSTRACT FROM AUTHOR]

The reaction of [Ln(hfac)3] ⋅2 H2O and pyridine- N-oxide (PyNO) leads to isostructural dimers of the formula [Ln(hfac)3(PyNO)]2 (Ln=Eu, Gd, Tb, Dy). The Dy derivative shows a remarkable single-molecule magnet behavior with complex hysteresis at 1.4 K. The dynamics of the magnetization features are two relaxation regimes: a thermally activated one at high temperature ( τ0=(5.62±0.4)×10−11 s and Δ=(167±1) K) and a quantum tunneling regime at low temperature with a tunneling frequency of 0.42 Hz. The analysis of the Gd derivative evidences intradimer antiferromagnetic interactions ( J=(−0.034±0.001) cm−1). Moreover, the Eu, Tb, and Dy derivatives are luminescent with quantum yield of 51, 53, and 0.1 %, respectively. The thermal investigation of [Dy(hfac)3(PyNO)]2 shows that the dimers can be sublimated intact, suggesting their possible exploit as active materials for surface-confined nanostructures to be investigated by fluorimetry methods. [ABSTRACT FROM AUTHOR]

A correction to the article "A Luminescent and Sublimable DyIII Based Single-Molecule Magnet"that was published in a 2012 issue is presented.