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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]

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]