17d,e Combination of two independent Dy 3 SMM-building blocks by a paramagnetic 4+ linker afforded an octanuclear Dy III complexes with SMM behavior inherited from its Dy 3 precursor. It was reported that linking of two such highly anisotropic Dy 3 triangles in different forms led to the creation of hexanuclear dysprosium SMMs, 17 of which enhanced slow magnetic relaxation was observed, 17b and enhanced toroidal magnetisms were obtained by fine-tuning the arrangements of the Dy III ions or by modifying the local ligand-field around the Dy III ions. 16 Stimulated by the fascinating magnetic behaviors of these intriguing Dy 3 triangles, research on the utilization of theirs as building blocks to construct larger SMMs with enhanced magnetic properties has attracted much attention. This system has an essentially nonmagnetic spin ground state, but exhibits SMM behavior of thermally populated excited states, as well as toroidal magnetic moments which are useful in molecule-based multiferroics. 1b,15Īmong the various Dy III-based SMMs reported, the Dy 3 triangular molecules have been found to be a magnetically interesting system. 14 A tetranuclear Dy III alkoxide cage complex and a square-based pyramid iso-propoxide-bridged pentanuclear Dy III complex have been reported to possess large thermal energy barrier for the reversal of magnetization. 13 A dinuclear Dy III complex bridged by an N 2 3− radical ligand was observed to show magnetic hysteresis up to 8.3 K. For example, mononuclear Dy III complexes with pentagonal bipyramidal coordination geometry featuring strong axial ligand field and weak equatorial donors exhibit very high effective energy barriers for magnetic relaxation. 7–11 In the past decade, a number of mono- and polynuclear Dy III complexes have been synthesized and characterized, 12 and many of them have been demonstrated to exhibit remarkable properties of single-molecule magnets. 1–6 Most of the 4f-based SMMs reported in the literature are derived from Dy III ion due to its unquenched orbital angular momentum and large intrinsic magnetoanisotropy. Introduction The synthesis of new single-molecule magnets (SMMs) containing lanthanide metals continues to grow because of their fascinating magnetic behaviours and potential applications in many fields such as high-density information storage, quantum computing, molecular spintronics etc. Both complexes exhibit slow magnetic relaxation behavior. Variable-temperature magnetic susceptibility measurements in the temperature range of 2–300 K indicate dominant ferromagnetic exchange interactions between the Dy III ions in the complexes. Each of the hexanuclear complexes is constructed with Dy 3 triangular motifs as building blocks, and the six Dy III ions are arranged in a chair-shaped conformation.
Two novel hexanuclear Dy III complexes with polyhydroxy Schiff-base ligands, Cl 2♲MeOH♲MeCN ( 1) and ( 2) (H 3L 1 = N, N′-bis(3-methoxysalicylidene)(propylene-2-ol)-1,3-diamine, H 3L 2 = 2,3-dihydroxypropylimino)methyl)-6-methoxyphenol, piv = pivalate), have been prepared under solvothermal conditions and structurally characterized by single-crystal X-ray diffraction, elemental analyses, thermal analyses, and IR spectroscopy.
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