[Show abstract][Hide abstract] ABSTRACT: Single-molecule magnets are compounds that exhibit magnetic bistability purely of molecular origin. The control of anisotropy and suppression of quantum tunneling to obtain a comprehensive picture of the relaxation pathway manifold, is of utmost importance with the ultimate goal of slowing the relaxation dynamics within single-molecule magnets to facilitate their potential applications. Combined ab initio calculations and detailed magnetization dynamics studies reveal the unprecedented relaxation mediated via the second excited state within a new DyNCN system comprising a valence-localized carbon coordinated to a single dysprosium(III) ion. The essentially C2v symmetry of the Dy(III) ion results in a new relaxation mechanism, hitherto unknown for mononuclear Dy(III) complexes, opening new perspectives for means of enhancing the anisotropy contribution to the spin-relaxation barrier.
[Show abstract][Hide abstract] ABSTRACT: The Schiff base ligand N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H2 valdien) and the co-ligand 6-chloro-2-hydroxypyridine (Hchp) were used to construct two 3d-4f heterometallic single-ion magnets [Co2 Dy(valdien)2 (OCH3 )2 (chp)2 ]⋅ClO4 ⋅5 H2 O (1) and [Co2 Tb(valdien)2 (OCH3 )2 (chp)2 ]⋅ClO4 ⋅2 H2 O⋅CH3 OH (2). The two trinuclear [Co(III) 2 Ln(III) ] complexes behave as a mononuclear Ln(III) magnetic system because of the presence of two diamagnetic cobalt(III) ions. Complex 1 has a molecular symmetry center, and it crystallizes in the C2/c space group, whereas complex 2 shows a lower molecular symmetry and crystallizes in the P21 /c space group. Magnetic investigations indicated that both complexes are field-induced single-ion magnets, and the Co(III) 2 -Dy(III) complex possesses a larger energy barrier [74.1(4.2) K] than the Co(III) 2 -Tb(III) complex [32.3(2.6) K].
Chemistry - An Asian Journal 05/2014; · 4.57 Impact Factor
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