Search

A Salen-type [Salen = N, N′-ethylene bis(salicylideneimine)] mononuclear lanthanide(III)-based Zn-Dy-Zn complex [Dy(ZnL)2(CH3COO)Cl2] ·CH2Cl2 ( 1) was prepared [H2L = N, N′-bis(3-ethoxysalicylidene)phenylene-1,2-diamine]. Single-crystal X-ray diffraction analysis revealed that DyIII was sandwiched between the two ZnL moieties, which was coordinated by three outer OO2 atoms and four inner N2O2 atoms from two Salen-type ligand, respectively, and an oxygen atom of acetic acid molecule completed the eight-coordinate arrangement. The continuous-shape-measures (CShMs) analysis to the DyIII coordination polyhedron revealed that the coordination environment lies among the ideal spherical triangular dodecahedron ( D2 d) and square antiprism ( D4 d), respectively, but with relative large deviation parameters. The alternative current (ac) susceptibility measurements shown that it behaved as a field-induced single-molecule magnet with relaxation energy barrier Ueff = 19 K and τ0 = 1.5 × 10-5 s. [ABSTRACT FROM AUTHOR]

A dinuclear dysprosium complex, [Dy2(tta)6(4‐mepyNO)2]·CHCl3 (tta = thenoyltrifluoroacetone, 4‐mepyNO = 4‐methylpyridine N‐oxide), has been structurally and magnetically characterized. Analysis of the single‐crystal structure revealed that the NO group serves as an effective bridge to link the two DyIII centres and combine with the peripheral β‐diketonate ligands to form an eight‐coordinate geometry of DyIII. Magnetic measurements showed significant zero‐field single‐molecule magnetic behaviour with a 3 K hysteresis temperature and 121 K energy barrier. Diamagnetic dilution studies revealed that the DyIII–DyIII coupling suppresses the quantum tunelling of magnetization, although the coupling is generally weak. The diluted system mainly displays decoupling single‐ion magnetic anisotropic behaviour with a higher hysteresis temperature of 3.5 K. [ABSTRACT FROM AUTHOR]

Abstract: Crystal structures, single‐molecule magnetic behavior, and ab initio calculations of four new phenoxo‐bridged dinuclear dysprosium complexes and their gadolinium(III) analogues are explored. Complexes [Dy2(DMOMP)2(DBM)4]2⋅CHCl3 (1; DMOMP=1‐methyl‐3,5‐dimethoxy‐4‐hydroxybenzene, DBM=1,3‐diphenylpropane‐1,3‐dione); [Dy2(DMOAP)2(DBM)4]2⋅CHCl3 (2; DMOAP=syringaldehyde); Dy2(DMOEP)2(DBM)4 (3; DMOEP=methyl syringate); and solvent‐free Dy2(DMOMP)2(DBM)4 (4), which is obtained by the transformation of single crystal into single crystal from 1, have nearly identical core structures and only differ in the substituents at the para position of the phenol moieties of the bridging ligand. In this system, the electronic effects are efficiently implemented to significantly modify the ligand field strength and exchange coupling by modulating the substituents on the phenol backbone. The effective energy barrier (Ueff) of magnetization reversal is improved significantly to fivefold magnitude, at most, and the hysteresis temperature up to 3.5 K by deliberately using the electron‐withdrawing substituent to replace the electron‐donating one. The origin of the two relaxation processes in 1 is mostly attributed to the existence of two molecules in one unit, which is illuminated by means of the transformation of single crystal into single crystal. [ABSTRACT FROM AUTHOR]

A series of {Ln 2 } have been prepared, and typical visible-infrared and magnetic behavior are detected in respect to the central Ln3+ ions. • A series of bifunctional dinuclear complexes have been synthesized. • High quantum yield and long luminescence life are found in {Eu2}. • Magnetization measurement indicate that 3 shows single molecule magnetic behavior. A series of bifunctional [Hpy] 2 [Ln 2 (NO 3) 2 (ampy) 4 (H 2 shi) 2 ] ({Ln 2 } ; Ln = Eu(1), Gd(2) and Dy(3); H 3 shi = salicylhydroxamic acid; Hampy = 5-aminopyridine-2-carboxylic acid) have been synthesized and characterized. Single-crystal X-ray diffraction analyses reveal that complexes 1 and 3 are isostructural. The complexes {Ln 2 } exhibit either photophysical or magnetic properties in respect to the central lanthanide ion. It is rarely observed that 1 gives bright and red emission with high quantum yield (16%) and a long luminescence lifetime (547 μs). Magnetic measurement reveals that 3 exhibits significant single molecule magnet behavior with an effective energy barrier of 31 K. [ABSTRACT FROM AUTHOR]