首页> 外文期刊>Chemistry: A European journal >Decanuclear Ln(10) Wheels and Vertex-Shared Spirocyclic Ln(5) Cores: Synthesis, Structure, SMM Behavior, and MCE Properties
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Decanuclear Ln(10) Wheels and Vertex-Shared Spirocyclic Ln(5) Cores: Synthesis, Structure, SMM Behavior, and MCE Properties

机译:十核Ln(10)轮和与顶点共享的螺环Ln(5)核:合成,结构,SMM行为和MCE属性

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摘要

The reaction of a Schiff base ligand (LH3) with lanthanide salts, pivalic acid and triethylamine in 1:1:1:3 and 4:5:8:20 stoichiometric ratios results in the formation of decanuclear Ln(10) (Ln=Dy(1), Tb(2), and Gd (3)) and pentanuclear Ln(5) complexes (Ln=Gd (4), Tb (5), and Dy (6)), respectively. The formation of Ln(10) and Ln(5) complexes are fully governed by the stoichiometry of the reagents used. Detailed magnetic studies on these complexes (1-6) have been carried out. Complex 1 shows a SMM behavior with an effective energy barrier for the reversal of the magnetization (U-eff)=16.12(8)K and relaxation time (iota(o))= 3.3 x 10(-5) s under 4000 Oe direct current (dc) field. Complex 6 shows the frequency dependent maxima in the out-of-phase signal under zero dc field, without achieving maxima above 2 K. Complexes 3 and 4 show a large magnetocaloric effect with the following characteristic values: -Delta S-m=26.6 J kg(-1)K(-1) at T = 2.2 K for 3 and -Delta S-m= 27.1 J kg(-1)K(-1) at T=2.4 K for 4, both for an applied field change of 7 T.
机译:Schiff碱配体(LH3)与镧系元素盐,新戊酸和三乙胺的化学计量比为1:1:1:3和4:5:8:20的反应导致形成癸核Ln(10)(Ln = Dy (1),Tb(2)和Gd(3))和五核Ln(5)配合物(Ln = Gd(4),Tb(5)和Dy(6))。 Ln(10)和Ln(5)配合物的形成完全取决于所用试剂的化学计量。已经对这些配合物(1-6)进行了详细的磁性研究。配合物1显示SMM行为并具有有效的能垒,可在4000 Oe直接作用下逆转磁化强度(U-eff)= 16.12(8)K和弛豫时间(iota(o))= 3.3 x 10(-5)s电流(dc)字段。复数6显示零直流场下异相信号的频率相关最大值,但未达到2 K以上的最大值。复数3和4显示出较大的磁热效应,具有以下特征值:-Delta Sm = 26.6 J kg(在施加的7 T的电场变化下,对于3 = T = 2.2 K时为-1)K(-1),对于4 = T = 2.4 K时为-Delta Sm = 27.1 J kg(-1)K(-1)。

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