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Zero Field SMM Behavior and Magnetic Refrigeration in Rare Heterometallic Double Stranded Helicates of Cu2Ln2 (Ln = Dy, Tb, Gd)
European Journal of Inorganic Chemistry ( IF 2.2 ) Pub Date : 2018-04-17 , DOI: 10.1002/ejic.201800075
Bijoy Dey 1 , Subhadip Roy 1 , Amit Kumar Mondal 1 , Atanu Santra 1 , Sanjit Konar 1
Affiliation  

The strategic design and synthesis of new double stranded helical structures, namely [Cu2Ln2(H2L1)2(L2)2(OMe)(NO3)]·8MeOH (1: Ln = DyIII), [Cu2Ln2(H2L1)2(L2)2(H2O)(OMe)(NO3)]·xH2O·7MeOH (2: Ln = TbIII, x = 0.5; 3: Ln = GdIII, x = 1) and [Cu2Ln2(HL1)2(L2)2(MeOH)2]·xMeOH (4: Ln = DyIII, x = 8.5; 5: Ln = TbIII, x = 8; 6: Ln = GdIII, x = 8.66), has been achieved by using a flexible helical ligand and a rigid tridentate ligand. Butanedihydrazide‐bridged bis(3‐ethoxysalicylaldehyde) (H4L1) was used as a primary ligand due to its flexible nature for constructing the helical strand and another rigid tridentate ligand, 2‐salicylideneaminophenol (H2L2), was used to accommodate the transition metal. The two series of complexes are analogous and differ only in terms of coordination geometry around the LnIII centers. Complexes 13 are composed of two non‐equivalent Cu–Ln pairs, where one LnIII center is eight‐coordinate and the other LnIII center is nine‐coordinate; whereas complexes 46 are made up of two equivalent Cu–Ln pairs, where both the LnIII centers are eight‐coordinate. Crystal structural analysis revealed that in all the complexes the deprotonated form of H4L1 binds in a helical fashion forming a mixture of left‐handed (Λ) and right‐handed (Δ) configurations (“meso”‐relation). AC magnetic susceptibility measurements demonstrate slow magnetic relaxation behaviors of complexes 1 and 4 in the absence of any external magnetic field. Complexes 3 and 6 exhibit ferromagnetic interaction and show magnetic refrigeration, notable in heterometallic 3d‐4f helicates.

中文翻译:

Cu 2 Ln 2(Ln = Dy,Tb,Gd)的稀有异金属双链螺旋物中的零场SMM行为和磁致冷

新的双链螺旋结构的战略设计和合成,即[Cu 2 Ln 2(H 2 L 12(L 22(OMe)(NO 3)] · 8MeOH(1:Ln = Dy III),[ Cu 2 Ln 2(H 2 L 12(L 22(H 2 O)(OMe)(NO 3)] · x H 2 O · 7MeOH(2:Ln = TbIIIx = 0.5;3:Ln = Gd IIIx = 1)和[Cu 2 Ln 2(HL 12(L 22(MeOH)2 ] · x MeOH(4:Ln = Dy IIIx = 8.5;5:Ln = Tb IIIx = 8; 6:Ln = Gd IIIx= 8.66),这是通过使用柔性螺旋配体和刚性三齿配体实现的。Butanedihydrazide桥连双(3- ethoxysalicylaldehyde)(H 4大号1由于其柔性性质用于构造螺旋链和另一刚性三齿配体,2- salicylideneaminophenol(H)作为主配体2大号2),被用来容纳过渡金属。这两个系列的复合物是相似的,仅在Ln III中心周围的配位几何上不同。配合物1 - 3由两个非等价的Cu-LN对,其中一个LN的III中心是八坐标和其他LN III中心是九坐标;而复合物46由两个等价的Cu–Ln对组成,其中Ln III的两个中心均为八坐标。晶体结构分析表明,在所有配合物中,H 4 L 1的去质子化形式以螺旋形式结合,形成左旋(Λ)和右旋(Δ)构型的混合物(“内消旋”关系)。交流磁化率测量表明,在没有任何外部磁场的情况下,配合物14的磁弛豫行为较慢。配合物36 表现出铁磁相互作用并显示出磁性制冷,这在3d-4f杂金属螺旋结构中尤为明显。
更新日期:2018-05-15
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