Utilization of diamagnetic Zn(II) ion to boost the anisotropic nature of Ln(III) ion in heterodinuclear Zn(II)-Ln(III) SMMs
Utilization of diamagnetic Zn(II) ion to boost the anisotropic nature of Ln(III) ion in heterodinuclear Zn(II)-Ln(III) SMMs
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利用抗磁性 Zn(II) 离子增强异双核 Zn(II)-Ln(III) SMM 中 Ln(III) 离子的各向异性
DOI：
10.1002/aoc.6914
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发表时间：
2022
影响因子：
3.9
通讯作者：
S. Das
中科院分区：
文献类型：
--
作者：
S. Roy;P. Shukla;R. Kumar;S. C. Sahoo;T. K. Pal;A. Rajpute;J. Klak; M. Hada;K. R. Vignesh;S. Das
在三乙胺存在下，通过隔室配体LH =（（E）-2-（（吡啶-2-基亚甲基）氨基）苯酚）与Ln（NO3）3·xH 2 O和Zn（NO3）2·xH 2 O反应，合成了一系列通式为[LnZn（L）3（NO3）2]·2CH 3OH（LnIII= DyIII（1），TbIII（2），GdIII（3））的ZnII-LnIII化合物.单晶XRD分析表明，两种金属离子通过完全去质子化配体中的酚氧原子相互连接。基于SHAPE分析，DyIII离子有9个配位数，具有扭曲的球帽正方形反棱柱几何构型，而ZnIII离子有6个配位数，具有扭曲的八面体几何构型.直流磁学研究表明，Zn Ⅱ和Ln Ⅲ金属中心之间存在反铁磁相互作用. AC磁性研究表明，配合物1显示出场致单分子磁体（SMM）性质，在施加0.1 T的直流场下有效能垒为155 K，而配合物2没有显示SMM行为。此外，我们进行了DFT和从头计算CASSCF + RASSI-SO计算，以探测Ln（III）离子的单离子性质，并了解抗磁性ZnIII离子在磁化弛豫中的作用，以解释实验观察结果。从头计算结果表明，Dy（III）离子在配合物1中基态的gz值是强轴性的，并允许通过激发态发生磁弛豫，其aU cal为380.8 K. DFT计算发现，反磁性Zn（II）离子的存在导致桥氧原子上的负电荷增加，这增强了Dy（III）离子的各向异性，从而降低了磁化量子隧穿（QTM）效应，并有助于实现更好的SMM特征。
A series of dimetallic ZnII–LnIIIcompounds of general formulae [LnZn(L)3(NO3)2]·2CH3OH (LnIII= DyIII(1), TbIII(2), GdIII(3)) was prepared by stepwise reaction of compartmental ligand LH = ((E)‐2‐((pyridin‐2‐ylmethylene)amino)phenol) with Ln (NO3)3·xH2O and Zn (NO3)2·xH2O in the presence of triethylamine as base. The single crystal XRD analysis indicated that both metallic ions are connected to each other through phenolic oxygen atom from fully deprotonated ligand. Based on the SHAPE analysis, the DyIIIion has nine coordination numbers with distorted spherical capped square antiprism geometry, while the ZnIIion has six coordination numbers with distorted octahedral geometry. DC magnetic studies reveal the existence of antiferromagnetic interaction between the ZnIIand LnIIImetal centers. AC magnetic studies reveal that the complex1show field‐induced single‐molecule magnet (SMM) properties with an effective energy barrier of 155 K under an applied dc field of 0.1 T, whereas complex2does not show SMM behavior. Furthermore, we conducted DFT and ab initio CASSCF + RASSI‐SO calculations to probe the single‐ion properties of Ln(III) ions and to understand the role of the diamagnetic ZnIIion in the magnetization relaxation in order to interpret the experimental observations. Ab initio calculations predict that the gzvalues are strongly axial in nature in the ground state of Dy(III) ion in complex1and that allows the magnetic relaxation to occur via excited states with aUcalof 380.8 K. DFT calculations discovered that the presence of the diamagnetic Zn(II) ion causes greater negative charges on the bridging oxygen atoms, which enhances the anisotropy of Dy(III) ion and thus reduces the quantum tunneling of magnetization (QTM) effects, and helps to achieve better SMM features for1.