A new centrosymmetric tetranuclear aggregate [Dy₄(L)₂(OAc)₈(CH₃OH)₂] (1) was assembled using a unique symmetrical Schiff base ligand 1,5-bis(salicylidene)-carbohydrazide (H₂L). Magnetic studies reveal ferromagnetic interactions between dysprosium ions and two obvious relaxation processes under zero dc field with effective energy barriers U_eff of 38 K and 223 K, the highest among the reported tetranuclear dysprosium molecular nanomagnets. To obtain further evidence on the origination of the slow magnetic relaxation, a diamagnetic yttrium analogue [Y₄(L)₂(OAc)₈(CH₃OH)₂] (2) and a diluted sample [(Dy_0.06Y_0.94)₄(L)₂(OAc)₈(CH₃OH)₂] (3) were synthesized. Further magnetic studies on the diluted sample combined with theoretical calculations indicate that the two-step magnetic relaxation processes in complex 1 originate from the single-ion magnetic behaviors of dysprosium ions with different coordination environments.

中文翻译：

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通过磁性稀释四核镝分子纳米磁体的两步弛豫过程的阐明†

使用独特的对称席夫碱配体1,5-双（水杨基）-碳酰肼（H ₂ L）组装了新的中心对称四核聚集体[Dy ₄（L）₂（OAc）₈（CH ₃ OH）₂ ]（1）。 。磁性研究表明，zero离子与两个明显的弛豫过程之间的铁磁相互作用在零dc场下具有38 K和223 K的有效能垒U _eff，是所报道的四核mag分子纳米磁体中最高的。为了获得有关慢磁弛豫起源的进一步证据，抗磁钇类似物[Y ₄（L）₂（OAc）合成₈（CH ₃ OH） ₂ ]（ 2）和稀释样品[（Dy _0.06 Y _0.94） ₄（L） ₂（OAc） ₈（CH ₃ OH） ₂ ]（ 3）。对稀释样品的进一步磁学研究与理论计算相结合表明，配合物1中的两步磁弛豫过程源自具有不同配位环境的离子的单离子磁行为。