Handzlik Gabriela, Magott Michał, Arczyński Mirosław, Sheveleva Alena M, Tuna Floriana, Baran Stanisław, Pinkowicz Dawid
Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland.
Dalton Trans. 2020 Sep 14;49(34):11942-11949. doi: 10.1039/d0dt02439b. Epub 2020 Aug 19.
Propeller-like lanthanide complexes with suitable chiral ligand scaffolds are highly desired as they combine chirality with possible magnetic bistability. However, the library of relevant chiral lanthanide-based molecules is quite limited. Herein we present the preparation, structures, magnetic behavior as well as EPR studies of a series of propeller-shaped lanthanide Single Ion Magnets (SIMs). Coordination of the smallest helicene-type molecule 1,10-phenanthroline-N,N'-dioxide (phendo) to Ln ions results in the formation of homoleptic complexes Ln(phendo)·xMeOH (Ln = Gd, Er, Yb) Gd, Er and Yb, where four phendos encircle the metal center equatorially in a four-bladed propeller fashion. The magnetization dynamics in these systems is studied by magnetic measurements and EPR spectroscopy for non-diluted as well as solid state dilutions of Er and Yb in a diamagnetic Y(phendo)·xMeOH (Y) matrix. Careful analysis of the slow magnetic relaxation in the diluted samples can be described by a combination of Raman and Orbach relaxation mechanisms. The most important finding concerns the identical power law τ≈T describing the anomalous Raman relaxation for all three reported compounds diluted in the Y matrix. This identical power law strongly suggests that the exponent of the Raman relaxation process in the series of solid-state diluted isostructural compounds is practically independent of the metal ion (as long as the molar mass changes are negligible) and highlights a possible experimental strategy towards reliable Raman relaxation determination.
具有合适手性配体支架的螺旋桨状镧系配合物备受青睐，因为它们将手性与可能的磁双稳性结合在一起。然而，相关的手性镧系分子库相当有限。在此，我们展示了一系列螺旋桨形状的镧系单离子磁体（SIMs）的制备、结构、磁行为以及电子顺磁共振（EPR）研究。最小的螺旋烯型分子1,10 - 菲咯啉 - N,N'-二氧化物（phendo）与镧系离子配位，形成了均配配合物Ln(phendo)·xMeOH（Ln = Gd、Er、Yb），其中四个phendo以四叶螺旋桨的方式环绕在金属中心赤道平面上。通过磁测量和EPR光谱对这些体系中的磁化动力学进行了研究，研究对象包括未稀释的以及在抗磁性的Y(phendo)·xMeOH（Y）基质中对Er和Yb进行固态稀释后的样品。对稀释样品中缓慢磁弛豫的仔细分析可以用拉曼弛豫和奥尔巴赫弛豫机制的组合来描述。最重要的发现涉及到相同的幂律τ≈T，它描述了在Y基质中稀释的所有三种报道化合物的反常拉曼弛豫。这种相同的幂律强烈表明，在一系列固态稀释的同构化合物中，拉曼弛豫过程的指数实际上与金属离子无关（只要摩尔质量变化可忽略不计），并突出了一种用于可靠确定拉曼弛豫的可能实验策略。
