Univ Rennes , INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) -UMR 6226 , F-35000 Rennes , France.
Inorg Chem. 2018 Sep 4;57(17):11044-11057. doi: 10.1021/acs.inorgchem.8b01640. Epub 2018 Aug 21.
The rational design of molecular chains made of 4f ions and substituted 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical is presented. The reaction of Ln(hfac)·2HO (hfac = hexafluoroacetylacetonate) and the 4-cyano-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO-CN) radical affords air- and moisture-stable isostructural molecular chains of the formula [Ln(hfac)TEMPO-CN] for Ln = Gd and Tb, whereas zero-dimensional complexes of the formula [Dy(hfac)(TEMPO-CN)][Dy(hfac)(HO)] are obtained for Ln = Dy. To the best of our knowledge, the Gd derivative, Gd-TEMPO-CN, shows one of the strongest antiferromagnetic (AF) couplings for Gd-radical pairs ever reported with J/ k = -21.18 K, 14.72 cm ( H = - JS S spin Hamiltonian convention). The Tb derivative, Tb-TEMPO-CN, also shows strong Tb-radical AF coupling, which has been rationalized using the ab initio CASSCF approach ( J = -23.02 K, -16.7 cm) and confirmed by luminescence measurements. Tb-TEMPO-CN shows remarkable properties for a Tb-radical-based single-molecule magnet ( U = 69.3 ± 1 K; τ = 1.3 × 10 s) and two different relaxation processes triggered by interchain magnetic coupling.
本文提出了一种由 4f 离子和取代的 2,2,6,6-四甲基哌啶-1-氧基（TEMPO）自由基组成的分子链的合理设计。Ln(hfac)·2HO（hfac = 六氟乙酰丙酮）与 4-氰基-2,2,6,6-四甲基哌啶-1-氧基（TEMPO-CN）自由基反应，得到了空气稳定且不吸潮的同构分子链[Ln(hfac)TEMPO-CN]，其中 Ln = Gd 和 Tb，而 Ln = Dy 则得到零维配合物[Dy(hfac)(TEMPO-CN)][Dy(hfac)(HO)]。据我们所知，Gd 衍生物 Gd-TEMPO-CN 表现出迄今为止报道的 Gd-自由基对中最强的反铁磁（AF）耦合之一，J/ k = -21.18 K，14.72 cm（H = - JS S 自旋哈密顿约定）。Tb 衍生物 Tb-TEMPO-CN 也表现出强烈的 Tb-自由基 AF 耦合，这已通过从头算 CASSCF 方法（J = -23.02 K，-16.7 cm）进行了合理化，并通过发光测量得到了证实。Tb-TEMPO-CN 表现出基于 Tb-自由基的单分子磁体的显著性质（U = 69.3 ± 1 K；τ = 1.3 × 10 s）和两种不同的弛豫过程，由链间磁耦合触发。
