Wu Jianfeng, Li Xiao-Lei, Zhao Lang, Guo Mei, Tang Jinkui
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, P. R. China.
University of Chinese Academy of Sciences , Beijing 100049, P. R. China.
Inorg Chem. 2017 Apr 3;56(7):4104-4111. doi: 10.1021/acs.inorgchem.7b00094. Epub 2017 Mar 14.
A series 1.Ln of tetranuclear lanthanide clusters [Ln(μ-O)L(PhCOO)]·solvent (Ln = Gd (1.Gd), Dy (1.Dy), Ho (1.Ho)) and octanuclear lanthanide Ln cluster pairs 2.Ln [Ln(μ-OH)(CO)L(PhCOO)]·solvent (Ln = Gd (2.Gd), Dy (2.Dy), Tb (2.Tb)) were assembled by using a bi-Schiff-based ligand HL and characterized structurally and magnetically. Interestingly, the octanuclear Ln cluster pairs 2.Ln are proposed to be assembled from the tetranuclear clusters 1.Ln through the uptake of CO from air in a more basic media. X-ray structural analyses approved the possible evolution mechanism. Magnetic studies reveal the coexistence of ferro- and anti-ferromagnetic interaction in 1.Gd and 2.Gd by simulating the direct-current magnetic susceptibility and indicate the CO bridges produce weak ferromagnetic interaction in 2.Gd rather than anti-ferromagnetic interaction by benzoate bridges in 1.Gd. The magnitude of the magnetocaloric effect has been examined and shows that complex 2.Gd exhibits larger magnetocaloric effect than 1.Gd, which could be probably ascribed to the weak ferromagnetic interaction produced by the CO bridges.
通过使用基于双席夫碱的配体HL组装了一系列四核镧系簇合物[Ln(μ-O)L(PhCOO)]·溶剂（Ln = Gd (1.Gd)、Dy (1.Dy)、Ho (1.Ho)）和八核镧系Ln簇对2.Ln [Ln(μ-OH)(CO)L(PhCOO)]·溶剂（Ln = Gd (2.Gd)、Dy (2.Dy)、Tb (2.Tb)），并对其进行了结构和磁性表征。有趣的是，八核Ln簇对2.Ln被认为是在碱性更强的介质中通过从空气中吸收CO由四核簇合物1.Ln组装而成。X射线结构分析证实了可能的演化机制。磁性研究通过模拟直流磁化率揭示了1.Gd和2.Gd中铁磁和反铁磁相互作用的共存，并表明CO桥在2.Gd中产生弱铁磁相互作用，而不是像1.Gd中苯甲酸酯桥那样产生反铁磁相互作用。已经研究了磁热效应的大小，结果表明配合物2.Gd表现出比1.Gd更大的磁热效应，这可能归因于CO桥产生的弱铁磁相互作用。
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