基于[Dy4(μ4-O)]四面体结构单元的八核和十核镝簇合物的合成、结构及其单分子磁体行为研究

1. 生物无机与合成化学教育部重点实验室 光电材料与技术国家重点实验室 中山大学化学与化学工程学院 广州 510275
• 投稿日期:2012-11-05 发布日期:2012-12-06
• 通讯作者: 童明良 E-mail:tongml@mail.sysu.edu.cn
• 基金资助:

项目受973计划(No. 2012CB821704)和国家自然科学基金(Nos. 91122032, 90922009, 21121061)资助.

Synthesis, Structures and Single-Molecule Magnet Behaviour of Octanuclear and Decanuclear Dysprosium Clusters Based on [Dy4(μ4-O)] Tetrahedral Subunits

Guo Penghu, Liao Xiaofen, Leng Jidong, Tong Mingliang

1. Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education/State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, China
• Received:2012-11-05 Published:2012-12-06
• Supported by:

Project supported by the “973 Project” (2012CB821704) and the National Natural Science Foundation of China (Nos. 91122032, 90922009 and 21121061).

Two novel [Dy44-O)] based dysprosium(III) clusters, namely, [Dy8(bpt)84-O)2(μ-OMe)81,1,3,3-N3)(μ1,3-N3)- (N3)2]·11H2O·9MeOH (1) and [Dy10(bpt)64-O)43-OMe)4(μ-OMe)8(μ-OAc)2(OAc)2]·40H2O (2) (Hbpt=3,5-bis(pyridin- 2-yl)-1,2,4-trizole), are synthesized successfully. To obtain complex 1, a mixture of DyCl3 (0.1 mmol), 2,2'-Hbpt (0.1 mmol) and NaN3 (0.15 mmol) was sealed in a 25 mL vessel and then heated at 160℃ in methanol condition (8 mL) for 72 h. The reaction of Dy(OAc)3 (0.17 mmol) and 2,2'-Hbpt (0.1 mmol) under the same condition as complex 1 yielded complex 2. Single-crystal X-ray diffraction reveals that complex 1 consists of a pair of [Dy44-O)] tetrahedral units bridged by two azido groups in μ1,1,3,3 and μ1,3 modes as well as two bpt ligands, while complex 2 possesses four edge-sharing [Dy44-O)] tetrahedral units. Magnetic susceptibility of polycrystalline samples were carried out using a SQUID magnetometer in the temperature range 2～300 K at 500 Oe dc field. The χMT value are 107.8 cm3·K·mol-1 for complex 1 and 133.6 cm3·K·mol-1 for complex 2 at 300 K, which are close to the expected values. The maximum values of magnetization at 1.8 K are 40.81 Nb and 51.62 Nb for 1 and 2, slightly smaller than the expected saturation values. For further investigation of the dynamic behaviour, ac susceptibility measurements were undertaken under zero-dc field between 1～1500 Hz, they both show temperature dependence and have maximum values in the χMvs v plots above 1.8 K, indicating the presence of slow relaxation of the magnetization. After linear fitting the first four points of ln(τ/s) vs 1/T plot, we get energy barrier Ueff=9.83(9) K, pre-exponential factor τ0=1.63(2)×10-5 s for 1, and Ueff=12.05(2) K, τ0=6.75(8)×10-7 s for 2 respectively. The bridging mode of azido in complex 1 is novel and complex 2 holds the record for highest nuclearity among the reported pure lanthanide single-molecule magnets (SMMs) under zero dc field.