具有磁制冷、慢磁弛豫和荧光特性的纳米级{LnIII(24)ZnII(6)}三角形金属环

Nanoscale {LnIII(24)ZnII(6)} Triangular Metalloring with Magnetic Refrigerant, Slow Magnetic Relaxation, and Fluorescent Properties.

作者信息

Zhang Li, Zhao Lang, Zhang Peng, Wang Chao, Yuan Sen-Wen, Tang Jinkui

机构信息

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.

出版信息

Inorg Chem. 2015 Dec 7;54(23):11535-41. doi: 10.1021/acs.inorgchem.5b02215. Epub 2015 Nov 24.

DOI:10.1021/acs.inorgchem.5b02215

PMID:26600284

Abstract

The self-assembly of Ln(ClO4)3 · 6H2O and Zn(OAc)2 · 2H2O with pyrazine-2-carboxylic acid (HL) results in the formation of three novel nanosized {LnIII(24)ZnII(6)} triangular metallorings, Gd24Zn6L24(OAc)22(μ3-OH)30(H2O)147(OAc) · 2CH3OH · 26H2O (1), Tb24Zn6L24(OAc)22(μ3-OH)30(CH3O)2(CH3OH)2(H2O)105(OH) · 6CH3OH · 12H2O (2), and (H3O)Dy24Zn6L24(OAc)22(μ3-OH)30(H2O)147(OAc)2 · 4CH3OH · 22H2O (3), having the largest nuclearity among any known Ln/Zn clusters. Magnetic and luminescent studies reveal the special prowess for each lanthanide complex. Magnetic studies reveal that 1 exhibits a significant cryogenic magnetocaloric effect with a maximum -ΔSm (isothermal magnetic entropy change) value of 30.0 J kg(-1) K(-1) at 2.5 K and 7 T and that a slow magnetization relaxation is observed for the dysprosium analogue. In addition, the solid-state photophysical properties of 2 display strong characteristic Tb(III) photoluminescent emission in the visible region, suggesting that Tb(III)-based luminescence is sensitized by the effective energy transfer from the ligand HL to the metal centers.

摘要

高氯酸镧（Ln(ClO4)3·6H2O）与醋酸锌（Zn(OAc)2·2H2O）和吡嗪 - 2 - 羧酸（HL）的自组装形成了三种新型的纳米尺寸{LnIII(24)ZnII(6)}三角形金属环，即Gd24Zn6L24(OAc)22(μ3 - OH)30(H2O)147(OAc)·2CH3OH·26H2O（1）、Tb24Zn6L24(OAc)22(μ3 - OH)30(CH3O)2(CH3OH)2(H2O)105(OH)·6CH3OH·12H2O（2）和(H3O)Dy24Zn6L24(OAc)22(μ3 - OH)30(H2O)147(OAc)2·4CH3OH·22H2O（3），它们是所有已知Ln/Zn簇合物中核数最大的。磁性和发光研究揭示了每种镧系配合物的特殊性能。磁性研究表明，1在2.5 K和7 T时表现出显著的低温磁热效应，最大 -ΔSm（等温磁熵变）值为30.0 J kg(-1) K(-1)，并且观察到镝类似物存在缓慢的磁化弛豫。此外，2的固态光物理性质在可见光区域显示出强烈的特征Tb(III)光致发光发射，这表明基于Tb(III)的发光是通过配体HL向金属中心的有效能量转移而被敏化的。