Four CoII-GdIII mixed-metal phosphonate clusters as molecular magnetic refrigerants

作者：Tang, Xiaoyan; Ye, Wenpeng; Hua, Jingkun; Chen, Ming; Cheng, Hongjian; Ma, Yunsheng^*; Yuan, Rongxin^*

来源：Inorganica Chimica Acta, 2016, 453: 142-148.

DOI：10.1016/j.ica.2016.08.021

• Phosphonate
• Fluorenyl
• Co-Gd cluster
• Magnetocaloric effect

The building of 3d-Gd clusters are very essential in the fields of magnetic refrigerants. Three bulky phosphonic acids: (9-methyl-9H-fluoren-9-yl)phosphonic acid (R'PO3H2), (2,7-di-tert-butyl-9-methyl-9H-fluoren-9-yl)phosphonic acid (R'PO3H2), and (9-(sec-butyl)-2,7-di-tert-butyl-9H-fluoren-9-y1) phosphonic acid (R"PO3H2) have been employed to construct four Co-II-G(III) clusters [(Co2Gd3III)-Gd-II(OH) (RPO3)(2)((BuCO2)-Bu-t)(8)((BuCO2H)-Bu-t)(2)(C5H5N)(H2O)(2)]center dot 2H(2)O center dot(BuCO2H)-Bu-t (1), [(Co4Ga3III)-Ga-II(OH)(2)(RPO3)(2)(`BuCO2)(11)(py) (CH3CN)(H2O)(2)]center dot CH3CN (2), [(CO3Gd3III)-Gd-II(OH)(2)(R'PO3)(2)((BuCO2)-Bu-t)(9)(`BuCO2H)(H2O)(2)]center dot(BuCO2H)-Bu-t center dot 2CH(2)CL(2) (3) and [(CO3GdIII)-Gd-II(R"PO3)(2)((BuCO2)-Bu-t)5(CH3CN)(H2O)(4)]center dot(BuCO2H)-Bu-t center dot 3CH(3)CN (4) under ambient condition. Clearly, the varied hindrance of fluorenyl groups are responsible for the formation of various clusters. Single crystal analysis indicates that the metal ions arrange in one plane in each cluster. Magnetic studies show that the entropy changes are 18.3, 19.8, 20.0 and 9.6 J kg(-1) K-1 for 1-4, respectively, from which we can see these values are nearly proportional to the percentage of the gadolinium in the core.

• 出版日期2016-11-1
• 单位常熟理工学院