Low‐Dimensional Carboxylate‐Bridged GdIII Complexes for Magnetic Refrigeration |
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Authors: | Dr Sui‐Jun Liu Chen‐Chao Xie Ji‐Min Jia Jiong‐Peng Zhao Song‐De Han Yu Cui Yue Li Prof Dr Xian‐He Bu |
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Institution: | Department of Chemistry, TKL of Metal‐ and Molecule‐Based Material Chemistry and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University, Tianjin 300071 (P.?R. China), Fax: (+86)?22‐23502458 |
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Abstract: | Four carboxylate‐bridged GdIII complexes ( 1 – 4 ) with 1D/2D structures have been synthesized by using the hydrothermal reaction of Gd2O3 with various carboxylate ligands. Compounds 1 and 2 contained the same 2n] GdIII? OH ladders, but with different crystallographically independent GdIII ions, whilst the structures of compounds 3 and 4 were composed of Gd4(μ3‐OH)2(piv)8(H2O)2]2+ units and 1D ladder GdIII chains, respectively. Antiferromagnetic interactions occurred in compounds 1 – 3 , owing to their small Gd? O? Gd angles, whereas ferromagnetic coupling occurred in compound 4 , in which the Gd? O? Gd angles were larger. These complexes exhibited a distinct magnetocaloric effect (MCE), which was affected by their different magnetic densities and exchange interactions. Among these compounds, complex 4 presented the largest MCE (?ΔSmmax=43.6 J kg?1 K?1), the lowest Mw/NGd ratio (the highest magnetic density), and weak ferromagnetic coupling. Therefore, a lower Mw/NGd ratio and weaker exchange interactions (a smaller absolute value of θ) between GdIII ions resulted in a larger MCE for the GdIII complexes. |
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Keywords: | bridging ligands carboxylate ligands gadolinium magnetic properties refrigeration |
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