Influence of the Coordinated Transition Metal Ion on Magnetic Relaxation of Lanthanide Based Complexes with Imino Nitroxide Biradical Ligands |
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| Authors: | Dr Lu Xi Chaoyi Jin Hongwei Song Xiaotong Wang Junfang Xie Prof Yue Ma Prof Jinkui Tang Prof Licun Li |
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| Institution: | 1. Key Laboratory of Advanced Energy Materials Chemistry, Department of Chemistry, College of Chemistry, Nankai University, Tianjin, 300071 China;2. State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 China |
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| Abstract: | In spite of achievement of a lot of Ln-radical SMMs, how to improve magnetic behavior of Ln-radical system remains challenging. Here, two series of Ln-radical complexes have successfully been built using an imino nitroxide biradical, namely, Ln2(hfac)6(ImPhPyobis)2] (LnIII=Gd 1 , Tb 2 , Dy 3 ) and Ln2Cu2(hfac)10(ImPhPyobis)2] (LnIII=Gd 4 , Dy 5 ; hfac=hexafluoroacetylacetonate and ImPhPyobis=5-(4-oxypyridinium-1-yl)-1,3-bis(1’-oxyl-4’,4’,5’,5’-tetramethyl-4,5-hydro-1H-imidazol-2-yl)benzene). For these biradical-metal complexes, two imino nitroxide biradicals bind two Ln(III) ions via their oxygen atoms coming from 4-oxypyridinium units to produce a binuclear {Ln2O2} unit. Those imino nitroxide groups are free for complexes 1 – 3 , however one of imino nitroxide groups of the biradical is ligated to the copper(II) ion for complexes 4 and 5 . The distinct magnetic relaxation behaviors are observed for two Dy derivatives, as revealed by ac magnetic studies: complex 3 presents one magnetic process with the effective energy barrier(Ueff) of 74.0 K while complex 5 exhibits dual relaxation processes with Ueff values for the fast- and slow-relaxation being 20.2 K and 30.9 K, respectively, which implies that the second coordination sphere of Dy ion plays a critical role for magnetic relaxation. |
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| Keywords: | imino nitroxide biradical lanthanides molecular magnetism magnetic relaxation SMMs |
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