Enhancement of TbIII–CuII single-molecule magnet performance through structural modification

Heras Ojea, María José and Milway, Victoria A. and Velmurugan, Gunasekaran and Thomas, Lynne H. and Coles, Simon J. and Wilson, Claire and Wernsdorfer, Wolfgang and Rajaraman, Gopalan and Murrie, Mark (2016) Enhancement of TbIII–CuII single-molecule magnet performance through structural modification. Chemistry - A European Journal, 22 (36). pp. 12839-12848. ISSN 0947-6539 (https://doi.org/10.1002/chem.201601971)

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Abstract

We report a series of 3d–4f complexes {Ln2Cu3(H3L)2Xn} (X=OAc−, Ln=Gd, Tb or X=NO3−, Ln=Gd, Tb, Dy, Ho, Er) using the 2,2′-(propane-1,3-diyldiimino)bis[2-(hydroxylmethyl)propane-1,3-diol] (H6L) pro-ligand. All complexes, except that in which Ln=Gd, show slow magnetic relaxation in zero applied dc field. A remarkable improvement of the energy barrier to reorientation of the magnetisation in the {Tb2Cu3(H3L)2Xn} complexes is seen by changing the auxiliary ligands (X=OAc− for NO3−). This leads to the largest reported relaxation barrier in zero applied dc field for a Tb/Cu-based single-molecule magnet. Ab initio CASSCF calculations performed on mononuclear TbIII models are employed to understand the increase in energy barrier and the calculations suggest that the difference stems from a change in the TbIII coordination environment (C4v versus Cs).

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