Assembly of Lanthanide(III) Cubanes and Dimers with Single-Molecule Magnetism and Photoluminescence

Discrete lanthanide­(III) tetranuclear cubane-like clusters seldom occur throughout the LnIII series and behave as single-molecule magnets (SMMs). Herein, a series of cubanes, [Ln4(μ3-OH)4(μ-tfa)4(hfa)4(phen)4] (1–9, Ln = La–Dy (except Pm), tfa = trifluoroacetate, hfa = hexafluoroacetylacetonate, ph...

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Published in:Inorganic chemistry 2018-06, Vol.57 (12), p.6893-6902
Main Authors: Wong, Ho-Yin, Chan, Wesley Ting Kwok, Law, Ga-Lai
Format: Article
Language:English
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Summary:Discrete lanthanide­(III) tetranuclear cubane-like clusters seldom occur throughout the LnIII series and behave as single-molecule magnets (SMMs). Herein, a series of cubanes, [Ln4(μ3-OH)4(μ-tfa)4(hfa)4(phen)4] (1–9, Ln = La–Dy (except Pm), tfa = trifluoroacetate, hfa = hexafluoroacetylacetonate, phen = 1,10-phenanthroline), and dinuclear clusters, [Ln2(μ-OH)2­(hfa)4(phen)2] (10–16, Ln = Tb–Lu), were synthesized and characterized. Two types of clusters were formed due to the change of preferred coordination geometry for lighter and heavier LnIII ions which favor nine-coordinated cubanes and eight-coordinated dimers, respectively. A magnetic study shows that 8-Tb4 and 9-Dy4 are ferromagnetically coupled and SMM in nature because of the larger Ln···Ln distance compared to other discrete cubanes. The anisotropic barriers, U eff, of 9-Dy4 are determined to be 67.0 K. In addition, the photophysical properties of 6-Eu4, 8-Tb4, and 10-Tb2 owing to tfa, hfa, and phen sensitization and O–H quenching are discussed.
ISSN:0020-1669
1520-510X
DOI:10.1021/acs.inorgchem.8b00505