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Influence of Peripheral Substitution on the Magnetic Behavior of Single-Ion Magnets Based on Homo- and Heteroleptic TbIII Bis(phthalocyaninate)

Authors

  • Carolina R. Ganivet,

    1. Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain), Fax: (+34) 914973966
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    • These authors contributed equally to this work.

  • Dr. Beatriz Ballesteros,

    1. Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain), Fax: (+34) 914973966
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    • These authors contributed equally to this work.

  • Dr. Gema de la Torre,

    1. Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain), Fax: (+34) 914973966
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  • Dr. Juan M. Clemente-Juan,

    1. Instituto de Ciencia Molecular, Universidad de Valencia c/Catedrático José Beltrán, 2, 46980 Paterna (Spain)
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  • Prof. Eugenio Coronado,

    Corresponding author
    1. Instituto de Ciencia Molecular, Universidad de Valencia c/Catedrático José Beltrán, 2, 46980 Paterna (Spain)
    • Instituto de Ciencia Molecular, Universidad de Valencia c/Catedrático José Beltrán, 2, 46980 Paterna (Spain)
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  • Prof. Tomás Torres

    Corresponding author
    1. Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain), Fax: (+34) 914973966
    2. IMDEA Nanociencia, c/Faraday, 9, Cantoblanco, 28049 Madrid (Spain)
    • Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain), Fax: (+34) 914973966
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Abstract

A series of homoleptic ([TbIII(Pc)2]) and heteroleptic ([TbIII(Pc)(Pc′)]) TbIII bis(phthalocyaninate) complexes that contain different peripheral substitution patterns (i.e., tert-butyl or tert-butylphenoxy groups) have been synthesized in their neutral radical forms and then reduced into their corresponding anionic forms as stable tetramethylammonium/tetrabutylammonium salts. All of these compounds were spectroscopically characterized and their magnetic susceptibility properties were investigated. As a general trend, the radical forms exhibited larger energy barriers for spin reversal than their corresponding reduced compounds. Remarkably, heteroleptic complexes that contain electron-donor moieties on one of the two Pc ligands show higher effective barriers and blocking temperatures than their homoleptic derivatives. This result is assigned to the elongation of the N[BOND]Tb distances in the substituted macrocycle, which brings the terbium(III) ion closer to the unsubstituted Pc, thus enhancing the ligand-field effect. In particular, heteroleptic [TbIII(Pc)(Pc′)] complex 4, which contains one octa(tert-butylphenoxy)-substituted Pc ring and one bare Pc ring, exhibits the highest effective barrier and blocking temperature for a single-molecule magnet reported to date.

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