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Influence of peripheral substitution on the magnetic behavior of single-ion magnets based on homo- and heteroleptic Tb(III) bis(phthalocyaninate).
Chemistry ; 19(4): 1457-65, 2013 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-23197446
ABSTRACT
A series of homoleptic ([Tb(III)(Pc)(2) ]) and heteroleptic ([Tb(III)(Pc)(Pc')]) Tb(III) 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-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 [Tb(III) (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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Texto completo: Disponível Coleções: Bases de dados internacionais Base de dados: MEDLINE Idioma: Inglês Revista: Chemistry Assunto da revista: Química Ano de publicação: 2013 Tipo de documento: Artigo País de afiliação: Espanha