Manipulation of the Coordination Geometry along the C4 Rotation Axis in a Dinuclear Tb3+ Triple-Decker Complex via a Supramolecular Approach.
Chemistry
; 26(21): 4805-4815, 2020 Apr 09.
Article
em En
| MEDLINE
| ID: mdl-31984579
ABSTRACT
A supramolecular complex (1â
C60 ) was prepared by assembling (C60-Ih)[5,6]fullerene (C60 ) with the dinuclear Tb3+ triple-decker complex [(TPP)Tb(Pc)Tb(TPP)] (1 Tb3+ =trivalent terbium ion, Pc2- =phthalocyaninato, TPP2- =tetraphenylporphyrinato) with quasi-D4h symmetry to investigate the relationship between the coordination symmetry and single-molecule magnet (SMM) properties. Tb3+ -Pc triple-decker complexes (Tb2 Pc3 ) have an important advantage over Tb3+ -Pc double-decker complexes (TbPc2 ) since the magnetic relaxation processes correspond to the Zeeman splitting when there are two 4f spin systems. The two Tb3+ sites of 1 are equivalent, and the twist angle (φ) was determined to be 3.62°. On the other hand, the two Tb3+ sites of 1â
C60 are not equivalent. The φ values for sites Tb1 and Tb2 were determined to be 3.67° and 33.8°, respectively, due to a change in the coordination symmetry of 1 upon association with C60 . At 1.8â
K, 1 and 1â
C60 undergo different magnetic relaxations, and the changes in the ground state affect the spin dynamics. Although 1 and 1â
C60 relax via QTM in a zero applied magnetic field (H), H dependencies of the magnetic relaxation times (τ) for H>1500â
Oe are similar. On the other hand, for H<1500â
Oe, the τ values have different behaviors since the off-diagonal terms ( B k q ; q ≠ 0 ) affect the magnetic relaxation mechanism. From temperature (T) and H dependences of τ, spin-phonon interactions along with direct and Raman mechanisms explain the spin dynamics. We believe that a supramolecular method can be used to control the magnetic anisotropy along the C4 rotation axis and the spin dynamic properties in dinuclear Ln3+ -Pc multiple-decker complexes.
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01-internacional
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MEDLINE
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article