Chiral Pseudo-<i>D</i><sub>6h</sub> Dy(III) Single-Molecule Magnet Based on a Hexaaza Macrocycle
A mononuclear complex [Dy(phenN<sub>6</sub>)(HL′)<sub>2</sub>]PF<sub>6</sub>·CH<sub>2</sub>Cl<sub>2</sub> (H<sub>2</sub>L′ = <i>R</i>/<i>S</i>-1,1′-binaphthyl-2,2′-diphenol) with local <i>D</i>...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-05-01
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| Series: | Molecules |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1420-3049/30/9/2043 |
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| Summary: | A mononuclear complex [Dy(phenN<sub>6</sub>)(HL′)<sub>2</sub>]PF<sub>6</sub>·CH<sub>2</sub>Cl<sub>2</sub> (H<sub>2</sub>L′ = <i>R</i>/<i>S</i>-1,1′-binaphthyl-2,2′-diphenol) with local <i>D</i><sub>6h</sub> symmetry was synthesized. Structural determination shows that Dy<sup>3+</sup> was encapsulated within the coordination cavity of the neutral hexaaza macrocyclic ligand phenN<sub>6</sub>, forming a non-planar coordination environment. The axial positions are occupied by two phenoxy groups of binaphthol in the <i>trans</i> form. The local geometry of Dy<sup>3+</sup> closely resembles a regular hexagonal bipyramid <i>D</i><sub>6h</sub> configuration. The axial Dy-O<sub>phenoxy</sub> distances are 2.189(5) and 2.145(5) Å, respectively, while the Dy-N bond lengths in the equatorial plane are in the range of 2.524(7)–2.717(5) Å. The axial O<sub>phthalmoxy</sub>-Dy-O<sub>phthalmoxy</sub> bond angle is 162.91(17)°, which deviates from the ideal linearity. Under the excitation at 320 nm, the complex exhibits a characteristic emission peak at 360 nm, corresponding to the naphthalene ring. The AC susceptibility measurements under an applied DC field of 1800 Oe show distinct temperature-dependent and frequency-dependent AC magnetic susceptibility, typical of single-molecule magnetic behavior. The Cole–Cole plot in the temperature range of 6.0–28.0 K was fitted using a model incorporating Orbach and Raman relaxation mechanisms, giving an effective energy barrier of <i>U</i><sub>eff</sub> = 300.2 K. Theoretical calculations on complex <b>1</b> reveal that the magnetization relaxation proceeds through the first excited Kramers doublets with a calculated magnetization blocking barrier of 404.1 cm<sup>−1</sup> (581.4 K). |
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| ISSN: | 1420-3049 |