Boosting the mono-axial crystal field in stable high-coordinate Dy(III) single-ion magnets by substitution of the phenoxy axial ligand

Ben Zhang; Yang Zhou; Chang Dong; Yi Xiang; Yanbo Shi; Chennan Zhang; Aihua Yuan; Shaojun Zheng; Zhao-Yang Li; Yi-Quan Zhang; Yong Yang; Lei Chen

doi:10.1039/d3dt01318a

Boosting the mono-axial crystal field in stable high-coordinate Dy(III) single-ion magnets by substitution of the phenoxy axial ligand

Dalton Trans. 2023 Aug 1;52(30):10465-10471. doi: 10.1039/d3dt01318a.

Authors

Ben Zhang¹, Yang Zhou¹, Chang Dong¹, Yi Xiang¹, Yanbo Shi¹, Chennan Zhang¹, Aihua Yuan¹, Shaojun Zheng¹, Zhao-Yang Li², Yi-Quan Zhang³, Yong Yang⁴, Lei Chen¹

Affiliations

¹ School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, PR China. chenlei@just.edu.cn.
² School of Materials Science and Engineering, Nankai University, Tianjin 300350, PR China. zhaoyang@nankai.edu.cn.
³ Jiangsu Key Laboratory for NSLSCS, School of Physical Science and Technology, Nanjing Normal University, Nanjing 210023, PR China. zhangyiquan@njnu.edu.cn.
⁴ College of Mechanical Engineering, Suzhou University of Science and Technology, Suzhou 215009, PR China.

PMID: 37439635
DOI: 10.1039/d3dt01318a

Abstract

Synthesis of air-stable and high-performance single-molecule magnets (SMMs) is challenging. Here, a heptadentate pentapyridyldiamine (BPA-TPA) ligand and fine-tuned axial phenoxy ligands are used to synthesize two triangular dodecahedral Dy(III) complexes [Dy(BPA-TPA)(4-methoxy-PhO)](BPh₄)₂·3CH₂Cl₂ (4) and [Dy(BPA-TPA)(2,4-dimethyl-PhO)](BPh₄)₂·0.85CH₂Cl₂ (5). Both complexes have high effective barriers exceeding 400 K and magnetic hysteresis up to 8 K, which is ascribed to one strong and short Dy-O bond combined with seven weak Dy-N bonds. Ab initio calculations reveal the thermally activated quantum tunneling of magnetization through the first excited Kramers doublet, due to the presence of a strong axial Dy-O crystal ligand. Substitution of the phenoxy ligand leads to more constrained vibrations, improving the magnetic hysteresis behavior for 5.