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Chen QW, Ding YS, Zhu XF, Wang BW, Zheng Z. Substituent Positioning Effects on the Magnetic Properties of Sandwich-Type Erbium(III) Complexes with Bis(trimethylsilyl)-Substituted Cyclooctatetraenyl Ligands. Inorg Chem 2024; 63:9511-9519. [PMID: 38135507 DOI: 10.1021/acs.inorgchem.3c03369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2023]
Abstract
Lanthanide complexes with judiciously designed ligands have been extensively studied for their potential applications as single-molecule magnets. With the influence of ligands on their magnetic properties generally established, recent research has unearthed certain effects inherent to site differentiation due to the different types and varying numbers of substituents on the same ligand platform. Using two new sandwich-type Er(III) complexes with cyclooctatetraenyl (COT) ligands featuring two differently positioned trimethylsilyl (TMS) substituents, namely, [Li(DME)Er(COT1,5-TMS2)2]n (Er1) and [Na(DME)3][Er(COT1,3-TMS2)2] (Er2) [COT1,3-TMS2 and COT1,5-TMS2 donate 1,3- and 1,5-bis(trimethylsilyl)-substituted cyclooctatetraenyl ligands, respectively; DME = 1,2-dimethoxyethane], and with reference to previously reported [Li(DME)3][Er(COT1,4-TMS2)2] (A) and [K(DME)2][Er(COT1,4-TMS2)2] (B), any possible substituent position effects have been explored for the first time. The rearrangement of the TMS substituents from the starting COT1,4-TMS2 to COT1,3-TMS2 and COT1,5-TMS2, by way of formal migration of the TMS group, was thermally induced in the case of Er1, while for the formation of Er2, the use of Na+ in the placement of its Li+ and K+ congeners is essential. Both Er1 and Er2 display single-molecule magnetic behaviors with energy barriers of 170(3) and 172(6) K, respectively. Magnetic hysteresis loops, butterfly-shaped for Er1 and wide open for Er2, were observed up to 12 K for Er1 and 13 K for Er2. Studies of magnetic dynamics reveal the different pathways for relaxation of magnetization below 10 K, mainly by the Raman process for Er1 and by quantum tunneling of magnetization for Er2, leading to the order of magnitude difference in magnetic relaxation times and sharply different magnetic hysteresis loops.
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Affiliation(s)
- Qi-Wei Chen
- School of Chemistry and Life Science, Changchun University of Technology, Changchun 130012, China
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - You-Song Ding
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
- Key University Laboratory of Rare Earth Chemistry of Guangdong, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Xiao-Fei Zhu
- School of Chemistry and Life Science, Changchun University of Technology, Changchun 130012, China
| | - Bing-Wu Wang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Zhiping Zheng
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
- Key University Laboratory of Rare Earth Chemistry of Guangdong, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
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Yang QQ, Wang YF, Wang YX, Tang MJ, Yin B. Ab initio prediction of key parameters and magneto-structural correlation of tetracoordinated lanthanide single-ion magnets. Phys Chem Chem Phys 2023. [PMID: 37401358 DOI: 10.1039/d3cp01766d] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2023]
Abstract
Single-molecule magnets (SMMs) have great potential in becoming revolutionary materials for micro-electronic devices. As one type of SMM and holding the performance record, lanthanide single-ion magnets (Ln-SIMs) stand at the forefront of the family. Lowering the coordination number (CN) is an important strategy to improve the performance of Ln-SIMs. Here, we report a theoretical study on a typical group of low-CN Ln-SIMs, i.e., tetracoordinated structures. Our results are consistent with those of experiments and they identify the same three best Ln-SIMs via a concise criterion, i.e., the co-existence of long τQTM and high Ueff. Compared to the record-holding dysprosocenium systems, the best SIMs here possess τQTM values that are shorter by several orders of magnitude and Ueff values that are lower by ∼1000 Kelvin (K). These are important reasons for the fact that the tetracoordinated Ln-SIMs are clearly inferior to dysprosocenium. A simple but intuitive crystal-field analysis leads to several routes to improve the performance of a given Ln-SIM, including compression of the axial bond length, widening the axial bond angle, elongation of the equatorial bond length and usage of weaker equatorial donor ligands. Although these routes are not brand-new, the most efficient option and the degree of improvement resulting from it are not known in advance. Consequently, a theoretical magneto-structural study, covering various routes, is carried out for the best Ln-SIM here and the most efficient route is shown to be widening the axial ∠O-Dy-O angle. The most optimistic case, having a ∠O-Dy-O of 180°, could have a τQTM (up to 103 s) and Ueff (∼2400 K) close to those of the record-holders. Subsequently, a blocking temperature (TB) of 64 K is predicted to be possible for it. A more practical case, with ∠O-Dy-O being 160°, could have a τQTM of up to 400 s, Ueff of around 2200 K and the possibility of a TB of 57 K. Although having an inherent precision limit, these predictions provide a guide to performance improvement, starting from an existing system.
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Affiliation(s)
- Qi-Qi Yang
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, Lab of Theoretical Molecular Magnetism (LTMM), College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, P. R. China.
| | - Yu-Fei Wang
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, Lab of Theoretical Molecular Magnetism (LTMM), College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, P. R. China.
| | - Yu-Xi Wang
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, Lab of Theoretical Molecular Magnetism (LTMM), College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, P. R. China.
| | - Ming-Jing Tang
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, Lab of Theoretical Molecular Magnetism (LTMM), College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, P. R. China.
| | - Bing Yin
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, Lab of Theoretical Molecular Magnetism (LTMM), College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, P. R. China.
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Tang J, Zhang S, Li L, Yao L, Zhang R, Yin B, Zhang J. Influence of ligand substitution and the solvent effect on the structures and magnetic properties of dinuclear Dy 2 supramolecular architectures constructed with the bis-β-diketonate-Dy 2 building block as a metalloligand. Dalton Trans 2023; 52:1366-1377. [PMID: 36633156 DOI: 10.1039/d2dt03468a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Based on the bis-β-diketonate-Dy2 metalloligand [Dy2(pbth)4]·2Et3N (1, pbth = (3z,3'z)-4,4'-(1,3-phenylene)bis(1,1,1-trifluoro-4-hydroxybut-3-en-2-one)), six dinuclear complexes with eight-coordinated geometries were synthesized solvothermally through different capping N-donor coligands or solvent systems. These complexes are namely [Dy2(pbth)3(Phen)2]·2C2H5OH (2), [Dy2(pbth)3(BPhen)2]·2C2H5OH (3), [Dy2(pbth)3(Dppz)2]·2C2H5OH (4), [Dy2(pbth)3(Dppz)2]·2CH3OH (4a), [Dy2(pbth)3(4-Dmbp)2]·CH3OH·C2H5OH (5) and [Dy2(pbth)3(5-Dmbp)2]·CH3OH (6) (Phen = 1,10-phenanthroline, BPhen = 4,7-diphenyl-1,10-phenanthroline, dppz = dipyrido [3,2-a:2',3'-c] phenazine, 4-Dmbp = 4,4'-dimethyl-2,2'-bipyridyl, 5-Dmbp = 5,5'-dimethyl-2,2'-bipyridyl), respectively. In the synthetic processes of 2-6, one of four bis-β-diketonate ligands in the metalloligand is replaced by two capping N-donor coligands. The coordination geometries, metal distances and M-L-M torsion angles of the synthesized complexes are perceptibly fine-tuned by the modification of the capping N-donor coligands or the latticed solvent molecules. Systematic magnetic investigations indicate the different magnetic relaxation dynamics of 1-6. Complex 1 displays no characteristics of single-molecule magnets (SMMs), while complexes 2-6 exhibit SMM behaviours in the absence of a static magnetic field. Complexes 2 and 3 possess effective energy barriers (Ueff) of 110.18 (2) K and 133.21 (4) K, respectively. Theoretical analysis based on ab initio calculation provides some interpretations of experimental observation.
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Affiliation(s)
- Jiamin Tang
- School of Science, Hainan University, Haikou 570228, China.
| | - Sheng Zhang
- School of Science, Hainan University, Haikou 570228, China.
| | - Linzhou Li
- School of Science, Hainan University, Haikou 570228, China.
| | - Linbin Yao
- School of Science, Hainan University, Haikou 570228, China.
| | - Ronghu Zhang
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou 570228, China. .,Institute of Processing&Design of Agroproducts, Hainan Academy of Agricultural Science, Haikou 571100, China
| | - Bing Yin
- Lab of Theoretical Molecular Magnetism (LTMM), College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, P. R. China.
| | - Jiangwei Zhang
- Science Center of Energy Material and Chemistry, College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, P. R. China.
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Qin Y, Wu Y, Luo S, Xi J, Guo Y, Ding Y, Zhang J, Liu X. Modulation of the magnetic dynamics of pentagonal-bipyramidal Co( ii) complexes by fine-tuning the coordination microenvironment. Dalton Trans 2022; 51:17089-17096. [DOI: 10.1039/d2dt02345h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dynamic magnetic behaviours of a series of Co(ii) SIMs with pentagonal-bipyramidal geometry have been modulated by an alteration of the ligand field effect.
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Affiliation(s)
- Yuanyuan Qin
- State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China
| | - Yuewei Wu
- State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China
| | - Shuchang Luo
- College of Chemical Engineering, Guizhou University of Engineering Science, Bijie 551700, China
| | - Jing Xi
- State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China
| | - Yan Guo
- State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China
| | - Yi Ding
- State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China
| | - Jun Zhang
- State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China
| | - Xiangyu Liu
- State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China
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