Embedding 1D or 2D cobalt-carboxylate substrates in 3D coordination polymers exhibiting slow magnetic relaxation behaviors: crystal structures, high-field EPR, and magnetic studies

By utilizing well-designed bifunctional ligands derived from 1H-imidazole-4,5-dicarboxylic acid, magnetic coordination polymers (CPs) that exhibit slow magnetic relaxation at the low temperature regions were constructed and further structurally characterized. In 1, 1D cobalt-carboxyl chains were sta...

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Published in:Dalton transactions : an international journal of inorganic chemistry 2017-04, Vol.46 (14), p.4786-4795
Main Authors: Mao, Nannan, Zhang, Biquan, Yu, Fan, Chen, Xi, Zhuang, Gui-Lin, Wang, Zhenxing, Ouyang, Zhongwen, Zhang, Tianle, Li, Bao
Format: Article
Language:English
Subjects:
Carboxylates
Computer simulation
Coordination polymers
Coupling (molecular)
Density functional theory
Ligands
Magnetic relaxation
Mathematical analysis
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Summary:By utilizing well-designed bifunctional ligands derived from 1H-imidazole-4,5-dicarboxylic acid, magnetic coordination polymers (CPs) that exhibit slow magnetic relaxation at the low temperature regions were constructed and further structurally characterized. In 1, 1D cobalt-carboxyl chains were stabilized in the final structure. In contrast, by adjusting the length of the substituted arms on imidazole-4,5-dicarboxylic acid, a novel 3D CP, 2 containing 2D 6 cobalt-carboxyl layer was obtained. A combination of Quantum Monte Carlo (QMC) simulations and the first-principles Density functional theory (DFT) calculations showed that compound 2 features weak ferro- and antiferro-magnetic coupling mechanisms with two different super-exchange paths of -/+/- for syn-anti carboxylate bridges and -/-/- for syn-syn carboxylate bridges. Through HF-EPR measurements performed on polycrystalline samples over the frequency range of 60-260 GHz and field range of 0-12 T, the effective g-values of 1 and 2 were all larger than 2.00, and the signs of their D values were probably positive.
ISSN:1477-9226
1477-9234
DOI:10.1039/c7dt00168a