Magneto-thermal properties and slow magnetic relaxation in Mn(ii)Ln(iii) complexes: influence of magnetic coupling on the magneto-caloric effect

Autor: Itziar Oyarzabal, Andoni Zabala-Lekuona, Antonio J. Mota, María A. Palacios, Antonio Rodríguez-Diéguez, Giulia Lorusso, Marco Evangelisti, Corina Rodríguez-Esteban, Euan K. Brechin, José M. Seco, Enrique Colacio
Přispěvatelé: Junta de Andalucía, Agencia Estatal de Investigación (España), Ministerio de Ciencia, Innovación y Universidades (España), Universidad de Granada, Universidad del País Vasco, Gobierno de Aragón, European Commission
Rok vydání: 2022
Předmět:
Zdroj: Oyarzabal, I, Zabala-lekuona, A, Mota, A J, Palacios, M A, Rodríguez Diéguez, A, Lorusso, G, Evangelisti, M, Rodríguez-esteban, C, Brechin, E K, Seco, J M & Colacio, E 2022, ' Magneto-thermal properties and slow magnetic relaxation in Mn(II)Ln(III) complexes: Influence of magnetic coupling on the magneto-caloric effect ', Dalton Transactions . https://doi.org/10.1039/D2DT01869A
ISSN: 1477-9234
1477-9226
DOI: 10.1039/d2dt01869a
Popis: A family of Mn(II)Ln(III) dinuclear and tetranuclear complexes (Ln = Gd and Dy) has been prepared from the compartmental ligands N,N′-dimethyl-N,N′-bis(2-hydroxy-3-formyl-5-bromobenzyl)ethylenediamine (H2L1) and N,N′,N′′-trimethyl-N,N′′-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H2L2). The Mn(II)Gd(III) complexes exhibit antiferromagnetic interactions between Mn(II) and Gd(III) ions in most cases, which are supported by Density Functional Theory (DFT) calculations. Experimental magneto-structural correlations carried out for the reported complexes and other related complexes found in bibliography show that the highest ferromagnetic coupling constants are observed in di-μ-phenoxido bridged complexes, which is due to the planarity of the Mn–(μ-O)2–Gd bridging fragment and to the high Mn–O–Gd angles. The effect of these angles has been studied by DFT calculations performed on a di-μ-phenoxido doubly bridged model. The magneto-thermal properties of the Mn(II)Gd(III) based complexes have also been measured, concluding that the magnitude of the Magneto-Caloric Effect (MCE) is due to the strength rather than to the nature of the magnetic coupling. Moreover, when two Mn(II)Gd(III) dinuclear units are connected by two carbonato-bridging ligands the MCE is enhanced, obtaining a maximum magnetic entropy change of 36.4 Jkg−1 K−1 at ΔB = 7 T and T = 2.2 K. On the other hand, one of the dinuclear Mn(II)Dy(III) complexes displays Single-Molecule Magnet (SMM) behaviour with an energy barrier of 14.8 K under an applied external field of 1000 Oe.
This work was supported by the Junta de Andalucía (FQM-195 and the Project I + D + i FEDER 2018, A-FQM-172-UGR), MICIU of Spain (Projects PGC2018-102052-B-C21 and RTI2018-098537-B-C22), the University of Granada, the University of The Basque Country UPV/EHU (GIU20/028) and the Gobierno de Aragón (E11 20R). We would like to thank the Centro de Supercomputación de la Universidad de Granada for computational resources. The authors acknowledge the technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF).
Databáze: OpenAIRE
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