Slow magnetic relaxation in {[CoCxAPy)] 2.15 H2O}n mof built from ladder-structured 2D layers with dimeric SMM rungs

Arauzo, Ana (Universidad de Zaragoza) ; Bartolomé, Elena ; Luzón, Javier ; Alonso, Pablo J. ; Vlad, Angelica ; Cazacu, Maria ; Zaltariov, Mirela F. ; Shova, Sergiu ; Bartolomé, Juan (Universidad de Zaragoza) ; Turta, Constantin

Resumen: We present the magnetic properties of the metal-organic framework {[CoCxAPy]·2.15 H2O}n (Cx = bis(carboxypropyl)tetramethyldisiloxane; APy = 4, 4`-azopyridine) (1) that builds up from the stacking of 2D coordination polymers. The 2D-coordination polymer in the bc plane is formed by the adjacent bonding of [CoCxAPy] 1D two-leg ladders with Co dimer rungs, running parallel to the c-axis. The crystal packing of 2D layers shows the presence of infinite channels running along the c crystallographic axis, which accommodate the disordered solvate molecules. The Co(II) is six-coordinated in a distorted octahedral geometry, where the equatorial plane is occupied by four carboxylate oxygen atoms. Two nitrogen atoms from APy ligands are coordinated in apical positions. The single-ion magnetic anisotropy has been determined by low temperature EPR and magnetization measurements on an isostructural compound {[Zn0.8Co0.2CxAPy]·1.5 CH3OH}n (2). The results show that the Co(II) ion has orthorhombic anisotropy with the hard-axis direction in the C2V main axis, lying the easy axis in the distorted octahedron equatorial plane, as predicted by the ab initio calculations of the g-tensor. Magnetic and heat capacity properties at very low temperatures are rationalized within a S* = 1/2 magnetic dimer model with anisotropic antiferromagnetic interaction. The magnetic dimer exhibits slow relaxation of the magnetization (SMM) below 6 K in applied field, with a tlf ˜ 2 s direct process at low frequencies, and an Orbach process at higher frequencies with U/kB = 6.7 ± 0.5 K. This compound represents a singular SMM MOF built-up of Co-dimers with an anisotropic exchange interaction.

Idioma: Inglés

DOI: 10.3390/molecules26185626

Año: 2021

Publicado en: Molecules 26, 18 (2021), 5626 [26 pp.]
ISSN: 1420-3049

Factor impacto JCR: 4.927 (2021)

Categ. JCR: CHEMISTRY, MULTIDISCIPLINARY rank: 65 / 179 = 0.363 (2021) - Q2 - T2
Categ. JCR: BIOCHEMISTRY & MOLECULAR BIOLOGY rank: 114 / 297 = 0.384 (2021) - Q2 - T2

Factor impacto CITESCORE: 5.9 - Pharmacology, Toxicology and Pharmaceutics (Q2) - Biochemistry, Genetics and Molecular Biology (Q2)

Factor impacto SCIMAGO: 0.705 - Analytical Chemistry (Q1) - Drug Discovery (Q1) - Pharmaceutical Science (Q1) - Molecular Medicine (Q1) - Organic Chemistry (Q1) - Medicine (miscellaneous) (Q1)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E12-20R
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PGC2018-099024-B-I00
Financiación: info:eu-repo/grantAgreement/ES/MINECO/MAT2017-83468-R

Tipo y forma: Article (Published version)

Área (Departamento): Servicios. Div.Caract.Físi.Quí (Serv.Gral. Apoyo Investigación)
Área (Departamento): Área Física Materia Condensada (Dpto. Física Materia Condensa.)