doi:10.3390/molecules26185626engArauzo, AnaBartolomé, ElenaLuzón, JavierAlonso, Pablo J.Vlad, AngelicaCazacu, MariaZaltariov, Mirela F.Shova, SergiuBartolomé, JuanTurta, ConstantinSlow magnetic relaxation in {[CoCxAPy)] 2.15 H2O}n mof built from ladder-structured 2D layers with dimeric SMM rungsART-2021-125798We 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.2021http://zaguan.unizar.es/record/13594910.3390/molecules26185626http://zaguan.unizar.es/record/135949oai:zaguan.unizar.es:135949info:eu-repo/grantAgreement/ES/DGA/E12-20Rinfo:eu-repo/grantAgreement/ES/MICINN/PGC2018-099024-B-I00info:eu-repo/grantAgreement/ES/MINECO/MAT2017-83468-RMolecules 26, 18 (2021), 5626 [26 pp.]byhttp://creativecommons.org/licenses/by/3.0/es/info:eu-repo/semantics/openAccess