Slow magnetic relaxation and antiferromagnetic ordering in a one dimensional nitronyl nitroxide–Tb(iii) chain

Abstract

Reaction of the nitronyl nitroxide radical NIT-3Brthien with Ln(hfac) 3 affords two onedimensional lanthanide-nitronyl nitroxide compounds [Ln(hfac) 3 (NIT-3Brthien)] (Ln = Gd(III) 1, Tb(III) 2; NIT-3Brthien = 2-(3 0 -bromo-2 0 -thienyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide). Single crystal X-ray crystallographic analysis reveals that both compounds are composed of linear chains built up by Ln(hfac) 3 units bridged by NIT-5Brthien radicals through their NO groups. DC magnetic measurements reveal that the Gd complex is paramagnetic above 2.0 K, while the Tb complex orders antiferromagnetically at 4.0 K. Moreover, complex 2 possesses frequencydependence of ac magnetic susceptibilities. The magnetic behavior of complex 2 is unique and exhibits the coexistence of slow magnetic relaxation, metamagnetism and antiferromagnetic threedimensional magnetic ordering. Experimental Materials and physical measurementsAll chemicals and solvents used for the syntheses were of analytical grade and were used without further purification. The radical ligand NIT-3Brthien was prepared according to a literature method. 11 Elemental analyses for C, H, and N were

Metal–Organic Framework Magnets

“…A number of structurally characterized 1D chain compounds have been reported to exhibit long-range magnetic order. ,− This class includes metalloporphyrin-based magnets comprising linear chains of [Mn III (TPP)] + (TPP 2– = meso -tetraphenylporphyrinato) or [Mn III (TXPP)] + [TXPP 2– = meso -tetrakis­(4-halophenyl)­porphyrinato; X = F, Cl, Br, or I] cations and TCNE –• or QCl 4 –• (QCl 4 = tetrachloro-1,4-benzoquinone) radical anions. − These materials behave as ferrimagnets or canted antiferromagnets with ordering temperatures in the range of 3.5–28 K, owing to antiferromagnetic coupling between S = 2 Mn III centers and S = 1 / 2 radical anions. However, complicated spin glass or metamagnetic behaviors are frequently observed at low temperatures.…”

Magnetic Slow Relaxation in a Metal–Organic Framework Made of Chains of Ferromagnetically Coupled Single‐Molecule Magnets

“…2) The topology of the magnetic MOFs is able to induce magnetic behavior unobservable on the isolated MBBs such as dynamic magnetic behavior upon external stimuli or upon host–guest removal . Even non‐porous MOFs can be appealing as the constraint on the chemical environment of the MBB can induce a strong magnetocaloric effect (MCE) or three‐dimensional (3D) magnetic ordering . This last feature implies strong magnetic interactions between the MBBs and we will focus on this particular point in this paper.…”

Field Induced Slow Magnetic Relaxation in a Non Kramers Tb(III) Based Single Chain Magnet

“…The systematic analysis of the co-ordination geometry around the metal centre using SHAPE 2.1 program [51] reveals the approximately triangular dodecahedron coordination sphere of the Tb(III) in complex 1 with D 2d geometry having the agreement factor of 0.723 (detailed geometric analysis is described in Table S2). A detailed comparisons reveal that the complex 1 has an apparent shortest Tb1−O1 bond (2.230(2) Å) as compared to already known Tb(III) based single chain magnets [43] (Table S4). The appearance of the shortest Tb1−O1 hydroxyl bond may significantly increase the single-ion anisotropy of the oblate Tb(III) spin responsible for the slow magnetic relaxation.…”

“…Along the crystallographic a axis, the Tb(III) ions are bridged by pairs of µ 2 -H 2 O and µ 2 -OH − groups to generate an infinite zig-zag chain (Figure 1c). The bridging angles of ∠Tb1-O2/O1-Tb1 1 [43,44] Table S3). This leads to the generation of a two-dimensional layer ( Figure 2) with interchain Tb .…”

“…In 2012, Pasca et al reported a cyanido bridged one dimensional chain of tungsten and terbium [42]. In 2012, Liu et al and in 2014, Hu et al reported Tb(III) based 1D chain where the bridging ligand was the basic unit of nitronyl nitroxide based radical [43,44]. In 2016, Turta et al reported a carboxylate bridged Tb(III) SCM by using α-furon carboxylic acid [41].…”