Slow Magnetic Relaxation Research Articles

Magnetic Relaxations of Chromium Nitride Porphyrinato Complexes Driven by the Anisotropic g-Factor.

Molecule-based magnetic materials are useful candidates as the spin qubit due to their long coherence time and high designability. The anisotropy of the g-values of the metal complexes can be utilized to access the individual spin of the metal complexes, making it possible to achieve the scalable molecular spin qubit. For this goal, it is important to evaluate the effect of g-value anisotropy on the magnetic relaxation behaviour. This study reports the slow magnetic relaxation behaviour of chromium nitride (CrN2+ ) porphyrinato complex (1), which is structurally and magnetically similar with the vanadyl (VO2+ ) porphyrinato complex (2) which is known as the excellent spin qubit. Detailed analyses for vibrational and dynamical magnetism of 1 and 2 revealed that g-value anisotropy accelerates magnetic relaxations greater than the internal magnetic field from nuclear spin does. These results provide a design criterion for construction of multiple spin qubit based on g-tensor engineering.

Honey-like Odor Meets Single-Ion Magnet: Synthesis, Crystal Structure, and Magnetism of Cobalt(II) Complex with Aromatic Trans-Cinnamic Acid

The hexacoordinate Co(II) complex [Co(neo)2(cin)][BPh4]·½Me2CO (1·½Me2CO) containing trans-cinnamic acid (Hcin) and neocuproine (neo) was prepared. The compound 1·½Me2CO was characterized via single-crystal X-ray analysis, FT-IR spectroscopy, and magnetic measurements. The coordination polyhedron of the complex cation adopts a deformed octahedron shape, and cinnamate exhibits a bidentate mode of coordination, which is unusual for mononuclear Co(II) cinnamate complexes. The analysis of DC magnetic measurements with zero-field splitting (ZFS) spin Hamiltonian revealed large magnetic anisotropy defined by the axial ZFS parameter D = +53.2 cm−1. AC susceptibility measurements revealed the slow relaxation of magnetization under the applied field; thus, 1·½Me2CO behaves as a field-induced single-molecule magnet. The analysis of magnetic properties was also supported by CASSCF/NEVPT2 calculations.

Slow Magnetic Relaxation in Silver(II) Macrocyclic Systems.

The spin-lattice relaxation time has been studied trough alternating-current susceptometry and ultralow-frequency Raman spectroscopy in a family of silver(II)-derived molecular systems with spin 1/2 and formulas [AgII(m-CTH)(NO3)2] (1) and [AgII(m-CTH)(ClO4)2] (2), where CTH = meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane. The combination of both techniques demonstrates the occurrence of slow spin magnetic relaxation induced by spin-phonon interaction. The magnetic behavior of these silver(II)-derived systems opens the door to a new cation in the scarce family of S = 1/2 systems with slow relaxation of magnetization.

Nd─Nd Bond in Ih and D5h Cage Isomers of Nd2 @C80 Stabilized by Electrophilic CF3 Addition.

Synthesis of molecular compounds with metal-metal bonds between 4f elements is recognized as one of the fascinating milestones in lanthanide metallochemistry. The main focus of such studies is on heavy lanthanides due to the interest in their magnetism, while bonding between light lanthanides remains unexplored. In this work, the Nd─Nd bonding in Nd-dimetallofullerenes as a case study of metal-metal bonding between early lanthanides is demonstrated. Combined experimental and computational study proves that pristine Nd2 @C80 has an open shell structure with a single electron occupying the Nd─Nd bonding orbital. Nd2 @C80 is stabilized by a one-electron reduction and further by the electrophilic CF3 addition to [Nd2 @C80 ]- . Single-crystal X-ray diffraction reveals the formation of two Nd2 @C80 (CF3 ) isomers with D5h -C80 and Ih -C80 carbon cages, both featuring a single-electron Nd─Nd bond with the length of 3.78-3.79 Å. The mutual influence of the exohedral CF3 group and endohedral metal dimer in determining the molecular structure of the adducts is analyzed. Unlike Tb or Dy analogs, which are strong single-molecule magnets with high blocking temperature of magnetization, the slow relaxation of magnetization in Nd2 @Ih -C80 (CF3 ) is detectable via out-of-phase magnetic susceptibility only below 3 K and in the presence of magnetic field.

Formation of a single-ion magnet in the lanthanum calcium silicate apatite structure by the cobalt oxide doping

A small amount of cobalt was incorporated into the lanthanum calcium silicate apatite structure by annealing at 1500 °C in argon. The compound exhibits easy-axis magnetic anisotropy with a zero-field splitting parameter 2D of −60 cm−1 and field- induced slow relaxation of magnetization with a remagnetization energy barrier of 58–63 cm−1. Thereby, for the first time, a cobalt-based single-ion magnet was created in silicate.

Identification of Favorable Silica Surface Sites for Single‐Molecule Magnets

AbstractIndustrial data storage application based on single‐molecule magnets (SMMs) necessitates not only strong magnetic remanence at high temperatures but also requires the implementation of SMMs into a solid material to increase their durability and addressability. While the understanding of the relationship between the local structure of the metal and the resulting magnetic behavior is well understood in molecular systems, it remains challenging to establish a similar understanding for magnetic materials, especially for isolated lanthanide sites on surfaces. For instance, dispersed Dy(III) ions on silica prepared via surface organometallic chemistry exhibit slow magnetic relaxation at low temperatures, but the origin of these properties remains unclear. In this work, we modelled ten neutral complexes with coordination numbers (CN) between three and six ([Dy(OSiF3)3(O(SiF3)2)CN‐3]) representing possible surface sites for dispersed Dy(III) ions and investigated their SMM potential via ab initio CASSCF/RASSI‐SO calculations. Detailed analysis of the data shows the strong influence of the spatial position of the anionic ligands while the neutral ligands only play a minor role for the magnetic properties. In particular, a T‐shape like orientation of the anionic ligands is predicted to exhibit good SMM properties making it a promising targeted coordination environment for molecular and surface‐based SMMs.

Spin Qubit in a 2D GdIII NaI -Based Oxamato Supramolecular Coordination Framework.

Qubits are the basic unit of quantum information and computation. To realize quantum computing and information processing, the decoherence times of qubits must be long enough. Among the studies of molecule-based electron spin qubits, most of the work focused on the ions with the spin S=1/2, where only single-bit gates can be constructed. However, quantum operations require the qubits to interact with each other, so people gradually carry out relevant research in ions or systems with S>1/2 and multilevel states. In this work, a two-dimensional (2D) oxygen-coordinated GdIII NaI -based oxamato supramolecular coordination framework, Na[Gd(4-HOpa)4 (H2 O)] ⋅ 2H2 O (1, 4-HOpa=N-4-hydroxyphenyloxamate), was selected as a possible carrier of qubit. The field-induced slow magnetic relaxation shows this system has phonon bottleneck (PB) effect at low temperatures with a very weak magnetic anisotropy. The pulse electron paramagnetic resonance studies show the spin-lattice and spin-spin relaxation times are T1 =1.66 ms at 4 K and Tm =4.25 μs at 8 K for its diamagnetically diluted sample (1Gd0.12 %). It suggested that the relatively long decoherence time is mainly ascribed to its near isotropic and the PB effect from resonance phonon trapped for pure sample, while the dilution further improves its qubit performance.

Slow Magnetization Relaxation in a Family of Triangular {CoIII 2 LnIII } Clusters: The Effect of Diamagnetic CoIII Ions on the LnIII Magnetic Dynamics.

The first use of the Schiff base chelate N-naphthalidene-o-aminophenol (naphH2 ) in Co/Ln chemistry has afforded a family of isostructural [CoIII 2 LnIII (OMe)2 (naph)2 (O2 CMe)3 (MeOH)2 ] (Ln=Tb, Dy and Er) complexes, revealing a rare {CoIII 2 Ln(μ3 -OMe)}8+ triangular core composed of two diamagnetic CoIII ions and a 4f-ion with slightly distorted square antiprismatic geometry. Alternating current (ac) magnetic susceptibility studies revealed that {Co2 Dy}, and its magnetic diluted analogue {Co2 Dy0.05 Y0.95 }, behave as mononuclear single-molecule magnets (SMMs) with similar energy barriers for the magnetization reversal, Ueff , of ~85-90 K. SMM properties were also detected for {Co2 Er}, with the compound exhibiting a Ueff of 18.7 K under an applied magnetic field of 800 Oe. To interpret the experimental magnetic results, ab initio CASSCF/RASSI-SO and DFT calculations were performed as a means of exploring the single-ion characteristics of LnIII ions and comprehend the role of the diamagnetic CoIII ions in the magnetization relaxation of the three heterometallic compounds.

Synthesis, Structure and Magnetic Behavior of a Novel Series of Trinuclear Windwheel Complexes

Comprehensive SummaryA new family of trinuclear windwheel complexes with molecular formula [MII3(tpa)3(μ‐ttc)](ClO4)3·n(sol) (ttc = 1,3,5‐triazine‐2,4,6‐trithiol; tpa = tris(2‐pyridylmethyl)amine; M = Mn, n = 2, sol = CH3CN, 1; M = Co, n = 1, sol = CH3CN, 2; M = Ni, n = 0, 3) were synthesized and characterized. Single‐crystal X‐ray diffraction revealed that three metal centers in 1—3 are connected by ttc bridge, forming a regular triangular MII3 core. Each metal center is bonded by chelating S, N atoms from ttc and by N atoms from tpa. Magnetic studies showed that 1—3 displayed antiferromagnetic behavior and further gave the easy‐axis anisotropy (D = −0.77 cm−1 for 1 and −8.13 cm−1 for 2) and easy‐plane anisotropy (D = 5.08 cm−1 for 3). Moreover, 2 exhibited field‐induced slow magnetic relaxation behavior and their effective energy barriers were roughly evaluated Ueff = 6.9 K.

Slow magnetic relaxation behaviors and diamagnetic dilution studies of a carboxyl bridged dinuclear dysprosium(III) complex

By using a rigid bulky carboxylic ligand α-cyanocinnamic acid (CCA), a dinuclear dysprosium (III) complex [Dy2(CCA)6 (MeOH)4] (1) was synthesized. Single crystal X-ray crystallography reveals that the two eight-coordinate dysprosium ions are bridged by four deprotonated carboxyl groups, forming a centrosymmetric paddle-wheel-like structure. Dynamic magnetic property measurements indicate that complex 1 displays field-induced slow magnetic relaxation. The temperature-dependent relaxation times can be fitted using Orbach and Raman processes with parameters of n = 2.8 (2), C = 27 (8) s−1/Kn, τ0 = 5 (2) × 10−10 s and Ueff = 40 (3) cm−1. Magnetic studies on the diamagnetic YIII-diluted analogue [Dy0.206Y1.794(CCA)6 (MeOH)4] (2) reveal its slow magnetic relaxation behavior without external dc field and the antiferromagnetic coupling between the DyIII ions in 1. Fits on the obtained relaxation times of 2 lead to the parameters of n = 4.5 (3), C = 0.7 (2) s−1/Kn, τ0 = 2.8 (2) × 10−9 s and Ueff = 38 (2) cm−1. The results suggest that slow magnetic relaxation originates from the single-ion relaxation of DyIII ions. Moreover, the diamagnetic dilution can suppress other fast relaxation pathways at low temperature, on account of the elimination of magnetic coupling and dipolar interaction. Ab initio calculations were then performed on the single DyIII ion species {YDy} and indicate that the first excited Kramers doublets (KDs) lie at ca. 76 cm−1, which is slightly higher than the experimental Ueff value. The intramolecular magnetic interactions were also calculated and indicate a weak ferromagnetic dipole-diploe magnetic interaction and an antiferromagnetic exchange coupling.

Molecular Network Approach to Anisotropic Ising Lattices: Parsing Magnetization Dynamics in Er3+ Systems with 0-3-Dimensional Spin Interactivity.

We present a wide-ranging interrogation of the border between single-molecule and solid-state magnetism through a study of erbium-based Ising-type magnetic compounds with a fixed magnetic unit, using three different charge-balancing cations as the means to modulate the crystal packing environment. Properties rooted in the isolated spin Hamiltonian remain fixed, yet careful observation of the dynamics reveals the breakdown of this approximation in a number of interesting ways. First, differences in crystal packing lead to a striking 3 orders of magnitude suppression in magnetic relaxation rates, indicating a rich interplay between intermolecular interactions governed by the anisotropic Ising lattice stabilization and localized slow magnetic relaxation driven by the spin-forbidden nature of quantum tunneling of the f-electron-based magnetization. By means of diverse and rigorous physical methods, including temperature-dependent X-ray crystallography, field, temperature, and time-dependent magnetometry, and the application of a new magnetization fitting technique to quantify the magnetic susceptibility peakshape, we are able to construct a more nuanced view of the role nonzero-dimensional interactions can play in what are predominantly considered zero-dimensional magnetic materials. Specifically, we use low field susceptibility and virgin-curve analysis to isolate metamagnetic spin-flip transitions in each system with a field strength corresponding to the expected strength of the internal dipole-dipole lattice. This behavior is vital to a complete interpretation of the dynamics and is likely common for systems with such high anisotropy. This collective interactivity opens a new realm of possibility for molecular magnetic materials, where their unprecedented localized anisotropy is the determining factor in building higher dimensionality.

Structure, slow magnetic relaxation behavior and bacteriostatic activity of a novel Dy4 cluster

A novel tetranuclear Dy(III)-based cluster, namely [Dy4(CO3)L4 (acac)2(CH3OH)2(CH2OH)2]·2CH3OH (1) (where H2L is 2-(hydroxyimino)-2-[(5-bromo-2-hydroxyphenyl)methylene]hydrazide and Hacacis acetylacetonate) has been constructed by employing a newly prepared Schiff based ligand H2L. X-ray diffraction data reveal that 1 is mainly consist of a rhombic Dy4core, in which the four Dy3+ ions are bridged by six μ-O atoms from four ligands H2L and two μ2-O atoms from thein situformed CO32−via spontaneous fixation of atmospheric CO2.The crystalstructure of 1 possesses two distinct Dy3+ ions coordinationcenter, and the nine-coordinated Dy73+ionscenter presenting a distorted spherical capped square antiprism geometry and eight-coordinated Dy43+ionscenter presenting a distorted triangular dodecahedron geometry.Magnetic study indicates that 1displays slow magnetic relaxation behavior under Hdc = 0 Oe filed. Furthermore, the fluorescence property investigation reveals that 1shows DyIIIcharacteristic emission peaks. Moreover, theantibacterial activity and mechanism of 1 have been systemically studied, and cluster 1 possesses well antibacterial activity on five common bacteria (Escherichia coli, Staphylococcus aureus, Staphylococcus albus, Bacillus subtilis, and Micrococcus luteus). Inaddition,the interaction between 1 and DNA have been studied.

Magnetic relaxations in La0.80Ag0.15MnO[formula omitted] nanoparticles

We have performed the study of spin dynamic on two samples of La0.80Ag0.15MnO3+δ nanoparticles with different ratio of double exchange and superexchange interaction due to heat treatment in Ar or in O2. Our study reports that the change of ground state by annealing affects relaxation processes only slightly. Cole–Cole analysis of the AC susceptibility data revealed the simultaneous existence of two separated relaxation processes with two different relaxation times τ1 of 10−4 s and τ2 of 10−1 s, which can be assigned to the relaxation of different magnetic entities. Faster relaxation processes connected with τ1 are associated with smaller value of Cole–Cole parameter α1 and slower relaxation are characterized by τ2 connected with higher value of Cole–Cole parameter α2. The temperature dependence of τ1 (T) differs from τ2 (T). The aging effect in magnetic relaxation we demonstrate on sample prepared in Ar atmosphere using measurements of the magnetization as a function of observation time which were analysed by stretched exponential expression at low and high temperatures. Our results indicate two different relaxation processes at low and high temperatures, the system of nanoparticles exhibits slow magnetic relaxation, i.e., spin glassy behaviour.

Syntheses, Structures, and Magnetic Properties of Three Cyano-Bridged FeII-MoIII Single-Molecule Magnets.

Three new cyano-bridged FeII-MoIII complexes assembled from the [MoIII(CN)7]4- unit, FeII ions, and three pentadentate N3O2 ligands, namely {[Fe2H3(dapab)2][Mo(CN)6]}n·2H2O·3.5MeCN (1), [Fe(H2dapb)(H2O)][Fe(Hdapb)(H2O)][Mo(CN)6]·4H2O·3MeCN (2), and [Fe(H2dapba)(H2O)]2[Mo(CN)7]·6H2O (3) (H2dapab = 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone), H2dapb = 2,6-diacetylpyridine bis(benzoylhydrazone), H2dapba = 2,6-diacetylpyridine bis(4-aminobenzoylhydrazone)), have been synthesized and characterized. Single-crystal structure analyses suggest that complex 1 contains a one-dimensional (1D) chain structure where two FeII ions are bridged by the in situ generated [MoIII(CN)6]3- unit through two trans-cyanide groups into trinuclear Fe2IIMoIII clusters that are further linked by the amino of the ligand into an infinite chain. Complexes 2 and 3 are cyano-bridged Fe2IIMoIII trinuclear clusters with two FeII ions connected by the [MoIII(CN)6]3- and [MoIII(CN)7]4- units, respectively. Direct current magnetic studies confirmed the ferromagnetic interactions between the cyano-bridged FeII and MoIII centers and significant easy-axis magnetic anisotropy for all three complexes. Furthermore, complexes 1-3 exhibit slow magnetic relaxation under a zero dc field, with relaxation barriers of 42.3, 21.6, and 14.4 K, respectively, making them the first examples of cyano-bridged FeII-MoIII single-molecule magnets.

Slow Magnetic Relaxation in a Mononuclear 8‐Coordinate Fe(II) Compound Bearing the Phenanthroline‐Amide Ligand

AbstractA mononuclear 8‐coordinate Fe(II) compound, [FeII(L1)2](CF3SO3)2 (1), was prepared from the reaction of a neutral tetradentate ligand (L1=N2,N9‐dibutyl‐1,10‐phenanthroline‐2,9‐dicarboxamide) and hydrated Fe(CF3SO3)2 in MeOH. 1 could be considered as an ‘ideal’ 8‐coordinate Fe(II) compound as compared with the previously reported Fe(II) analogs, because all the terminal Fe−O bond lengths are in the normal range. The magnetic properties investigation shows that 1 exhibit field‐induced slow magnetic relaxation behavior.

Desolvation-induced magnetic switching from single-ion magnetism to spin-crossover in a halogen-functionalized cobalt(II) complex

The switching between spin-crossover (SCO) and single-ion magnet (SIM) are fascinating because the process provides potential in-depth understating of different bistability. Herein, we present a rare example of the desolvation-induced magnetic switching from single-ion magnetism to SCO between a halogen-functionalized cobalt(II) complex, [Co(Brphtpy)2](PF6)2·2MeOH (Brphtpy = 4′-(4-Bromophenyl)-2,2′:6′,2′'-terpyridine, 1·2MeOH) and its desolvated material of [Co(Brphtpy)2](PF6)2 (1). The temperature-dependent magnetic susceptibility and variable-temperature single crystal X-ray diffraction results show a high spin state of the Co(II) ions in 1·2MeOH. At lower temperature, frequency- and temperature-dependent slow magnetic relaxation behaviors were evidenced under an applied dc field of 1000Oe, originating from the easy-plane magnetic anisotropy (D=43.5 cm−1) of Co(II) ions. After the release of methanol molecules, interestingly, the desovated material 1 display a complete and cooperative two-step spin transitions with transition temperatures being 350 and 125K. Differential scanning calorimetry measurements support the stepwise SCO behavior and reveal the related ΔH and ΔS.

Bifunctional Lanthanide-Based Coordination Polymers: Conversion of CO2 and Highly Selective Luminescence Sensing for Acetylacetone.

A series of bifunctional Ln(III)-based coordination polymers (CPs) {Ln(L)(DMA)2(NO3)}n [Ln(III) = Eu (1), Gd (2), and Dy (3); organic ligand H2L = 2,2'-(1,3,5,7-tetrahydroxyoctahydro-4,8-ethanopyrrolo[3,4-f]isoindole-2,6(1H,3H)-diyl)diacetic acid)] have been successfully synthesized. CPs 1-3 are isostructural and constructed from the dimeric Ln2 unit in which two adjacent LnIII ions are bridged by two μ3-carboxyl oxygens, and the Ln2 dimeric unit is connected by two NO3- ions, four DMA molecules, and four completely protonated L2- ligands forming a 2D layer structure. The magnetic research reveals that CP 2 shows a significant cryogenic magnetocaloric effect (-ΔSm = 22.9 J kg-1 K-1; T = 2.0 K and ΔH = 7.0 T), whereas CP 3 exhibits slow magnetic relaxation property under Hdc = 0 Oe field. Additionally, the luminescence explorations revealed that CP 1 can act as a recyclable luminescent probe for pollutant acetylacetone among various small organic solvent molecules, and the corresponding detection limit is 10-7 mol/L. More importantly, CP 1 also exhibits good catalytic performance in the cycloaddition reaction of CO2 and epoxides or cyanamides under mild conditions. As far as we know, CP 1 represents the first bifunctional lanthanide homogeneous catalyst that can efficiently catalyze the reaction of cyanamides/epoxides with CO2 simultaneously.

Pyrrolyl-Bridged Metallocene Complexes: From Synthesis, Electronic Structure, to Single-Molecule Magnetism.

The π- and σ-basicity of the pyrrolyl ligand affords several coordination modes. A sterically encumbering coordination sphere around metal centers may foster new coordination modes for the pyrrolyl ligand. Here, we present three dinuclear rare earth complexes [Cp*2RE(μ-pyr)]2, [RE = Y (1), La (2), Dy (3); Cp* = pentamethylcyclopentadienyl, pyr = pyrrolyl], which were synthesized through a protonolysis reaction between allyl complexes and H-pyrrole. Each metal is ligated by two Cp* ligands and the N atom of the pyrrolyl ring while interacting with the π-system of the other pyrrolyl ligand, yielding an unprecedented coordination mode for pyrrolyl best described as [((η5-Cp*)2RE)2(μ-1η2-pyr-2κN)(μ-2η2-pyr-1κN)]. The steric congestion implemented by the Cp* ligands forces this asymmetric coordination of the pyrrolyl ligand. 1-3 were characterized by crystallography, electrochemistry, and spectroscopy. Density functional theory calculations on 1 uncovered the bonding situation between the pyrrolyl ligand and the yttrium(III) ion. Excitingly, 3 displays slow magnetic relaxation under zero dc field with Ueff = 98.9(7) cm-1 and τo = 6.7(1) × 10-8 s, placing it among coveted dinuclear metallocene single-molecule magnets. CASSCF calculations provided the energy of the crystal field states of DyIII and confirmed the barrier height.

Field-induced Co(II) single-ion magnet in octahedral [S6] coordination environment

The soft donor ligands are of great importance to the pursuit of 3d transition-metal complexes with large magnetic anisotropy. Herein, a soft tripodal ligand, hydrotris(mercaptobenzothiazolyl)borate (Tbz) was used to construct a high-spin mononuclear complex [CoII(Tbz)2] (1), having an octahedral geometry in an S6 donor set. The combination of direct-current (dc) magnetic susceptibility and Low-temperature high-field electron paramagnetic resonance (HFEPR) reveals the easy-axis magnetic anisotropy of 1. Complex 1 shows field-induced slow relaxation of magnetization at an applied magnetic field of 1000 Oe, indicating the behavior of single-molecule magnet. The foregoing result constitutes the first instance of Co(II)-based single-ion magnet containing a CoS6 unit.

2p-4f Loop-chains {[Ln(hfac)3]2-radical}n achieved through multidentate nitronyl nitroxide radicals

Reactions of the designed multidenate nitronyl nitroxide radical ligands Nit-pH-3,5-bPy or Nit-pH-3,5-btrz (Nit-pH-3,5-bPy = 2-[3,5-bis(4-pyridyl)-phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; Nit-pH-3,5-btrz = 2-[3,5-bis(1H-1,2,4-triazol-1-yl)-phenyl]-4,4,5,5- tetramethylimidazoline-1-oxyl-3-oxide) with Ln(hfac)3 obtained four rare Ln-radical loop-chains, namely, {[Ln(hfac)3]2(Nit-pH-3,5-bPy)}n (LnIII = Gd 1, Tb 2; hfac = hexafluoroacetylacetonate) and {[Ln(hfac)3]2(Nit-pH-3,5-btrz)}n (LnIII = Tb 3, Ho 4). In all complexes, each pyridyl- or triazolyl-functionalized radical ligand is binded to four Ln(hfac)3 centers with a μ4-η1:η1:η1:η1-coordination mode through its two NO units and two N atoms of pyridines/triazoles, giving rise to interesting radical-bridged loop-chains with the scarcely reported 4f-2p-4f structural motifs. Magnetic measurements indicate that there are ferromagnetic interactions between the Ln(III) ions and the coordinated NO groups in these compounds. Tb 2 exhibits clear frequency-dependent out-of-phase (χ′′) signals in a zero dc field indicating slow relaxation of magnetization, while no non-zero χ′′ signals are observed for Tb 3 without an external magnetic field, which could be ascribed to the slightly different heterocyclic ligands.