Series Of Ln Research Articles

A series of three-dimensional homoligand Ln(III) 2-iodoterephthalates: Structural features and luminescent behavior

A series of nine 3D metal-organic frameworks based on Ln3+ and 2-diodoterephthalate (2-I-bdc) with general formula {[Ln2(2-I-bdc)3(H2O)]·xH2O·yCH3CN} (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho, 1–9) were obtained. According to X-ray diffractometry, all these complexes belong to two structural types (La to Nd and Sm to Ho, respectively). Some of complexes in the 1–9 series demonstrate luminescent properties.

Tetradentate Ligand's Chameleon-Like Behavior Offers Recognition of Specific Lanthanides.

The surging demand for high-purity individual lanthanides necessitates the development of novel and exceptionally selective separation strategies. At the heart of these separation systems is an organic compound that, based on its structural features, selectively recognizes the lighter or heavier lanthanides in the trivalent lanthanide (Ln) series. This work emphasizes the significant implications resulting from modifying the donor group configuration within an N,O-based tetradentate ligand and the changes in the solvation environment of Ln ions in the process of separating Lns, with the unique ability to achieve peak selectivity in the light, medium, and heavy Ln regions. The structural rigidity of the bis-lactam-1,10-phenanthroline ligand enforces size-based selectivity, displaying an exceptional affinity for Lns having larger ionic radii such as La. Modifying the ligand by eliminating one preorganization element (phenanthroline → bipyridine) results in the fast formation of complexes with light Lns, but, in the span of hours, the peak selectivity shifts toward middle Ln (Sm), resulting in time-resolved separation. As expected, at low nitric acid concentrations, the neutral tetradentate ligand complexes with Ln3+ ions. However, the change in extraction mechanism is observed at high nitric acid concentrations, leading to the formation and preferential extraction of anionic heavy Ln species, [Ln(NO3)x+3]x-, that self-assemble with two ligands that have undergone protonation, forming intricate supramolecular architectures. The tetradentate ligand that is structurally balanced with restrictive and unrestrictive motifs demonstrates unique, controllable selectivity for light, middle, and heavy Lns, underscoring the pivotal role of solvation and ion interactions within the first and second coordination spheres.

Synthesis, Spectroscopy and Biological Activities of Some Trivalent Lanthanide Complexes of Octadecyl N-salicylaldimine (ONsal)

A series of Ln(III) complexes of octadecyl N-salicylaldimine (ONsal) were synthesized and characterized by CHN analysis, magnetic moment, conductivity, thermoanalytical and spectroscopic methods. Elemental and thermal analysis data confirmed the formation of heptacoordinated [Ln(ONsal)2Cl2(H2O)]Cl complexes where Ln = Ce3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, which is further supported by the respective mass spectra. The ligand acts as a neutral bidentate species coordinating through azomethine nitrogen and phenolic O-atom. The linkage of one H2O molecule in all the complexes has been inferred from the thermal analysis. All the Ln(III) complexes are paramagnetic in nature and act as 2:1 electrolyte in 0.002 M DMF at 25 ºC. The complexes of Sm(III), Eu(III) and Tb(III) display luminescent properties. The powder XRD patterns of Nd(III) and Dy(III) complexes could be successfully indexed for monoclinic crystal systems, while the diffraction lines of Eu(III) complex are indexed for a triclinic crystal system. Methanolic solutions of the ligand and complexes were checked for α-glucosidase and α-amylase inhibitory properties where some of the Ln(III) complexes show significant α-glucosidase inhibitory potency while only Tb(III) complex shows inhibition against α-amylase.

Assessing Lanthanide-Dependent Methanol Dehydrogenase Activity: The Assay Matters.

Artificial dye-coupled assays have been widely adopted as a rapid and convenient method to assess the activity of methanol dehydrogenases (MDH). Lanthanide(Ln)-dependent XoxF-MDHs are able to incorporate different lanthanides (Lns) in their active site. Dye-coupled assays showed that the earlier Lns exhibit a higher enzyme activity than the late Lns. Despite widespread use, there are limitations: oftentimes a pH of 9 and activators are required for the assay. Moreover, Ln-MDH variants are not obtained by isolation from the cells grown with the respective Ln, but by incubation of an apo-MDH with the Ln. Herein, we report the cultivation of Ln-dependent methanotroph Methylacidiphilum fumariolicum SolV with nine different Lns, the isolation of the respective MDHs and the assessment of the enzyme activity using the dye-coupled assay. We compare these results with a protein-coupled assay using its physiological electron acceptor cytochrome cGJ (cyt cGJ ). Depending on the assay, two distinct trends are observed among the Ln series. The specific enzyme activity of La-, Ce- and Pr-MDH, as measured by the protein-coupled assay, exceeds that measured by the dye-coupled assay. This suggests that early Lns also have a positive effect on the interaction between XoxF-MDH and its cyt cGJ thereby increasing functional efficiency.

Are 4f-Orbitals Engaged in Covalent Bonding Between Lanthanides and Triphenylphosphine Oxide? An Oxygen K-Edge X-ray Absorption Spectroscopy and Density Functional Theory Study.

The bonding covalency between trivalent lanthanides (Ln = La, Pr, Nd, Eu, Gd) and triphenylphosphine oxide (TPPO) is studied by X-ray absorption spectra (XAS) and density functional theory (DFT) calculations on the LnCl3(TPPO)3 complexes. The O, P, and Cl K-edge XAS for the single crystals of LnCl3(TPPO)3 were collected, and the spectra were interpreted based on DFT calculations. The O and P K-edge XAS spectra showed no significant change across the Ln series in the LnCl3(TPPO)3 complexes, unlike the Cl K-edge XAS spectra. The experimental O K-edge XAS spectra suggest no mixing between the Ln 4f- and the O 2p-orbitals in the LnCl3(TPPO)3 complexes. DFT calculations indicate that the amount of the O 2p character per Ln-O bond is less than 0.1% in the Ln 4f-based orbitals in all of the LnCl3(TPPO)3 complexes. The experimental spectra and theoretical calculations demonstrate that Ln 4f-orbitals are not engaged in the covalent bonding of lanthanides with TPPO, which contrasts the involvement of U 5f-orbitals in covalent bonding in the UO2Cl2(TPPO)2 complex. Results in this work reinforce our previous speculation that bonding covalency is potentially responsible for the extractability of monodentate organophosphorus ligands toward metal ions.

Lanthanide(III) SMMs with cationic and anionic complex fragments formed by a Schiff base: structure, luminescence, magnetic properties and ab initio calculations.

The syntheses, structures, luminescence and magnetic properties of a new series of Ln(III) complexes of the formula [Ln(L)(H2O)2(DMF)2][Ln(L)2] (in which H2L is N,N'-ethylaminebis[1-phenyl-3-methyl-4-formylimino-2-pyrazoline-5-one]; Ln(III) - Gd (1), Tb (2), or Dy (3) ions). The crystal structures were determined by single-crystal X-ray diffraction measurements for all the above-mentioned complexes. The crystals of these compounds consist of cationic [Ln(L)(H2O)2(DMF)2]+ and anionic [Ln(L)2] moieties which form a 3D supramolecular architecture by the H-bonds and electrostatic forces. Luminescence emission in the visible range was observed for Tb(III) and Dy(III) compounds upon ligand sensitization, with moderate quantum yields of 3.2% for the Dy complex and 24.2% for the Tb analogue. Moreover the Tb(III) complex demonstrates triboluminescence activity. The dynamic magnetization studies revealed that 1 and 2 demonstrate field-induced magnetic relaxation with effective energy barriers, ΔE|kB = 24 K (for 1) and 85 K (for 2), while the Dy complex 3 exhibits slow relaxation of magnetization in zero field with an activation energy of 256 K.

Lanthanide complexes facilitate wound healing by promoting fibroblast viability, migration and M2 macrophage polarization.

A tridentate ligand LH3 ((2-hydroxy-3-methoxybenzylidene)-2-(hydroxyimino)propanehydrazide) comprising o-vanillin, hydrazone and oxime donor groups has been employed to prepare a series of tetranuclear Ln(III) complexes. The reaction of ligand LH3 with Ln(NO3)3 [Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er] in MeOH yielded Ln4(LH)6(MeOH)2 (Ln = Sm(1), Eu(2), Gd(3), Tb(4), Ho (6) and Er (7))] whereas the corresponding reaction with Dy(NO3)3 afforded Dy4(LH)4(LH2)2(OH)2 (5). All complexes were characterized by various analytical techniques including single crystal X-ray diffraction, IR spectroscopy, UV-Vis spectroscopy, and elemental analysis. To investigate the potential of these lanthanide complexes for wound healing applications, their effects on fibroblast viability, migration, and M2 macrophage polarization were evaluated. The cytotoxicity assessment revealed that complexes 2(Eu), 4(Tb), 5(Dy), and 7(Er) significantly enhanced fibroblast viability compared to the negative control (NC). In vitro wound healing assay demonstrated that complexes 2(Eu) and 7(Eu) substantially promoted fibroblast migration compared to the NC. Moreover, complex 2(Eu) exhibited significant anti-inflammatory effects by reducing the phagocytic ability of lipopolysaccharide (LPS)-stimulated macrophage cells and attenuating nitric oxide (NO) production. In conclusion, among the series of complexes tested, complex 2(Eu) displayed the most potent anti-inflammatory effect on macrophage cells, while simultaneously promoting fibroblast viability and migration. This unique combination of properties renders complex 2 (Eu) highly promising for wound healing applications.

LANTHANIDE CONTRACTION IN CHELATES OF ETHYLENEDIAMINETETRAACETIC ACID BASED ON CRYSTALLOGRAPHIC DATA: A SHORT REVIEW

The lanthanide (Ln) series has been attracted so much attention not only for its physical properties but also for its applications in organic synthesis and biomedical engineering. In the lanthanide chemistry, lanthanide contraction is a crucial concept meaning the gradual decrease in ionic radii as the atomic number of the Ln series increases. As a prominent chelator, ethylenediaminetetraacetic acid (EDTA) has been well-known to give stable complexes with various metals including Ln ions, resulted in forming (EDTA−4H)4− anion by deprotonation; over 100 kinds of Ln-EDTA complexes have hitherto been synthesized and structurally characterized using X-ray crystallography. While the lanthanide contraction phenomenon has been extensively studied in certain complexes of Ln, systematization on the Ln-EDTA remains inadequate though the chelates of EDTA are commonly used. Thus, this study presents a comprehensive analysis based on the data from the Cambridge Crystallographic Data Centre (CCDC). In mononuclear EDTA complexes X[Ln(EDTA−4H)(H2O)m]·nH2O (X+ = NH4+and its analogues) systematic lanthanide contraction depending on their coordination number are presented except for a few cases. However, in the case of non-mononuclear complexes or coordination polymers, the compositions become more complicated, and a greater variation in atomic bond length occurs, which is unusual for the lanthanide contraction studies in previous research. These varieties are considered to be influenced by different types of counter-cations, inorganic anions, solvent molecules and bridging O atoms from another EDTA anions. This suggests the flexibility and versatility of EDTA as a ligand. Such findings in the Ln-EDTA complexes could potentially provide us further development of a novel function in the future.

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.

Effect of Reaction Time on Lanthanide Borate Perrhenate Complexes.

Six new trivalent lanthanide borate perrhenate structures─the isostructural series Ln[B8O11(OH)4(H2O)(ReO4)] (Ln = Ce-Nd, Sm, Eu; 1) and La[B6O9(OH)2(H2O)(ReO4)] (2)─have been prepared and structurally characterized. Single-crystal X-ray diffraction analysis reveals that both structures crystallize in the P21/n space group, contain 10-coordinated trivalent lanthanides in a capped triangular cupola geometry, are 3D borate framework materials, and contain either terminal (1) or bridging (2) perrhenate moieties. The presence or lack of a bridging perrhenate, along with the identity of the basal ligands, dictates how the layers are tethered together, ultimately leading to the different structures. Furthermore, the formation of 1 is sensitive to the reaction time employed. Herein, the synthesis, structural descriptions, and spectroscopy of these trivalent lanthanide perrhenate borate complexes are presented.

Combined experimental and theoretical studies on a series of mononuclear LnIII single-molecule magnets: dramatic influence of remote substitution on the magnetic dynamics in Dy analogues.

A series of LnIII complexes of general formula [Ln(H2L1)2(NO3)2(H2O)](NO3) (1-5) [Ln = Dy (1), Tb (2) Ho (3), Er (4), and Yb (5)] and an analogous DyIII complex with ligand H2L2, [Dy(H2L2)2(NO3)3(H2O)](NO3) (6), where H2L1 and H2L2 stand for (E)-2-[(2-hydroxyphenyl)iminomethyl]-6-methoxy-4-methylphenol and (E)-2-[(2-hydroxy-5-methylphenyl)iminomethyl]-6-methoxy-4-methylphenol, respectively, have been synthesized and magneto-structurally characterized. All these complexes are isostructural and isomorphous, in which the zwitterionic form of the ligands predominantly coordinate the metal centers. The magnetic study revealed that complex 3 displays negligible SMM behaviour, while 1 and 6 are zero field SMMs, the performance of which can largely be improved in the presence of an applied dc field by lowering under barrier relaxation processes, and finally 2, 4, and 5 are field-induced SMMs. The most remarkable observation in the present study is the dramatically-enhanced SMM performance in 6 compared to 1, achieved by only a remote methyl substitution at the ligand framework to increase the intermolecular separation. Although SINGLE_ANISO ab initio calculations for 1 and 6 are very similar, the POLY_ANISO module revealed weak dipolar interactions in both the compounds but significant antiferromagnetic interaction in 1, thereby justifying the experimental fact. The present work discloses that even a small substitution such as a methyl group can adequately increase the intermolecular separation, leading to several-fold enhanced effective energy barrier.

Dy(OH)3: a paramagnetic magnetocaloric material for hydrogen liquefaction

Dy(OH)3 has impressive magnetocaloric performance optimised around 20 K making it suitable for hydrogen liquefaction using magnetic cooling.

Norm-Conserving 4f-in-Core Pseudopotentials and Basis Sets Optimized for Trivalent Lanthanides (Ln = Ce–Lu)

We present here a set of scalar-relativistic norm-conserving 4f-in-core pseudopotentials, together with complementary valence-shell Gaussian basis sets, for the lanthanide (Ln) series (Ce-Lu). The Goedecker, Teter, and Hutter (GTH) formalism is adopted with the generalized gradient approximation (GGA) for the exchange-correlation Perdew-Burke-Ernzerhof (PBE) functional. The 4f-in-core pseudopotentials are built through attributing 4f-subconfiguration 4fn (n = 1-14) for Ln (Ln = Ce-Lu) into the atomic core region, making it possible to circumvent the difficulty of the description of the open 4fn valence shell. A wide variety of computational benchmarks and tests have been carried out on lanthanide systems including Ln3+-containing molecular complexes, aqueous solutions, and bulk solids to validate the accuracy, reliability, and efficiency of the optimized 4f-in-core GTH pseudopotentials and basis sets. The 4f-in-core GTH pseudopotentials successfully replicate the main features of lanthanide structural chemistry and reaction energetics, particularly for nonredox reactions. The chemical bonding features and solvation shells, hydrolysis energetics, acidity constants, and solid-state properties of selected lanthanide systems are also discussed in detail by utilizing these new 4f-in-core GTH pseudopotentials. This work bridges the idea of keeping highly localized 4f electrons in the atomic core and efficient pseudopotential formalism of GTH, thus providing a highly efficient approach for studying lanthanide chemistry in multi-scale modeling of constituent-wise and structurally complicated systems, including electronic structures of the condensed phase and first-principles molecular dynamics simulations.

Bond Dissociation Energies Reveal the Participation of d Electrons in f-Element Halide Bonding.

Bond dissociation energies (BDEs) reported in the literature for lanthanide monofluorides and lanthanide monochlorides LnX, where X = F or Cl, exhibit substantial irregular variations across the Ln series. It is demonstrated here that correlations of these variations with reported experimentally based atomic energies to prepare the Ln constituent for bonding reveal the nature of the bonding. Whereas some molecular characteristics are well understood in the context of highly ionic bonding, with LnX considered to be (Ln+)(X-), some significant variations in BDEs are not well rationalized simply by ionization to convert Ln to Ln+ for bonding. Focusing here on lanthanide monofluorides LnF, a consideration of alternative Ln preparation schemes shows that a particularly good rationalization of BDEs is obtained by invoking the participation of a lanthanide 5d electron in bonding. This 5d participation could be in ionic (Ln+)(F-) via π-donation from F- 2p to empty Ln+ 5d orbitals or in covalent π-bonded Ln:F via polarization from Ln 5d to F 2p, with these ionic and polar covalent perspectives ultimately being equivalent. The inference of lanthanide 5d involvement suggests that the valence 4f and 6s electrons do not effectively participate in some key aspects of the bonding, presumably due to poor spatial overlap with F 2p orbitals. An extension to actinide monofluorides, AnF, assumes analogous ionic or polar covalent bonding involving a valence 6d electron and results in predictions for BDEs that include a general decrease from left to right across the series, except for a distinctive local minimum at AmF. Determining the BDE for AmF would serve to evaluate the predictions and the underlying assumption of 6d bonding. The BDE assessments/predictions for neutral monofluorides, LnF and AnF, are also applied to cationic LnF+ and AnF+, and it is noted that the approach can be directly extended to f-element monochlorides, monobromides, and monoiodides.

Synthesis and Structures of Tris(cyclononatetraenyl) Rare-Earth Complexes [Ln(C9H9)3] (Ln = Y, Gd, Tb, Dy, Ho, Er, Tm)

The article reports the synthesis and structural characterization of a series of Ln(C9H9)3 complexes with the cyclononatetraenyl (Cnt, C9H9) ligand (Ln = Y, Gd, Tb, Dy, Ho, Er, Tm). The Yb and Sm complexes were not obtained, and the reaction of the potassium salt of the Cnt ligand with trivalent halide salts of the corresponding metals led to the known bis-Cnt sandwich compounds Ln(C9H9)2. The X-ray diffraction studies on the trivalent complexes show that the Cnt ligand is significantly bent in order to accommodate the large size of the ligand while it maintains its aromaticity. When the size of the lanthanide ion decreases, the ligand does not switch away but swings over the metal ion in order to maximize the electrostatic interactions. 1H NMR and UV–visible spectra, as well as the solid-state magnetism, were recorded. UV–visible spectroscopy highlights a remarkable charge-transfer band in the Tm complex, while ligand-based transitions are principally observed with all other metal ions. The magnetic behavior of the series agrees with trivalent lanthanide ions, and the computations at the CASSCF level confirm the trivalent electronic structure.

Six-coordinated dinuclear lanthanide(III) amide complexes: investigation of magnetization relaxation dynamics and their electronic structures.

A series of rare six-coordinated dinuclear Ln(III) complexes [Ln2(μ-Cl)2Cl4Li2(L)2(THF)6] were structurally characterized using a bulky amide ligand (L; Ln = Gd(1), Dy(2) and Y(3)). Detailed magnetic studies disclose that a weak antiferromagnetic coupling exists within 1 (-0.09 cm-1) and 2 (-0.07 cm-1; -2J Hamiltonian). Additionally, this study unveils the importance of the amide ligand at the coordination site of Dy(III), which manifests a slow relaxation of magnetization in the absence of an external magnetic field. This has been rationalized by detailed ab initio calculations as well as the electronic structure determination of 1 and 2.

Multifunctionality of the [C2mim][Ln(fod)4] series (Ln = Nd–Tm except Pm): magnetic, luminescence and thermochemical studies

The [C2mim][Ln(fod)4] series presents a rare and reversible polymorphism, NIR and visible emission as well as SMM behavior. The varieties of physical behaviors make these compounds suitable for potential technological and/or biomedical applications.

A series of carbonate-brisdged Ln (Ln = Eu, Tb, Gd) frameworks: Colour tunability for barcode applications and selective luminescence sensing towards nitroimidazole antibiotics

Three metal–organic frameworks, TbCO3OH (ZH-103), EuCO3OH (ZH-104), and GdCO3OH (ZH-105), were synthesised using DMF/H2O under solvothermal conditions. Multiple types of bimetallic doped EuxTb1 − X-ZH-103 frameworks, which showed unique colour changes, were obtained by adjusting Eu3+/Tb3+ ion ratios. Subsequently, multiple types of trimetallic doped EuxGdyTb1 − x − y-ZH-103 frameworks were obtained by tuning Eu3+/Gd3+/Tb3+ ion ratios. These frameworks also exhibited striking colour changes, including white light emissions, and showed potential for their use in barcode applications. In addition, ZH-103 showed high selectivity towards nitroimidazole antibiotics, including metronidazole (MDZ), dimetridazole (DTZ), and ornidazole (ODZ), through luminescence quenching. The detection of one antibiotic using ZH-103 was not interfered with by other antibiotics. The calculated limits of detection for MDZ, DTZ, and ODZ were 0.12, 0.23, and 0.09 mM, respectively.

Separation of Light and Middle Lanthanides Using Multistage Extraction with Diglycolamide Extractant.

We investigated the chemical behavior of lanthanides (Ln) by multistage extraction. Using 10 aqueous phases with Ln and 3 organic phases, we drew the breakthrough curves for light and middle Ln. Our study reveals that the limit of metal extraction depends on their D values and the metal concentration employed in experiments. From the multistage extractions of 15 stage aqueous phases and 15 stage organic phases, three curves (extraction curves, back-extraction curves, and separation curves) were obtained. Setting appropriate conditions, adequate separation of light Ln from middle ones can be achieved. As an example, under the condition of the separation curve experiment (aqueous phase: 0.5 M HNO3, organic phase: 0.1 M TDDGA (N,N,N',N'-tetradecyl-diglycolamide) in n-dodecane), the recovery of more than 99% of Sm in the organic phase with less than 1% of Nd can be obtained, even in the case of two metals adjacent to each other in the Ln series.

Larger magnetocaloric effect and single molecule magnet behavior in dinuclear Ln(III)-based compounds constructed from Schiff base ligand

A series of Ln(III)-based compounds with the formula [Ln2(HL)2(acac)2(CH3OH)2] (Ln (III) = Gd (1), Tb (2), Dy (3), Ho (4) and Er (5), Hacac = acetylacetone, H3L = 3-hydroxy-N’-[(1E)-(2-hydroxy-3-methoxyphenyl)methylidene]pyridine-2-carbohydrazide) based on a flexible Schiff base ligand H3L have been successfully synthesized, and the structures and magnetic properties of 1–5 have been systematacially studied. The crystal structures study indicates that compounds 1–5 are isostructural and possess a parallelogram Ln2O2 core. Magnetic properties measurements reveal that an antiferromagnetic interaction is exsisted in 1 and ferromagnetic interactions are exsisted in compounds 3 and 4. Remarkably, compound 1 displays well cryogenic magnetic refrigeration property with a larger magnetic entropy (−ΔSm = 28.79 J K−1 kg−1, T = 2.0 K and ΔH = 70 kOe). Moreover, alternating-current (ac) magnetic susceptibility research reveals that compound 3 shows slow magnetic relaxation behavior under zero dc field. Furthermore, under an external dc field of 1500 Oe, compound 3 displays remarkable SMM behavior with the effective barrier (ΔE/kB) of 14.9 K.