Dysprosium Complexes Research Articles

Molecular dysprosium complexes for white-light and near-infrared emission controlled by the coordination environment

A series of single-molecule dysprosium (Dy3+) complexes consisting of β-diketonate ligands, L1 = 4,4,4-trifluoro-1-phenyl-1,3-butadionate and L2 = 4,4,4-trifluoro-1-(4-chlorophenyl)-1,3-butadionate, as water-containing complexes, and the auxiliary triphenylphosphine oxide (tppo) ligand as water-free complexes were investigated as potential white-light emitters. The coordination environment and choice of the ligands play an important role in the behavior of the yellow/blue emission of the Dy3+ complexes (Y: 4F9/2 → 6H13/2 – yellow, and B: 4F9/2 → 6H15/2 and ligand phosphorescence – blue) based on the sensitization efficiency of the Dy3+ ion by the ligands. By introducing the auxiliary tppo ligand in the complex, the relative intensity of the Dy3+ emission increases due to a more efficient sensitization of the Dy3+ ion. The CIE (Commission International d’Eclairage) coordination at room temperature for water-containing, DyL1H2O (0.340, 0.333), and DyL2H2O (0.270, 0.249), and for water-free complexes, DyL1tppo (0.364,0.391) and DyL2tppo (0.316, 0.331), are close to the coordinates of ‘ideal’ white light (0.333, 0.333). The CCT (Correlated Color Temperature) values at room temperature for DyL1H2O (5129 K), DyL2H2O (18,173 K), and DyL2tppo (6319 K) correspond to ‘cold-white-light’ emitters, while the DyL1tppo (4537 K) matches a ‘warm-white-light’ emitter. Beside emitting in the visible (Vis) region, the Dy3+ complexes also show emission in the near-infrared (NIR) part of spectrum, which has been studied in detail.

Low-Coordinate Dinuclear Dysprosium(III) Single Molecule Magnets Utilizing LiCl as Bridging Moieties and Tris(amido)amine as Blocking Ligands

A low-coordinate dinuclear dysprosium complex {[Dy(N3N)(THF)][LiCl(THF)]}2 (Dy2) with a double bridging ‘LiCl’ moiety and tris(amido)amine (N3N)3− anions as a blocking ligand is synthesized and characterized structurally and magnetically. Thanks to the use of the chelating blocking ligand (N3N)3− equipped with large steric –SiMe3 groups, the coordination sphere of both DyIII ions is restricted to only six donor atoms. The three amido nitrogen atoms determine the orientation of the easy magnetization axes of both DyIII centers. Consequently, Dy2 shows slow magnetic relaxation typical for single molecule magnets (SMMs). However, the effective energy barrier for magnetization reversal determined from the AC magnetic susceptibility measurements is much lower than the separation between the ground and the first excited Kramers doublet based on the CASSCF ab initio calculations. In order to better understand the possible influence of the anticipated intramolecular magnetic interactions in this dinuclear molecule, its GdIII-analog {[Gd(N3N)(THF)][LiCl(THF)]}2 (Gd2) is also synthesized and studied magnetically. Detailed magnetic measurements reveal very weak antiferromagnetic interactions in Gd2. This in turn suggests similar antiferromagnetic interactions in Dy2, which might be responsible for its peculiar SMM behavior and the absence of the magnetic hysteresis loop.

Enhancing Steric Hindrance via Ligand Design in Dysprosium Complexes: From Induced Slow Relaxation to Zero-Field Single-Molecule Magnet Properties.

The synthesis and magnetic characterization of three novel Dy compounds, [Dy{PPh2S(NtBu)2}2(μ-Cl2)Li(THF)2] (1), [Dy{PhS(NtBu)2}2(μ-Cl2)Li(THF)2] (2), and [Dy{MeS(NtBu)3}2(μ-Cl2)Li(THF)2] (3), based on the sulfur-nitrogen ligands RS(NtBu)x- (where R = PPh2, x = 2 for (1); R = Ph, x = 2 for (2); and R = Me, x = 3 for (3)) are reported. They represent rare examples of lanthanide-based complexes containing sulfur-nitrogen ligands, whose suitability to enhance the magnetic anisotropy in 3d metals was only recently established. Changes in the ligand field environment drastically affect the magnetic properties, with compounds 1 and 2 displaying field-induced single-molecule magnet (SMM) behavior, while compound 3 shows slow relaxation at zero field. These trends strongly suggest that ligand engineering strategies toward linear dysprosium complexes, similar to those for dysprosocenium complexes, should enhance the SMM performances of SN-based lanthanide compounds.

THE COORDINATION COMPOUNDS Gd (III) AND Dy(III) WITH SOME β-DIKETONES

New complexes of Dy (III) and Gd (III) with b-diketones containing unsaturated and aryl substituents were synthesized. Metal polymers based on synthesized complexes were obtained by the method of radical polymerization. The composition and structure of synthesized complexes and metal polymers are established. It is shown that during polymerization the coordination environment of the central ion remains unchanged. The spectral-luminescent cha­racteristics of the synthesized compounds were studied. The presence of water molecules in the immediate coordination environment causes a low intensity of emission of monomeric dysprosium complexes. In the luminescence spectra of metal polymers, there are bands magnetic dipole transition (4F9 → 6H15/2) and electric dipole transition (4F9 → 6H13/2). The close energies of the triplet level of the ligand and the resonant level of the dysprosium ion cause low emission characteristics of the synthesized dysprosium complexes.

NMR thermosensing properties on binuclear triple-decker complexes of terbium(III) and dysprosium(III) with 15-crown-5-phthalocyanine

In this paper, we have firstly demonstrated the thermosensing properties of binuclear triple-decker terbium(III) and dysprosium(III) complexes with 15-crown-5-phthalocyanine Tb2[(15C5)4Pc]3 (I) and Dy2[(15C5)4Pc]3 (II) in the physiological temperature range (303–323 K). Measuring the LIS values for I and II in CDCl3 has revealed high temperature sensitivity for the signals of the aromatic protons of the inner deck of the complexes: ∂δ/∂T = 1.1 and 0.55 ppm/K for I and II, respectively. Terbium-containing complex I has the highest sensitivity of the LIS among the published complexes of 4f and d elements with polydentate ligands in organic media. A significant impact of the Curie-spin contribution to the paramagnetic spin–spin relaxation rate enhancement has been found, which has a pronounced temperature dependence.The results obtained for kinetically and thermodynamically stable Ln2[(15C5)4Pc]3 complexes allow one to consider them pronounced NMR thermosensors in nonpolar solutions. The possibility of the solubilization of complex I in aqueous media due to the presence of crown ether moieties has been also demonstrated.

Thermodynamic and Optical Properties of Mixtures Based on Mesogenic Dysprosium (III) Complex and Nematic Liquid Crystal

Thermodynamic and Optical Properties of Mixtures Based on Mesogenic Dysprosium (III) Complex and Nematic Liquid Crystal

A study of cation-dependent inverse hydrogen bonds and magnetic exchange-couplings in lanthanacarborane complexes

SummaryTen lanthanacarborane complexes were synthesized to study the rare B−Hδ−∙∙∙Mn+ inverse hydrogen bonds (IHBs). The average bonding energy of B−Hδ−∙∙∙Ln3+ is theoretically determined to be larger than 24 kJ/mol, which is comparable to moderately strong hydrogen bonds (21–56 kJ/mol). In addition to NMR and IR, magnetometer was used to study the exchange-coupling interaction via such B−Hδ−∙∙∙Ln3+ IHBs in detail, and the coupling constant is determined to be −2.0 cm−1, which is strong enough to compare with single-atom bridged dysprosium(III) complexes. Two imidazolin-iminato incorporated complexes have shown energy barrier for magnetization reversal larger than 1000 K, and the exchange-biasing effects are evident. Moreover, the bonding strengths of B−Hδ−∙∙∙Mn+ IHBs are cation-dependent. If M = Na, the B−Hδ−∙∙∙Na+ bonding energy is reduced to 14 kJ/mol, and the dimerization process is no longer reversible. The exchange-biasing effect is also disappeared. We believe such a finding extends our knowledge of IHBs.

Chelating Guanidinates for Dysprosium(III) Single‐Molecule Magnets†

Main observation and conclusionTwo chelating guanidinate‐based dysprosium(III) complexes, namely the monomeric {(Me3Si)2NC(NiPr)2}2Dy(μ‐Cl)2Li(THF)2 1 and the dimeric [{(Me3Si)2NC(NiPr)2}2Dy(μ‐Cl)]2 2, have been confirmed to be single‐molecule magnets. Moreover, the alteration from 1 to 2 leads to an obvious mitigated quantum tunnelling of magnetization at zero field of the hysteresis loop and much enhanced magnetic relaxation barrier (up to 312 K). 5% dilution with the yttrium(III) analogue for 2 shows no clear change for the hysteresis, indicating the single‐ion nature of the magnetic behavior.

Spectroscopic and Electrochemical Analyses for Dysprosium Complexes In Potassium Bis(trifluoromethylsulfonyl)amide Melts

The coordination states of multivalent dysprosium complexes of potassium bis(trifluoromethylsulfonyl) amide (K[NTf2]) were investigated by Raman spectroscopy. The concentration dependence of the deconvoluted Raman spectra was investigated for 0.23−0.45 mol kg−1 Dy(III), and a mixed sample of Dy(II)/Dy(III) (molar ratio 1/3), in K[NTf2]. Using conventional analysis, the solvation number, n, of the dysprosium complexes was determined to be 4.12 for Dy(II) and 5.09 for Dy(III). The electrochemical behavior of [DyIII(NTf2)5]2– in K[NTf2] melts was also investigated in this study. It is speculated that the first reduction peak at approximately +2.24 V probably corresponds to the formation of [DyII(NTf2)4]2–. Electrochemical analysis revealed that the reduction peak of [DyIII(NTf2)5]2– at approximately +0.81 V at 483 K is based on an electrodeposition reaction from [DyIII(NTf2)5]2– to Dy(0). The diffusion coefficient and activation energy of [DyIII(NTf2)5]2– in K[NTf2] melts were measured in the range 473–493 K by semi-integral and semi-differential analyses. Furthermore, the nucleation behavior of [DyIII(NTf2)5]2– was evaluated using chronoamperometry. The results indicated that the nucleation mechanism of Dy nuclei changed from instantaneous to progressive nucleation when the overpotential became more negative than the deposition potential of Dy(0). The electrodeposits were identified as mostly the metallic state by X-ray photoelectron spectroscopy.

Synthesis of cool white light emitting novel dysprosium (Dy3+ ) complexes with tetradentate β-ketoamide and heterocyclic auxiliary ligands.

To improve current multiphase white light emitting diodes (WLEDs), a novel series of five complexes consisting of one binary and four ternary complexes that emitted cool white light was successfully synthesized using a chelating tetradentate ligand and auxiliary ligands, i.e. 5,6-dimethyl-1,10-phenanthroline, 1,10-phenanthroline, 4,4'-dimethyl-2,2'-bipyridyl, and 2,2'-bipyridyl. The series was examined structurally using elemental analysis, Fourier transform infrared spectroscopy, energy dispersive X-ray analysis, ultraviolet-visible spectroscopy, and proton nuclear magnetic resonance spectroscopy. These complexes had the appropriate thermal stability required for the generation of white organic LEDs (WOLEDs). Dysprosium (III) (Dy3+ ) ion complexes demonstrated the characteristic emission peaks of blue colour at 482 nm and yellow colour at 572 nm, respectively, when excited using near ultraviolet light. Band gap, refractive index, and decay lifetime of the optimized samples were recorded as 2.68 eV, 2.12, and 1.601 ms, respectively. Correlated colour temperature value (7875 K), Commission International de l'Eclairage coordinates (0.300, 0.294), and colour purity (21.04 × 10-2 ) of the optimized complex were near to those of white illuminants as defined by the National Television System Committee. These complexes had promise as commercial LEDs for the advanced optoelectronics devices, especially as WOLEDs for illumination applications.

Heterocyclic-Additive-Activated Dinuclear Dysprosium Electrocatalysts for Heterogeneous Water Oxidation.

Heterogeneous catalysis based on air-stable lanthanide complexes is relatively rare, especially for electrochemical water oxidation and reduction. Therefore, it is highly desired to investigate the synergy caused by cocatalysts on the lanthanide complex family for heterogeneous catalysis because of their structural diversity, air/moisture insensitivity, and easy preparation under an air atmosphere. Two mononuclear and three dinuclear dysprosium complexes containing a series of Schiff-base ligands have been demonstrated as robust electrocatalysts for triggering heterogeneous water oxidation in alkaline solution, in which the complex [Dy2(hmb)2(OAc)4]·MeCN(3) was revealed to have the best activity toward heterogeneous water oxidation among all five complexes in the present study. The molecular activation of dysprosium complexes has also been investigated with a series of N-containing heterocyclic additives [i.e., 4-(dimethylamino)pyridine (DMAP), bis(triphenylphosphine)iminium chloride ([PPN]Cl), indole, and quinoline]. In particular, the corresponding overpotential was effectively enhanced by 211 mV (at a current density of 10 mA cm-2) with the assistance of DMAP. On the basis of electrochemical and ex situ/in situ spectroscopic investigations, the best catalyst, DMAP-complex 3 on a carbon paper electrode, was confirmed with well-maintained molecular identity during heterogeneous water oxidation free of forming any dysprosium oxide and/or undesired products.

Molecular magnetic properties of a dysprosium(III) complex coordinated to a nonadentate bispidine ligand

AbstractThe DyIII complex of the nonadentate bispidine L1 (bispidine=3,7‐diazabicyclo[3.3.1]nonane) has a capped square antiprismatic structure, known to lead to suppressed quantum relaxation of magnetization by quantum tunneling. [DyIIIL1]OTf indeed is an SMM with a modest barrier to magnetization relaxation. The experimentally determined barrier of 46 cm−1 is confirmed by ab initio calculations (43.5 cm−1), and the quantum‐chemical analysis indicates that ligand modifications, leading to a higher symmetry and a stronger axial ligand field should significantly increase the effective barrier to magnetization relaxation.

Syntheses, structural modulation, and slow magnetic relaxation of three dysprosium(iii) complexes with mononuclear, dinuclear, and one-dimensional structures

Three mononuclear, dinuclear and one-dimensional dysprosium(iii) complexes based on 3-azotriazolyl-2,6-dihydroxybenzoic acid displaying slow magnetic relaxation were synthesized and characterized.

Imidosulfonate scorpionate ligands in lanthanide single-molecule magnet design: slow magnetic relaxation and butterfly hysteresis in [ClDy{Ph2PCH2S(NtBu)3}2

Single-molecule magnets (SMMs) harbour vast opportunities for potential pioneering applications upon optimization like big data storage and quantum computing. Lanthanides were found to be highly suitable candidates in the design of such molecules, as they intrinsically hold a large unquenched orbital momentum and a strong spin-orbit coupling, warranting a high magnetic anisotropy. An indispensable element in successfully tailoring SMMs is the ligand design. Polyimido sulfur ligands offer a promising choice because the polar S+-N--bond facilitates both electronic and geometric adaptability to various f-metals. In particular, the acute N-Ln-N bite angle generates advantageous magnetic properties. The [Ph2PCH2S(NtBu)3]- anion, introduced from [(thf)3K{Ph2PCH2S(NtBu)3}] (2) to a series of complexes [ClLn{Ph2PCH2S(NtBu)3}2] with Ln = Tb (3a), Dy (3b), Er (3c), Ho (3d), and Lu (3e), provides tripodal shielding of the metal's hemisphere as well as a side-arm donation of a soft phosphorus atom. For the Tb and Er complexes 3a and 3d, slow magnetic relaxation (Ueff = 235 and 34.5 cm-1, respectively) was only observed under an applied dc field. The dysprosium congener 3b, however, is a true SMM with relaxation at zero field (Ueff = 66 cm-1) and showing a butterfly hysteresis close to 3.5 K. Upon magnetic dilution with the diamagnetic and isostructural lutetium complex 3e or application of a magnetic field, the energy barrier to spin reversal is increased to 74 cm-1.

New lanthanoid biphenolate complexes, their further reactivity with trimethylaluminium and catalytic activity for the polymerisation of rac-lactide.

A series of rare earth biphenolate complexes of the general form [Ln(mbmp)(mbmpH)(thf)3] (Ln = Y (1), Nd (2), Gd (3), Dy (4), Er (5), Tm (6) and Lu (7)) have been synthesised by redox transmetallation/protolysis (RTP) from the free rare earth metal, Hg(C6F5)2 and 2,2'-methylenebis(6-tert-butyl-4-methylphenol) (mbmpH2). The rare earth metal is six coordinate with one chelating biphenolate mbmp2- ligand and one unidentate monophenolate mbmpH- ligand. The yttrium complex, when crystallised from hot toluene or deuterated benzene, loses a coordinated thf and exhibits coordination through all three phenolate oxygen atoms, as well as the oxygen of the phenol, yielding two solvates [Y(mbmp)(mbmpH)(thf)2]·nsolv (solv = PhMe, n = 1 (8a) or C6D6, n = 2 (8b)). Of these rare earth complexes, the yttrium derivative (1) yielded the heterobimetallic complex [AlMe2Y(mbmp)2(thf)2] (9) when treated with trimethylaluminium, whereas all other complexes produced the transmetallation product [AlMe(mbmp)(thf)] (11). The dinuclear dysprosium complex [Dy2(mbmp)3(thf)3] (10) was isolated alongside 11 from the reaction of 4 with trimethylaluminium, suggesting trimethylaluminium instigates a redistribution reaction. The ROP activity of the mononuclear neodymium, dysprosium, lutetium, and aluminium complexes towards rac-lactide in toluene at 70 °C was found to be poor compared to rare earth complexes of monodentate aryloxides, but increased with increased rare earth ion size.

Synthesis, structures and magnetic properties of dysprosium(iii) complexes based on amino-bis(benzotriazole phenolate) and nitrophenolates: influence over the slow relaxation of the magnetization

Field-induced slow relaxation in dysprosium amino-bis(benzotriazole) phenolate complexes.

High magnetization reversal barriers in luminescent dysprosium octahedral and pentagonal bipyramidal single-molecule magnets based on fluorinated alkoxide ligands.

We report the synthesis and structures of three luminescent dysprosium(iii) complexes based on fluorinated alkoxide ligands of formulas [Dy(L1)2(THF)4][BPh4]·0.5THF (1), [Dy(L2)2(THF)5][BPh4]·2.5THF (2) and [Dy(L3)2(THF)5][BPh4]·2THF (3) (L1 = (CF3)3CO-, L2 = C6F5C6F4O-, L3 = C6F5C(CH3)O-). Despite the different dysprosium ion geometries (octahedral vs. distorted pentagonal bipyramidal), these systems exhibit a single-molecule magnet (SMM) behavior, but with distinct relaxation dynamics. Moreover, a typical dysprosium-based luminescence is observed for the three complexes, which make them bifunctional magneto-luminescent SMMs. Remarkably, complex 3 exhibits a high anisotropy barrier of 1469 cm-1 and a blocking temperature of 22 K, making it one of the most performant alkoxide-based SMMs with the highest blocking temperature for a luminescent SMM.

The construction of dynamic dysprosium-carboxylate ribbons by utilizing the hybrid-ligand conception.

By utilizing the hybrid-ligand conception, three novel dysprosium complexes Dy(2-py-4-pmc)(L)(H2O) (H2-py-4-pmc = 2-(2-pyridyl)pyrimidine-4-carboxylic acid; L = fumarate (fum, 1), succinate (suc, 2), or pimelate (pim, 3)) have been successfully synthesized. Structural analysis reveals that the dicarboxylate ligands connect 2-py-4-pmc--protected Dy3+ to form one-dimensional molecular ribbons. Magnetic measurements indicate that the three complexes exhibit typical slow magnetic relaxation under a zero dc field with effective reversal barriers Ueff of 180 K, 145 K and 137 K for 1-3, respectively, which is mainly attributed to the strong Ising anisotropy of dysprosium ions induced by the appropriate arrangement of carboxylate groups. Ab initio calculations demonstrate that the charge distribution around dysprosium ions and the magnetic interactions between them are key contributions to their different dynamic behaviour.

Ligand field and anion-driven structures and magnetic properties of dysprosium complexes

Based on the organic ligand H2L, three Dy-based complexes were synthesized, and structurally and magnetically characterized. Theoretical calculations are performed to analyze the performance of single molecule magnets.

Eight coordinated mononuclear dysprosium complexes of heptadentate aminophenol ligands: the influence of the phenol substituents and the ancillary donors on the magnetic relaxation.

The mononuclear complexes [Dy(3Br,5Cl-H3L1,1,4)(D)]·solvate (D = H2O, solvate = 0.25MeOH, 1W·0.25MeOH; D = Py without solvate, 1Py), and [Dy(3NO2,5Br-H3L1,1,4)(H2O)] (2W) were isolated. The crystal structures of 1W·0.25MeOH, 1Py and 2W·2CH3C6H5 show that the DyIII ion is octacoordinated, in N4O4 or N5O3 environments, with distorted geometries, between square antiprism, biaugmented trigonal prism and triangular dodecahedral. A similar environment for the metal ion is shown in the chiral crystals of the diamagnetic yttrium analogue [Y(3Br,5Cl-H3L1,1,4)(MeOH)] (3M), which were spontaneously resolved. Magnetic analyses of the three dysprosium complexes, and their diluted analogous 1W@Y, 1Py@Y and 2W@Y, reveal that none of them seem to relax through an Orbach mechanism at Hdc = 0. However, the three complexes show Orbach relaxation under Hdc = 1000 Oe, and 1Py is the in-field SIM with the highest energy barrier among these complexes, with a Ueff value of 358 K. Analysis of ac magnetic data shows that the electron-withdrawing substituents on the phenol rings of the aminophenol ligands, as well as the auxiliary oxygen donors from water ligands, reduce the energy barriers of the complexes, which is attributed to a charge reduction in the coordinating atoms of the aminophenol donor. Ab initio calculations support the experimental results.