Erbium Complexes Research Articles

Crystal structure and cryomagnetic study of a mononuclear erbium(III) oxamate inclusion complex.

The synthesis, crystal structure and magnetic properties of an oxamate-containing erbium(III) complex, namely, tetrabutylammonium aqua[N-(2,4,6-trimethylphenyl)oxamato]erbium(III)-dimethyl sulfoxide-water (1/3/1.5), (C16H36N)[Er(C11H12NO3)4(H2O)]·3C2H6OS·1.5H2O or n-Bu4N[Er(Htmpa)4(H2O)]·3DMSO·1.5H2O (1), are reported. The crystal structure of 1 reveals the occurrence of an erbium(III) ion, which is surrounded by four N-phenyl-substituted oxamate ligands and one water molecule in a nine-coordinated environment, together with one tetrabutylammonium cation acting as a counter-ion, and one water and three dimethyl sulfoxide (DMSO) molecules of crystallization. Variable-temperature static (dc) and dynamic (ac) magnetic measurements were carried out for this mononuclear complex, revealing that it behaves as a field-induced single-ion magnet (SIM) below 5.0 K.

Retraction: Experimental and theoretical investigations of Erbium complex: DNA/BSA interaction, anticancer and antibacterial studies

Retraction: Experimental and theoretical investigations of Erbium complex: DNA/BSA interaction, anticancer and antibacterial studies

Erbium(III) complexes with fluoroquinolones: Structure and biological properties

Four erbium(III) complexes with the fluoroquinolones enrofloxacin, levofloxacin, flumequine and sparfloxacin as ligands were synthesized and characterized by a wide range of physicochemical and spectroscopic techniques as well as single–crystal X–ray crystallography. The compounds were evaluated for their activity against the bacterial strains Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Xanthomonas campestris, which was higher than that of the corresponding free quinolones. The interaction mode of the complexes with calf–thymus DNA is via intercalation, as suggested by diverse studies such as UV–vis spectroscopy, DNA–viscosity measurements and competitive studies with ethidium bromide. Fluorescence emission spectroscopy revealed the high affinity of the complexes for bovine and human serum albumin and the determined binding constants suggested a tight and reversible binding of the compounds with both albumins.

Preparation, structure and properties of a novel one-dimensional erbium (III) complex

A novel one-dimensional erbium complex [ErL2(NO3)(H2O)2]n (HL = 2-picolinic acid) was synthesized by hydrothermal methods, and its crystal structure was determined by single crystal x-ray diffraction. The complex crystallize in monoclinic system, space group C2/c with a = 15.7525(5) Å, b = 11.4958(4) Å, c = 9.7977(3) Å, β = 102.862(3) º, V = 1729.72(10) Å3, C12H10ErN3O9, Mr = 507.49, Z = 4, Dc = 1.949 g•cm-3, F(000) = 972,  = 4.901 mm-1, S= 1.119, λ(MoKα) = 0.071073 nm, R = 0.0239 and wR = 0.0668. The 2-picolinic acid ligand adopts bidentate bridging coordination mode to connect adjacent erbium ions to form a one-dimensional chain structure. A series of properties of the complex were measured by solid-state photoluminescence, solid-state diffuse reflection and differential scanning calorimetry.

High Quantum Yields from Perfluorinated Binolate Erbium Complexes and Their Circularly Polarized Luminescence.

High quantum yield and circularly polarized luminescence (CPL) brightness values are reported from Shibasaki-type erbium complexes supported by a perfluorinated Binol ligand (F12Binol). The total fluorination of the ligand circumvents nonradiative quenching from Csp2-H vibrations and leads to quantum yields of up to 11% and CPL brightness values of up to 317 M-1 cm-1 (a 19- and 6-fold increase, respectively, compared to (Binol)3ErNa3). These values are the highest values for any molecular erbium complex to date, making them comparable to Yb emitters. A series of fluorinated Shibasaki-type complexes are synthesized by varying the alkali metal (K, Na, Li) in the secondary coordination sphere, leading to unexpected structural differences. NMR (19F, 7Li) and chiroptical spectroscopy analyses provide insights into their structural geometry. With much improved quantum yields and CPL brightness values, we provide synthetic design principles toward other practical candidates for use in quantum communication technologies.

Coordination compounds of indium, gadolinium, and erbium nitrates with low urea content

Objectives. To date, compounds of rare earth nitrates with urea in a ratio of 1:4 and indium in a ratio of 1:6 have been synthesized and structurally characterized. However, there is a lack of research into similar compounds having a lower urea content. The purpose of this work was to continue the search for regularities of structure formation for complexes of various elements with urea.Methods. Novel coordination compounds were synthesized and characterized by powder- and single-crystal X-ray diffraction analysis, as well as infrared spectroscopy.Results. The interaction of indium, gadolinium and erbium nitrates with urea (Ur) in an aqueous solution under conditions of ligand deficiency produces the previously unknown coordination compounds cis-[In(Ur)4(NO3)2]NO3, [Gd(H2O)2(Ur)2(NO3)3], and [Er(H2O)2(Ur)(NO3)3]. The indium complex is shown to have an ionic structure, whereas the gadolinium and erbium complexes have a molecular structure. In the indium complex, the coordination number is 6; the cation has an octahedral structure; it involves two cis-arranged monodentate nitrate groups and four monodentate urea molecules. The coordination number of gadolinium is 10; here, the coordination polyhedron is a distorted pentagonal bipyramid at the vertices of which there are two water molecules, while in the internal polygonal base there are two monodentate urea molecules and three bidentate chelating nitrate groups oriented perpendicular to the polygonal base of the bipyramid. The coordination number of erbium is 9; the coordination polyhedron is a distorted tricapped trigonal prism.Conclusions. In contrast with the gadolinium complex, one urea molecule is coordinated in the erbium complex instead of two, decreasing the coordination number from 10 to 9. In the indium complex cation, the coordination number is 6; unlike the gadolinium and erbium complexes, the cation does not contain water, and the nitrate groups are monodentate.

Mono- and dichlorido terbium(iii) and erbium(iii) complexes coordinated by diazabutadiene ligands in different redox states

Treatment of 1,4-diazabutadienes (DADs) of formula DippN=C(R)C(R)=NDipp (Dipp = 2,6-Pr2iC6H3, R = H or Me) with 2 or 1 equiv. of potassium metal in THF leads to the corresponding dianions (DAD2–) or radical anions (DAD•−), respectively. The subsequent salt metathesis between LnCl3 (Ln = Tb or Er) and the above dianions affords dimeric monochlorido complexes [(DAD2–)Ln(THF)2(μ-Cl)]2 with bridging chlorine atoms between the lanthanides. The reaction of the radical anion species with LnCl3, if R = H, gives monomeric dichlorido complexes (DAD•−)Ln(THF)2Cl2; however, if R = Me, the activation of one methyl group occurs, which in the reaction with TbCl3 leads to the formation of a product with shifted double bonds [DippN=C(Me)C(=CH2)N(Dipp)]Tb(THF)2Cl2.

Impact of the experimental bandwidth on circularly polarized luminescence measurements of lanthanide complexes: the case of erbium(iii)

The NIR circularly polarized luminescence of erbium complexes is strongly dependent on the experimental conditions and in particular on the experimental bandwidth.

Polymer Optical Waveguide Amplifiers Doped with Phosphine Oxide Erbium Complex Based on 365 nm LED Pumping

Polymer Optical Waveguide Amplifiers Doped with Phosphine Oxide Erbium Complex Based on 365 nm LED Pumping

Substituent Positioning Effects on the Magnetic Properties of Sandwich-Type Erbium(III) Complexes with Bis(trimethylsilyl)-Substituted Cyclooctatetraenyl Ligands.

Lanthanide complexes with judiciously designed ligands have been extensively studied for their potential applications as single-molecule magnets. With the influence of ligands on their magnetic properties generally established, recent research has unearthed certain effects inherent to site differentiation due to the different types and varying numbers of substituents on the same ligand platform. Using two new sandwich-type Er(III) complexes with cyclooctatetraenyl (COT) ligands featuring two differently positioned trimethylsilyl (TMS) substituents, namely, [Li(DME)Er(COT1,5-TMS2)2]n (Er1) and [Na(DME)3][Er(COT1,3-TMS2)2] (Er2) [COT1,3-TMS2 and COT1,5-TMS2 donate 1,3- and 1,5-bis(trimethylsilyl)-substituted cyclooctatetraenyl ligands, respectively; DME = 1,2-dimethoxyethane], and with reference to previously reported [Li(DME)3][Er(COT1,4-TMS2)2] (A) and [K(DME)2][Er(COT1,4-TMS2)2] (B), any possible substituent position effects have been explored for the first time. The rearrangement of the TMS substituents from the starting COT1,4-TMS2 to COT1,3-TMS2 and COT1,5-TMS2, by way of formal migration of the TMS group, was thermally induced in the case of Er1, while for the formation of Er2, the use of Na+ in the placement of its Li+ and K+ congeners is essential. Both Er1 and Er2 display single-molecule magnetic behaviors with energy barriers of 170(3) and 172(6) K, respectively. Magnetic hysteresis loops, butterfly-shaped for Er1 and wide open for Er2, were observed up to 12 K for Er1 and 13 K for Er2. Studies of magnetic dynamics reveal the different pathways for relaxation of magnetization below 10 K, mainly by the Raman process for Er1 and by quantum tunneling of magnetization for Er2, leading to the order of magnitude difference in magnetic relaxation times and sharply different magnetic hysteresis loops.

Preparation and physico-chemical properties of lanthanide(III) complexes with 2-((E)- (tert- butylimino)methyl)-6-methoxyphenol

ABSTRACT. The reactions of lanthanide nitrates with 2-((E)-(tert-butylimino)methyl)-6-methoxyphenol (HL1) have yielded five complexes that are described by the formulae [Ce(HL1)2(NO3)3]∙MeOH and [Ln(HL1)2(NO3)3] (Ln = Nd(III), Gd(III), Ho(III) and Er(III)) and were characterized using physico-chemical techniques including single-crystal X-ray diffraction spectroscopy. The cerium complex crystallized in a triclinic P-1 space group, while the rest of the complexes crystallized in the monoclinic P21/c space group. All the complexes are ten-coordinate, adopting a tetradecahedron geometry with two HL1 molecules coordinated through the phenolic and methoxy oxygen atoms. The coordination sphere is completed by six oxygen atoms from three bidentately coordinated nitrate ligands. Electronic data reveals that only the neodymium, holmium and erbium complexes exhibit weak f-f transitions in the visible region.
 KEY WORDS: Preparation, Physico-chemical properties, Lanthanide, Schiff base complexes, Crystal structure, Geometry
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1397-1410. DOI: https://dx.doi.org/10.4314/bcse.v37i6.8

Nanoscale Study of the Polar and Electronic Properties of a Molecular Erbium(III) Complex Observed via Scanning Probe Microscopy

We successfully synthesized millimeter-sized single crystals of the molecular erbium(III) complex Er(acac)3(cphen), where acac = acetylacetonate and cphen = 5-chloro-1,10-phenanthroline. The novelty of this work stems from the exhaustive examination of the polar and electronic properties of the obtained samples at the macro-, micro-, and nanoscale levels. The single crystal X-ray diffraction method demonstrates the monoclinic (noncentrosymmetric space group P21) crystallographic structure of the synthesized samples and scanning electron microscopy exhibits the terrace–ledge morphology of the surface in erbium(III) crystals. By using the piezoelectric force microscopy mode, the origin of the polar properties and the hyperpolarizability in the synthesized samples were assigned to the internal domain structure framed by the characteristic terrace–ledge topography. The direct piezoelectric coefficient (~d33) was found to be intensely dependent on the local area and was measured in the range of 4–8 pm/V. A nanoscale study using the kelvin probe force and capacitance force (dC/dz) microscopy modes exposed the effect of the Er ions clustering in the erbium(III) complex. The PFM method applied solely to the Er ion revealed the corresponding direct piezoelectric coefficient (~d33) of about 4 pm/V. Given the maximum piezoelectric coefficient in the erbium(III) complex at 8 pm/V, we highlight the significant importance of the spatial coordination between the lanthanide ion and the ligands. The polar coordination between the lanthanide ion and the nitrogen and oxygen atoms was also corroborated by Raman spectroscopy supported by the density functional theory calculations. The obtained results can be of paramount importance for the application of molecular erbium(III) complex crystals in low-magnitude magnetic or electric field devices, which would reduce the energy consumption and speed up the processing switching in nonvolatile memory devices.

Experimental and theoretical investigations of Erbium complex: DNA/BSA interaction, anticancer and antibacterial studies.

To assess the biological potential of an Er complex that contains a 2,2'-bipyridine ligand, various techniques such as multispectral and molecular modeling procedures were utilized to examine its DNA-binding ability, BSA binding affinity, antimicrobial effects, and anticancer properties. By analyzing fluorescent information and employing the vant' Hoff equation, important parameters such as the innate docking coefficient (Kb), Stern-Volmer coefficient (KSV), and thermodynamic properties including modifications in liberated energy (ΔG°), enthalpy (∆H°), and entropy (∆S°) were determined. The trial findings suggest that the compound can bind to DNA, primarily through groove binding. Additionally, the engagement between the Er compound and the protein BSA was examined using emission spectroscopy technique, revealing a powerful binding affinity between the compound and BSA. The Er complex binds to BSA primarily via hydrogen links and van der Waals forces, as indicated by the adverse values of ΔH° and ∆S°. Through a static quenching process, the complex significantly reduces the intrinsic fluorescence of BSA. Molecular binding calculations and rivalrous binding trials confirm that this compound dock to hydrophobic remains found in site III of BSA. Additionally, the Er complex demonstrates promising results in terms of its anticancer and antimicrobial activities based on screening tests.

The Organic Ammonium Counterion Effect on Slow Magnetic Relaxation of the [Er(hfac)4]− Complexes

The first mononuclear anionic erbium complex [Er(hfac)4]− (hfac = hexafluoroacetylacetone) with an organic ammonium cation [(CH3)4N+] as the counterion was synthesized and structurally and magnetically characterized. The coordination geometries around the Er ions are square antiprisms with pseudo-D4d symmetry. The complex shows distinct field-induced slow magnetization relaxation, which is described by a combination of Orbach (Ueff/kB~28.54(8) K.) and direct mechanisms. Quantum chemical calculations were performed to analyze the magnetic properties of the complex under consideration.

Effect of Erbium Complexes on the Anti-Stokes Luminescence of Y2O2S:Er Ceramics

Effect of Erbium Complexes on the Anti-Stokes Luminescence of Y2O2S:Er Ceramics

Micelle Sensitized Physicochemical Studies on Erbium(III) Complexes with Hypoglycemic Sulfonylurea Drugs

Hypoglycemic sulfonylurea derivatives ligands viz. glimepiride, glibenclamide, gliclazide and glipizide show interaction with lanthanide metal Er (III) in non-micellar and micellar medium. Anionic, cationic and non-ionic surfactant micellar media show great variation in oscillator strength of Er (III) with hypoglycemic sulfonylurea drugs as reflected in UVVisible absorption spectra. Interpretation of UVVisible absorption spectra produced that 4G11/2 ← 4I15/2 and 2H11/2 ← 4I15/2 electronic transition bands show different behavior on account of oscillator strength (P) compared to other electronic f-f transitions, depicted as hypersensitive peaks which are characterized as ratio of Pmicellar / PDMF. Exploitation of different parameters viz: oscillator strength (P), Judd-Ofelt parameter Tλ, nephelauxetic effect 𝛽 and bonding parameter b1/2 from absorption spectra supports the covalency characters in metal ligand Er (III)-drugs doped systems to a greater extent. Thermodynamic exploits of hypersensitive transition correlate the spectroscopic data via Work function A, Thermodynamic efficiency of transition TET and Partition function Q. Thermodynamic parameters notify the microscopic behaviour of Er (III)- sulfonylurea drugs.

Erbium(III) coordination compounds with substituted salicylaldehydes: Characterization and biological profile

Five erbium(III) complexes with salicylaldehyde (saloH for 1), and mono– (5–X–saloH; X = NO2 and Me for 2 and 3, respectively) or di–substituted salicylaldehydes (3,5–diX–saloH; X = Cl and Br for 4 and 5, respectively) were synthesized and characterized by physicochemical and spectroscopic techniques and single–crystal X–ray crystallography. All five complexes have the general formula [Er(deprotonated salicylaldehyde)3(MeOH)(H2O)]. The structure of complexes [Er(3,5–diCl–salo)3(MeOH)(H2O)]·1.5MeOH (complex 4) and [Er(3,5–diBr–salo)3(MeOH)(H2O)]·1.75MeOH (complex 5) were verified by single–crystal X–ray crystallography. The evaluation of antioxidant activity of the complexes was focused on their ability to scavenge 1,1–diphenyl–picrylhydrazyl and 2,2′–azinobis–(3–ethylbenzothiazoline–6–sulfonic acid) free radicals and to reduce H2O2. The interaction of the complexes with calf–thymus DNA was investigated by UV–vis spectroscopy, viscosity measurements and via competitive studies with ethidium bromide in order to evaluate the possible DNA–binding mode and to determine the corresponding DNA–binding constants. The affinity of the complexes for bovine and human serum albumins was explored by fluorescence emission spectroscopy and the corresponding binding constants were determined.

Features of the Electronic and Local Atomic Structures of Erbium Complexes of Tetraphenylporphyrin: Analysis of the Data of Photoelectron Spectroscopy and X-Ray Absorption Spectroscopy

Features of the Electronic and Local Atomic Structures of Erbium Complexes of Tetraphenylporphyrin: Analysis of the Data of Photoelectron Spectroscopy and X-Ray Absorption Spectroscopy

Dual visible and near-infrared luminescence in mononuclear macrocyclic erbium(III) complexes via ligand and metal centred excitation.

Considering the structural design of some of the scarce molecular-based Er-centred emitters in the literature, we explored the optical properties of three ErIII hexaazamacrocyclic complexes, namely Er-EDA (1), Er-OPDA(2) and Er-DAP(3). The macrocyclic ligands in these complexes differ in the lateral spacers, and are derived from 2,6-pyridine-dicarbaldehyde and ethylenediamine (EDA), ortho-phenylenediamine (OPDA) or 1,3-diaminopropane (DAP). Upon ligand-centred excitation, the bluish-green and green emissions of the ErIII ion were detected only for the complexes containing macrocycles with aliphatic spacers (1 and 3), which evidenced that these ligands can sensitize the ErIII luminescence. On the other hand, the ligand derived from the aromatic diamine (2) does not sensitize the ErIII luminescence. Energy transfer mechanisms, temperature sensing, CIE coordinates and CCT values were analyzed. Besides the excitation in the ligands, the erbium-centred excitation at 980 nm allowed the detection, in all cases, of bluish-green, green and red up-converted emissions, and also the downshifted NIR emission. The possible mechanisms involved in these transitions were described and analyzed according to the available data.

Features of the Electronic and Local Atomic Structures of Erbium Complexes of Tetraphenylporfyrin: Analysis of the Data Photoelectron Spectroscopy and X-Ray Absorption Spectroscopy

Features of the Electronic and Local Atomic Structures of Erbium Complexes of Tetraphenylporfyrin: Analysis of the Data Photoelectron Spectroscopy and X-Ray Absorption Spectroscopy