Neodymium Complexes Research Articles

Structure, optical absorption and NIR-Photoluminescence of ternary Neodymium (III) complexes with fluorinated β-diketone and heterocyclic Lewis bases

Four heteroleptic neodymium complexes, [Nd(fod)3(phen)] (Nd-1), [Nd(fod)3(bpy)] (Nd-2), [Nd(fod)3(im)2] (Nd-3) and [Nd(fod)3(μ-bpp)Nd(fod)3] (Nd-4) (fod is the anion of 6,6,7,7,8,8,8- heptafluoro-2,2-dimethyl-3,5-ocanedione (Hfod), phen is 1,10-phenanthroline, bpy is 2,2′-bipyridine, im is imidazole and bpp is 2,3-bis(2-pyridyl) pyrazine) are synthesized and thoroughly characterized by elemental analysis, TGA, DTA, 1H NMR and infra-red spectroscopy. The complexes Nd-3 and Nd-4 are new; however, the synthesis of Nd-1 and Nd-2 has been reported elsewhere and were resynthesized to investigate their photoluminescence properties. The complexes, retain their identity at higher temperatures and evaporate in the temperature range between 220 and 327-°C without decomposition. The single crystal X-ray structure has been determined for the Nd-1 complex, and ground state geometries of the other three complexes have been predicted using the Sparkle/PM7 model. The optical absorption in different solvents is studied and evaluated in terms of oscillator strength and band shape. The oscillator strength of the hypersensitive 4G5/2,2G7/2 ← 4I9/2 transition is highest in non-coordinating solvents (chloroform and dichloromethane), indicating that the ligand environment around the metal ion is adequately asymmetric. The near IR luminescence, decay curves, and intrinsic quantum yield of these complexes in chloroform are investigated and discussed. It is observed that the replacement of water molecule from the inner coordination sphere of [Nd(fod)3(H2O)] (τ = 1.37µs) by different ancillary ligands markedly enhance the decay time; Nd-2 (2.06 µs) > Nd-4 (1.98 µs) > Nd-1 (1.82 µs) > Nd-3 (1.38 µs) and intrinsic quantum yield (Nd-2 (0.82) > Nd-4 (0.79) > Nd-1 (0.73) > Nd-3 (0.55) of the complexes in chloroform. The scheme energy transfer process is presented, and it has been shown that the ancillary ligands are efficient in enhancing luminescence in the complexes. The CH vibrational quenching of the excited state of Nd3+ can effectively be reduced by using fluorinated ligands in the coordination sphere.

Electrochemistry of Neodymium in an Equimolar NaCl-KCl Melt without and with Addition of Fluoride Ions

An investigation of compounds of those few elements in the oxidation state (II), by opposition to the general trivalent lanthanides is of special interest. The present work follows our previous investigations on samarium, europium ytterbium chloride systems and, in particular, the electrochemical behavior of the Sm(III)/Sm(II), Eu(III)/Eu(II) Yb(III)/Yb(II) redox couples. It deals with neodimium compounds.The electrochemical behavior of NdCl3 in molten salts was studied in few works, but only melts with a low melting point LiCl-KCl and LiCl-KCl-CsCl were investigated.The electroreduction of NdCl3 in an equimolar NaCl-KCl mixture was studied in the temperature range 973-1123 K by different electrochemical methods. It was shown that the discharge of Nd(III) to Nd(II) is complicated by the disproportionation reaction (DPP):3Nd(II) ↔ 2Nd(III) + Nd (1)Ignoring of reaction DPP can lead to incorrect determination of values diffusion coefficients and formal standard redox potentials of the Nd(III)/Nd(II) redox couple. The relatively narrow interval of polarization rate was found when the recharge process was reversible and not accompanied by the DPP reaction. At these scan rates the diffusion coefficients and formal standard redox potentials of the Nd(III)/Nd(II) redox couple were determined by cyclic voltammetry.The standard rate constants for the redox reaction Nd(III) + e- ↔ Nd(II) were calculated on the basis of cyclic voltammetry at sweep rates corresponding to the quasy-reversible process. The nature of working electrode on the rate of charge transfer for the Nd(III)/Nd(II) redox couple was studied. It was found that the values of k s determined at a molybdenum electrode were higher than those at a glassy carbon electrode.The introduction of fluorine anions into a chloride melt at a molar ratio of F-/Nd(III) = 5 leads to the disappearance of the recharge wave and only an ascending section associated with joint discharge of neodymium complexes and sodium and potassium cations was observed. Thus, the introduction of fluorine anions leads to stabilization of the highest oxidation state of neodymium in chloride-fluoride melt and neodymium in the oxidation state +2 does not exist in the melt.Introducing of fluoride ions to the melt NaCl-KCl containing Nd(II) accompanied by reaction of disproportionation:3NdCl4 2- + 12F- ↔ 2NdF6 3- + Nd + 12Cl- (2)The standard rate constants of charge transfer for the Nd(III)/Nd(II) redox couple were compared with the values obtained for other redox couples of lanthanides and these results were discussed in connection with the strength and stability of complexes.

Synthesis, Structure, and Properties of Volatile Lanthanide Dialkyltriazenides.

Several dialkyltriazenide complexes of the lanthanide elements neodymium, europium, and erbium have been prepared; these include the homoleptic complex Er(ButN3But)3, the tetrahydrofuran monoadducts Ln(ButN3But)3(THF) where Ln = Nd or Eu, and the lithium salts [Li(THF)][Ln(MeN3But)4] where Ln = Eu or Er. Crystal structures, nuclear magnetic resonance data, and infrared data are reported for all complexes. The di-tert-butyltriazenide complexes are thermally stable, sublime at reasonably low temperatures, and show smooth volatilization without decomposition, which make them potentially useful in lanthanide separation processes and as chemical vapor deposition precursors for lanthanide nitrides and other phases.

Synthesis, Structures, optical properties and DFT studies of neodymium complexes containing octanoyl amino carboxylic acids

Amino acid rare-earth complexes are widely used due to their unique physical and chemical properties. In this study, three kinds of neodymium (III) complexes with octanoyl-aminocarboxylate ligands (abbr. Nd(oct-ala)3, Nd(oct-phe)3, Nd(oct-ser)3) were prepared by a chemical reaction method in methanol as the solvent. The chemical formulas and coordination modes of the neodymium complexes were determined by elemental analysis, 1H NMR and FT-IR. Additional analyses by X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that the neodymium complexes have lamellar irregular shapes and long-range disordered amorphous structures. The thermal performance of the complexes was determined by differential scanning calorimetry (DSC) and thermal gravimetry-differential thermal analysis (TG-DTA). Nd(oct-phe)3 and Nd(oct-ser)3 appeared glassy when heated. The solubility of the complexes in various organic reagents was also measured. The optical properties of the complexes were examined using UV–Vis absorption, polarizing microscopy observations, fluorescence spectra, quantum yield, and fluorescence lifetime. The luminescence properties of the complexes as a function of temperature were further observed by analysis of temperature-dependent emission spectra. The polarizing microscopy observations show that the three neodymium complexes exhibited the characteristic properties of thermotropic liquid crystals. UV–Vis, fluorescence spectroscopy, and quantum yield results show that they have excellent light absorption and luminescence properties. Temperature-dependent emission spectra show that the complexes have good luminescence properties in the temperature range of 25–160 °C. The powdered complexes and the complexed solutions in methanol were irradiated with 380 nm UV light, resulting in blue-violet light emission. A warm white-light device was constructed to further verify the luminescence of the complexes after combining with three kinds of rare-earth complexes (Nd(oct-phe)3, Eu(oct-phe)3, and Tb(oct-phe)3. The color rendering index (CRI) and color temperature (CCT) were measured. In addition, the density functional theory (DFT) was used to determine the geometric structures (Fig S1), and obtain 1H NMR, FT-IR spectra of the neodymium complexes (Fig S2, S3). Their structures were further examined by comparing the calculated with the experimental spectra. The results show that the ligands coordinate to the central Nd3+ through the bidentate chelation mode.

Triply bridged binuclear lanthanides-Zwitterion complexes: synthesis and characterization of (Gd(III), Nd(III), Sm(III)) complexes

2,2'-((1E,1'E)-(Butane-1,4-diylbis (azanylylidene))bis (methanylylidene)) diphenol zwitterion (L) (4′) was prepared by treatment of two equiv. of (3-(2-furyl)acrolein) (1) with one equiv. of 1,4-butanediamine (2) in refluxing ethanol through an intramolecular Diels-Alder reaction. Three new lanthanide compounds based on (4′), [Ln2(NO3)4(H2O)2L3]·2NO3 (5) (a, Ln = Gd; b, Ln = Nd; c, Ln = Sm), have been obtained and further characterized by elemental analysis, conductivity, magnetic measurements, FT-IR, powder X-ray and thermogravimetric analysis. Compounds 5a–c exhibit a discrete dinuclear structure constructed by three ligands coordinating two Ln3+ ions. The oxygen atoms of the diphenol are involved in the coordination of 5, while the nitrogen atoms of the imines are not involved. Hypersensitive transitions could be observed at 877, 807, 753, 588, and 522 nm in the UV–visible absorption spectrum of the neodymium complex 5 b, corresponding to 4I9/2→4F3/2 (877 nm); 4I9/2→4F5/2, 2H9/2 (807 nm); 4I9/2→4S3/2, 4F7/2 (753 nm); 4I9/2→2G7/2, 4G5/2 (588 nm); 4I9/2→4G9/2 4G7/2, and 2K13/2 (522 nm), respectively. Emission spectra of the ligand and its samarium complex 5c revealed characteristic luminescence within the visible region with the emission of the samarium complex being relatively red shifted.

Characterization of a Ternary Neodymium-HEDTA-Citrate Complex in the Actinide Lanthanide Separation Process.

The actinide lanthanide separation (ALSEP) process is a modern solvent extraction approach used for the separation of the minor actinides americium and curium from the lanthanide fission products for transmutation, a process that can significantly reduce the long-term radioactivity and heat loading of nuclear waste. This process, inspired by existing chemistry, uses the aminopolycarboxylate N-(2-hydroxyethyl)ethylenediamine-N,N′,N′-triacetic acid (HEDTA) to selectively separate the actinides by stripping them from the organic phase while leaving the lanthanides behind. HEDTA is used in this separation as it has been shown to exhibit faster extraction kinetics than other aminopolycarboxylates, but its lower coordination number can allow for the formation of higher order complexes with the typically 8- to 9-coordinate f-elements. ALSEP uses a carboxylic acid buffer in the aqueous phase to control the pH of the system during metal stripping, and this buffer has the ability to complex actinide(III) and lanthanide(III) ions. The presence of a previously uncharacterized ternary lanthanide-HEDTA-citrate complex was detected during single-phase spectroscopy experiments. A combination of partitioning experiments and spectrophotometric titrations led to the identification of a 1:1:1 complex containing a partially protonated citrate ligand and determination of the stability constant of its neodymium complex.

Synthesis, Characterization and Biological Activities of New Schiff Base Compound and Its Lanthanide Complexes.

The thermal condensation of 3-(2-Furyl)acrolein with 2-Amino-6-ethoxybenzothiazole generated a new Schiff base, (1E,2E)-N-(6-ethoxybenzo[d]thiazol-2-yl)-3-(furan-2-yl)prop-2-en-1-imine (L), with general formula of C16H14N2O2S. Also, a series of lanthanide complexes of gadolinium, samarium, and neodymium (La–Lc) were synthesized utilizing acetonitrile as the solvent and triethylamine as a buffer and catalyst. Based on elemental analysis, mass spectroscopy, and FTIR analysis, all of the Bis-(1E,2E)-N-(6-ethoxybenzo[d]thiazol-2-yl)-3-(furan-2-yl)prop-2-en-1-iminetri-nitratolanthanide(III) complexes with the general formula [LnL2(NO3)3]·H2O are solids with a 2:1 molar ratio (ligand: metal). Based on conductivity estimates, they are nonelectrolytes and monoatomic paramagnetic according to the magnetic moment measurements, and one mole of lattice water was found after thermal gravimetric measurements and FTIR analysis. Therefore, the lanthanide complexes show a ten-coordination structure with a deformed bicapped square antiprismatic. The Schiff base and its complexes were screened for their antimicrobial, antifungal, antioxidant, and antitumor properties. Their antimicrobial and antifungal activities were strong, and they also produced good antioxidant and antitumor effects.

Strong Circularly Polarized Luminescence at 1550 nm from Enantiopure Molecular Erbium Complexes.

Circularly polarized luminescence (CPL) in two subregions of the near-infrared (NIR) has been achieved. By leveraging the rigidity and diminishing detrimental vibrations of the heterobimetallic binolate complexes of erbium [(Binol)3ErNa3], species exhibiting an exceptionally high dissymmetry factor (|glum |) of 0.47 at 1550 nm were obtained. These erbium complexes are the first reported examples of CPL observed beyond 1200 nm. Analogous complexes of ytterbium and neodymium also exhibited strong CPL (|glum| = 0.17, 0.05, respectively) in a higher energy NIR window (800-1200 nm). All complexes exhibit high quantum yields (Er: 0.58%, Yb: 17%, Nd: 9.3%) and high BCPL values (Er: 57 M-1 cm-1, Yb: 379 M-1 cm-1, Nd: 29 M-1 cm-1). Because of their strong CPL emission in the telecom band (1550 nm), biologically relevant NIR emission window (800-1100 nm), and synthetic versatility, the complexes reported here could permit further promising developments in quantum communication technologies and biologically relevant sensors.

Novel pyrazole-based carboxylate ligand as a building block for assembling lanthanides in luminescent 2D and 3D MOFs

New pyrazole-based carboxylic ligand 1-(carboxymethyl)-1H-pyrazole-3,5-dicarboxylic acid (H3L) as well as its lanthanide complexes [LnL(H2O)2]n, Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8) and [LnL(H2O)]n, Ln = Dy (9), Ho (10), Er (11), Tm (12), Yb (13), Lu (14) have been prepared and studied. Compounds 1–8 represent a 3D polymer structure while 9–14 are 2D-polymers. Lanthanide-centered luminescence of compounds 4–9 is studied in detail. It is shown that high energy triplet level of H3L ligand (27100 cm−1) is able to sensitize not only the yellow-green luminescence of Tb3+ and Dy3+ ions, but also the red-orange luminescence of Sm3+ and Eu3+. NIR-luminescence of the neodymium complex 4 is possible upon direct excitation through the f-f transition of the Nd3+ ion.

Synthesis, characterization, and crystal structure of LnIII – (1E,2E)-3-(furan-2-yl)-N-(4H-1,2,4-triazol-4-yl)prop-2-en-1-imine

New neodymium (1a) and samarium (1 b) complexes with the general formula [LnIII(NO3)3(H2O)3 L]·L (1) were synthesized based on the previously reported ligand L (L = (1E,2E)-3-(furan-2-yl)-N-(4H-1,2,4-triazol-4-yl)prop-2-en-1-imine) which were investigated by X-ray analysis. Through X-ray studies, it was shown that the Schiff base L coordinates to LnIII via κN-bonding of one of the triazole ring nitrogen atoms as a monodentate ligand, three κ2 OO′-bonded nitrate ions and three κO-bonded water molecules completing the coordination sphere around the LnIII ion, resulting in a tenfold-coordinated LnNO9 unit in a distorted bicapped square antiprismatic geometry. The mononuclear complex units [Ln(NO3)3(H2O)3·L] are linked to the L molecule through intermolecular hydrogen-bonding interactions to form a 2 D polymeric supramolecular architecture. The complexes are neutral and paramagnetic mononuclear complexes, as determined by conductivity and magnetic investigations at room temperature, as well as findings from FT-IR and UV–vis spectroscopy. Finally, thermogravimetric measurements confirm the presence of three water molecules in the coordination sphere. In the visible region, the spectrum of the complex shows typical parity forbidden narrow 4f–4f absorptions originating from the 4 I 9/2 ground state to the various excited states of NdIII.

Characterization of the ALSEP Process: Investigating Equilibrium and Intermediate Complexes of the Scrub Stage

ABSTRACT A unique combination of real-time and conventional optical spectroscopy, off-line chemical analyses, and equilibrium solvent extraction measurements were employed to monitor progressive changes in the speciation of the organic-phase complexes of neodymium or americium in the biphasic scrub stage of the Actinide-Lanthanide Separation (ALSEP) solvent extraction process proposed for trivalent actinide/lanthanide separations. Consistent with the findings of other researchers, four unique organic-phase species are identified by three separate methods of multivariate analysis. The organic phase initially contains M(TEHDGA)2(HEH[EHP])2(NO3)3 complexes. As the ALSEP organic phase is scrubbed with an aqueous malonate buffer, the complex loses HNO3 to form M(TEHDGA)2(H(EH[EHP])2)(NO3)2 as the first organic-phase intermediate species. Further contact with the scrub aqueous phase forms a second intermediate species, M(TEHDGA)(H(EH[EHP])2)2(NO3), and eventually a complex containing only HEH[EHP], M{H(EH[EHP])2}3 (where TEHDGA = N,N,N’,N’-tetra(2-ethylhexyl)diglycolamide and HEH[EHP] = 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester). Similar intermediate species were also observed in equilibrium ALSEP organic phases when lower aqueous concentrations of nitric acid (e.g., 0.5 M HNO3) were used to extract actinides or lanthanides.

Optical Absorption, Kinetics and Thermodynamic Studies of Pr(III) and Nd(III) Ions with N-Acetyl L-Cysteine in Presence of Ca(II) ions

Interaction of N-acetyl-L-cysteine (NAC) with Pr3+ (Pr(NO3)3·6H2O) and Nd3+ (Nd(NO3)3·6H2O) ions are studied in presence of Ca2+ (Ca(NO3)3·4H2O) ion in an aqueous and organic solvent by applying the spectroscopic technique for quantitative probe of 4f-4f transition. The complexation was determined by the variation in the intensities of 4f-4f absorption spectral bands and by applying the change of symmetric properties of electronic-dipole known as Judd-Ofelt parameters Tλ (λ = 2,4,6). On the addition of Ca2+ ion in the binary complexation of praseodymium and neodymium with N-acetyl-L-cysteine (NAC) there is an intensification of bands which shows the effect of Ca2+ toward the heterobimetallic complex formation. Other parameters like Slater-Condon (Fk), bonding (b1/2), the Nephelauxetic ratio (β), percentage covalency (δ) are also used to correlate the complexation of metals with N-acetyl-L-cysteine (NAC). With the minor change in coordination around Pr3+ and Nd3+ ions, the sensitivity of 4f-4f bands is detected and further used to explain the coordination of N-acetyl-L-cysteine (NAC) with Pr3+ and Nd3+ in presence of Ca2+. The variation in oscillator strength (Pobs), energy (Eobs) and dipole intensity parameter help in supporting the heterobimetallic complexation of N-acetyl-L-cysteine. In kinetics investigation, the rate of the complexation of both hypersensitive and pseudo-hypersensitive transition is evaluated at various temperature in DMF solvent. The value of the thermodynamic parameters such as ΔHo, ΔSo and ΔGo and activation energy (Ea) also evaluated.

A Nd6 molecular butterfly: a unique all-in-one material for SMM, MCE and maiden photosensitized opto-electronic device fabrication.

Besides iron, ironically neodymium (Nd) is the most ubiquitously used metal for magnetic purposes, even among the lanthanides, when it comes to the field of molecular magnetism, yet it ranks among the least studied metals. However, strong apathy towards this magnetic lanthanide means that vital information will be missed, which is required for the advancement of the subject. Herein, we have successfully demonstrated the usefulness of a hexanuclear neodymium complex as a magnetic material, and also in electronic device fabrication. A {NdIII6} cage with an aesthetically pleasing butterfly topology was synthesized using a rather non-conventional N-rich pyridyl-pyrazolyl based ligand. The cage shows single molecule magnet (SMM) properties, with an effective energy barrier, Ueff, value of 3.4 K and relaxation time, τ0, of 3.1 × 10-4 s, originating from an unusual occurrence of metal centres with different coordination environments. Furthermore, magnetic studies reveal significant cyrogenic magnetic cooling, with a magnetic entropy change of 8.28 J kg-1 K-1 at 5 T and 3 K. To the best of our knowledge, the titular compound is the only example of a Nd-complex that exhibits concomitant magnetocaloric effect (MCE) and SMM properties. Complete active space self-consistent field (CASSCF) calculations were carried out to shed light on the origin of the magnetic anisotropy and magnetic relaxation of the compound. The same uniqueness is also true for the first electronic investigation carried out on the Nd complex. The maiden electronic device fabricated using the Nd complex shows an interesting intertwining of electronic and optical features, which contribute towards its improved photosensitized optoelectronic data.

NIR luminescence, hypersensitivity in the 4f ‒ 4f absorption spectra and NMR of seven-, eight- and nine-coordinate ternary neodymium(III) complexes

Four new Nd (III) ternary complexes of [Nd(fod) 3 (H 2 O)] where fod is the anion of 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione with monodentate (indazole and triphenylphosphine oxide (tppo)), bidentate (2-(1H-imidazole-2-yl)pyridine (impy)) and tridentate (2,4,6-tris(2-pyridyl)- s -triazine (tptz)) ancillary ligands. The isolated complexes [Nd(fod) 3 (tptz)] ( 1 ), [Nd(fod) 3 (indazole)] ( 2 ), [Nd(fod) 3 (impy)] ( 3 ) and [Nd(fod) 3 (tppo) 2 ] ( 4 ) have been characterized by elemental analysis, TGA, DTA, 1 H NMR and infra-red spectroscopy. The optical absorption in different solvents is studied and evaluated in terms of oscillator strength and band shape. The oscillator strength of the hypersensitive transition of the most asymmetric seven-coordinate indazole complex ( 2 ) is highest among the complexes in any given solvent and this strengthens the premise that the oscillator strength depends upon symmetry of the complex. The solution and solid-state near IR luminescence, decay curves and intrinsic quantum yield of these complexes are investigated and discussed. Most importantly, the replacement of water molecule from the inner coordination sphere of [Nd(fod) 3 (H 2 O)] with different ancillary ligands markedly boosts the decay time (τ = 1.37μs ([Nd(fod) 3 (H 2 O)]); 5.52 μs ( 1 ); 2.29 μs ( 2 ); 4.04 μs ( 3 ) and 3.95 μs (4) in chloroform solution and (2.29 μs (Nd(fod) 3 (H 2 O)]); 9.15 μs ( 1 ); 4.27 μs ( 2 ); 8.27 μs ( 3 ) and 6.24 μs (4) in solid state) and intrinsic quantum yield (Φ Nd % = 0.54 ([Nd(fod) 3 (H 2 O)]); 2.21 ( 1 ); 1.03 ( 2 ); 1.61 ( 3 ) and 1.58 (4) in chloroform solution and (0.91% ([Nd(fod) 3 (H 2 O)]); 3.66 ( 1 ); 1.71 ( 2 ); 3.31 ( 3 ) and 2.49 (4) in solid state). The luminescence observed from the present complexes entails positive effect of the ancillary ligands on luminescence of Nd (III). The energy transfer process is discussed. In this work, we correlate the luminescence intensity with the nature of ancillary ligand, coordination geometry and energy difference. • Four new ternary complexes [Nd(fod)3(X)], (X = 1 for tptz, indazole, impy and 2 for tppo] have been synthesized and characterized • The optical absorption in different solvents is studied and evaluated in terms of oscillator strength and band shape. • Solution and solid-state NIR luminescence, decay curves and intrinsic quantum yield are investigated and discussed. • Presence of perfluoryl groups, substitution of water by ancillary ligands markedly boosts the decay time and quantum yield • Luminescence intensity is correlated with ancillary ligands, coordination geometry and energy difference

Sorption of NdF3 and ThF4 from the LiF\u2013NaF\u2013KF Melt

The sorption of neodymium and thorium fluorides by AG-3 activated carbon from molten alkali metal fluorides LiF–NaF–KF has been studied. The sorption isotherm of neodymium fluoride at 650°C has a pronounced convex and is adequately described by the Langmuir equation. The sorption of thorium fluoride under the same conditions is much weaker than that of neodymium fluoride, which is determined by the size of the neodymium and thorium fluoride complexes. The kinetic dependence of the sorption of neodymium fluoride at a temperature of 650°С is adequately described by a first-order equation for a reversible reaction. The temperature dependence of sorption capacity in the range 550–750°С passes a maximum within 600–650°С.

Cyclopentadienyl lanthanide borohydrides derived from the unsubstituted cyclopentadienyl ligand. Unprecedented structural diversity and ε-caprolactone polymerization

A series of mono-, bis- and tris(cyclopentadienyl) complexes of La, Nd and Tb with borohydride ligand were synthesized and structurally characterized. Various structural types of complex anions and cations containing cyclopentadienyl and borohydride ligands in the coordination sphere of Ln3+ have been studied by single-crystal X-ray diffraction. Five different structural types of Cp-lanthanide borohydrides were found for neodymium: {CpNd(BH4)2} in [(CpNd(BH4)2(THF)2] (2Nd); {Cp2Nd(BH4)2}− in [Cp2Nd(BH4)2][Na(18-crown-6)(THF)2] (3Nd); {Cp2Nd(BH4)} in [Cp2Nd(BH4)(THF)] (4Nd); {CpNd(18-crown-6)(BH4)}+ in [Cp2Nd(BH4)2]2[CpNd(18-crown-6)(BH4)][Na(18-crown-6)(THF)2] (6Nd); {Cp3Nd(BH4)}− in [Cp3Nd(BH4)][Na(18-crown-6)(THF)2] (8Nd). Complex anions {Cp2Nd(BH4)2}− and {Cp3Nd(BH4)}− are able to replace each other in the crystal lattice. Mono- and bis(cyclopentadienyl)borohydride complexes of neodymium effectively initiate ε-caprolactone polymerization.

Near infrared luminescence of Nd, Er and Yb complexes with perfluorinated 2-mercaptobenzothiazolate and phosphine oxide ligands

In order to obtain new NIR luminescent lanthanide complexes free of C-H and C-O bonds the perfluorinated 2-mercaptobenzothiazolate (mbtF) was used as organosulphide antenna ligand and the perfluorinated triphenylphosphine oxide (TPPOF) was used to saturate the coordination sphere of the lanthanide ion. Targeted complexes Ln(mbtF)3(TPPOF)2 (Ln = Nd(1), Er(2) and Yb(3)) were synthesized in high yields from respective silylamides Ln[N(SiMe3)2]3, HmbtF and TPPOF using dry toluene as a solvent. Upon near UV light excitation the compounds 1–3 in the solid state showed an intense NIR photoluminescence which is characteristic for corresponding lanthanide ions. This luminescence was studied at a room temperature by time-resolved methods. The study revealed the presence of intermediate f-f transitions in the time resolved photoluminescence spectrum of 2. The measured lifetimes of Nd and Er NIR emission in 1 and 2 are 39.5 and 53.5 μs respectively. It was found that these lifetimes are among the longest for neat erbium and neodymium complexes with organic ligands.

Alternating copolymerization of CO2 and cyclohexene oxide initiated by rare-earth metal complexes stabilized by o-phenylenediamine-bridged tris(phenolate) ligand

A series of o-phenylenediamine bridged tris(phenolate) ligand-stabilized rare-earth metal complexes were synthesized and characterized. Lanthanum (complex 1), neodymium (complex 2tBu), and yttrium (complex 3) complexes stabilized by ligand of bulky tert-butyl substituents are mononuclear, whereas neodymium complexes 2Me and 2Cl bearing smaller methyl and chloro substituents are dinuclear, respectively. They were applied in the alternating copolymerization of CO2 and cyclohexene oxide. The addition of benzyl alcohol is beneficial to improving yields (up to 86%) and selectivity of poly(carbonate) (up to 99%). Stoichiometric reaction of benzyl alcohol with rare-earth metal complexes 1 and 2tBu results in formation of complexes 4 and 5 as dinuclear complexes with benzyl alcohol coordination, which was confirmed via single crystal X-ray diffraction analysis, and nuclear magnetic resonance (NMR) spectroscopy (for 4). Complex 5 shows equally good activity and selectivity of that of complex 2tBu and benzyl alcohol, consolidating that complex 5 is indeed generated during polymerization. The neodymium tris(phenolate) 5 is one of the few examples of rare-earth metal complex as a single-component initiator for copolymerization of epoxide and CO2. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry analysis proves benzyloxy group as the chain end. 1H NMR monitoring suggests that the insertion of CO2 may be the first step in the growth of the polymer chain.

Theoretical and Experimental Vibrational Characterization of Biologically Active Nd(III) Complex.

The neodymium(III) complex of orotic acid (HOA) was synthesized and its structure determined by means of analytical and spectral analyses. Detailed vibrational analysis of HOA, sodium salt of HOA, and Nd(III)–OA systems based on both the calculated and experimental spectra confirmed the suggested metal–ligand binding mode. Significant differences in the IR and Raman spectra of the complex were observed as compared to the spectra of the ligand. The calculated vibrational wavenumbers, including IR intensities and Raman scattering activities, for the ligand and its Nd(III) complex were in good agreement with the experimental data. The vibrational analysis performed for the studied species, orotic acid, sodium salt of orotic acid, and its Nd(III) complex helped to explain the vibrational behaviour of the ligand’s vibrational modes, sensitive to interaction with Nd(III). In this paper we also report preliminary results about the cytotoxicity of the investigated compounds. The cytotoxic effects of the ligand and its Nd(III) complex were determined using the MTT method on different tumour cell lines. The screening performed revealed that the tested compounds exerted cytotoxic activity upon the evaluated cell lines.

A simple way to obtain stable mono-decker porphyrin complexes with heavy metal atoms

The article presents data on the development of simple and efficient ways to obtain stable mono-decker complexes of porphyrins with rare-earth elements. Non-metallic porphyrins with halogen atoms as substituents on the periphery of various structures were cleaned and characterized. Further, by reacting the deprotonated forms of the obtained porphyrin-ligands with the acetates of rare-earth elements, mono-decker complexes of neodymium and samarium were synthesized with 5,10,15,20-tetra(trifluoromethyl)porphyrin and 5,10,15,20-tetra (trifluoromethyl)-2,3,7,8,12,13,17,18-octabromoporphyrin, respectively. The significance of converting porphyrin-ligands into anionic form is noted as a key factor in obtaining metal: ligand = 1: 1 structures. The structures of all the compounds obtained were confirmed by IR, NMR spectroscopy, electron absorption spectroscopy, elemental analysis, and mass spectrometry. The spectral and luminescent properties of the compounds were studied. The resulting complexes, potentially, can be used to produce thin films used in electrical engineering.