Dysprosium(III) catalysis in organic synthesis

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Determination of Dysprosium(III) Ion in Soil and Sediment Samples by an Original Potentiometric Dysprosium(III) Membrane Sensor

Abstract

A PVC membrane electrode for dysprosium(III) [Dy(III)] ions was constructed, having its basis on benzoxazoleguanidine (BG) as a suitable ionophore. The sensor presents a linear dynamic range of 1.0 × 10^?6–1.0 × 10^?1 M, with a Nernstian slope of 19.5 ± 0.4 mV decade^?1 and a detection limit of 4.7 × 10^?7 M. The response time is quick (less than 10 s). It can be used in the pH range of 3.3–8.4, and its duration is at least 2 mo without any considerable, noticeable potential divergence. The recommended sensor revealed comparatively good selectivity with respect to most alkali, alkaline earth, some transition, and heavy metal ions. It was successfully employed as an indicator electrode in the potentiometric titration of Dy(III) ions with EDTA. The membrane sensor also applied to the determination of concentration of Dy(III) ions in soil and sediment samples. Validation with certified reference materials (CRMs) was also carried out.     

The Solid State Electrochemistry of Dysprosium(III) Hexacyanoferrate(II)

A new electroactive polynuclear inorganic compound of rare earth metal hexacyanoferrate, dysprosium hexacyanoferrate (DyHCF), was prepared chemically and characterized using techniques of FTIR spectroscopy, thermogravimetric analysis (TGA), UV‐vis spectrometry and X‐ray photoelectron spectroscopy (XPS) etc. The cyclic voltammetric behavior of DyHCF mechanically attached to the surface of graphite electrode was well defined and exhibited a pair of redox peaks with the formal potential of 217 mV (vs. SCE) at a scan rate of 100 mV/s in 0.2 M NaCl solution and the redox peak currents increased linearly with the square root of the scan rates.     

Photoluminescent layered Y(III) and Tb(III) silicates doped with Ce(III)

The synthesis and structural characterization of new layered rare-earth silicates K(3)[M(1-a)Ce(a)Si(3)O(8)(OH)(2)], M = Y(3+), Tb(3+), a < 1 (AV-22 materials), have been reported. These materials combine the properties of layered silicates, such as intercalation chemistry, and photoluminescence and may find applications in new types of sensor devices. For mixed Tb/Ce-AV-22, evidence has been found for the energy transfer from the large Ce(3+) 4f( 1) --> 5d(1) broad band to the sharp Tb(3+) 4f (8) lines. This energy transfer allows the fine-tuning of the color emission in the blue-green region of the chromaticity diagram. Upon Ce(3+) excitation (342 nm), the radiance of Tb/Ce-AV-22 is approximately 2 times higher than that measured under direct Tb(3+) excitation, which reinforces the existence of effective room-temperature Ce(3+)-to-Tb(3+) energy transfer.     

Luminescence of antimony(III) halide complexes with aniline

The antimony(III) chloride and bromide complexes with aniline, (C₆H₅NH₃)₂SbCl₅·(C₆H₅NH₃)Cl·H₂O (I) and (C₆H₅NH₃)₂SbBr₅ (II), were synthesized, and their spectral luminescence properties were studied. An interesting peculiarity of I and II is the possibility of selective excitation of luminescence in the π system of the (C₆H₅NH₃)⁺ outer sphere anilinium cation and intrinsic luminescence of the s ² ion. The population scheme for the luminescent antimony ³ P ₁ level in I and II is discussed using the luminescence, UV, and photoelectron spectroscopy data. Original Russian Text ? T.V. Sedakova, A.G. Mirochnik, V.E. Karasev, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 2, pp. 380–382.     

Luminescence and energy transfer in poly(N-vinylcarbazole) blends doped by a highly anisometric Eu(III) complex

Highly fluorescent blends based on PVK (poly(N-vinylcarbazole)) doped by a new greatly anisometric Eu(III) mesogenic complex were described. The structure of the ligands in the complex was selected in such a way that its absorption maximum was close to the emission maximum of the polymer. The full-energy transfer conditions in the conjugated polymer–lanthanide complex blends were revealed. Improving luminescence efficiency of the blend occurs due to an increase in the threshold concentration of the emitting ions to prevent self-quenching phenomena. The resulting relative luminescence quantum yield of the blend increases more than twice in comparison with the individual complex. The optimized blends may be promising for application as red emitters for OLED, etc.     

Luminescence Spectral Properties of Europium(III) and Terbium(III) Complexes with Cinnamic Acid

Europium and terbium mixed-ligand complexes with cinnamic acid of composition Ln(Cin)₃· nD · xH₂O, where Ln = Eu³⁺or Tb³⁺, Cin is a cinnamate ion (C₆H₅CH=CHCOO^–), D = 1,10-phenantroline, 2,2"-dipyridyl, benzotriazole (n= 2, x= 0), triphenylphosphine oxide (n= 1, x= 2), or H₂O (n= 0 or 1, x= 0), were synthesized. The compounds were characterized by elemental analysis, IR and luminescence spectroscopy. The Stark structure of the ⁵ D ₀–⁷ F _j(j= 0, 1, 2) electronic transitions in the low-temperature luminescence spectra of europium complexes was analyzed. IR study has revealed a bidentate coordination of the cinnamate ion in the compounds.     

State and Stability of Erbium(III) and Dysprosium(III) Complexes of Octaphenyltetraazaporphine in Proton-Donor Media

The acid-base interaction of chloro(octaphenyltetraazaporphinato)erbium(III), (acetylacetonato)(octaphenyltetraazaporphinato)erbium(III), and (acetylacetonato)(octaphenyltetraazaporphinato)dysprosium(III) in AcOH and in AcOH-benzene and AcOH-H₂SO₄ systems involves one meso-nitrogen atom of the complexes; the stability constants of the resulting acid forms were estimated. The solvoprotolytic dissociation of the complexes in the AcOH-H₂SO₄ system was studied, its kinetic parameters were determined, and some suggestions as to the dissociation mechanism were made.     

Solvent-Induced Single-Crystal-to-Single-Crystal Transformation in Multifunctional Chiral Dysprosium(III) Compounds

Two new enantiomeric ionic chiral dysprosium(III) compounds were designed and synthesized. These compounds show simultaneously the optical activity, ferroelectric effects, nonlinear-optical effects, and slow magnetic relaxation behavior. More interestingly, these compounds exhibit reversible single-crystal-to-single-crystal transformations associated with the release or absorption of solvent molecules. The structure transformations are accompanied by distinct changes in the physical properties.     

Luminescence of neodymium(III) carboxylate complexes with different ligands

The spectral and luminescent characteristics of neodymium(III) carboxylate complexes with different nitrogen- and phosphorus-containing neutral ligands were studied and the relationship between the intensity of luminescence and the composition of the coordination sphere was established. The most intensive luminescence of neodymium(III) compounds in the IR region was observed from the complexes with toluic and cinnamic acids.     

Luminescence of ytterbium(III) cinnamate compounds

The spectral luminescent characteristics of mixed-ligand compounds of ytterbium (III) with cinnamic acid, nitrogen- and phosphorus-containing neutral ligands were studied by the methods of fluorescent spectroscopy. The luminescence intensity of the obtained compounds was measured and it was found that the highest intensity of luminescence has the polymeric ytterbium(III) cinnamate.     

A Study of Magnetic Relaxation in Dysprosium(III) Single-Molecule Magnets

Although the development of single-molecule magnets (SMMs) is rapid, there are only two families of high energy barrier (U_eff) dysprosium(III) SMMs known so far: the cyclopentadienyl (Cp) family with a sandwich structure and the pentagonal-bipyramidal (PB) family with D_5h symmetry. These high-barrier SMMs, which usually possess U_eff>500 cm⁻¹ allow the separate study of the four magnetic relaxation paths, namely, direct, quantum tunnelling, Raman and Orbach processes, in detail. Whereas the first family is chemically more challenging to modify the Cp rings, it is shown herein that the latter family, with the common formulae [DyX¹X²(L_eq)₅]⁺, such as X¹/X²=⁻OCMe₃, ⁻OSiMe₃, ⁻OPh, Cl⁻ or Br⁻; L_eq=THF/pyridine/4-methylpyridine, can be readily fine-tuned with a range of axial and equatorial ligands by simple substitution reactions. This allows unambiguous confirmation that the U_eff mainly depends on the identity of X¹ and X², rather than on L_eq. More importantly, the fitted parameters are barrier dependent. If X¹ is an O donor and X² is a halide, 500<U_eff<600 cm⁻¹, log τ_0avg (s)=−10.66, log C_avg (s⁻¹ K⁻ⁿ)= −5.05, n_avg=4.1 and T_H=9 K (in which τ₀ is the pre-exponential factor for the Orbach relaxation process, C and n are parameters used to describe Raman relaxation, and T_H is the highest temperature at which magnetic hysteresis is observed). For cases in which both X¹ and X² are O donors, 900<U_eff<1300 cm⁻¹, log τ_0avg (s)=−11.63, log C_avg (s⁻¹ K⁻ⁿ)= −6.03, n_avg=4.1 and 18<T_H<25 K. Based on these results, it can be further concluded that U_eff not only has a linear correlation to the axial Dy−X bond lengths, but also to T_H for these PB SMMs. This represents the first systematic study of a family of lanthanide SMMs and derives the first magneto-structural correlation in Dy SMMs.     

Ligand Sensitized Flourometric Determination of Dysprosium(III) Ion Using Terephthalic Acid

Several trivalent lanthanide ions are known to exhibit excellent luminescence characteristics when they are coordinated with appropriate organic ligands. Various analytical methods have been developed to determine lanthanide ions or organic compounds by taking advantage of these luminescence characteristics. The luminescence enhancement of the lanthanide ions by complexation with organic ligands has been explained on the basis of a ligand to metal energy transfer process.     

Slow Magnetic Relaxation in Condensed versus Dispersed Dysprosium(III) Mononuclear Complexes

Reaction of the ligands 4,5‐bis(propylthio)tetrathiafulvalene‐2‐(2‐pyridyl)benzimidazole ( L¹ ) and 4,5‐bis(propylthio)tetrathiafulvalene‐2‐(2‐pyridyl)‐3‐(2‐pyridinylmethyl)benzimidazole ( L² ) with Dy(hfac)₃ ? 2 H₂O (hfac=1,1,1,5,5,5‐hexafluoroacetylacetonate) gave mononuclear complexes [Dy(hfac)₃( L¹ )] ( 1 ) and [Dy(hfac)₃( L² )] ( 2 ). In both compounds the Dy^III ion is surrounded by six oxygen and two nitrogen atoms. Complex 1 displays single‐ion magnet (SIM) behaviour only in solution (Δ=12(1) K and τ₀=1.9(4)×10^?6 s), while complex 2 is a SIM in both solution (Δ=15(2) K and τ₀=1.5(3)×10^?6 s) and solid state (Δ=17(2) K and τ₀=9.5(2)×10^?6 s). The SIM behaviour is obtained if the hydrogen bond is broken by dissolution ( 1 in solution) or by alkylation ( 2 ). Multiple relaxation processes were identified for 2 with two competing processes: a fast one in zero field and a slow one for fields higher than 500 Oe. The two processes coexist for intermediate applied magnetic field. Magnetic‐dilution and frozen‐solution measurements led to the conclusion that the origin of these multiple relaxation processes is not due to the property of a single molecule.     

Luminescence Investigations on Eu(III) Thenoyltrifluoroacetonate Complexes with Amide Ligands

The influence of amide ligands on the photoluminescent behavior of tris(thenoyltrifluoroacetonate)- europium(III) in the solid state is reported. Elemental analysis showed that these compounds have the following formulas [Eu(TTA)₃·(ANL)₂] and [Eu(TTA)₃·PZA], where ANL = acetanilide and PZA = pyrazinamide. The photoluminescence spectra of the complexes recorded in the range 420-720 nm at 77 K show narrow bands arising from the ⁵D₀ → ⁷F _J transitions (where J = 0-4), under excitation at 394 nm. Based on the emission spectra and luminescence decay curves the intensity parameters (Ω_λ), lifetime (τ) and emission quantum efficiency (η) were determined. The Ω₂ values indicate that the Eu³⁺ion in these complexes is in a highly polarizable chemical environment. The higher value of η (60%) obtained for the complex with the ANL ligand, in comparison with the complex with the PZA ligand (30%), indicates a more efficient deactivation of the Eu³⁺ion in the [Eu(TTA)₃·PZA] complex.     

Luminescence of Europium(III) Chelates with 4-(Arylethynyl)pyridines as Ligands

Some Spectral properties and luminescence intensities of Eu^III chelates with 4-(arylethynyl)pyridine-2,6-dicarboxylic acids 1 – 15 and 2,2′,2″,2′″-{[4-(arylethynyl)pyrridine-2,6-diyl]bis(methylenenitrilo)} tetrakis(acetic acids) 16 – 26 were measured both in H₂O and EtOH solutions for the purpose of developing suitable labels to be used in time-resolved luminescence-based bioaffinity assays (Tables 1 and 2). The substitution at the Ar group has a significant effect upon the observed luminescence intensities, excitation wavelengths, and decay constants of the complexes, Moreover, the changes in the environment cause great variation in those properties of certain Eu^III chelates.