Tris-(4,4,4-trifluoro-1-(-2-thienyl)-1,3-butandiono)-europium(III) als NMR-Verschiebungsreagens

The shift reagent behaviour of europium thenoyltrifluoroacetonate has been investigated for various substrates. Due to its good solubility this complex is superior to Eu(DPM)₃ for weak complexing substrates. Thus, it was possible to assign the C₉ and C₁₀ signals in the ¹³C–NMR spectra of D(+)-Camphor.     

二甲亚砜-二[4,4,4-三氟-1-(2-噻吩基)-1,3-丁二酮]合铜(II)的晶体结构

制备了标题化合物单晶,确定了它的分子和晶体结构,结果表明Cu(II)与五个氧原子配位,其中之一来自沿轴向(CH3)2SO.形成略为变形的四方锥结构.在配体上的噻吩基取顺式围绕差Cu(II)原子,这可以共轭效应来解释.     

Emission efficiency of diamine derivatives of tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanediono]europium

Diamine derivatives of tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanediono]europium were synthesized and characterized by NMR, IR and UV-vis spectroscopy. The emission efficiency and decay times of the produced Eu(III) coordination complexes in acetone solutions were measured upon ligand excitation. The effect of the amine ligands was studied and the relation between the emission and the structure of the synthesized compounds was discussed.     

Laser-induced fluorescence and infrared spectroscopic studies on the specific solvation of tris(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)europium(III) in an ionic liquid

The extraction constant and the two-phase stability constant (K_D,Mβ₃) of tris(2-thenoyltrifluoroacetonato)europium(III) between 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C₄mim][Tf₂N]) as an ionic liquid and an aqueous phase were determined by considering the extraction equilibria including anionic tetrakis(2-thenoyltrifluoroacetonato)europate(III). Specific solute-solvent interactions between the neutral Eu(III) chelate and [C₄mim][Tf₂N] molecules were revealed from the relationships between the distribution constant of the enol form of 2-thenoyltrifluoroacetone (Htta) as a proton chelate and the distribution constant (K_D,M) of the neutral Eu(III) chelate because the [C₄mim][Tf₂N] system gave the high K_D,Mβ₃ value compared with those in conventional molecular solvents such as benzene and 1,2-dichloroethane. The coordination environment of Eu³⁺ in the neutral Eu(III) chelate in [C₄mim][Tf₂N] was investigated by time-resolved laser-induced fluorescence spectroscopy and infrared absorption spectroscopy. Both methods consistently indicated that not only the Eu(III) chelate extracted but also Eu(tta)₃(H₂O)₃ synthesized as a solid crystal were almost completely dehydrated in [C₄mim][Tf₂N] saturated with water. Consequently, the higher K_D,M or extractability of the neutral Eu(III) chelate in the [C₄mim][Tf₂N] system can be ascribed to the dehydration of the Eu(III) chelate, which is caused by the specific solvation with [C₄mim][Tf₂N] molecules.     

Time discrimination in the laser fluorimetry and ultratrace determination of europium(III) and samarium(III) with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione

Efficient application of time discrimination has succeeded in substantial reduction of the detection limit of laser fluorimetry. A nitrogen laser and a pulse-gated photon counting method are combined. The detection limits for europiuni(III) and samarium(III) with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione in solution are 0.4 pg l^-1 and 0.3 ng l^-1, respectively. The results are attributed to effective removal of the short-lived unwanted signals. This technique makes possible the ultratrace determination of a fluorescent molecule in a mixture with others by making the most of the difference of their emission lifetimes. The europium(III) complex can be determined with high selectivity and sensitivity in a large excess of the samarium(III) complex     

Encapsulation of 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione into the silica gel matrix for capturing uranium(VI) ion species

Journal of Radioanalytical and Nuclear Chemistry - The thenoyl-trifluoro-acetone (tta: 4,4,4-Trifluoro-1-(2-Thienyl)-1,3-butanedione) has been successfully encapsulated into the silica gel matrix...     

Nickel(II) complex with 4,4,4-trifluoro-1-(2-thienyl)butane-1,3-dione and dimethyl sulfoxide: Crystal and molecular structures

A nickel(II) complex with 4,4,4-trifluoro-1-(2-thienyl)butane-1,3-dione and dimethyl sulfoxide, [Ni(C₈H₄F₃O₂S)₂(C₂H₆OS)₂], was obtained and examined by X-ray diffraction. The crystals are monoclinic: a = 7.557(2) Å, b = 17.854(3) Å, c = 10.470(2) Å, β = 106.412(3)°, V = 1355.1(4) ų, ρ_calcd = 1.611 g/cm³, Z = 2, space group P2₁, R = 0.032. The coordination polyhedron of the nickel atom is a distorted octahedron consisting of four equatorial O atoms of two β-diketonate ligands and two axial O atoms of DMSO. The average Ni-O_ax and Ni-O_eq distances are 2.083(2) and 2.019(2)Å, respectively. The crystal structure is built from the discrete mononuclear complexes [Ni(C₈H₄F₃O₂S)₂(C₂H₆OS)₂] linked only by van der Waals contacts.     

Use of 1-alkyl-3-methylimidazolium hexafluorophosphate room temperature ionic liquids as chelate extraction solvent with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione

Possible use of room temperature ionic liquids (RTILs) as chelate extraction solvent was evaluated by using 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF₆]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([omim][PF₆]). These RTILs showed high extraction performance for divalent metal cations with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (Htta). The extracted metals were back-extracted into 1 mol dm⁻³ nitric acid quantitatively. Furthermore, the extracted species were estimated as neutral hydrated complexes M(tta)₂(H₂O)_n (n= 1 or 2) for M = Ni, Cu and Pb and anionic complexes M(tta)₃⁻ for M = Mn, Co, Zn and Cd.     

Ring-chain isomeric transformations. The cyclohemiketal structure of 4,4,4-trifluoro-1-(2-hydroxyphenyl)-1,3-butanediones

Compounds $\text{4}$-$\text{8}$ exist only in the cyclohemiketal form both in the solid state and in solution, in contrast with earlier assumptions on their enolic structure.     

Synthesis of (R)-4,4,4-trifluoro-2-mercaptobutyric acid

Syntheses of (R)-4,4,4-trifluoro-2-mercaptobutyric acid from (S)-malic acid via a Mitsunobu reaction and from (rac)-thiomalic acid on enzymatic resolution, using Pseudomonas cepacia (Amano lipase PS), are described. A new method for direct determination of ees for (R)- and (S)-4,4,4-trifluoro-2-mercaptobutyric acid derivatives by HPLC on a polysaccharide phase is disclosed.     

Crystal Structure of Complex Tris(4,4,4-trifluoro-1-phenyl-1,3-butanedione)(1,10-phenanthroline) Europium(III)

IntroductionCertainlanthanideionspossessharpemissionlinesinthevisibleregions.Thepossibilityoftransferringenergyeffi cientlytotheseionsbywayofstronglyabsorbingtransitionscharacteristicoforganicligandshasspurredmanyworkerstoinvestigatelanthanidechelatesaspotentiallasermaterials .Amongthemtheternarycomplexesofeuropium(III)andter bium(III)withtris(β diketonates)andanneutralligandhaveespeciallyattractedmuchattentionfortheirstronglumi nescence.Itmakethemaextensiveapplicationsindevelop mentofnewl…     

Thermodynamic study of the sublimation of crystalline tris(1,1,1-trifluoro-2,4-pentanedionate)ruthenium(III) and tris(1,1,1,5,5,5-hexafluoro-2,4-pentanedionate)ruthenium(III)

The Knudsen mass-loss effusion technique was used to measure the vapour pressures at different temperatures of two crystalline ruthenium complexes: tris(1,1,1-trifluoro-2,4-pentanedionate)ruthenium(III) {Ru(tfacac)₃}, between T =  350.20 K and T =  369.17 K and tris(1,1,1,5,5,5-hexafluoro-2,4-pentanedionate)ruthenium(III) {Ru(hfacac)₃} between T =  299.15 K and T =  313.14 K. From the temperature dependence of the vapour pressure of the crystalline compounds, the standard molar enthalpies of sublimation were derived by the Clausius–Clapeyron equation and the molar entropies of sublimation at equilibrium pressures were calculated. By using an estimated value for the heat capacity differences between the gas and the crystal phases the standard, p^o =  10⁵Pa, molar enthalpies, entropies, and Gibbs energies of sublimation at T =  298.15 K, were derived:     

Photophysical properties of near-infrared-emitting Ln(III) complexes with 1-(9-Anthryl)-4,4,4-trifluoro-1,3-butandione (Ln = Nd and Er)

We report the synthesis and photophysical properties of Nd(III) and Er(III) complexes with 1-(9-anthryl)-4,4,4-trifluoro-1,3-butandione (9-ATFB). The complexes of [Nd(9-ATFB)4]- and [Er(9-ATFB)4]- produced sensitized near-infrared (NIR) luminescence via the excitation of anthracene. This suggests that the intramolecular energy transfer occurred from the singlet excited state of anthracene to the resonance levels of the metal ions, since the phosphorescence of anthracene is forbidden under normal conditions. The observed quantum yield of the visible luminescence showed that the energy transfer is more efficient for [Nd(9-ATFB)4]- than for [Er(9-ATFB)4]-. The lifetimes of the NIR luminescence of the complexes were in the microsecond range. The quantum yields of the sensitized NIR of the complexes were estimated using the lifetime and the energy-transfer quantum yield.     

Structure and dynamics of binary and ternary lanthanide(III) and actinide(III) tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione] (TTA) complexes. Part 2, the structure and dynamics of binary and ternary complexes in the Y(III)/Eu(III)-TTA-tributylphosphate (TBP) system in chloroform as studied by NMR spectroscopy

The stoichiometric reaction mechanisms, rate constants and activation parameters for inter- and intramolecular ligand exchange reactions in the binary Y/Eu(TTA)(3)(OH(2))(2)-HTTA and the ternary Y/Eu(TTA)(3)(OH(2))(2)-TBP systems have been studied in chloroform using (1)H and (31)P NMR methods. Most complexes contain coordinated water that is in very fast exchange with water in the chloroform solvent. The exchange reactions involving TTA/HTTA and TBP are also fast, but can be studied at lower temperature. The rate constant and activation parameters for the intramolecular exchange between two structure isomers in Y(TTA)(3)(OH(2))(2) and Y(TTA)(3)(TBP)(OH(2)) were determined from the line-broadening of the methine protons in coordinated TTA. The rate equations for the intermolecular exchange between coordinated TTA and free HTTA in both complexes are consistent with a two-step mechanism where the first step is a fast complex formation of HTTA, followed by a rate determining step involving proton transfer from coordinated HTTA to TTA. The rate constants for both the inter- and intramolecular exchange reactions are significantly smaller in the TBP system. The same is true for the activation parameters in the Y(TTA)(3)(OH(2))(2)-HTTA and the ternary Y/Eu(TTA)(3)(TBP)(OH(2))-HTTA systems, which are ΔH(≠) = 71.8 ± 2.8 kJ mol(-1), ΔS(≠) = 62.4 ± 10.3 J mol(-1) K(-1) and ΔH(≠) = 38.8 ± 0.6 kJ mol(-1), ΔS(≠) = -93.0 ± 3.3 J mol(-1) K(-1), respectively. The large difference in the activation parameters does not seem to be related to a difference in mechanism as judged by the rate equation; this point will be discussed in a following communication. The rate and mechanism for the exchange between free and coordinated TBP follows a two-step mechanism, involving the formation of Y(TTA)(3)(TBP)(2).     

Neodymium(III) tris(1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)propane-1,3-dionato)(1,10-phenanthroline): Synthesis and photophysical properties

The reaction of NdCl₃ with 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)propane-1,3-dione (HL) and 1,10-phenanthroline (Phen) in the presence of a base afforded complex [Nd(L)₃Phen] (I). Unstable solvate I · 2CH₂Cl₂ was obtained from a solution of the complex in dichloromethane, and its structure was determined by X-ray diffraction analysis. The photophysical properties of the complex were studied. Possible routes for the energy transfer in the course of photoluminescence were proposed.