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     

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.     

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.     

Synthesis and reactions of (E)-1,1,1-trifluoro-2-methyl-2-penten-4-ylidene-malonodinitrile

Condensation of (E)-1,1,1-trifluoro-2-methyl-2-penten-4-one with malonodinitrile affords mixtures of unsaturated nitriles. Attempted cyclization of these nitriles in concentrated sulfuric acid furnishes derivatives of alkylidenecyanoacetamides and alkylidenemalonodiamide.     

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...     

Synthesis,spectroscopy, and X-ray crystal structures of copper(II) complexes of the tridentate ONS ligand formed by condensation of 4,4,4-trifluoro-1-(2-thienyl)-2,4-butanedione with S-benzyldithiocarbazate

A new tridentate ONS ligand, H₂L, has been synthesized by condensing thenoyltrifluoroacetone(4,4,4-trifluoro-1-(2-thienyl)-2,4butaneanedione) with S-benzyldithiocarbazate and its structure determined by X-ray diffraction. In the solid state, the Schiff base exists as the ketoamine-thioketo tautomer but in solution and in the presence of copper(II), it converts to the enol-thiol form and deprotonates to give copper(II) complexes of formula, [CuL] and [CuLL¹] (L = doubly deprotonated form of the ligand; L¹ = py, bipy or phen] which have been characterized by magnetic, spectroscopic, and X-ray diffraction studies. An X-ray crystallographic analysis shows that [CuL(py)] has a square-planar geometry with the ligand coordinated to the copper(II) center via the enolate oxygen, the azomethinic nitrogen and the thiolate sulfur, the fourth coordination position being occupied by pyridine. The [CuL(bipy)] complex is five-coordinate with a structure close to square-pyramidal in which the Schiff base acts as a doubly deprotonated tridentate ONS ligand and bipy is bidentate.     

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:     

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.     

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.     

Bromination of 4-(2-thienyl)thiazoles and 2-(2-thienyl)quinoline

Depending on the substituent, the bromination of 4-(2-thienyl)thiazoles and 2-(2-thienyl)quinoline takes place in the 5 position of the thiophene or thiazole ring. When an amino group is present in the 2 position of the thiazole ring, bromination takes place in the 5 position of the thiazole ring. When excess brominating agent is present, a second bromine atom enters the 5 position of the free ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 35–38, January, 1982.     

Kinetics of reduction of tris(4,4,4-trifluoro-1-(2-thienyl)-butane-1,3-dionato)ruthenium(III) in methanol

Reduction of tris(4,4,4-trifluoro-1-(2-thienyl)-butane-1,3-dionato) ruthenium(III) in methanol solution containing potassium hydroxide has been studied kinetically. The results suggest outer-sphere complex formation between ruthenium(III) species and methoxide anion.

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(4,4,4--1-(2-)--1,3)(III) . , -.

     

Crystal structure of nickel(II) bis-(1,1,1,-trifluoro-5,5-dimethyl-2,4-hexanedionate)-1,3-diaminopropane

The structure of the complex of nickel(II) bis-(1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedionate) with 1,3-diaminopropane is determined by single crystal X-ray diffraction at a temperature of 150 K. Crystallographic data for C₂₀H₃₄F₆N₂NiO₅: a = 17.5446(8) ?, b = 18.1171(10) ?, c = 18.6654(7) ?, β = 115.4150(10)°, space group C2/c, V = 5358.8(4) ?³, Z = 8, d _calc = 1.376 g/cm³, R = 0.0435. The structure is molecular; the metal atom coordinates four oxygen atoms of two β-diketonate ligands and two nitrogen atoms of propylenediamine. In the crystal, the molecules are bonded only by van der Vaals interactions.     

Crystal structure of lithium(i) 1,1,1,-trifluoro-5,5-dimethyl-2,4-hexanedionate

Lithium pivalyltrifluoroacetonate has been studied by X-ray crystallography. The compound has a structure of a coordination polymer [Li(pta)]_∞ with Li…Li distances of 2.74 Å. Crystal data for C₁₆H₂₀F₆Li₂O₄: a = 19.151(4) Å, b = 10.723(2) Å, c = 19.801(4) Å, space group Pbca, Z = 8, d _calc = 1.321 g/cm³.     

Extraction and spectrophotometric determination of copper(II) with 1,1,1-trifluoro-3-(2-thenoyl)acetone

Copper(II)-trifluorothenoylacetone complex in chloroform does not undergo decomposition when scrubbed with sodium hydroxide solution. This allows the complete removal of the residual reagent, and a highly sensitive method for the extraction and spectrophotometric determination of copper(II) results.     

Detection of europium(III) and samarium(III) by chelation and laser-excited time-resolved fluorimetry

Among the luminophores potentially usable as markers for biological molecules (e.g., antibodies and nucleic acids) the lanthanide cations (Ln^3su+) are the most efficient in terms of both signal selectivity and analytical sensitivity. These ions, chelated by certain β-diketones, in particular 2- naphthoyltrifiuoroacetone, can be detected at concentrations down to ca. 10^?18 mol in 300 μl by means of a pulsed excitation source (e.g., a laser) coupled to a time-resolved luminescence detection system. Such a device permits the total rejection of the optical background. The simultaneous quantitation of Eu³⁺ and Sm³⁺ is evaluated, and their use for possible simultaneous double labelling of biomolecules is predicted.     

Crystal and Molecular Structure of Nickel(II) trans-Bis-(1,1,1-trifluoro-4-iminopentan-2-onate)

A method of synthesis and the structure of the -iminoketonate complex of Ni(II) based on 1,1,1-trifluoro-4-iminopentan-2-one (CF₃–CO–CH₂–C(NH)–CH₃) are described.     

Crystal and Molecular Structure of Platinum(II) trans-Bis-(1,1,1-trifluoro-4-iminopentan-2-onate)

This paper describes a new method for the synthesis of the -iminoketonate complex Pt(ktf)₂ using 1,1,1-trifluoro-4-iminopentan-2-one as a bidentate ligand. An X-ray study has been performed on the polycrystals and single crystals of the compound. The single crystal X-ray diffraction analysis was carried out on a CAD-4 diffractometer (MoK radiation, /2 scan mode). Crystal data: a = 10.217(2), b = 10.231(2), c = 10.924(2) , = 83.12(3), = 63.38(3), = 70.77(3)°, V = 963.4(3) ³, space group P1, Z = 2, d _calc = 1.721 g/cm³. The Pt atom has a distorted planar square environment; the average lengths of Pt–N and Pt–O coordination bonds coincide (1.97 ). The mean value of the chelate angle is 94.2°. The environment of Pt is completed to bipyramid by the hydrogen atoms of the neighboring molecules. The structure of the compound is molecular. The differently oriented molecules of the complex are linked into chains down the x axis with Pt...Pt distances of 5.10 . A comparative crystal-chemical analysis of the structures of Pt(ktf)₂ and Pd(ktf)₂ and their O,O-chelate analogs — Pt(II) and Pd(II) trifluoroacetylacetonates — has been carried out. An X-ray study of Pt(tfa)₂ and Pd(tfa)₂ has been accomplished, and crystal data are given.     

Cyclometallation of 2-(2-thienyl)pyridine and 2-(3-thienyl)pyridine with palladium(II), rhodium(III) and ruthenium(II)

Summary 2-(2-Thienyl)pyridine [H(2-tp)] and 2-(3-thienyl)pyridine [H(3-tp)] react with lithium tetrachloropalladate(II), hexachlorotetrakis(tri-n-butylphosphine) dirhodium(III), and tetrachlorohexacarbonyldiruthenium(II) to give [PdCl(C-N)]₂-(CN=2-tp and 3-tp), [RhCl₂(C-N)PBu₃]₂ (C-N = 2-tp and 3-tp), and [RuCl(2-tp)(CO)₂]₂, respectively. Some bromo analogues are also prepared. These complexes react with pyridine and tri-n-butylphosphine to give adducts in which 2-tp is chelated through pyridine-N and thiophene-3-C and 3-tp through pyridine-N and thiophene-2-C atoms. The structures of these complexes are similar to those of the corresponding complexes of cyclometallated 2-phenylpyridine.