Novel fluorinated polymer from 18-crown-6 by radical polyaddition

Radical polyaddition of bis(α-trifluoromethyl-β,β-difluorovinyl) terephthalate [CF₂C(CF₃)OCOC₆H₄COOC(CF₃)CF₂] (BFP) with 18-crown-6 to produce fluorinated polymer bearing crown ether moiety in main chain is described. Prior to polyaddition, the model reaction of 2-benzoxypentafluoropropene [CF₂C(CF₃)OCOC₆H₅] (BPFP) with 18-crown-6 was investigated to afford suitable reactions condition for polyaddition. The polyaddition of BFP with 18-crown-6 yielded a soluble polymer bearing M_n=5.5×10⁴ with unimodal molecular weight distribution after purification by reprecipitation with cold ethanol.     

Side arm participation in lariat ether carboxylate-alkali metal cation complexes in solution

Lariat ether carboxylic acids of structure CECH₂OCH₂C₆H₄-2-CO₂H with crown ether (CE) ring sizes of 12-crown-4, 15-crown-5 and 18-crown-6 are prepared and converted into alkali metal-lariat ether carboxylate complexes. Absorptions for the diastereotopic benzylic protons in the ¹H NMR spectra of the complexes in CDCl₃ are utilized to probe the extent of side arm interaction with the crown ether-complexed metal ion as a function of the crown ether ring size and identity of the alkali metal cation.     

Tribenzo-18-crown-6 aceto­nitrile disolvate

Tribenzo-18-crown-6 binds two aceto­nitrile ligands, i.e. C₂₄H₂₄O₆·2C₂H₃N, one to each face of the crown ring. The crown conformation is relatively low in energy, but does not appear optimized for cation binding. Few significant intermolecular interactions are observed.     

Effect of 18-Crown-6 on the Separation Selectivity of Organic Compounds by Reversed-Phase High-Performance Liquid Chromatography

The effect of the addition of 18-crown-6 to the water–methanol and water–acetonitrile mobile phase on the selectivity of the separation of different derivatives of phenol, aniline, and benzoic acid by reversed-phase high-performance liquid chromatography was studied. It was demonstrated that the retention of compounds with the protonated primary amino group is increased in the presence of 18-crown-6 in the eluent, which can be explained by complexation between analyte compounds and macrocycles. For compounds containing the hydroxyl group (phenol and its derivatives), the addition of 18-crown-6 to the mobile phase leads to some decrease in retention. It was demonstrated that the selectivity of 18-crown-6 can change depending on the nature of the positional isomer (ortho, meta, orpara) of the analyte and the nature of the solvent increasing or decreasing the complexing ability of the sorbate with the macrocycle. The effect of the concentration of crown ether on the retention of compounds with the protonated amino group was revealed, and the complexation mechanism was suggested.     

Complex Formation of Potassium Hexachloroplatinate with 18-Crown-6 and Dibenzo-18-Crown-6 in Acetonitrile

The products of the reactions between potassium hexachloroplatinate {K₂PtCl₆} and 18-crown-6 or dibenzo-18-crown-6 in acetonitrile were studied. Pure crystalline compounds [2K·2(18-crown-6)· 2CH₃CN]²⁺·[PtCl₆]^2-·2H₂O, [2K·dibenzo-18-crown-6·CH₃CN]^{2 +}·[PtCl₆]^{2 -}, and [2K·dibenzo-18-crown-6·CH₃CN]^{2 +}·[Pt₂Cl₁₀]^{2 -} were obtained. Physicochemical properties of these compounds were studied, and their near- and far-IR IR spectra and thermogravimetric curves were considered. The composition of the complexes is determined by metal:ligand molar ratio and crown ether nature. It was found that acetonitrile is coordinated via the nitrogen atom.     

Solvent extraction of amino acids into a room temperature ionic liquid with dicyclohexano-18-crown-6

Amino acids Trp, Gly, Ala, Leu are extracted efficiently from aqueous solution at pH 1.5–4.0 (Lys and Arg at pH 1.5–5.5) into the room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF₆) with dicyclohexano-18-crown-6 (CE). The most hydrophilic amino acids such as Gly are extracted as efficiently as the less hydrophilic (92–96%). The influence of pH, amino acid and crown ether concentration, volume ratio of aqueous and organic phases, and presence of some cations on amino acid recovery were studied. The ratio of amino acid to crown ether in the extracted species is 1:1 for cationic Trp, Leu, Ala, and Gly and to 1:2 for dicationic Arg and Lys. This ionic liquid extraction system was used successfully for the recovery of amino acids from pharmaceutical samples and fermentation broth, and was followed by fluorimetric determination.These results were published in part in Smirnova SV (2002) Ph.D. Thesis, Moscow State University.     

Extraction of technetium by DB18C6 and 18C6 into nitrobenzene and acetylacetone from an aqueous phase containing NaBH4

The extraction of technetium by DB18C6 and 18C6 into nitrobenzene and different solvents from aqueous phase containing NaBH₄ was investigated. The experimental data indicate that the main extracted species have the formulas TcO/OH/₂.CE or 2TcO/OH/₂.3CE, where CE refers to the crown ethers. The effects of crown ether concentration, pH and organic solvent on the distribution ratio are discussed. The extent of extraction from different solvents decreases in the order nitrobenzene >acetylacetone>1-butanol>toluene> benzene.     

Effect of the 18-crown-6 and benzo-18-crown-6 on the solvent extraction and separation of lanthanide(III) ions with 8-hydroxyquinoline

The synergistic solvent extraction of 13 lanthanides with mixtures of 8-hydroxyquinoline (HQ) and the crown ethers (S) 18-crown-6 (18C6) or benzo-18-crown-6 (B18C6) in 1,2-dichloroethane has been studied. The composition of the extracted species has been determined as LnQ₃ · S. The values of the equilibrium constant and separation factor have been calculated. Here, the effect of the synergistic agent (18C6 or B18C6) on the extraction process is discussed.     

The 1 : 1 complexes between benzo-18-crown-6, 18-crown-6 and aminosulfuric acid

The title compounds were prepared by treating a methanol solution of the corresponding crown ether with an aqueous solution of aminosulfuric acid.Crystals of [benzo-18-crown-6·H₂NSO₂OH] suitable for X-ray crystallography were obtained by recrystallization from methanol. The crystals are orthorhombic, space groupP2₁2₁2₁,a = 14.310(7),b = 12.516(4),c = 10.890(4) Å. Refinement led to a final conventionalR value of 0.051 for 909 reflections.Crystals of [18-crown-6·H₂NSO₂OH] suitable for X-ray crystallography were obtained by recrystallization from acetone. They are orthorhombic, space groupP2₁2₁2₁,a = 17.027(6),b = 14.866(5),c = 8.345(4) Å. The structure was solved by a heavy atom method and refined to an agreement value of 0.067.     

Radiation chemical synthesis of polyethylene oxide hydrogel containing DCH18C6 crown ether: A new approach

Polyethylene oxide hydrogels containing physically immobilized dicyclohexano-18-crown-6 were prepared by radiation chemical synthesis. Doses of gel formation were found to depend on the molecular weight of the polyethylene oxide and were about 20 and 4 kGy for M_w of 10⁵ and 3·10⁶, respectively. An increase in the crown ether concentration resulted in the decrease of the efficiency of hydrogel formation, whereas the effect of polymer concentration was less pronounced. It was found that dicyclohexano-18-crown-6 immobilized in the PEO hydrogel showed relatively high resistance toward washout in aqueous media.This revised version was published online in November 2005 with corrections to the Cover Date.     

Solubilization of Benzene and Several Benzene Derivatives in Dilute Aqueous Solution of 18-Crown-6

Solubilities of benzene, toluene, nitrobenzene, p-and o-nitrotoluene in dilute aqueous solutions of 18-crown-6 have been determined by UV-spectrometry at 15, 25, and 35°C. The saturation concentration of each aromatic solute depends linearly on the l8-crown-6 concentration. Experimental results show that 18-crown-6 molecules form host-guest complexes (with 1:1 stoichiometry) with the aromatic molecules, which supports the assumption that the force of combination between the crown ether and the aromatic molecules is a weak hydrophobic interaction.     

Separation of rhenium by extraction with crown ethers and flow-injection extraction—spectrophotometric determination with Brilliant Green

The extraction behavior of perrhenate with crown ethers was studied and methods for the separation and determination of rhenium were developed. The distribution ratio of perrhenate with dicyclohexano-18-crown-6 (DC18C6) increases with increases in the dielectric constant of organic solvents and in the potassium ion concentration of aqueous solution. The molar ratios of crown ether to KReO₄ in the extracted species are probably 1:1 for DC18C6, dibenzo-18-crown-6 and 18-crown-6 and 2:1 for benzo-15-crown-5 and 15-crown-5. Microgram amounts of rhenium were satisfactorily separated from large amounts of molbdenum(VI) by extraction with DC18C6 in 1,2-dichloroethane from 2 M potassium hydroxide solution containing tartrate and by back-extraction with sodium phosphate buffer solution after the addition of a twofold volume of hexane to the organic phase. Rhenium was determined by the flow-injection extraction-photometric method with Brilliant Green. Rhenium was satisfactory determined in molybdenite and other ore samples.     

Kronenetherkomplexe von Blei(II). Die Kristallstrukturen von [PbCl(18-Krone-6)][SbCl6], [Pb(18-Krone-6)(CH3CN)3][SbCl6]2, and [Pb(15-Krone-5)2][SbCl6]2

Crown Ether Complexes of Lead(II). The Crystal Structures of [PbCl(18-Krone-6)][SbCl₆], [Pb(18-Krone-6)(CH₃CN)₃][SbCl₆]₂ und [Pb(15-Krone-5)₂][SbCl₆]₂ . [PbCl(18-crown-6)][SbCl₆] has been prepared in low yield besides [Pb(CH₃)₂(18-crown-6)][SbCl₆]₂ by the reaction of Pb(CH₃)₂Cl₂ with antimony pentachloride in acetonitrile solution in the presence of 18-crown-6, forming pale-yellow crystals. The other two title compounds are formed as colourless crystals by the reaction of PbCl₂ with antimony pentachloride in acetonitrile solutions in the presence of 18-crown-6 and 15-crown-5, respectively. The complexes were characterized by IR spectroscopy and by crystal structure determinations. [PbCl(18-crown-6)][SbCl₆]: Space group P2₁/c, Z = 8, 5 003 observed unique reflections, R = 0.046. Lattice dimensions at - 80°C: a = 1 386.9; b = 1 642.7; c = 2 172.1 pm, β = 92.95°. The lead atom in the cation [PbCl(18-crown-6)]⁺ is surrounded in an almost hexagonal-planar construction by the six oxygen atoms of the crown ether and an axially oriented Cl atom. [Pb(18-crown-6)(CH₃CN)₃][SbCl₆]₂: Space group P1 , Z = 2, 6 128 observed unique reflections, R = 0.076. Lattice dimensions at - 70°C: a = 1 228.0; b = 1 422.9; c = 1 463.2 pm, α = 69.08°; β = 65.71°; γ = 64.51°. In the cation [Pb(18-crown-6)(CH₃CN)₃]²⁺ the lead atom is coordinated by the six oxygen atoms of the crown ether and by the three nitrogen atoms of the acetonitrile molecules. The structure determination is restricted by disorder. [Pb( 15-crown-5)₂][SbCI₆]₂: Space group P6₃/m, Z = 6, 5 857 observed unique reflections, R = 0.059. Lattice dimensions at -70°C: a = b = 2 198.5; c = 1499.4 pm, α = β = 90°, γ = 120°. In the cation [Pb(l5-crown-5)₂]² the lead atom is sandwich-like coordinated by the ten oxygen atoms of the two crown ether molecules. The structure determination is restricted by disorder.     

Rubidium-di(methansulfonyl)amid, 18-Krone-6 und Wasser als Bausteine eines dreidimensionalen Wasserstoffbrücken-Netzwerks: Darstellung und Kristallstruktur von [Rb(18-Krone-6)(H2O)2{(MeSO2)2N}] · H2O

Polysulfonylamines. CXV. Rubidium Di(methanesulfonyl)amide, 18-Crown-6, and Water as Building Blocks of a Three-Dimensional Hydrogen-Bond Network: Preparation and Crystal Structure of [Rb(18-crown-6)(H₂O)₂{(MeSO₂)₂N}] · H₂O The title complex (orthorhombic, space group P2₁2₁2₁, Z = 4, X-ray analysis at –130 °C) was obtained by co-crystallizing equimolar amounts of RbN(SO₂Me)₂ and 18-crown-6 from water/methanol (1/1). The crown ether displays effective D_3d symmetry; the Rb^⊕ ion is displaced by 99.5(1) pm from the mean plane of the macrocyclic oxygen atoms [Rb–O 290.2(3)–309.7(3) pm] and thus adopts a typical “sunrise coordination”. Two Rb–O contacts from water molecules [295.1(4) and 323.0(4) pm] and a Rb–O contact from the anion [292.0(4) pm], all situated on the opposite side from the crown ether, complete the coordination of the cation. Hydrogen bonding plays a major role in the crystal packing. The complex units, excluding the non-coordinating water molecules, are associated into strands by (H₂O)_∞ catenation and water…anion hydrogen bonds. The non-coordinating water molecules, located between the parallel strands, cross-link each of them with four adjacent equivalents via water…anion bonds to generate a three-dimensional network.     

18-crown-6 ether complexes with aralkylammonium perchlorates

Thermochemical properties of crown ether complexes have been studied by simultaneous TG-DTA (thermogravimetric analysis-differential thermal analysis) coupled with a mass spectrometer, DSC (differential scanning calorimetry) and hot stage microscopy (HSM). The examined complexes contain benzylammonium- [BA], (R)-(+)-a-phenylethylammonium- [(R)-PEA], (R)-(+)- and (S)-(-)-a-(1-naphthyl)ethylammonium perchlorate [(R)-NEA and (S)-NEA] salts as guests. In the cases of BA and (R)-PEA an achiral pyridono-18-crown-6 ligand [P18C6], and in the case of (R)-NEA and (S)-NEA a chiral (R,R)-dimethylphenazino-18-crown-6 ligand [(R,R)-DMPh18C6] was used as host molecule to obtain four different crown ether complexes. In all cases, the melting points of the complexes were higher than those of both the host and the guest compounds. The decomposition of the complexes begins immediately after their melting is completed, while the BA and (R)-PEA salts and the crown ether ligands are thermally stable by 50 to 100 K above their melting points. During the decomposition of the salts and the four complexes strongly exothermic processes can be observed which are due to oxidative reactions of the perchlorate anion. Ammonium perchlorate crystals were identified among the decomposition residues of the salts. P18C6 was observed to crystallize with two molecules of water. The studied complexes of P18C6 did not contain any solvate. BA was observed to exhibit a reversible solid-solid phase transition upon heating. The heterochiral complex consisting of (S)-NEA and (R,R)-DMPh18C6 shows a solid-solid phase transition followed by two melting points. HSM observations identified three crystal modifications, two of them simultaneously co-existing. This revised version was published online in July 2006 with corrections to the Cover Date.     

Reaction of lead halides with 18-crown-6 and dicyclohexano-18-crown-6: Solvent extraction,synthesis and crystal structure of [Pb(18-crown-6)I2]

Abstract

Solvent extraction of lead halides with 18-crown-6 (18C6), dicyclohexano-18-crown-6 (DC18C6, cis-syn-cis and cis-anti-cis isomers) in chloroform was studied, and the extraction constants corrected for side reactions and ionic strength effects were obtained. The compounds of the same composition as those being extracted were also isolated in crystal form. The molecular structure of the [Pb(18C6)I₂] complex has been determined. Crystals are monoclinic, P2₁/n, a = 11.237(2), b = 10.992(2), c = 8.139(2)Å, β = 97.32(3)°, V = 997.1(7)ų, D_calc = 2.416(2)gcm^?3, Z = 2 for the composition C₁₂H₂₄O₆PbI₂. The final R-factor is 0.043 for 558 unique reflections. The lead atom is coordinated to six oxygen atoms of the crown ether and two iodine atoms forming a hexagonal bipyramidal coordination polyhedron. The 18C6 molecule and the two halogen atoms form a hydrophobic coating for the lead atom which may be assumed to be the main reason of high extraction constants of the iodine complexes. For 10-coordinate lead ion (bidentate counter ions) the cis-syn-cis isomer of DC18C6 appears to be the best extraction reagent, while for 8-coordinate lead ion (monodentate halide anion) no difference between isomers was observed.     

Synthesis and Cation Recognition Study of Novel Benzo Crown Ether Functionalized Enamine Derivatives

A novel series of benzo crown ether (dibenzo 18-crown-6 ether, benzo 18-crown-6 ether, and benzo 15-crown-5 ether) functionalized enamines derivatives from amino benzo crown ether (4-amino dibenzo 18-crown-6 ether, 4-amino benzo 18-crown-6 ether, 4-amino benzo 15-crown-5 ether) and substituted 3-(dimethylamino)-1-phenylprop-2-en-1-one compounds have been synthesized. All the synthesized compounds were characterized by infrared, ¹H NMR, ¹³C NMR, distortionless enhancement polarization transfer, and mass and elemental analysis techniques. The cation recognition property for benzo crown ether enamine 8a was studied by absorption and fluorescence spectroscopy.     

Polysalt complexes of poly(vinylbenzo-18-crown-6) and of poly(crown acrylate)s with polyanions

Macrocyclic polyether or crown ether ester derivatives of acrylic and methacrylic acid were synthesized and polymerized. The cation binding properties of the polymers determined by extraction of picrate salts were similar to those obtained for poly(crown ether)s derived from styrene. In the presence of a crown-complexable cation both polymers form insoluble polysalt complexes with sodium carboxymethylcellulose, potassium poly(styrene sulfonate), and potassium polyacrylate. The extent of precipitation depends on the type and concentration of cation as well as on the ratio polyanion to poly(crown ether). The precipitate appears to have an equal number of positive and negative charges. An insoluble hydrogen-bonded complex is formed in the absence of salt when poly(vinylbenzo-18-crown-6) and poly(acrylic acid) are mixed in 0.01M HCl. Organic solutes bound to the poly(crown ether)s, which occur in an aqueous mixture of poly(vinylbenzo-18-crown-6) and picrate anions, are precipitated with the poly(crown ether) when the polysalt complex is formed.     

Application of crown ethers as modifiers for the separation of amines by capillary electrophoresis

The separation of amines with capillary electrophoresis (CE) was made possible by applying crown ethers such as 18-crown-6 and 15-crown-5 as modifiers. Crown ether 18-crown-6 performed better as a modifier than 15-crown-5. The mobility change of primary amines with 18-crown-6 was larger than that for secondary and tertiary amines. The mobility change of various amines with 18-crown-6 were in the order: 1-aminobutane>2-aminobutane>2-amino-2-methylpropane. Effects of crown ether concentration, pH and cations in the eluent of CE were also investigated and discussed. Some neurotransmitters such as dopamine, serotonin, epinephrine, isoproterenol and phenylalanine were separated successfully by using crown ethers in CE analysis.     

Supramolecular 1D assemblies of polyfluorinated arylenediamines and 18-crown-6

Rods (1D assemblies) formed by alternate crown ether and arylenediamine molecules are the motif of the supramolecular architecture of crystals of molecular associates of 18-crown-6 with tetrafluoro-1,4- and -1,3-phenylenediamines, hexafluoro-2,6- and -2,7-naphthylenediamines. Molecules in the assemblies are arranged via H-bond predominantly between the crown ether oxygen atoms and the polyfluoroarene amino group hydrogen atoms. Influence of the amino groups mutual arrangement and the aromatic framework size on the crystal supramolecular architecture is characterized. Specific melting heats of the crystalline 1D assemblies of para- and pseudo-para-arylenediamines are higher than those of meta- and pseudo-meta-analogs; the associates having higher melting heats selectively crystallize from solutions of isomeric phenylene- or naphthylenediamine mixtures.