Alexander Y. Nazarenko

Lead(II) ion sorption and transport using polymer inclusion membranes containing tri-octylphosphine oxide

Abstract A polymer material composed of cellulose triacetate as support, dioctyl terephthalate or o-nitrophenyl octyl ether as plasticizer (solvent) and tri-octylphosphine oxide as complexant, was investigated as a solid extractant for Pb(II) ion sorption and as a membrane material for lead(II) ion transport. The influence of the counter-ion on sorption and transport processes was investigated. High permeabilities of PbI2 and Pb(SCN)2 complexes were observed for both solvents studied. The transport mechanism is described in terms of diffusion coefficients (D) and distribution constants (KP).

Selective Transport of Lead(II) and Strontium(II) Through a Crown Ether-Based Polymer Inclusion Membrane Containing Dialkylnaphthalenesulfonic Acid

New polymer inclusion membranes (PIMs) containing 18-membered crownethers and dialkylnaphthalenesulfonic acid are proposed for Sr2+ and Pb2+removal from nitric acid solutions. The influence of source phasecomposition and stripping agents was characterized and permeabilitycoefficients were calculated. The PIMs are easy to prepare and may be usefulin separation and concentration procedures for these cations from complexmixtures such as nuclear waste. Long-term stability was obtained for atleast several weeks of constant use during which no significant change ofpermeability was observed.

Enantiomeric recognition and separation of chiral organic ammonium salts by chiral pyridino-18-crown-6 ligands

Abstract Optically pure allyloxy and dimethyl-substituted pyridino-18-crown-6 (8) was attached to silica gel by the following reactions. 4-Allyloxy-2,6-pyridinedimethyl ditosylate (23) was first prepared from chelidamic acid. Ditosylate 23 was treated with (S,S)-dimethyl-substituted tetraethylene glycol to form 8. Ligand 8 was treated with triethoxysilane using a platinum catalyst. The resulting chiral crown-substituted triethoxysilane 32 was reacted with silica gel in toluene at 90 C to attach the crown to silica gel. Preliminary results of the separation of [α-(1-naphthyl)ethyl]ammonium perchlorate into its (R) and (S) forms using the bound chiral crown with acetone/methanol (7/3) (v/v) as the eluant are reported. The preparation of chiral dimethyl(allyloxyphenyl)pyridino-18-crown-6 (9) that could be attached to silica gel on the side opposite to the pyridine ring is also reported.

Selective metal ion sorption and transport using polymer inclusion membranes containing dicyclohexano-18-crown-6

Abstract A novel polymer material composed of cellulose triacetate as support, o-ni-trophenyl octyl ether as plasticizer (solvent), and dicyclohexano-18-crown-6 as carrier was investigated as a solid extractant for metal ion sorption and as a membrane material for ion transport. Selective extraction and transport of Pb(II), Ga(III), and Fe(III) were observed. The influence of the source solution counterion on sorption and transport processes was investigated. The transport mechanism is discussed in terms of diffusion coefficients (D) and extraction constants (K 1). A diffusion-limited transport model has been found to accurately describe metal ion transport by dicyclohexano-18-crown-6 in these systems. The membranes are easy to prepare in the laboratory, and they may be useful in separation and concentration procedures.

NOVEL SOLVENT SYSTEM FOR METAL ION SEPARATION : IMPROVED SOLVENT EXTRACTION OF STRONTIUM(II) AND LEAD(II) AS DICYCLOHEXANO-18-CROWN-6 COMPLEXES

As a part of our study of hazardous metal ion separations, the extraction of Sr2+ and Pb2+ from solutions containing nitric acid and various nitrate salts has been investigated. High partition ratios (DSr > 100−10)) were observed using comparatively low (10–50 mM) concentrations of dicyclohexano-18-crown-6 in a group of nitrile solvents with relatively high dielectric constants (adiponitrile, glutaronitrile, succinonitrile, malononitrile; e = 30–60) which are able to participate in coalescence extraction. Equilibria in the solvent extraction system were characterized, with Sr(II) and Pb(II) occurring in the organic phase primarily as partially dissociated ion pairs. A dramatic increase of extraction efficiency over traditional systems is achieved because of the formation of solvated cationic complexes in the organic phase.

New cyclam-type copper(II) complexes with amide molecular padlock: synthesis, properteis and crystal structure

Abstract The macrocyclic complex CuL1(ClO4)2 (L1: 1-formyl-1,3,6,10,13-pentaazacyclotetradecane) has been prepared. Two isomeric forms of CuL1(ClO4)2 were obtained. The structures of these isomers were determined by X-ray diffraction analysis. The structure of the closest homologue, CuL2(ClO4)2·MeCN (L2: 1-acetyl-1,3,6,10,13-pentaazacyclotetradecane), was determined for comparison. Macrocyclization was also successful using Cu(en)22+ as the starting compound. The decrease of the locking fragment size in 1-formyl-1,3,6,10,13-pentaazacycloteradecane complexes changes the counterion coordination to the macrocyclic cation. No direct interaction between the locking nitrogen atom and the central metal ion was detected. The syntheses of CuL3(ClO4)2 (L3: 1,8-diformyl-1,3,6,8,10,13-hexaazacyclotetradecane) and CuL4(ClO4)2 (L4: 1-(hydroxypropionyl)-1,3,6,10,13-pentaazacyclotetradecane) are also reported.

Novel extraction of metal ions from acidic media using poly(ethylene oxide) phases

A novel type of extraction system based on poly(ethylene oxide) (PEO) has been developed. Interaction of the aqueous solution of PEOs and trichloroacetic acid (TCA) leads to the formation of a second liquid phase without the addition of any organic diluent. Liquid associates of PEOs with trichloroacetic acid show excellent Pb2+ and Ba2+ extraction from strongly acidic media. The same effect was also observed on the surface of the polystyrene beads, coated with poly(ethylene oxide) chains. Both liquid and solid systems based on PEO associates demonstrate quantitative extraction of GaIII, FeIII, InIII, AuIII and TlIII from various acidic solutions. High extraction of TcO4– is expected on the basis of ReO4– extraction. PEOs present an environmentally acceptable, inexpensive alternative to standard solvent extraction systems for metals separation.

Crystal Structure of the Complex of 1,4,7,10,13,16-Hexaoxacyclooctadecane with Lithium Picrate Dihydrate

Abstract A lithium dihydrate picrate complex with 18-crown-6 (18C6) has been synthesized. Solvent extraction in the CH2Cl2/H2O system was studied (log Kex = 2.04). Crystals of Li(H2O)2(18C6)Picrate are triclinic, space group P1, with a = 7.744(2), b = 11.848(3), c = 14.532(4), α = 76.33(2)°, β = 75.80(2)°, γ = 77.81(2)°, Z = 2; final R = 0.039, wR2 = 0.094 (GOOF = 1.035) for 3218 independent reflections. The coordination polyhedron is a distorted trigonal bipyramid. The coordinated water molecules are involved in a hydrogen bond network with the oxygen atoms of 18C6 and the picrate ion. This network stabilizes the metal ion complex with the crown ether and changes the selectivity of the extraction process.

ANTIMONY AS A DONOR ATOM IN SILVER COORDINATION CHEMISTRY : SYNTHESIS, IR SPECTRA AND STRUCTURE OF THE SILVER(I) CYANOXIMATE COMPLEXES WITH TRIPHENYLS TIBINE AND TRIPHENYLPHOSPHINE MODEL COMPOUNDS

Silver(I) cyanoximate complexes Ag{ONC(CN)-R} (R = COPh, {L1}; COC(CH3)3, {L2}; benzothiazol-2-yl, {L3}) with triphenylphosphine and -stibine of compositions Ag(PPh3)n{L} (n = 2, 4) and Ag(SbPh3)n{L} (n = 3 for {L1} and {L2}, n = 2 for {L3}) were synthesized by the reaction of the components in acetonitrile solution and characterized by elemental analyses and IR spectroscopy. The crystal structures of Ag(SbPh3)3{L} (L = {L1} (1), {L2} (2), Ag(SbPh3)2{L3} ∙ CH3CN (3) and Ag(PPh3)2{L1} ∙ CH3CN (4), have been determined by X-ray diffraction. For all the compounds examined the coordination environment of the silver atom has the geometry of a distorted terahedron ([AgP2NO] (4); [AgSb3N] (1), (2); [AgSb2N2] (3)). The bis adducts Ag(EPh3)n{L} adopt molecular structures, in which the organic anions are coordinated in bidentate chelate fashion via the nitroso nitrogen atom and the oxygen (nitrogen for {L3}) atom of the substituent R. In the tris-stibino complexes (Ag-Sb 2.670(4) - 2.7748(8) Å; Sb-Ag-Sb 108.87(4) - 115.00(2)°) the cyanoximates are unidentate ligands and coordinated via the nitroso nitrogen atoms (Ag-N ca. 2.35(1) Å). The different behaviour of N ,O and N,N chelating cyanoximes under the same conditions suggests, that the Sb donor triphenylstibine is able to substitute the oxygen atoms in the silver(I) coordination sphere, but not the nitrogen ones. This causes the formation of 1:3 adducts of Ag{L} with SbPh3 for N ,O donors {L1} and {L2}, and only 1:2 for N,N donor anionic {L3}.

Crown Ether-Dinitrile Interaction: An X-ray Study

Formation of the host-guest compounds between isomers of dicyclohexano-18-crown-6 as hosts (DC18C6) and various dinitriles as guests has been observed. The structures of two representative compounds (cis-anti-cis-DC18C6...2(NCCH2CH2CN) ( I) and (cis-syn-cis-DC18C6...(NCCH2CH2CH2CN) ( II) were obtained using X-ray diffractometry. Crystal data: ( I) P=¯1, a = 8.586(3), b = 9.324(3), c = 10.714(4) Å α = 72.47(3)°, β = 73.57(3)°, γ = 72.37(3), R1 = 0.034, GooF 1.08, Z = 1; ( II) Pbca, a = 12.881(5), b = 17.887(8), c = 23.042(13) Å, R1 = 0.049, GooF 1.02, Z = 8. Both structures show weak C–-H...O interactions between α-methylene protons of dinitrile guest molecules and oxygen atoms of the macrocyclic host ring.