A novel preconcentration method for determination of iron and lead using Chromosorb-103 and flame atomic absorption spectrometry

Syringe connected-minicolumn (SCM) method for the preconcentration/separation of iron and lead prior to their determination by flame atomic absorption spectrometry (FAAS) was developed. The proposed method is substituted for classical batch and column methods. The method proposed was compared with the column method with respect to easiness, rapidness, simplicity and some analytical performance criteria such as recovery, precision, accuracy and risk of contamination. A minicolumn was filled with Chromosorb-103 as a sorbent and connected with a syringe. The experimental conditions such as pH of sample, concentration and amount of eluent, flow rates of sample and eluent, concentration of 8-hydroxyquinoline (oxine) as a complexing agent were optimized. The sample solution with or without oxine was drawn into the syringe and discharged manually passing through the resin. Analytes were retained at pH ≥5 and eluted with 1 M nitric acid in acetone quantitatively. Analyte elements could be concentrated up to 200-fold. The iron and lead in river-water samples and in certified reference Bovine Liver (NIST 1577b) were quantitatively recovered with relative standard deviation lower than 10%.     

Synthesis, structural and optical properties of novel borylated Cu(II) and Co(II) metal complexes of 4-benzylaminobiphenylglyoxime

4-Benzylaminobiphenylglyoxime ligand and its Cu(II) and Co(II) complexes were prepared. -bridge containing 4-benzylaminobiphenylglyoxime complexes were obtained by replacing of the bridging protons of the dioxime complexes with BF₂ group. These compounds have been characterized by elemental analysis, spectroscopic (ICP-OES, infra-red) and magnetic susceptibility measurements. Thermal decomposition of the complexes is studied in nitrogen atmosphere. The final decomposition products are found to be the corresponding metal oxides. The optical constants such as optical conductivity, dielectric constant, refractive index were determined for the complexes. The analysis of the optical absorption data revealed that the band gap E_g was direct transitions. The optical dispersion parameters were determined according to Wemple and Didomenico method.     

Copper(II) and palladium(II) complexes of 2-amino-5-chlorobenzophenone and 2-(2-hydroxybenzylidene)amino-5-chlorobenzophenone-<Emphasis Type="Italic">S</Emphasis>-methyl-thiosemicarbazones

The S-methyl thiosemicarbazone derivatives of 2-amino-5-chlorobenzophenone and 2-(2-hydroxybenzylidene)amino-5-chlorobenzophenone (L^I and L^II) and their copper(II) and palladium(II) chelates were synthesized. The solid compounds, [Cu(L^I)Cl]Cl · 2H₂O, [Cu(L^II)Cl]Cl · H₂O, [Pd(L^I)Cl]Cl, and [Pd(L^II)Cl₂], were characterized by elemental analysis, thermogravimetric measurements, electronic, i.r., ¹H-n.m.r. and e.p.r. spectroscopy. The ligand behavior of the L^I and L^II explained by means of spectroscopic data. The experimental X-band e.p.r. spectra recorded from two different copper(II) ion coordinated powder complexes have characteristic line shapes that exhibit the axial symmetry around the paramagnetic ions. The theoretically well fitted spectra prove this case too. The absence of hyperfine signals has been attributed to the strong covalency effects of copper electrons with neighbouring N atoms. Orbital energy levels for magnetic electrons were determined from Spin Hamiltonian parameters. The anisotropic Lande splitting factors were specified in an order of and this case indicates that the unpaired electrons are located mainly in the orbital.     

The impact of [1,2,5]chalcogenazolo[3,4-f]-benzo[1,2,3]triazole structure on the optoelectronic properties of conjugated polymers

Two novel conjugated near-infrared (NIR) absorbing donor–acceptor type copolymers comprising benzodithiophene as the donor and [1,2,5]chalcogenazolo[3,4-f]-benzo[1,2,3]triazole derivatives as the acceptors, spaced with thiophene as the π-bridge, were designed and synthesized via Stille polycondensation reaction. The effect of acceptor strength on optoelectronic properties was targeted and investigated. Branched alkyl chains (the extended 2-octyl-1-dodecyl alkyl chain;  C₈C₁₂) were introduced to 5H-[1,2,3]triazolo[4′,5′:4,5]benzo[1,2-c][1,2,5]thiadiazole and 5H-[1,2,3]triazolo[4′,5′:4,5]benzo[1,2-c][1,2,5]selenadiazole for enhanced solubility of polymers which ease the processability hence device constructions. The strongly electron-withdrawing units lead to a substantial change in the absorption properties via promotion of the intramolecular charge transfer band alongside the π–π* transition. The resultant soluble polymers were characterized via cyclic voltammetry to determine highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels as −5.00 and −3.92 eV for PSBT and −4.86 and −4.04 eV for PSeBT, respectively. Electronic band gaps of the copolymers were calculated as 1.08 eV for PSBT and 0.82 eV for PSeBT, respectively. NIR absorbing copolymers were used to construct electrochromic devices.     

Catena-Poly[[[2,4-dichloro-6-{[(2-hydroxyethyl)imino]methyl}phenolato-κ3N,O,O']-copper(II)]-μ-chlorido]monohydrate]: Synthesis,structural, spectroscopic and luminescent properties

A new chloride bridged polymeric Cu(II) complex, [Cu(HL)(μ-Cl).H₂O]_n, 1, (H₂L = 2,4-dichloro-6-{[(2-hydroxyethyl)imino]methyl}phenol) has been synthesized and characterized by elemental-spectral analysis, crystal structure analysis and photoluminescence measurements. The Copper(II) atom is five-coordinate in a slightly distorted square-pyramidal geometry (τ = 0.085), with one N and two O atoms of the Schiff base ligand and one Cl atom defining the basal plane and a symmetry-related Cl atom occupying the apical position. The bridging Cl atom lies in apical position for one Cu(II) ion and basal for the other, and it makes this structural arrangement unusual. The linked moieties form polymeric zigzag chains running along the c axis. This zigzag chains connect each other with intramolecular and intermolecular O–H···O hydrogen bonds, which form 3D structure through π?π interactions. Furthermore, the photoluminescence properties of H₂L and 1 were investigated, they exhibit unique bright green visible emissions in the solid state, under the excitation of 349 nm UV light. The strong luminescence emission of them makes 1 a potentially useful photoactive material in photo-physical chemistry.     

Sequential photodecomposition of bisacylgermane type photoinitiator: Synthesis of block copolymers by combination of free radical promoted cationic and free radical polymerization mechanisms

A block copolymer of cyclohexene oxide (CHO) and styrene (St) was prepared by using bifunctional visible light photoinitiator dibenzoyldiethylgermane (DBDEG) via a two‐step procedure. The bifunctionality of the photoinitiator pertains to the sequential photodecomposition of DBDEG through acyl germane bonds. In the first step, photoinitiated free radical promoted cationic polymerization of CHO using DBDEG in the presence of diphenyliodonium hexafluorophosphate (Ph₂I⁺PF) was carried out to yield polymers with photoactive monobenzoyl germane end groups. These poly(cyclohexene oxide) (PCHO) prepolymers were used to induce photoinitiated free radical polymerization of styrene (St) resulting in the formation of poly(cyclohexene oxide‐block‐styrene) (P(CHO‐b‐St)). Successful blocking has been confirmed by a strong change in the molecular weight of the prepolymer and the block copolymer as well as NMR, IR, and DSC spectral measurements. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4793–4799, 2009     

ChemInform Abstract: Structural and Energetic Properties of Closed Shell XFn (X: Cl,Br, and I; n = 1—7) and XOnFm (X: Cl,Br, and I; n = 1—3; m = 0—6) Molecules and Ions Leading to Stability Predictions for Yet Unknown Compounds.

Atomization energies at 0 K and heats of formation at 0 and 298 K are calculated for the title halogen fluorides and oxofluorides using a composite electronic structure approach based on CCSD(T) computations extrapolated to the complete basis set limit.