Structural, Spectroscopic, and Thermal Behaviour of Bis-(thiosaccharinate)-aqua-cadmium(II)

Summary.  The crystal structure of the title complex, [Cd(tsac)₂(H₂O)], has been determined by single crystal X-ray diffraction methods. It crystallizes in the monoclinic space group C2/c (a = 12.236(3), b = 8.919(3), c = 16.655(3) ?, β = 96.18(2)°, Z = 4). The molecular structure was solved from 1705 independent reflections with I > σ(I) and refined to R ₁ = 0.0489. Infrared and Raman spectra of the complex were recorded and are briefly discussed. Its thermal behaviour was investigated by thermogravimetry and differential thermal analysis. Received December 18, 2000. Accepted February 19, 2001     

Structural, Spectroscopic, and Thermal Behaviour of Bis -(thiosaccharinate)-aqua-cadmium(II)

 The crystal structure of the title complex, [Cd(tsac)₂(H₂O)], has been determined by single crystal X-ray diffraction methods. It crystallizes in the monoclinic space group C2/c (a = 12.236(3), b = 8.919(3), c = 16.655(3) ?, β = 96.18(2)°, Z = 4). The molecular structure was solved from 1705 independent reflections with I > σ(I) and refined to R ₁ = 0.0489. Infrared and Raman spectra of the complex were recorded and are briefly discussed. Its thermal behaviour was investigated by thermogravimetry and differential thermal analysis.     

Effect of swift heavy ions in Ni-Al nanocrystalline films studied by X-ray absorption spectroscopy

X-ray absorption spectroscopic measurements have been used to compare the electronic structures of swift heavy ions (100 MeV Si ions) irradiated and pristine Ni-Al nanocrystalline films. Results from X-ray diffraction (XRD), X-ray absorption near-edge structure (XANES) spectra at Al K-, and Ni L(2,3)-edges and extended X-ray absorption fine structure (EXAFS) at Ni K-edges are discussed. The observed XRD peaks indicate the improvement of crystalline nature and Al(111) clustering after the swift heavy ion interactions. While the XANES spectra at Ni L(2,3)-edges show decrease in the intensity of white line strength, the Al K-edge shows increase in intensity after irradiation. Above results imply that swift heavy ions induce low Z (i.e., Al) ion mass transport, changes in Al sp-Ni-d hybridization, and charge transfer. EXAFS results show that crystalline nature is improved after swift heavy irradiation which is consistent with XRD results.     

Theoretical study on decomposition of γ-halo allylalkoxide and β-halo acrylate ions

β, γ-Substituted γ-halo allylalkoxide ions decompose to form a halogen ion, formaldehyde, and an alkyne under mild conditions, for example at room temperature. The E isomer does not differ from the Z isomer in terms of activation energy. We attempted to shed light on the mechanism of the reaction by using ab initio molecular orbital calculations. The observed propensity was confirmed by the present calculation on model molecules, γ-chloro allylalkoxide ions. We conducted further calculations and compared the alkoxide results with a similar reaction of β-haloacrylate ions that release carbon dioxide instead of formaldehyde. This similar reaction needs heating as high as 150°C. The activation energy of the acrylate ions (36–39 kcal mol⁻¹) was calculated to be about 10 kcal mol⁻¹ higher than that of the alkoxide ions. The activation energy of the E acrylate ion is smaller by 0.8 kcal mol⁻¹ than that of the Z isomer at the MP2/6-31+G**//RHF/6-31+G* level of theory. This is consistent with experimental results. While the ready deprotonation from the carboxylic group does not activate the acrylate ion very much, the alkoxide ion is destabilized to a great degree in the process of anion formation. The difficulty in deprotonation that proceeds from the neutral molecule is seen in the difference in the activation energies for the decomposition of the corresponding anions. Therefore, the pK _a of a hydroxy or a carboxylic group plays the leading role in determining the magnitude of activation energies of allyl halides with a negatively charged fragment. Received: 2 July 1998 / Accepted: 9 September 1998 / Published online: 8 February 1999     

A Simple Fluorometric Method Using Chlorophyll a for Determination of Hg2+ Ion

A simple and green analytical procedure based on chlorophyll a is presented for the determination of Hg²⁺ ion. Chlorophyll a was extracted and purified from the leaves of pea and is employed as a reagent for analysis of Hg²⁺ ion. It displays remarkable fluorescence emission at 674 nm when excited at 412 nm. The emission intensity decreased significantly on exposure to various concentrations of Hg²⁺ ion. This forms the basis for the determination of Hg²⁺ ion. The proposed method was evaluated for sensitivity and selectivity. The linear concentration range was found to be 2.0–10 μM with r² = 0.997 and the limit of detection for Hg²⁺ ion was 1.3 μM. Ions including Pb²⁺, Cd²⁺, Ag⁺, Zn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Mg²⁺, Mn²⁺, Ru³⁺, Er³⁺, K⁺, Na⁺, NH₄⁺, Cl⁻, NO₃⁻, CH₃COO⁻ and SO₄²⁻ did not interfere with the measurement of Hg²⁺ ion even at 500-fold excess. Since chlorophyll a is widely available in the leaves of most plants, and the extraction and purification process is simple, this technique can provide an alternative, sensitive and economical way to determine Hg²⁺ ion.     

Copper(II) ion-selective microelectrochemical transistor

A device has been developed for the measurement of copper(II) ions (Cu²⁺) in aqueous medium. The device reported here is an electrochemical transistor which consists of two platinum electrodes separated by 100 μm spacing and bridged with an anodically grown film of polycarbazole. Polycarbazole film (undoped form) is observed to be highly selective for the Cu(II) ions. In a completed device, the conductivity of the polycarbazole film changes on addition of Cu(II) ions. The change in conductivity is attributed to the conformational changes in the polymer phase on occupation of the Cu(II) ions, without affecting electron/proton transfer. The device turns on by adding 2.5 × 10⁻⁶ M Cu(II) ions and reaches a saturation region beyond 10⁻⁴ M Cu(II) ion concentrations. In the above concentration range, the device response [I _D vs. log Cu(II) ion concentration] is linear. The selectivity of the device for other metal ions such as Cu(I), Ni(II), Co(II), Fe(II), Fe(III), Zn(II) and Pb(II) is also studied. Received: 6 April 1999 / Accepted: 20 August 1999     

On-Line Solid Phase Extraction and Simultaneous Determination of Hafnium and Zirconium by ICP–Atomic Emission Spectroscopy

A new simple flow injection analysis (FIA) system is described for on-line preconcentration by solid phase extraction and simultaneous determination of Hf and Zr in different samples using inductively coupled plasma atomic emission spectroscopy with a charge coupling detector (CCD). Quinalizarin (QA) was loaded on an octadecyl silica-polyethylene mini-column for the retention of Hf and Zr ions in complexed form. A 0.3 M ammonium acetate was used as buffer for providing suitable conditions for complexation and increasing reproducibility. Retained ions on the solid phase were then eluted by a solution containing 3.0 M HCl and 0.5 M HNO₃. In this work, for reducing bandwidths of eluted ions, elution of minicolumn was carried out from opposite direction. The same solution was used as both carrier and eluent, in order to increase the reproducibility. The eluted ions were introduced into the conventional nebulizer of ICP–AES instrument. Effects of different parameters, including instrumental parameters of ICP and FIA were optimized. An enrichment factor of 330 for each analyte ion was obtained at a concentration level of 80 ppb. The detection limits of the proposed method for Hf and Zr were 0.16 ng mL⁻¹ and 0.04 ng mL⁻¹ respectively. The ability of the method for the recovery of Hf and Zr ions was tested in the presence of several diverse metal ions in a synthetic mixture and some real matrices. It was also applied to the determination of Zr and Hf ions in a standard soil and in a standard alloy as real samples.     

Liquid chromatography–mass spectrometric determination of plasmalogens in human plasma

A new liquid chromatography–mass spectrometry (LC/MS) method has been developed for the quantitative analysis of plasmalogens in human plasma using a nonendogenous plasmalogen (1-O-1′-(Z)-tricosenyl-2-oleoyl-rac-glycero-3-phosphocholine, PLS 23:0/18:1) as an internal standard. 1-O-1′-(Z)-Tricosenyl glyceryl ether was prepared by reacting lithioalkoxyallyl with 1-iodoeicosane as the key intermediate in the formation of PLS 23:0/18:1. In LC/MS analyses, PLS 23:0/18:1 generated significant fragment ions in positive and negative modes. In positive ion mode, the [M+H]⁺ of PLS 23:0/18:1 yielded unique fragments with cleavages at the sn-1 and sn-2 positions of the glycerol backbone. In negative ion mode, the [M+CH₃COO]⁻ of PLS 23:0/18:1 resulted in characteristic fragmentation at the sn-2 and sn-3 positions. 1-O-1′-(Z)-Hexadecenyl-2-linoleoyl-rac-glycero-3-phosphocholine (PLS 16:0/18:2) and 2-arachidonoyl-O-1′-(Z)-hexadecenyl-rac-glycero-3-phosphocholine (PLS 16:0/20:4) were chemically synthesized as PLS 23:0/18:1. The calibration curves obtained for PLS 16:0/18:2 and PLS 16:0/20:4 were linear throughout the calibration range (0.04–1.60 pmol). The LOD (S/N = 5:1) was 0.008 pmol and the LOQ (S/N = 6:1) was 0.01 pmol for both PLS 16:0/18:2 and PLS 16:0/20:4. Plasma concentrations of PLS 16:0/18:2 and PLS 16:0/20:4 were 4.0 ± 1.3 μM and 3.5 ± 1.2 μM (mean ± SD), respectively, in five healthy volunteers.     

Preparation, Characterization and Crystal Structure of [Be(NCSe)2(HCON(CH3)2)2]

 Di-N-selenocyanato-bis(N,N′-dimethylfor- mamide)beryllium (1) was prepared and characterized by chemical analyses, and single crystal X-ray structure analysis. Crystals of 1 are monoclinic with a = 1837.2 (8) pm, b = 547.1 (2) pm, c = 1435.6 (6) pm, β = 93.27 (4)°, space group C2/c, Z = 4. Beryllium is tetrahedrally coordinated by two N-bonded selenocyanate and two O-bonded N,N′-dimethylformamide ligands and intermolecular Se ⋯ Se as well as Se ⋯ H interactions are observed.     

Determination of the Mg-Concentration Profile in Near-Surface Layers of Materials Using the 24Mg(α,p)27Al Nuclear Reaction

 The ²⁴Mg(α, p)²⁷ Al nuclear reaction was applied for the determination of the magnesium distribution in near-surface layers of materials. The cross sections of this reaction were determined in the energy region between 4.5 and 5.5 MeV in steps of 5 to 10 KeV (θ_lab : 158°) using thin magnesium films. The investigated projectile energy region included five main resonances allowing the determination of magnesium. The uncertainty of the cross-section determination was of the order of 7%. The applicability of the technique was tested using Mg-implanted AISI 321 steel samples. Depth resolution of 100 nm and detection limits of the order of 0.1 ppm were achieved for the determination of magnesium in steel samples using the 4805 keV resonance of the ²⁴Mg(α, p)²⁷ Al nuclear reaction. The shape and height of the magnesium depth-profile in the Mg-implanted steel samples were compared with corresponding values obtained by X-ray photoelectron spectroscopy. Received July 15, 1999. Revision March 30, 2000.     

Application of chitosan functionalized with 3,4-dihydroxy benzoic acid moiety for on-line preconcentration and determination of trace elements in water samples

Chitosan resin functionalized with 3,4-dihydroxy benzoic acid (CCTS-DHBA resin) was used as a packing material for flow injection (FI) on-line mini-column preconcentration in combination with inductively coupled plasma-atomic emission spectrometry (ICP-AES) for the determination of trace elements such as silver, bismuth, copper, gallium, indium, molybdenum, nickel, uranium, and vanadium in environmental waters. A 5-mL aliquot of sample (pH 5.5) was introduced to the minicolumn for the adsorption/preconcentration of the metal ions, and the collected analytes on the mini-column were eluted with 2 M HNO₃, and the eluates was subsequently transported via direct injection to the nebulizer of ICP-AES for quantification. The parameters affecting on the sensitivity, such as sample pH, sample flow rate, eluent concentration, and eluent flow rate, were carefully examined. Alkali and alkaline earth metal ions commonly existing in river water and seawater did not affect the analysis of metals. Under the optimum conditions, the method allowed the determination of metal ions with detection limits of 0.08 ng mL⁻¹ (Ag), 0.9 ng mL⁻¹ (Bi), 0.07 ng mL⁻¹ (Cu), 0.9 ng mL⁻¹ (Ga), 0.9 ng mL⁻¹ (In), 0.08 ng mL⁻¹ (Mo), 0.09 ng mL⁻¹ (Ni), 0.9 ng mL⁻¹ (U), and 0.08 ng mL⁻¹ (V). By using 5 mL of sample solution, the enrichment factor and collection efficiency were 8–12 fold and 96–102%, respectively, whereas the sample throughput was 7 samples/hour. The method was validated by determining metal ions in certified reference material of river water (SLRS-4) and nearshore seawater (CASS-4), and its applicability was further demonstrated to river water and seawater samples.     

Oxidation, Diffusion and Segregation in CuNi(Mn) Films Studied by AES

 The surface and in-depth compositions of sputter-deposited Cu_0.57Ni_0.42Mn_0.01 thin films were studied by Auger electron depth profiling after thermal treatment. The samples were thermally cycled to maximum temperatures of 300 °C to 550 °C in air, argon and forming gas (N₂, 5 vol. % H₂). Linear least-squares fit to standard spectra and factor analysis were applied to separate the overlapping Auger transitions of Cu and Ni. Under bombardment by 4 keV argon ions, CuNi(Mn) layers display bombardment-induced surface enrichment of Ni in the same extent as binary CuNi alloys. At sufficiently high oxygen partial pressures, a duplex oxide layer is formed and a thick surface copper oxide overgrows the initial nickel oxide. In reducing atmosphere selective oxidation of manganese takes place. A capping NiCr layer prevents CuNi(Mn) from being oxidized, but the film configuration is degraded with increasing annealing temperature due to formation of a surface chromium oxide and diffusion of Ni from the CuNi(Mn) layer into the NiCr/CuNi(Mn) interface.     

Polygermanosilyne Calcium Hydroxide Intercalation Compounds Formed by Topotactic Transformation of Ca(Si 1 − x Ge x )2 Alloy Zintl Phases in Ambient Atmosphere

Summary.   Epitaxial thin films of Ca(Si _1 − x Ge _x )₂ with 0 < x ≤ 1 are found to react with the moisture of ambient atmosphere to form new Ca-Si-Ge-O-H compounds which were studied by X-ray diffraction, energy dispersive X-ray analysis, infrared absorption, and thermally induced hydrogen desorption measurements. Pure CaGe₂ forms the polygermyne calcium hydroxide intercalation compound Ca(OH)₂(GeH)₂ upon exposure to humidity, with a trigonal tr6 crystal lattice with a = 4.00(1) and c = 65.3(1)?. In mixed Ca(Si _1 − x Ge _x )₂ with smaller Ge content, the group-14 layers are subject to intense oxidation leading to decreased crystallinity. The products exhibit characteristic colours and intense photoluminescence, the peak luminescence varying from 1.35 eV for the reaction product of Ca(Si_0.3Ge_0.7)₂ to 2.6 eV for that of Ca(Si_0.5Ge_0.5)₂. Received March 12, 2001. Accepted (revised) May 2, 2001     

Solid State Analysis with the New Leipzig High-Energy Ion Nanoprobe

 The high-energy ion nanoprobe LIPSION at the University of Leipzig has been operational since October 1998. The ultrastable single ended 3.5 MV SINLETRON^TM accelerator supplies the H⁺ or He⁺ ion beam. A magnetic scanning system moves the focused beam across the sample. At present, a resolution of 150 nm in the low current mode and 300 nm at 5 pA could be achieved. The UHV grade experimental chamber is equipped with electron-, energy dispersive X-ray-, and particle detectors. They can be used simultaneously to analyse the sample by means of PIXE (particle induced X-ray emission), RBS (Rutherford backscattering) and in the case of thin samples STIM (scanning transmission ion microscopy). A goniometer allows the application of channeling measurements in single crystals in combination with these methods. The detection limits depend on the elements to be analysed and range from (1000⋯1) μg/g relative and (1⋯0.01) pg absolute. The analysis is nondestructive, but the sample has to be vacuum resistant. Applications of the nanoprobe in the field of semiconductor research, biomedicine, and archaeology will be described.     

Electrochemical modification of Bi2S3 coatings in a nickel plating electrolyte

The electrochemical behavior of Bi₂S₃ coatings in Watts nickel plating electrolyte was investigated using the cyclic voltammetry, electrochemical quartz crystal microbalance, X-ray diffraction, and energy dispersive X-ray analysis methods. During the bismuth sulfide coating reduction in Watts background electrolyte in the potential region from −0.4 to −0.6 V, the Bi₂S₃ and Bi(III) oxygen compounds are reduced to metallic Bi, and the decrease in coating mass is related to the transfer of S²⁻ ions from the electrode surface. When the bismuth sulfide coating is reduced in Watts nickel plating electrolyte, the observed increase in coating mass in the potential region −0.1 to −0.4 V is conditioned by Ni²⁺ ions reduction before the bulk deposition of Ni, initiated by Bi₂S₃. In this potential region, the reduction of Bi(III) oxygen compounds can occur. After the treatment of as-deposited bismuth sulfide coating in nickel plating electrolyte at E = −0.3 V, the sheet resistance of the layer decreases from 10¹³ to 500–700 Ω cm. A metal-rich mixed sulfide Ni₃Bi₂S₂–parkerite is obtained when as-deposited bismuth sulfide coating is treated in Watts nickel plating electrolyte at a potential close to the equilibrium potential of the Ni/Ni²⁺ system and then annealed at temperatures higher than 120 °C.     

Nanometer-sized zirconium dioxide microcolumn separation/preconcentration of trace metals and their determination by ICP-OES in environmental and biological samples

A new method is proposed using a microcolumn (20 mm × 2.0 mm) packed with nanometer-sized zirconia as solid-phase extractor for the separation/preconcentration of Mn, Cu, Cr, Zn, Ni and Co prior to their determination by inductively coupled plasma optical emission spectrometer (ICP-OES) in environmental samples. The factors affecting the separation and preconcentration of analytes such as pH, sample flow rate and volume, eluent concentration and volume were determined, interfering ions were studied, and the optimal experimental conditions were established. The adsorption capacity of nanometer-sized ZrO₂ for Mn, Cu, Cr, Zn, Ni and Co was found to be 1.3, 1.3, 1.7, 2.0, 3.9 and 1.5 mg g⁻¹, respectively. The detection limits of the method were 12, 58, 24, 2, 7 and 36 ng L⁻¹, respectively, with a preconcentration factor of 25. The precision of this method was 1.7% (Mn), 2.9% (Cu), 5.9% (Mn), 3.8% (Mn), 6.2% (Mn) and 4.3% (Mn) with 9 determinations of 10 ng mL⁻¹ of target analytes, respectively. The method was successfully applied to the determination of trace metals in lake water, dried fish samples, certified reference materials of human hair and milk, and provided satisfactory results.     

Polymorphism and Pressure Driven Thermal Spin Crossover Phenomenon in [Fe( abpt )2(NC X )2] ( X =?S, and Se): Synthesis, Structure and Magnetic Properties

Summary.  The monomeric compounds [Fe(abpt)₂(NCX)₂] (X = S (1), Se (2) and abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole) have been synthesized and characterized. They crystallize in the monoclinic P2₁/n space group with a = 11.637(2) ?, b = 9.8021(14) ?, c = 12.9838(12) ?, β = 101.126(14)°, and Z = 2 for 1, and a = 11.601(2) ?, b = 9.6666(14) ?, c = 12.883(2) ?, β = 101.449(10)°, and Z = 2 for 2. The unit cell contains a pair mononuclear [Fe(abpt)₂(NCX)₂] units related by a center of symmetry. Each iron atom, located at a molecular inversion center, is in a distorted octahedral environment. Four of the six nitrogen atoms coordinated to the Fe(II) ion belong to the pyridine-N(1) and triazole-N(2) rings of two abpt ligands. The remaining trans positions are occupied by two nitrogen atoms, N(3), belonging to the two pseudo-halide ligands. The magnetic susceptibility measurements at ambient pressure have revealed that they are in the high-spin range in the 2 K–300 K temperature range. The pressure study has revealed that compound 1 remains in high-spin as pressure is increased up to 4.4 kbar, where an incomplete thermal spin crossover appears at around T _1/2 = 65 K. Quenching experiments at 4.4 kbar have shown that the incomplete character of the conversion is a consequence of slow kinetics. Relatively sharp spin transition takes place at T _1/2 = 106, 152 and 179 K, as pressure attains 5.6, 8.6 and 10.5 kbar, respectively. Corresponding author. E-mail: jose.a.real@uv.es Received June 12, 2002; accepted July 1, 2002     

Photo-stimulated luminescence of KCl:Eu under X-ray and ion irradiation

We compared the photo-stimulated luminescence (PSL) process of storage phosphor KCl:Eu under the irradiation of X-ray, 2.0 MeV H⁺ ions and 2.0 MeV He⁺ ions. The purpose of the irradiation of H⁺ and He⁺ ions was to mimic the irradiation effects of neutrons. In each case, it was revealed that F-centers were involved in the PSL process. We observed an entirely different fluence-dependent PSL behavior between the X-ray and the ion irradiation, whereas the behavior of the F-center absorption was quite similar. This difference was due to the different yields of the trapping sites for the electrons liberated from the F-centers, and the difference in the yield was ascribed to the difference in the excitation density. This result clearly indicated a marked difference in the PSL process under X-ray and neutron irradiations and indicated that the analysis of the PSL process under ion irradiation is highly important for the application of PSL phosphors to neutron radiography.     

A New Differential Pulse Voltammetric Method for the Determination of Nitrate at a Copper Plated Glassy Carbon Electrode

 A differential pulse voltammetric method for the determination of nitrate has been described, which is applicable to the analysis of natural water samples with nitrate levels greater than 2.8 × 10⁻⁶ M. A reduction peak for the nitrate ions at a freshly copper plated glassy carbon electrode was observed at about −0.50 V vs Ag ∣AgCl∣KCl_satd electrode in a solution of 2.0 × 10⁻² M Cu²⁺, 0.5 M H₂SO₄ and 1.0 × 10⁻³ M KCl and exploited for analytical purposes. The working linear range was established by regression analysis and found to extend from 2.8 ×10⁻⁶ M to 8.0 × 10⁻⁵ M. The proposed method was applied for the determination of nitrate in natural waters. The detection limit of the method was 2.8 × 10⁻⁶ M and the sensitivity was 0.9683 A·L/mol. The possible interferences by some ions such as phosphate, nitrite and some halides were determined and found to lead to shifts of the peak position and increasing the peak heights. Received March 15, 1999. Revision July 9, 1999.     

Polymer supported 5,10,15,20-tetrakis(phenoxy acetic acid)porphyrin derivative for separation and preconcentration of d- and f-electron metals

5,10,15,20-tetrakis(phenoxy acetic acid) porphyrin (PAAP) was covalently linked to Merrifield chloromethylated resin. Characterization of PAAP and the modified polymeric matrix were performed by ¹H NMR, FTIR and elemental analysis. The sorbent was used for the separation and enrichment of the d-electron metals (Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) at pH 6–8 and of the f-electron metals U(VI) and Th(IV) at pH 4–5. The metals ions were preconcentrated with a concentration factor range of 115–215 and then determined by flame atomic absorption spectrometry or visible spectrophotometry using Arsenazo(III). The retained metals were eluted with 2.0 mol L⁻¹ HNO₃ in the case of the d-electron metals and 0.1/0.25 mol L⁻¹ HCl in the case of the f-electron metals. The procedure was validated by analyzing the NIST standard reference material 2709 (San Joaquin Soil). Correspondence: Melek Merdivan, Chemistry Department, Faculty of Arts and Sciences, Dokuz Eylul University, 35160 Buca, Izmir, Turkey