Electroreductive polymerization of trans-[RuCl 2(vpy) 4] on Nd-Fe-B magnets: electrochemical impedance spectroscopy interpretation, Raman spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy analysis

The electropolymerization of trans-[RuCl₂(vpy)₄] (vpy=4-vinylpyridine) monomer on Nd-Fe-B magnets was studied by electrochemical impedance spectroscopy (EIS). Impedance diagrams obtained during the polymerization process were used to monitor film formation. The EIS results gave insight into the electrochemical phenomena occurring at the magnet surface as the polymerization process progressed. The film structure and morphology were also studied by X-ray photoelectron spectroscopy, scanning electron microscopy and Raman spectroscopy. The Raman spectroscopy results showed that the polymerization takes place at the vinyl groups of the monomer and also that the redox polymer structure is very similar to that of the monomer. The ratio of the intensity of the XPS peaks for fluorine (from the electrolyte PF₆ ^–) and ruthenium present in the film showed that the polymer on Nd-Fe-B contained an equal proportion of Ru²⁺ and Ru³⁺, indicating that part of the film is positively charged, i.e. {[RuCl₂(vpy)₄]⁺} _n .     

An in situ STM study on the long-range surface restructuring of Au(1 1 1) in a non-chloroaluminumated ionic liquid

We report an in situ STM study of a potential-dependent long-range surface restructuring of Au(1 1 1) electrode in neat 1-butyl-3-methylimidazolium tetrafluoroborates (BMIBF₄) ionic liquid. Au(1 1 1) undergoes a significant long-range surface restructuring upon cathodic excursion to −1.0 V vs. Pt quasi-reference. The restructuring involves the formation of tiny pits, which then develops into a stable worm-like network with an average width of the network grids 2 nm. Electrochemical annealing occurs at the cathodic limit with the presence of a reduction product of cation BMI⁺. A smooth surface is recovered with the appearance of the typical (√3 × 22) reconstruction of Au(1 1 1). The surface restructuring is reestablished upon anodic excursion to −1.3 V after the adsorbed reduction product is oxidized. The long-range surface restructuring phenomenon is tentatively explained as a result of partial charge transfer to the weakly adsorbed BMI⁺, which reduces the metal–metal cohesive energy. In addition, the synergetic effect of the counter anion BF₄⁻ may also be involved. The results provide a knowledge of Au(1 1 1) electrode behavior in the neat ionic liquid and are beneficial to understanding in situ STM results involving surface morphological changes in such a media.     

Counterpoise-corrected potential energy surfaces of simple H-bonded systems

Geometries and stabilization energies of various simple H-bonded complexes (water dimer, hydrogen fluoride dimer, formamide dimer, formic acid dimer) have been determined by a gradient optimization that eliminates the basis set superposition error (BSSE) by the counterpoise (CP) method in each gradient cycle as well as by the standard gradient optimization. Both optimization methods lead to different potential energy surfaces (PES). The difference depends on the theoretical level used and is larger if correlation energy is considered. Intermolecular distances from the CP-corrected PES are consistently longer, and this difference might be significant (∼0.1 ?); also angular characteristics determined from both surfaces differ significantly. Different geometries were obtained even when passing to larger basis sets (aug-cc-pVDZ). The standard optimization procedure can result in a completely wrong structure. For example, the “quasi-linear” structure of the (HF)₂ (global minimum) does not exist at the standard MP2/ 6-31G** PES (where only cyclic structure was detected) and is found only at the CP-corrected PES. Stabilization energies obtained from the CP-corrected PES are always larger than these from the standard PES where the BSSE is added only a posteriori for the final optimized structure; both energies converge only when passing to a larger basis set (aug-cc-pVDZ). Received: 11 March 1998 / Accepted: 19 June 1998 / Published online: 4 September 1998 RID=" ID=" <E6>Acknowledgements.</E6> The project was supported by the Grant Agency of the Czech Republic (Grant No. 203/98/1166). RID=" ID=" <E5>Correspondence to</E5>: P. Hobza     

乙二醛双缩(2-羟基苯胺)(GBHA)在稀土离子分析中的应用

利用乙二醛双缩（2－羟基苯胺）（GBHA）对Ln^3 系离子进行分组分析，同时以GBHA为显色剂，用分光光度法分别测定了Ho^3 ,Yb^3 ,Er^3 ,Dy^3 和Tb^3五种离子，其检出限为10^-6mol/L，工作曲线线性范围为10^-5－－10^-3mol/L。     

Ab initio through‐space/bond interaction analysis of the long C–C bonds in Bi(anthracene‐9,10‐dimethylene) photoisomers

The bi(anthracene‐9,10‐dimethylene) photoisomer has remarkably long C–C single bonds. To examine the lengthening of the C–C bond, we propose a novel procedure for quantitatively analyzing orbital interactions in a molecule at the level of the ab initio molecular orbital method. In this procedure, we can cut off the specific through‐space/bond interactions in a molecule by artificially increasing the absolute magnitude of the exponents in a Gaussian function. Then, the spatial orbital interactions were perfectly cut off, and, each term that makes up the total energy, that is, the nuclear–electron attractions, the electron–electron repulsions, and the nuclear–nuclear repulsions cancel each other. Several model molecules of the photoisomer were analyzed by this procedure. It was found that the orbital interaction between the p orbital on the benzene ring and the σ* orbital on the C–C bond in question, σ→σ* electron transfer through π orbital, weakens the C–C bond efficiently when these orbitals were located in the “periplanar” conformation. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001     

桥联双（甲巯咪唑）化合物的合成和配位性能

研究了桥联双(甲巯咪唑)化合物(Ⅰ_a—Ⅳ_a、Ⅰ_b)的合成和配位性能。UV谱显示Ⅰ_a—Ⅳ_a与UO_2~(2+)离子(硬酸)配位,溶液中形成3:1的配合物。Ⅰ_b与Hg~(2+)、Au~(3+)离子(软酸)配位形成2:1的配合物,用CNDO/2方法计算了各配体分子中原子净电荷密度和HOMO、LUMO能量。     

A convergent synthesis of octadeca-2E, 13Z-dienyl acetate, a pheromone component ofSynanthedon tipuliformis C.

A convergent synthesis of octadeca-2E, 13Z-dienyl acetate, a pheromone component ofSynanthedon tipuliformis C., has been developed. The synthesis is based on cross-coupling of 8-iodooct-2E-en-I-ol THP ether with dec-5Z-enyl bromide catalyzed by CuBr. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1529–1531, August, 1997.     

Specific Uphill Transport of Zinc as Zn(SCN)42− Ion using Na+-Dicyclohexyl-18-Crown-6 as Carrier

Sodium-dicyclohexyl- 18-crown-6 complex cation was used as carrier for the uphill transport of zinc as Zn(SCN)₄^2? complex anion. By using L-cysteine as a metal ion acceptor in the receiving phase at the optimized pH of 7.6, the amount of zinc transport through the liquid membrane after 90 min was 97.2 ± 1.0%. The selectivity and efficiency of zinc transport from aqueous solutions containing equimolar mixtures of Ag⁺, Cd²⁺ Co²⁺, Cu²⁺, Fe²⁺, Ni²⁺, Pb²⁺, Pd²⁺, Sr²⁺, Bi³⁺, Cr³⁺ and Fe³⁺ ions was investigated. In the presence of NH₂OH.HCl as a suitable masking agent in the source phase, the interfering effect of Cu²⁺ and Pb²⁺ ions was diminished drastically.     

A statistical method to detect chromosomal regions with DNA copy number alterations using SNP-array-based CGH data

Single nucleotide polymorphism (SNP) arrays were used to detect chromosomal regions with DNA copy number alterations. Current statistical methods for microarray-based comparative genomic hybridization (array-CGH) analysis generally assume certain relationships among adjacent markers on the same chromosome, and these assumptions may be questionable. For an SNP-array-based CGH study, multiple normal reference SNP arrays were collected. In order to utilize these normal reference SNP arrays, we derived an empirical distribution of signal ratios for each SNP marker. With an assumed threshold value for the overall error rate control and the defined signal ratio ranges for chromosomal amplification and deletion, we proposed a procedure to identify chromosomal alteration regions based on several bootstrapped one-sample t-tests and the false discovery rate control. When we have multiple arrays for different individuals with the same disease, our method can also be used to detect SNP markers for chromosomal alteration regions that are common among these individuals. We applied our method to a published SNP array data set for breast carcinoma cell lines. For an individual with breast cancer, numerous chromosomal alteration regions were identified. Compared to results of previous studies, our method identified more chromosomal alteration regions, with some being implicated in the literature to harbor genes associated with breast cancer. For multiple cancer arrays, our results suggested the existence of common chromosomal alteration regions. However, a high proportion of false positives also indicated that genetic variations among different individuals with breast cancer can be present.     

Viscosities of poly(N-vinylacetamide) solutions in the presence of salts, urea and guanidine hydrochloride

Summary  In the aqueous solutions of poly(N-vinylacetamide) in the presence of Na₂SO₄ or (NH₄)₂SO₄, the intrinsic viscosities were small and the Huggins constants were large compared with those in water. Similar but much less effects were observed for NaF. Opposite effects were found, however, for NaSCN. The poor solvent quality of aqueous sulfate solutions was significantly improved by the addition of guanidine hydrochloride to 3 M or higher. Urea was much less effective in improving the solvent quality. The different M28.8neffects observed between urea and GdnHCl may be explained by their different binding affinities to amide group. Solubilization of PNVA flocculates induced by the presence of 0.8 M Na₂SO₄ took place by adding urea to 1 M, although only small changes were detected in the viscosity behavior accompanying the addition of 1 M urea. Received: 12 June 1997 Accepted: 4 August 1997