A 1H NMR study of 1,4-bis(N-hexadecyl-N, N-dimethylammonium)butane dibromide/sodium anthranilate system: spherical to rod-shaped transition

The effect of addition of sodium anthranilate to 5 mM micellar solutions of gemini surfactant 1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide is investigated by ¹H NMR. The solubilization site of anthranilate anion near the micellar surface is inferred. In the micelles, the An⁻ ions intercalate among the surfactant headgroups producing morphological changes.     

Molecular orbital study for Na, Mg, and Al adsorption on the Si (111) surface

We investigated the interactions between the Si(111) surface and the Na, Mg, and Al atoms using cluster model calculations. Calculations were performed at levels of complete-active-space self-consistent-field (CASSCF) and multi-reference singly and doubly excited configuration interaction (MRSDCI) calculations using the model core potential method. Our calculations revealed that the most favorable sites of Na, Mg, and Al adsorption on Si(111) are on top (T₁), bridge (B₂), and 3-fold filled (T₄) sites, respectively. The nature of chemical bonds between these metal atoms and the dangling bonds of the surface Si atoms are found to be essentially covalent.     

Bibliometric Analysis of the <Emphasis Type="Italic">Journal of Structural Chemistry</Emphasis>

Bibliometric analysis has been carried out for the Journal of Structural Chemistry (JSC) published since 1960 by the Siberian Branch of the Russian Academy of Sciences. All JSC publications which appeared between 1960 and 2002 have been chosen online from the Chemical Abstracts and Science Citation Index databases of the STN International net and analyzed according to topics, authors, affiliations, and other criteria. JSC authors and publications with the largest numbers of citations have been identified. The impact factor has been determined for JSC 2002.Original Russian Text Copyright © 2004 by V. M. Buznik, I. V. Zibareva, V. N. Piottukh-Peletskii, and N. I. Sorokin__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 1142–1153, November–December, 2004.     

Synthesis and characterization of sodium titanates Na2Ti3O7 and Na2Ti6O13

Na₂Ti₃O₇ and Na₂Ti₆O₁₃ were synthesized by sol-gel method in order to obtain pure phases. Different heat-treatments were applied on powders and pellets of these materials. The effects were studied by XRD, dilatometry, TGA-DTA, SEM and electrochemical impedance spectroscopy. Pure Na₂Ti₃O₇ was obtained at 973 K. Sintering at 1373 K caused a partial decomposition into Na₂Ti₆O₁₃. The Na₂Ti₃O₇ powder sintered at 1273 K showed polygonal microstructure. Na₂Ti₃O₇ pellets sintered at 1323 K for 10 h exhibited large structures. This latter microstructure decreased the electrical conductivity of Na₂Ti₃O₇. Pure Na₂Ti₆O₁₃ was obtained at 873 K. Sintering at 1073 K caused a partial decomposition into TiO₂ (rutile). Na₂Ti₆O₁₃ pellets sintered at 1323 K for 10 h exhibited common shrinkage behavior. This shrinkage process increased the electrical conductivity of this material. The presence of TiO₂ resulted in a oxygen partial pressure dependence of the electrical conductivity.     

单晶电极表面研究中的超高真空技术

阐述了超高真空和电化学联合技术的性能,这种技术是获取电极-溶液界面微观信息的一种手段.给出了有关样品制备和表面分析技术在实验中的方方面面,并选取了一些单晶电极表面研究的最近成果--电化学池中重构的Au(100)-hex和Pt(100)-hex单晶电极的相转变以及Pt在Ru(0001)和Ru(1010)表面,RuO2(100)在Ru(0001)上外延生长的结构研究.     

Geometrical characteristics of four-coordinate complexes of Ni,Pd, and Pt containing triphenylphosphine as ligand

A statistical analysis based on crystal structure results of 4-coordinated complexes of Ni, Pd, and Pt containing triphenylphosphine as ligand has been performed using the Cambridge Structural Data Base. Distorted square-planar coordination appears as the most probable one presented by these metals.

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Geometrische Charakteristika von vier-koordinierten Komplexen des Ni, Pd und Pt mit Triphenylphosphin als Ligand

Zusammenfassung Es wurde unter Verwendung der Cambridge Strukturdatenbank eine statistische Analyse von Resultaten an vier-koordinierten Komplexen des Ni, Pd und Pt mit Triphenylphosphin-Ligand durchgeführt. Dabei ergab sich eine verzerrte quadratisch-planare Koordination als die am meisten wahrscheinliche Geometrie.

     

Experimental evidence of structural transition from fcc to bulk bcc in nanophase metal clusters of (Fe)n, (Cr)n, (Mo)n and (W)n produced by CO2 laser multiphoton decomposition of metal carbonyls

We have produced nanophase metal clusters, (Fe)_n, (Cr)_n, (Mo)_n and (W)_n, by multiphoton decomposition of the corresponding metal carbonyls with a 10.6 μm CO₂ laser in the presence of Ar and SF₆. The size distribution was narrow and the average diameter was 6, 3.5, 2 and 1 nm for Fe, Cr, Mo and W clusters, respectively. The structure was found to be bcc for both Fe and Cr clusters, fcc for Mo clusters, and amorphous for W clusters (note that all the bulk metals have bcc structure). Considering the cluster sizes (9630, 1870, 230 and 30 for Fe, Cr, Mo and W clusters, respectively) estimated from their average diameters, it is likely that there exists a structural transition from fcc to bulk bcc with increasing cluster size in these metal clusters.     

Substitutional carbon defects in silicon: A quantum mechanical characterization through the infrared and Raman spectra

The infrared (IR) and Raman spectra of eight substitutional carbon defects in silicon are computed at the quantum mechanical level by using a periodic supercell approach based on hybrid functionals, an all electron Gaussian type basis set and the CRYSTAL code. The single substitutional C _s case and its combination with a vacancy (C _sV and C _sSiV) are considered first. The progressive saturation of the four bonds of a Si atom with C is then examined. The last set of defects consists of a chain of adjacent carbon atoms C, with i = 1–3. The simple substitutional case, C _s, is the common first member of the three sets. All these defects show important, very characteristic features in their IR spectrum. One or two C related peaks dominate the spectra: at 596 cm⁻¹ for C _s (and C _sSiV, the second neighbor vacancy is not shifting the C _s peak), at 705 and 716 cm⁻¹ for C _sV, at 537 cm⁻¹ for C and C (with additional peaks at 522, 655 and 689 for the latter only), at 607 and 624 cm⁻¹, 601 and 643 cm⁻¹, and 629 cm⁻¹ for SiC, SiC, and SiC, respectively. Comparison with experiment allows to attribute many observed peaks to one of the C substitutional defects. Observed peaks above 720 cm⁻¹ must be attributed to interstitial C or more complicated defects.     

Synthesis and structural revision of naturally occurring ayapin derivatives

The synthesis of three highly oxygenated naturally occurring coumarins, 8-methoxy-6,7-methylenedioxycoumarin, 5-methoxy-6,7-methylenedioxycoumarin and 5,8-dimethoxy-6,7-methylenedioxycoumarin is described for the first time, together with a new method for the preparation of ayapin (6,7-methylenedioxycoumarin). Comparison of the spectroscopic data of the synthetic tetraoxygenated coumarin 5,8-dimethoxy-6,7-methylenedioxycoumarin with literature reports resulted in the structural revision of several natural coumarins. Two coumarins, both identified as 5,8-dimethoxy-6,7-methylenedioxycoumarin must have other structures, while the structure of another coumarin, described as the isomeric 7,8-dimethoxy-5,6-methylenedioxycoumarin has to be revised to 5,8-dimethoxy-6,7-methylenedioxycoumarin.     

以对-(4-烯丙氧基苯甲酰氧基)苯甲酸对-甲氧基苯酚酯为单体的液晶聚硅氧烷的合成与表征

侧链型液晶聚合物是目前很有兴趣的研究课题之一。在国内,有关的研究报道也逐渐增多,本工作设计并合成了对-(4-烯丙氧基苯甲酰氧基)苯甲酸对-甲氧基苯酚酯单体,其结构式为: