Correlation of the position of the bond functions in H-X with electronegativity

S type Gaussian bond functions are optimized for HF, H₂O, NH₃, and CH₄. The optimization is carried out with respect to the exponent and position in the H-X bond. The position is found to correlate well with the electronegativity of Pauling and Allred-Rochow.     

The use of “actinometer” gases in optical diagnostics of plasma etching mixtures: SF6-O2

The spectroscopic emission intensities from excited F atoms in SF₆-O₂ discharges at 1 torr have been correlated to the densities of atoms in their ground electronic state by measuring the excitation efficiencies of the electrons in the energy range 11 to 17 eV with a method which essentially consists in the analysis of the emission of Ar or N₂, added as actinometer gases to the discharge mixtures. The general applicability of the method has been tested by a direct titration of F atoms with chlorine. The spectroscopic analysis has allowed the determination of useful information on the trends of both the electron densities and their energies as a function of the oxygen percent in the feed.     

Condensed rare-earth metal-rich tellurides. Extension of layered Sc6PdTe2-type compounds to yttrium and lutetium analogues and to Y7Te2, the limiting binary member

Six isotypic R₆ZTe₂ phases have been synthesized in Ta at elevated temperatures and characterized by single crystal X-ray refinements for R=Y, Z=Rh, Pd, Ag, Y and for R=Lu, Z=Cu, Ag. All crystallize in the Sc₆PdTe₂-type structure, Pnma, Z=4, a∼21.5 Å, b∼4.1 Å, c∼11.4 Å. The results can be viewed as the replacement of Te3 atoms in the parent isotypic Sc₂Te (or in the hypothetical Y₂Te or Lu₂Te analogues) by the above the Z, the Y example giving the new binary phase Y₇Te₂. The shorter (and stronger) metal-metal bonds concentrate in the region of metal (Z, Y) substitution, as revealed by larger integrated crystal orbital Hamilton population (ICOHP) values derived from linear muffin-tin-orbital (LMTO) calculations. Partial densities-of-states data for Y₇Te₂ reflect a similar behavior. Individual R-R bond distances are seen to deviate appreciably from the more fundamental overlap population measures for each.     

Direct synthesis of protected diethyl 1,2-diaminoalkylphosphonates

An efficient, diastereoselective synthesis of 5-substituted (2-thioxo-imidazolidin-4-yl)phosphonic acid diethyl esters from metallated diethyl isothiocyanatomethylphosphonate and activated imines has been developed. The three-step transformation of imidazolidine-2-thione derivatives into 1,2-diaminoalkylphosphonic acids is also described.     

Mannich reaction in the synthesis of N,S-containing heterocycles. 1. Synthesis of novel derivatives of imidazo[2,1-<Emphasis Type="Italic">b</Emphasis>][1,3,5]thiadiazine

Reactions of (Z)-5-benzylidene-2-thiohydantoin with formaldehyde and primary aromatic amines afforded novel derivatives of imidazo[2,1-b][1,3,5]thiadiazine in 50–69% yields. Dedicated to Academician N. S. Zefirov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2158–2160, September, 2005.     

Reactions of Amidines with 5-Methylene-1,3-dioxolan-2-ones

The composition and yields of the products from the reaction of 4,4-dialkyl-5-methylene-1,3-dioxolan-2-ones with amidines depend on the structure of the initial amidine and on the reaction conditions. 2-Aminopyridines lead to 3-substituted 4-hydroxy-4-methyloxazolidin-2-ones and 4-methylene-oxazolidin-2-ones and also to sym-carbamides. 2-Amino-4,6-dimethylpyrimidine leads to the corresponding 4-methyleneoxazolidin-2-one. 3-Aminothiazoles give linear oxourethanes and sym-carbamides.     

The Excited‐State Dynamics of Phycocyanobilin in Dependence on the Excitation Wavelength

The primary light‐induced processes of phycocyanobilin were studied by means of transient‐grating spectroscopy, whereby the excitation wavelength was varied over the spectral region of the ground‐state absorption. On the basis of the results obtained, both the rate of the photoreaction in phycocyanobilin and the ratio of the decay of different excited‐state species via two decay channels depend on the excitation wavelength. Furthermore, the formation of the photoreaction product is also dependent on the pump color. These data support a recently established model for the primary photoprocesses in phycocyanobilin. In addition, phycocyanobilin protonated at the basic pyrrolenine‐type nitrogen atom was included in the transient absorption study. The decay behavior was found to be almost unchanged when compared with the unprotonated form, and this suggests that protonation of the tetrapyrrole ring structure has no effect on the overall photochemistry.     

用共振光散射技术研究蛋白质与丽春红2R的相互作用

在pH3．50的Britton-Robinson缓冲溶液中，丽春红2R与蛋白质发生结合反应，使最大波长为352．5nm的共振散射光谱得到加强。据此建立了利用丽春红2R作探针，用共振散射光谱技术测定蛋白质的新方法。散射光强度与牛血清白蛋白(BSA)、人血清白蛋白(HAS)和免疫球蛋白(IgG)的浓度在0．25～17．5μg／mL范围内成正比。方法的稳定性好，快速、简便，绝大多数氨基酸、金属离子均不产生干扰，用于人血清样品中蛋白质的测定，获得了满意的结果，加标回收率为93．4％～100．1％。     

高折光指数光学树脂的合成——相转移法合成不饱和硫醇酯单体的条件控制

采用正常的低温相转移催化（ＰＴＣ）和反滴碱溶液ＰＴＣ法分别合成了含硫双烯ＭＥＳＤＭＡ和单烯ＭＥＰＳＭＡ．１Ｈ ＮＭＲ分析证明ＭＥＳ中的杂质主要是由原料ＴＤＧ引入的．对含单个巯基的ＭＥＰＳ的正常ＰＴＣ酯化接枝双键，因存在巯基和不饱和双键的加成反应而导致失败．作者最终得到了折光指数在１６２５以上的ＭＥＳＤＭＡ／ＭＥＰＳＭＡ共聚物．     

钌（Ⅱ）－联吡啶－巴比妥酸－Ce（Ⅳ）化学发光体系测定巴比妥酸的研究

利用巴比妥酸对Ｃｅ（Ⅳ）氧化钌（Ⅱ）－联吡啶化学发光反应的增强作用，建立了痕量巴比妥酸的自动脉冲注射化学发光测定法方法的检出限为１０×１０－９ｇ／ｍＬ，线性范围为５０×１０－８－６．２×１０－５ｇ／ｍＬ巴比妥酸的衍生物如巴比妥、苯巴比妥和戊巴比妥对Ｃｅ（Ⅳ）氧化钌（Ⅱ）联吡啶化学发光反应无增强作用据此对合成样中巴比妥酸作选择性检测探讨了巴比妥酸的增强机理