飞行时间二次离子质谱(TOF-SIMS)结合化学衍生法分析杂环新化合物的结构

飞行时间二次离子质谱(TOF-SIMS)分析了难挥发的杂环新化合物咪唑啉硫氰酸盐及其三种衍生物, 确认出很强的氢离化及银离化准分子离子峰, 通过对各种衍生物谱图的对照分析, 确认出较强的含有结构特征的碎片离子峰, 并对该化合物在离子轰击下的裂解规律作了分析, 支持了对该新化合物结构的鉴定。     

Overpressured thin-layer chromatography

The properties, apparatus and applications of overpressured thin-layer chromatography (OPTLC) have been reviewed. In the Introduction planar chromatography has been briefly characterized, with particular attention to TLC. The general properties of OPTLC and methods of development of chromatograms in this technique have been then given. The construction of chambers and equipment for OPTLC has been described, paying attention to two-dimensional columns. The properties of chambers for OPTLC have been characterized considering the flow of eluent, sorbent-eluent interactions and the efficiency of various systems. OPTLC, TLC and HPTLC have been compared and also a comparison between OPTLC with a constant (linear) eluent flow-rate and with a decreasing eluent flow-rate has been made. Analytical applications of OPTLC have been described and examples of separations of mixtures have been given.     

Synthese de substances macromoleculaires renfermant des motifs monomeres derives de colorants—XIX: Synthese d'oligoethers et d'oligoesters colores par structure

Oligo-oxyethylenes and oligo(oxyethylenes-Co-oxypropylenes) with hydroxy end-groups have been modified by nitration and amination of the end-groups; the modification was partial in some cases and complete in others. Amino end-groups have been diazotized and the oligomers with azo end-groups have been coupled with β oxynaphthic acid and N,N′diethylaniline. Oligomers with chromophoric and hydroxy groups in the chain have been used to prepare polyurethane foams. Structurally coloured polyesters have been synthesized similarly and used to prepare polyurethane elastomers. All these oligomers have been characterized by i.r. and visible spectroscopy, NMR, end-group titration, vapour pressure osmometry and thermal differential analysis.     

Structure and reactions of reduction products in crystalline and polymeric materials by combining pulse radiolysis and ESR

The structure and the reactions of primary oxidation and reduction products in irradiated organic crystals and solid polymers have been investigated. The data from pulse radiolysis with nanosecond time resolution have been combined in a new manner with the data obtained by low-temperature irradiation and ESR spectroscopy. By this combination optical spectra have been assigned, reaction mechanisms have been studied and ESR components have been identified using the kinetic data from pulse radiolysis. The method has been particularly useful in the study of negative-ion radicals in carboxylic acid derivatives, of trapped electrons in polyhydroxy compounds, and of ionic species in polymers.     

Short peptides as biosensor transducers

This review deals with short peptides (up to 50 amino acids) as biomimetic active recognition elements in sensing systems. Peptide-based sensors have been developed in recent years according to different strategies. Synthetic peptides have been designed on the basis of known interactions between single or a few amino acids and targets, with attention being paid to the presence of peptide motifs known to allow intermolecular self-organization of the sensing peptides over the sensor surface. Sensitive and sophisticated sensors have been obtained in this way, but the use of designed peptides is limited by severe difficulties in their in silico design. Short peptides from random phage display have been selected in a random way from large, unfocussed, and often preexisting and commercially available phage display libraries, with no design elements. Such peptides often perform better than antibodies, but they are difficult to select when the target is a small molecule because of the need to immobilize it with considerable modifications of its structure. Artificial, miniaturized receptors have been obtained from the reduction of the known sequence of a natural receptor down to a synthesizable and yet stable one. Alternatively, binding sites have been created over a designed, stable peptide scaffold. Short peptides have also been used as active elements for the detection of their own natural receptors: pathogenic bacteria have been detected with antimicrobial and cell-penetrating peptides, but key challenges such as detection of bacteria in real samples, improved sensitivity, and improved selectivity have to be faced. Peptide substrates have been conjugated to fluorescent quantum dots to obtain disposable sensors for protease activity with high sensitivity. Ferrocene–peptide conjugates have been used for electrochemical sensing of protease activity.     

Chiral cyclohexane based fluorescent chemosensors for enantiomeric discrimination of aspartate

Some new chiral cyclohexyl based fluorescent anion receptors have been synthesized and their absolute configuration has been determined by using circular dichroism (CD). Complexation experiments have been carried out with several dicarboxylates, and stoichiometries and complexation constants for the corresponding complexes have been determined. The chiral discrimination ability of these ligands for chiral dicarboxylates has been studied and the best results have been obtained with TMA aspartate.     

Effect of the composition of polyacrylimide-forming copolymers on their processing

Thermomechanical studies of thermosetting copolymers of acrylonitrile with methacrylic acid and acrylamide with acrylic acid that form similar polyacrylimide foam plastics during curing have been performed. The dependence of the glass-transition temperatures of the copolymers on the degrees of intramolecular imidization has been calculated and confirmed experimentally. Procedures to control the curing rate have been proposed. The influence of plasticizing additives on the glass-transition temperatures, imidization, and foaming of foam-forming compositions has been studied. Plasticized powdered foam-forming compositions with delayed imidization have been developed, and temperature conditions for their processing have been determined.     

Preparation and characterization of water-in-oil decane/AOT microemulsions containing silver and gold nanoparticles and large amounts of water

Stable microemulsions with water contents as high as 10 vol % have been obtained, including those additionally containing silver and gold nanoparticles. Especial attention has been focused on the influence of water and stabilizer contents on the structure of adsorption layers on nanoparticles. The properties of nanoparticles obtained via the traditional microemulsion synthesis have been compared with the properties of nanoparticles that have preliminarily been concentrated with the help of electrophoresis and dried. The electrophoretic concentration and drying of nanoparticles have been shown to improve the stability of their microemulsions. Microemulsions with the highest content of water have been studied to determine the occurrence of percolation and the influence of nanoparticles on their percolation temperature and electrical conductivity.     

Frequency-modulated simultaneous multielement atomic absorption spectrometry using electrothermal atomizer and deuterium background correction

Characteristic data of the frequency-modulated simultaneous multielement atomic absorption spectrometry (FREMSAAS) using electrothermal atomizer with deuterium background correction, have been determined. The data obtained have been processed by using several statistical tests recommended for quality control purposes. The instrumentation has been presented as well as procedures of separating elements into measure groups and fixing of variable conditions. Detection limits, characteristic masses and working ranges have been given for the eleven elements examined. The data have been in good agreement to results obtained with conventional one-channel AAS instruments. The eleven elements have been simultaneously determined in a standard reference material (SRM) and all results are compatible with a 95% certainty with the certified values. FREMSAAS has been applied to a real sample.Dedicated to Professor Dr. Dieter-Klockow on the occasion of his 60th birthday     

Chromatography of alkaloids on titanium arsenate papers and quantitative separation of some alkaloids from nicotine on titanium arsenate columns

Columns and papers of titanium arsenate have been utilized for chromatographic studies of several alkaloids in aqueous and mixed solvent systems. The results have been compared with those obtained with plain papers. A number of separations have been achieved on papers impregnated with titanium arsenate. Distribution coefficients of these alkaloids have been determined. A number of alkaloids have been separated quantitatively from nicotine on titanium arsenate columns.     

The Synthesis and Biological Evaluation of Regioisomeric Benzothiazolyl Coumarins

Various 4-aryloxymethylcoumarins have been obtained by the r.t. allylic substitution with formylphenols. These have been further reacted with o-aminothiophenol resulting in the formation of a benzothiazole skeleton. These compounds have been synthesised with a view to study their potential as microbial growth inhibitors. Comparative studies on the spectral and antimicrobial activities have also been carried out.     

Approximations of the nucleus size spectrum in nucleation kinetics under gradually varied external conditions

Several simple approximations have been presented for describing evolution of a condensing system at the stage of nucleation under dynamic conditions. All of them have been compared with the exact numerical solution, and their errors have been determined. All relative errors have been shown to be rather small.     

Mass spectra of some oxadiazole derivatives

The mass spectra of some substituted oxadiazoles have been determined and analysed with the aid of high resolution mass spectrometry. Some characteristic and major differences between their spectra have been noted, and possible rationalizations have been advanced. The main fragmentation patterns of the 1,3,4-oxadiazole derivatives have been interpreted in terms of diazirine intermediates. Specific skeletal rearrangement processes have been observed in the spectra of the 1,3,4- and 1,2,4-oxadiazoles, and possible mechanisms are proposed.     

Behavior of acetyl modified amino acids in reverse micelles: a non-invasive and physiochemical approach

The well-characterized, monodisperse nature of reverse micelles formed by sodium bis-(2-ethylhexyl)sulfosuccinate/water/isooctane and their usefulness in assimilating compounds of varied interests have been exploited to investigate the effect of acetyl modified amino acids (MAA) viz., N-acetyl-L-glycine (NAG), N-acetyl-L-aspartic acid (NAA) and N-acetyl-L-cysteine (NAC), on the water pool and physiochemical properties. Non-invasive techniques such as FTIR and UV-vis absorption spectroscopy have been employed to analyze the interactions of MAA with core water and the AOT headgroup. The micropolarities on both sides of AOT interface have further been investigated by UV-vis absorption probes, methyl orange (MO) and methylene blue (MB). The dynamics of water and temperature induced percolation process have also been studied. The MAA molecules have been found to assist the process with the increase in water content where as a contrary behavior has been observed with the increase in temperature. Conductivity results have been further rationalized in terms of scaling equations, which delineate the dynamic nature of the percolation process. The results have also been analyzed in the light of activation energy of the percolation process and thermodynamics of droplet clustering.     

系列长链烷氧基苯甲醛的合成研究

以长链正烷基醇为原料与氢溴酸作用 ,合成了长链正烷基溴 6个 ;再与对或间羟基苯甲醛反应 ,合成了烷氧基苯甲醛 9个、间烷氧基苯甲醛 8个 .由于烷基链长的不同 ,其产率为 70 %～ 94% .考察了催化剂、烷基链长、羟基位置对长链烷氧基甲醛合成的影响 .解析了各种产物的红外光谱 .     

ClO与ClO自由基反应机理及电子密度拓扑分析

利用密度泛函理论对ClO与ClO自由基反应机理进行了深入理论探讨,在B3LYP/6-311＋＋G（3df）水平上对该反应体系的反应物、中间体、过渡态及产物进行了几何构型优化,对反应通道进行了IRC(内禀反应坐标）路径解析,计算了沿各反应通道的能垒和离解能,并进行了零点能校正.从量子拓扑学的角度,对反应通道IRC途径上一些重要点进行了电子密度拓扑分析,讨论了反应过程中化学键的断裂、生成以及键的变化规律,找到了反应途径的能量过渡态和结构过渡态.     

Sulfonamide carbazole receptors for anion recognition

Carbazole-based receptors functionalized with two sulfonamide groups have been synthesized and their properties as anion receptors have been evaluated. The receptor with bis(trifluoromethyl)aniline groups has shown a very high affinity for halide ions, especially remarkable as only two hydrogen bonds are formed in the complexes. (1)H NMR and fluorescence titrations have been carried out and binding constants up to 7.9 × 10(6) M(-1) have been reached. X-ray structures have been obtained and a modelling study has shown the possible reasons for the large affinity of these compounds for halide anions.     

Sulphur-containing polyarylenequinodiimides

Different synthetic approaches have been used for preparing some new polymers relating to sulphur-containing polyarylenequinodiimides. The latter have been obtained both from quinodi-imidedichloride and aromatic dithioles and directly from 1,4-phenylenediamine and disulphenylchlorides. The mechanism of this process has been proposed on the basis of studying a model reaction of phenylsulphenylchloride with 1,4-phenylenediamine. Polyarylenesulphonequinodi-imides have been obtained by selective oxidation of polyarylenesulphoneamides with phenyliodozoacetate. Their structure has been proved by IR, PMR, and ¹³C-NMR spectroscopies. Electrophysical properties of synthesized polymers have been studied.