Effects of structural factors on the pi-dimerization and/or disproportionation of the cation radical of extended TTF containing thiophene-based pi-conjugated spacers

The electrochemical and chemical oxidation of extended TTF 4 and 5 are analysed by cyclic voltammetry, Visible/NIR and ESR spectroscopies, and the X-ray structures of the new salts 5 x BF(4)(CH(2)Cl(2)) and 4 x ClO(4)(THF)(1/2) are presented. The effects of structural factors on the pi-dimerization or the disproportionation reaction of the cation radical are shown. The oxidation of compound 4 presents the successive formation of stable cation radical and dication species both in dichloromethane (DCM) and in a CH(3)CN/THF mixture. In contrast, for compound 5, the stability of the oxidation states strongly depends on the nature of the solvent. In DCM, the oxidation of 5 proceeds by two close one-electron transfers while in CH(3)CN/THF the dication is directly formed via a two-electron process. The X-ray structures of the two salts reveal the formation of pi-dimers of cation radical. While the dimer (5(2))(2+) is due mainly to pi-pi interactions between the conjugating spacer, the multiplication of the sulfur atoms in compound 4 contributes to stabilize the dimer by the combined effects of S-S and pi-pi interactions. Visible/NIR and ESR experiments confirm the higher tendency of 4(+)(.) to dimerize with the occurrence of dimer and monomer in solution, while for 5(+)(.) only the monomer is detected in DCM. On the other hand, by dissolution of 5 x BF(4)(CH(2)Cl(2)) in CH(3)CN, only the neutral and the dicationic states of compounds 5 are observed owing to the disproportionation reaction.     

巯基化合物的电位分析法研究

本文对用直接电位法测试巯基化合物的可行性进行了研究。发现由硫化银，硫化汞等金属难溶盐制成的膜电极对６－巯基嘌呤，高胱氨酸，１，４－二巯基苏糖经合物可产生响应，其斜率为３０－１１０ｍＶ／ｐＣ，电极响应时间，则为十几秒至十几分钏，测试结果具有较好的重现性。因此，该方法可望得到应用。文中还对有关响应机理进行了探讨。     

HZSM－20沸石分子筛的水蒸汽改性

ＨＺＳＭ－２０沸石分子筛的水蒸汽改性项寿鹤，任大立，王敬中，李赫晅（南开大学化学系，天津３０００７１）关键词ＨＺＳＭ－２０沸石，水蒸汽处理，改性ＺＳＭ－２０沸石是一种具有大孔和开放结构的分子筛［１］，其结构与八面沸石（如Ｙ型沸石）类似，但其硅铝比较高...     

Template-Reaktion von Bis(acetylacetonato)-dioxo-molybdän(VI) mit Benzoylhydrazin

Template Reaction of Bis(acetylacetonato)-dioxo-molybdenum(VI) with Benzoylhydrazone By reaction of bis(acetylacetonato)-dioxo-molybdenum(VI) with benzoylhydrazine benzoylhydrazido(2?)-acetylacetonebenzoylhydrazonato(2?)-oxo-molybdenum(VI) was formed beside another species. The compound was characterized by mass spectrometry and X-ray structural analysis. Crystallographic data see ?Inhaltsübersicht”?.     

Extraction of environmental information from large aerosol data sets through combined application of cluster and factor analyses

To reveal useful environmental information which is contained in large analytical data sets, an approach, based on the successive application of hierarchical cluster analysis and factor analysis, is proposed. Estimation criteria to determine the most suitable number of clusters and/or factors, are discussed and the interpretation of the cluster and factor analyses results is performed using visual techniques. The data sets were obtained by scanning electron microscope-energy-dispersive X-ray analysis of individual North Sea aerosol particles.     

Calix[4]arenes containing benzodiazepinone fragments at the lower rim

A series of p-tert-butylcalix[4]arene derivatives containing 1,4(1,5)-benzodiazepinone fragments as substituents were prepared. The biological activity of the compounds, namely, their antispasmodic activity in mice, was evaluated by antagonism with a spasmodic agent, Corazol, upon transdermal administration. According to the data obtained, benzodiazepine derivatives of calixarenes show higher antispasmodic activity compared to 3-hydroxyphenazepam, taking into account their considerably higher molecular weight.     

Determination of binding sites in carboplatin-bound cytochrome c using electrospray ionization mass spectrometry and tandem mass spectrometry

Interaction of carboplatin with cytochrome c (Cyt. c) has been investigated by electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS). ESI-MS studies revealed that the ring-opened adducts of carboplatin with Cyt. c were formed in the stoichiometric ratio of 1:1 and 2:1 at pH 5.0 and 37 degrees C and in the stoichiometric ratio of 1:1 only at pH 7.0 and 37 degrees C. It was also found that Cyt. c could be cleaved by carboplatin at pH 2.5 and 50 degrees C. The cleaved fragments of Cyt. c were determined by ESI-MS and MS/MS analysis to be Glu66 approximately Met80, Ac-Gly01 approximately Met65, Glu66 approximately Glu104, Ac-Gly01 approximately Met80 and Ile81 approximately Glu104. The carboplatin prefers to anchor to Met65 first, then to Met80. To further confirm the binding site of Met, AcMet-Gly was used as the model molecule to investigate its interaction with carboplatin and its hydrolysis reaction. On the basis of species detected during the reaction monitored by ESI-MS, a possible pathway of the cleavage reaction was proposed.     

New phosphorus-containing macroheterocyclic cavitands

Previously unknown phosphorus-containing macroheterocycles were prepared from an accessible symmetrical dipentaerythritol derivative and trivalent phosphorus compounds. The difference in the properties of the phosphocycles containing one and two phosphoric functions was revealed.     

Solid-phase extraction of iron(III) with an ion-imprinted functionalized silica gel sorbent prepared by a surface imprinting technique

A new Fe(III)-imprinted amino-functionalized silica gel sorbent was prepared by a surface imprinting technique for selective solid-phase extraction (SPE) of Fe(III) prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Compared with non-imprinted polymer particles, the ion-imprinted polymers (IIPs) had higher selectivity and adsorption capacity for Fe(III). The maximum static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Fe(III) was 25.21 and 5.10 mg g⁻¹, respectively. The largest selectivity coefficient of the Fe(III)-imprinted sorbent for Fe(III) in the presence of Cr(III) was over 450. The relatively selective factor (α_r) values of Fe(III)/Cr(III) were 49.9 and 42.4, which were greater than 1. The distribution ratio (D) values of Fe(III)-imprinted polymers for Fe(III) were greatly larger than that for Cr(III). The detection limit (3σ) was 0.34 μg L⁻¹. The relative standard deviation of the method was 1.50% for eight replicate determinations. The method was validated by analyzing two certified reference materials (GBW 08301 and GBW 08303), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace iron in plants and water samples with satisfactory results.