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71.
Paul T. Beurkens Aurea Perales Francisco J. Martín-Gil J. Martín-Gil 《Monatshefte für Chemie / Chemical Monthly》1988,119(11):1189-1199
New complexes of the formulaetrans-Pd(Creat)2Cl2·2H2O (I) andcis-Pt(Creat)2I2·3H2O (II) have been prepared and their structures and stabilities studied by X-ray diffraction and thermal analysis. Both compounds have a squareplanar geometry, the two Cl atoms and N1 creatinine atoms are coordinated to Pd intrans configuration, while in compoundII the I atoms and N1 atoms are coordinated incis configuration. In spite of the earlier differences, the TG and DTA curves of the complexes show that their stability is very similar. Since an extended hydrogen bond system is present in the crystals, especially inII, the possible consequences in biological media are discussed briefly.
Kristallstrukturen und thermische Zersetzung vontrans-Pd(Creat)2Cl2·2H2O undcis-Pt(Creat)2I2·3H2O
Zusammenfassung Es wurden neue Komplexe der Formelntrans-Pd(Creat)2Cl2·2H2O (I) undcis-Pt(Creat)2I2·3H2O (II) hergestellt und ihre Strukturen und Stabilitäten mittels Röntgenstrukturanalyse bzw, thermischer Analyse untersucht. Beide Komplexe haben quadratisch-planare Struktur, die zwei Cl-Atome und die N1-Creatinin-Atome sind an Pd intrans-Konfiguration koordiniert, währenddessen in VerbindungII die I-Atome und die N1-Atome incis-Konfiguration zueinander stehen. Trotz früherer Differenzen zeigen die TG- und DTA-Kurven der Komplexe, daß ihre Stabilitäten sehr ähnlich sind. Da besonders inII ein ausgedehntes Wasserstoffbindungssystem vorhanden ist, werden auch mögliche Konsequenzen bezüglich biologischer Wirksamkeit kurz diskutiert.相似文献
72.
Edy I. Rivas Alejandro Paladini Jr Giuseppe Cilento 《Photochemistry and photobiology》1984,40(5):565-568
Abstract —Human and bovine serum albumin quench enzyme-generated acetone phosphorescence ( K sv = ca . 104 M 1 ). Concomitantly, these proteins are altered as shown by diminished tryptophan absorption at 280 nm, appearance of products of the formylkynurenine type (max = ca . 320 nm) and disappearance of tryptophan fluorescence. These alterations—which are similar to those induced photochemically—were also observed with serum albumins exposed to enzyme-generated triplet acetaldehyde. On the other hand, triplet acetone generated by the thermolysis of tetramethyldioxetane failed to induce alterations. Presumably energy transfer occurs from the enzyme-generated triplet species to tryptophan group(s) in the serum albumin associated with the acting enzyme. The detailed mechanism is, however, not yet understood. 相似文献
73.
Ana Rivas Nicolás Olea Fátima Olea-Serrano 《Trends in analytical chemistry : TRAC》1997,16(10):613-619
A relationship has been hypothesized between adverse effects on human and wildlife reproductive health and a number of chemical substances capable of altering hormonal homeostasis. A testing system to screen for endocrine activities and the development of appropriate biomarkers of cumulative exposure are required. This article reports the work of our group in the following areas
- 1. (i) the identification of chemical agents with estrogenic hormonal activity,
- 2. (ii) existing evidence on forms and sources of human exposure, and
- 3. (iii) developing a methodology to assess the total estrogenic burden, defined as the estrogenic activity in a bioassay of human samples from which ovarian estrogens have been previously eliminated.
74.
The mass spectra of 1,2-cycloaddition products obtained from the benzophenone photosensitized irradiation of 2,3-dimethyl maleic and citraconic anhydride in several thiophen derivatives are prsented and discussed. 相似文献
75.
The powerful Buchwald-Hartwig amination was utilized for the construction of the benzimidazole nucleus with the substituted nitrogen atom bearing a chiral substituent. A successive amination/imination was followed by an acid-catalyzed ring closure step to give the benzimidazole ring. The products were deprotonated and acylated at the C2 position and could be alkylated on nitrogen to give chiral benzimidazolium salts. 相似文献
76.
Peix A Rivas R Velázquez E Mateos PF Martínez-Molina E Muñoz-Herrera A Gómez-Alonso A Velázquez E 《Electrophoresis》2005,26(23):4402-4410
The random intergenic spacer analysis is a recently developed technique for the study of microbial populations. The bacterial intergenic spacer (ITS) is located between 16S rRNA and 23S rRNA genes and presents different length and sequence among bacterial species. Therefore, the amplicons can be separated by electrophoresis commonly performed at low voltage during several hours. Although this technique is especially useful for unculturable microorganisms, it has not been applied before to clinical sample analysis. As these samples have a limited number of bacterial species, the size of the gels may be reduced to facilitate their handling and to reduce the running time. To obtain maximum separation among the ITS bands, we analysed in this work different electrophoretical conditions including staircase electrophoresis, a technique based on the application of several voltage steps. The results obtained showed a different behaviour of the electrical resistance during the performance of submarine horizontal and vertical staircase electrophoresis. In the first case the resistance decreased during most of the running time whereas in the second case it increased. Here, we show that the performance of horizontal staircase electrophoresis reduces the running time more than 80% with respect to conventional electrophoresis at low voltages. This procedure was applied to the separation of ITS bands from bacterial DNA present in a tissue from a vocal cord biopsy. The sequencing of these bands allowed their identification. This new procedure may be very useful in the rapid diagnosis of bacteria present in human, animal and plant tissues. 相似文献
77.
Ten new pyrazoles have been prepared and their 13C nmr chemical shifts compared with those of twelve other pyrazoles, some of them prepared purposely for this study. The chemical shifts are discussed statistically assuming that they are additive. A formyl group in the position 4 of the pyrazole ring produces a large effect on carbon C4 (SCS = 17.3 ppm) and medium effects on carbons C3 (SCS = 1.9 ppm) and C5 (SCS = 3.8 ppm). The azines derived from pyrazole-4-carboxaldehydes are of the E,E-configuration. 相似文献
78.
The assignment of the carbon-13 nmr resonances of a series of oxetanes derived from the photoaddition of benzophenone and 2-naphthaldehyde to furan and some of its methyl derivatives and of benzophenone to 2,5-dimethylthiophene has been made. The assignments were made by chemical shift arguments, by the use of C-13 labelling when required and different decoupling techniques. This information may be useful in the identification of new compounds with analogous carbon skeleton. 相似文献
79.
S. Yez Vilar A. Castro‐Couceiro B. Rivas‐Murias A. Fondado J. Mira J. Rivas M. A. Searís‐Rodríguez 《无机化学与普通化学杂志》2005,631(11):2192-2196
The dielectric properties of mixed‐oxide CaMn7O12 are reported. This compound exhibits a high dielectric constant at room temperature (ε′r> 104), for frequencies up to 104 Hz, values that make it very attractive for potential applications provided that its rather high losses can be minimized. Complex plane analysis of the obtained data reveal an important extrinsic contribution to these high ε′r values; and also that the intrinsic dielectric constant of this material is ε′r,∞ ≈ 30, a value rather high for this type of compounds, that could be related to the electronic process of charge‐ordering present in this oxide below 440 K. 相似文献