摘要:

AbstractThree methylating agents with different carcinogenic powers, dimethyl sulphate [(CH3O)2SO2(DMS)], methyl methanesulphonate [CH3SO2OCH3(MMS)] andN‐methyl‐N‐methyl‐N‐nitrosourea [CH3N(NO)CONH2(MNU)], were studied by Raman spectroscopy in order to identify the reactive species which are formed in buffered aqueous solution at neutral pH.In all cases, the formation of methanol was observed. By hydrolysis DMS produces CH3OSO3−, and H3O+ions, and MMS produces CH3SO3−and H3O+ions. In the case of MNU the reaction is more complex and proceeds with gaseous products to give methanol quantitatively.This investigation is a preliminary to the study of molecular interactions between the three methylating agents and nucleic ac

ISSN:0377-0486    

DOI:10.1002/jrs.1250180202

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe Raman and IR spectra of adenine (AH3) and of its derivatives adenine hydrochloride (AH4Cl), 1‐methyladenine (1MeAH2) and 1‐methyladenine hydrochloride (1MeAH3Cl) are discussed in relation to the mutagenic and carcinogenic activities that they display.The spectra give evidence for a shift of tautomeric stability from the aminic form, which is favoured in AH3, toward the iminic, or iminic‐derived form, in the derivatives AH4Cl, 1MeAH2and 1MeAH3Cl.The different biological activities of this series of compounds, in particular the mutagenic and carcinogenic effects, can be interpreted in terms of different reactivites associated with the π electronic systems, and of a hydrogen‐bond coupling different from the canonical Watson–

ISSN:0377-0486    

DOI:10.1002/jrs.1250180203

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractRaman spectra of Br2, Cl2and I2adsorbed on graphite, KBr and fused quartz substrates are reported. The results demonstrate that the process of adsorption is strictly related to the type of adsorbate. Different Raman modes were observed for each kind of molecule adsorbed on the substrates. With adsorbed I2, the continuum resonance Raman spectra for the fundamental solid I2and no frequencies due to adsorption were observed.

ISSN:0377-0486    

DOI:10.1002/jrs.1250180204

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractLattice vibrations of polycrystalline CH2Br2and CD2Br2, obtained by Raman and far‐infrared spectroscopy, are reported. The observed peaks are compared with the predictions of a group theoretical analysis based on the known structure of the stable phase. Assignments are proposed on the basis of isotopic shifts and intensities. Evidence of a metastable phase is presented, but attempts to isolate this phase at low temperatures were unsuccessfu

ISSN:0377-0486    

DOI:10.1002/jrs.1250180205

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractResults of a micro‐Raman spectral investigation of K+‐doped BaSO4crystals prepared by a previously described radiochemical coprecipitation procedure are reported. Changes in the spectral bands of the ν1, ν2, ν3and ν4modes of the sulphate ion as a function of K+concentration in the BaSO4crystals reflect changes in the local environment of the SO42−ion indicating mixed‐crystal formation. These preliminary results show that Raman spectroscopy can be used to characterize changes in the BaSO4lattice due to coprecipitated

ISSN:0377-0486    

DOI:10.1002/jrs.1250180206

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractTwo transient species involved in the photochromism of 4‐(2′, 4′‐dinitrobenzyl)pyridine have been detected by time‐resolved resonance Raman spectroscopy. Comparison of the spectra of the shorter and longer lived transient species with those of the anion and theN‐CH3derivative, respectively, revealed that the shorter lived species is identical with the anion and the longer lived species is the NH quinoid tautomer. It is shown that the photochromism of this compound can be interpreted in terms of the involvement of the anion as the intermediate to the NH quinoid which is the photo‐activated transient blue substance

ISSN:0377-0486    

DOI:10.1002/jrs.1250180207

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractLa comparaison des intensités théoriques et des intensités expérimentales, réalisée sur la forme β du poly(fluorure de vinylidéne) orientée monoaxialement nous a permis d'attribuer les raies Raman observées aux différents modes de vibration de la chaǐne. Nous précisons plus particulièrement l'attribution des raies de fréquences 1278, 882 et 840 cm−1(raies qui subissent une profonde modification lors de la transition ferro–paraélectrique des copolymères contenant du PVF2β) aux mouvements νs(CC), ρ(CH2) et νs(CF2), respectivement. Enfin, nos résultats vérifient que les groupements CH2et CF2conservent une bonne individualité

ISSN:0377-0486    

DOI:10.1002/jrs.1250180208

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractRaman spectra of di‐n‐butylamine show bands whose temperature‐dependent intensities clearly suggest the occurrence of different conformers in simultaneous equilibria. In particular, the Raman spectrum of the solid phase is compared with that of n‐nonane in order to identify the more stable conformation. In addition, intensity rations vs temperature for pairs of Raman bands in the CH stretching region exhibit a smooth variation between the liquid an

ISSN:0377-0486    

DOI:10.1002/jrs.1250180209

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractRaman spectra of yeast alcohol dehydrogenase in buffered, aqueous solutions and in D2O, and FTIR spectra of aqueous solutions and thin films have been collected and analyzed. No significant differences between the Raman spectra in the pH range 6.00–7.50 and between the infrared spectra of the solution and film have been observed. The tyrosine doublet strongly favors exposed hydroxyl groups and the Raman spectra indicate multiple conformations for the disulfide moieties. Analysis of Raman intensities favors significant α‐helix and random coil contents. The secondary structure of yeast alcohol dehydrogenase based on Raman data is compared with the better characterized secondary structure of equine liver alcohol dehydroge

ISSN:0377-0486    

DOI:10.1002/jrs.1250180210

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractRaman spectra of oriented single crystals of potassium peroxodisulphate have been measured and revised x‐ray structural data are briefly presented. An assignment of the internal modes of the S2O82−ion was possible on the basis of intensities under different orientati

ISSN:0377-0486    

DOI:10.1002/jrs.1250180211

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY