摘要:

AbstractThe infrared (3500–50 cm−1) and Raman spectra (3500‐10 cm−1) have been recorded for cyclopropyldimethylborane in both the gaseous and solid states. Additionally, the Raman spectrum of the liquid was recorded and qualitative depolarization values were obtained. Only one conformation has been found in all three physical states and, on the basis of the polarized nature of the Raman band assigned as the BC2antisymmetric stretch, this conformer is identified as being the bisected structure withCsmolecular symmetry. A complete vibrational assignment, except for the BC2and two methyl torsional modes, is proposed based on the depolarization data, infrared gas phase band contours, and group frequencies. These results are compared to the corresponding data for several other organo

ISSN:0377-0486    

DOI:10.1002/jrs.1250120204

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe sensitivity of the bandwidths of the 2103 cm−1symmetric methylene CD2stretching modes to lateral chain‐chain interactions and to intrachain rotamer formation is demonstrated for membrane bilayer systems composed of deuterated phospholipids. Temperature profiles, constructed from three separate linewidth parameters, illustrate the effects of bilayer rearrangements both in pure DMPC‐d54liposomes and in DMPC‐d54multilayers containing melittin in a lipid:polypeptide mole ratio of 14:1. Evidence is presented for a class of immobilized deuterated boundary lipids surrounding the poly

ISSN:0377-0486    

DOI:10.1002/jrs.1250120205

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractEach of the hypoxauthine residues of the dinucleoside monophosphate, inosylyl(3′→5′)inosine (IpI), manifests the same rate of deuterium exchange of the proton at the 8‐C ring position, as measured by Raman spectrophotometry. In the temperature interval 30–80°C and at neutral pD, the exchange rate constants yield Arrhenius parameters (Ea= 22.4±0.6 kcal mol−1;A= 2.13 × 1013h−1) that are identical to values obtained on inosine‐3′:5′‐monophosphate (cIMP), but different from those of inosine‐5′‐monophosphate (5′‐IMP) which exchanges more slowly. The results confirm that nucleotides containing the monovalent phosphate anion, exchange more rapidly than those containing the divalent phosphate anion, and suggest further that base stacking in IpI does not greatly retard the speed of 8‐CH exchange

ISSN:0377-0486    

DOI:10.1002/jrs.1250120206

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractResonance Raman spectra of photo‐activated transient blue species of 2‐(2′,4′‐dinitrobenzyl)pyridine and 4‐(2′,4′‐dinitrobenzyl)pyridine have been measured in methanol solutions using a dual beam pump/probe laser technique and a continuous flow method. Comparison of the Raman spectra with those of N‐methyl derivatives of both compounds and with those of 1‐methyl‐2‐pyridonemethide and dehydrogenated 5‐nitro‐o‐toluic acid indicates that the transient blue species of both compounds take an NH quinoid form and not an aci‐nitro form. The photo‐activated blue species of 4‐(2′,4′‐dinitrobenzyl)pyridine in the molten state is found to be identical with the trans

ISSN:0377-0486    

DOI:10.1002/jrs.1250120207

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractA method is described for preparing oriented monodomains of phospholipids multilayers from which polarized Raman spectra can be obtained. Typical polarized Raman spectra are shown and the band intensity changes are briefly discussed.

ISSN:0377-0486    

DOI:10.1002/jrs.1250120208

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractWe have obtained the spectrum of β‐poly(L‐alanine‐ND), and find three bands in the ND stretching region. By comparison with Fermi resonance analyses of deuterated derivatives of polyglycine I as well as with α‐poly(L‐alanine‐ND), we conclude that a three‐level Fermi resonance is involved in the β polypeptide, and that the unperturbed ND stretch fundamental occur

ISSN:0377-0486    

DOI:10.1002/jrs.1250120209

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractN‐methylacetamide dissolved in1H2O was rapidly mixed with2H2O by the use of a stopped‐flow device, and Raman spectra of the mixed solution were observed at various times in the course of the deuteration reaction by the use of a multi‐detector system. With continuous wave excitation (Ar+laser), the time‐resolution reached by our present setup was about 50 ms. The molecular association ofN‐methylacetamide in H2O was found to cause a low‐frequency shift of the amide III Raman band at 1317 cm−1by 9 cm−1. The effect of this association upon the deuteration rate, however, was not found to be appreciable. At 25°C, the rate constants were determined to be 0.067, 0.14, 0.20, 0.41, and 0.63 s−1at pH = 6.43, 6.87, 7.15, 7.39, and

ISSN:0377-0486    

DOI:10.1002/jrs.1250120210

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractRaman and infrared spectra have been measured for CH3O(CH2)nOCH3(n= 3–5), as model compounds of polyethers [O(CH2)n]m, in the liquid and crystalline solid states. The spectra were analysed on the basis of a normal coordinate treatment. The CH2O stretching vibration is sensitive to the conformation about the CC bond next to the CO bond. The molecular conformations of the model compounds in the crystalline solid state aretrans‐gauche‐gauche‐transforn= 3 and all‐transforn= 4 and 5. These conformations coincide with the chain conformations of the polymers in the most stable crystal modification. For the model compounds in the liquid state, thegaucheconformation about the CC bond next to the CO bond is more stable th

ISSN:0377-0486    

DOI:10.1002/jrs.1250120211

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe Raman spectra of L‐histidine, L‐histidine‐13C (labelled at C2of the imidazole ring) and related compounds, namely, imidazole, 4‐methylimidazole, N‐acetyl‐L‐histidine methylamide, were observed in H2O and D2O solutions at various pH and pD values. A strong Raman band at around 1410 cm−1was found for these compounds in acidic D2O solutions, and it was assigned to a mode characteristic of the N‐deuterated imidazolium ring (Im+) in which the N1C2N3symmetric stretching and ND bending vibrations are mixed. It is concluded that this band would be useful as a probe for studying the ionization states of histidi

ISSN:0377-0486    

DOI:10.1002/jrs.1250120212

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe polarized Raman spectra in the region 0–400 cm−1of oriented single crystals of La2(SO4)3.9H2O and La2(SO4)3. 9D2O have been recorded between 14 and 297 K. The behaviour of the external modes is analysed in order to elucidate the role of the hydrogen‐bonds and the lanthanum‐oxygen interactions in the order‐disorder transition observed at approximately 170 K. Large changes in the shape and intensities of the external bands with temperature (not detected in the region of internal vibration of the spectrum) have been

ISSN:0377-0486    

DOI:10.1002/jrs.1250120213

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY