摘要:

High resolution proton and carbon-13 NMR spectra of 2-alkyl thio-; 2-alkyl sulfinyl, and 2-alkyl sulfonyl-5-phenyl-1, 3,4-thiadiazoles were analysed. The chirality of the sulfoxide group induced proehiralty at the oα-methylene or β-methylene carbon atom. Further more the S-oxidation and dioxidation effects on the carbon-13 chemical shifts were summarised.

ISSN:0038-7010    

DOI:10.1080/00387018808082351

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The shape changes observed in the fluorescence spectra of chlorophylladissolved in polar solvents when the solute concentration is increased from 10−6to 10−4mol dm −3are shown to be due to reabsorption of the emitted light by the solute. Furthermore a reported anomaly of the concentration dependence of the fluorescence of chlorophyll a in diethyl ether below about 10−1010 mol dm −3is shown to be the consequence of the presence of impurities in the solvent used.

ISSN:0038-7010    

DOI:10.1080/00387018808082352

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The trinuclear [Ru30(00CCH3)6, (pyrazine)3] cluster reacts with pentaammineruthenium(II) ions, yielding a hexanuclear pyrazine bridged complex. The hexanuclear cluster exhibits a broad absorption band around 1000 nm and a strong band at 533 nm, ascribed to metal-metal and metal-pyrazine charge transfer transitions, respectively. Excitation at the visible band leads to the enhancement of the totally symmetric vibrational modes of pyrazine at 1605, 1230, 1085 and 700 cm−1, and of a vibrational peak at 335 cm−1, ascribed to the Ru(peripheral)-N(pyrazine) stretching mode. The spectroscopic data are consistent with a weak coupling between the central and peripheral ruthenium ions.

ISSN:0038-7010    

DOI:10.1080/00387018808082353

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A comparative analysis of theoretical and experimental rotational diffusion constants was performed for a series of liquid phase prolate symmetric top molecules. It was observed that the tumbling diffusion constants, D⊥, predicted by the extended Hynes-Kapral Weinberg (HKW) model were invariably in closer agreement with experiment than were values determined by the Hu-Zwanzig (HZ) slip model of molecular reorientation. The HKW theory also yielded superior estimates of D‖ for two -CCI3rotors. However, the experimental spinning diffusion coefficients for methyl (-CD3) rotors were much closer to the slip (Free Rotor) limit.

ISSN:0038-7010    

DOI:10.1080/00387018808082354

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The structure elucidation of a new flavone, 5,6,4′-trihydroxy-7,8,3′-trimethoxyflavone, was performed by the use of Insensitive Nuc1ei Assigned by Polarization Transfer (INAPT), a simple and sensitive NMR technique. Application of INAPT allowed the unambiguous identification of the new flavonoid. The use of this powerful method as a general tool for structure elucidations of flavonoids will be discussed.

ISSN:0038-7010    

DOI:10.1080/00387018808082355

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

We have explored the basic theory and quantitative methods for the measurement of motorcycle exhaust using a Fourier transform infrared interferometer system. Remote sensing direct measurements were made and the species carbon monoxide, carbon dioxide, nonmethane paraffinic carbon(CHx) and unburned additional harmful species in motorcycle exhaust were determined. Typical concentrations observed in absorption for carbon monoxide, carbon dioxide and nonmethane paraffinic carbon were about 1.11%, 1.91%, 0.54% respectively. Furthemore, this paper describes the remote sensing Fourier transform infrared spectrometer system. The system covers the infrared spectral region from 700 to 6000 cin−1at a maxim resolution of 0.06 cm−1for beamsplitter of gerrniuiirun coated zinc selenide and receiver telescope with zinc selriide leis. For air multipollutant monitoring the analytica1 methods have the potential and become important. The remote measurements usirig the Fourier transform inf raid spectroscopy could become niore practical.

ISSN:0038-7010    

DOI:10.1080/00387018808082356

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A1H NMR spectroscopic determination for acetate and lactate in intravenous and haemodialysis solutions is reported. The methyl resonances of acetate and lactate were chosen for integration using N-methylurea and sodium acetate, respectively, as internal standards. The results obtained indicate that the quantitative measurements are reproducible. The method provides also a specific identification of the analytes.

ISSN:0038-7010    

DOI:10.1080/00387018808082357

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The quantitative determination of the analgesic anti-inflammatory compound, 4- (anisylideneamino) antipyrine, in authentic samples, I, and capsules, II, was achieved by an accurate and reproducible analytical procedure using the PMR spectroscopy. A sensitive colorimetric method was also developed based on the azo formation using barbituric acid. The azo derivative was synthesized and identified. Experimental conditions were carefully studied. The PMR proposed method has proved to be advantageous being rapid and of a simpler manipulating technique; it helps identify the active ingredient and check its purity.

ISSN:0038-7010    

DOI:10.1080/00387018808082358

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Lead Titanate (FT) materials were prepared by a sol-gel process in an air atmosphere using lead acetate and titanium propoxide in methoxyethanol as the precursor materials. FTIR and Raman spectroscopy were used to characterize the various structural changes that occurred during various stages of the preparation. A new crystalline lead titanate phase was detected by both Raman spectral and X-ray diffraction techniques when heating the gelled material at 430°C. In-situ Raman spectra were measured at high temperatures for the resulting sol-gel prepared PT material to investigate its phase-transition and soft-mode behavior.

ISSN:0038-7010    

DOI:10.1080/00387018808082359

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

An influence of the protic solvents on the electronic absorption spectra of chromium (III) complexes was investigated. The high correlation between dielectric constant of solvents and the crystal field parameter Dq as well as between refractive index and oscillator strength of d-d bands were observed. The significance of the ligand - second sphere interactions for studying of solvent effect on complex spectra was stated.

ISSN:0038-7010    

DOI:10.1080/00387018808082360

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor