摘要:

Chemisorption and conformation of 10-mercapto-l-decanol and Cefazolin sodium on chemically reduced silver film have been observed by Fourier transform Surface Enhanced Raman Scattering spectroscopy (FT-SERS). These compounds can easily be chemisorbed on silver film by the cleavage of S-H or nitrogen and sulfur coordination to form self-assembled monolayers.

ISSN:0038-7010    

DOI:10.1080/00387019708006749

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

New 2′-hydroxychalcone and flavone derivatives have been synthesised. Their [1H] and [13C] NMR spectra were assigned by the application of COSY and HETCOR experiments and allowed the discussion of some structural aspects. It was shown on the basis of NOE experiments some configurational and conformational features of both type of compounds.

ISSN:0038-7010    

DOI:10.1080/00387019708006750

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The 200 MHz1H NMR spectra of the analgesic, antipyrine, 1, have been studied in CDC13solution at ambient temperatures with the achiral lanthanide shift reagent (LSR) tris (6, 6, 7, 7, 8, 8, 8-heptafluoro-2, 2-dimethyl-3, 5-octanedionato) europium (III), Eu(FOD)3,2, and with the chiral LSR, tris[3-(heptafluoropropylhydroxymethylene)-(+)-camphorato]europium(III), Eu(HFC)3, 3., Lanthanide-induced shift (LIS) magnitudes and broadening of selected signals are consistent with predominant LSR binding at the carbonyl oxygen with either2or3.Of the different possible conformational regimes for the N-phenyl group of1, our results appear to rule out a slow exchange limit (SEL) system with the N-phenyl coplanar with the heterocyclic ring. Perpendicular rings in an SEL regime can not be ruled out. A rapidly-rotating N-phenyl (fast exchange limit, FEL system) would also be consistent with observed results. Accurate chemical shifts for the aryl protons (overlapped in the 200 MHz spectrum of unshifted1) are determined from spectra with added LSR by extrapolation to zero molar ratios of [LSR]:[1]. Relative slopes in the plots of chemical shift versus [LSR]:[1] molar ratios are calculated for each proton signal of1.

ISSN:0038-7010    

DOI:10.1080/00387019708006751

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A potentially useful simple method is proposed to determine whether theN-phenyl rings in the analgesic drug, antipyrine (and analogs), preferentially exist in a conformation which is approximately coplanar with, or is perpendicular to, the five-membered heterocyclic rings. The method is based on the magnitude of “spectral dispersion,” that is, the degree of NMR chemical shift differences for the proton and the protonated carbon signals of theN-phenyl. A narrow range of chemical shifts is considered suggestive of a preferred perpendicular conformation, which reduces mesomeric effects of conjugation and minimizes steric hindrance with nearby groups. Representative chemical shift data for model compounds are presented.

ISSN:0038-7010    

DOI:10.1080/00387019708006752

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Quality control of pharmaceutical aspirin powder was studied using first order differential near-infrared diffuse reflectance spectra and four standard multivariate methods, hierarchical clustering analysis, stepwise clustering analysis, principal components analysis, and stepwise discrimination. The qualified, inferior, and fake pharmaceutical aspirin powders of independent samples can be distinguished by the multivariate analysis methods based on the reflectance spectra. The proposed methods are reliable, fast and nondestructive.

ISSN:0038-7010    

DOI:10.1080/00387019708006753

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

4-Methyl-1, 2, 4-triazoline-3, 5-dione was produced by lead tetraacetate oxidation of 4-methylurazole and allowed to react with phencyclone,1-The resulting Diels-Alder adduct,2, has been characterized by one-and two-dimensional1H and13C NMR at 300 and 75 MHz, respectively, at ambient temperatures in different solvents. The NMR data are consistent with hindered rotation of the bridgehead unsubstituted phenyl groups about the C(sp2)-C(sp3) bonds, based on numbers of absorption signals in the1H and13C NMR aryl region, together with magnetic anisotropic effects in the1H spectrum. The spectral simplicity suggests further that stereochemistry at the ring junction nitrogens involves only a single isomer or very rapidly interconverting “exo”/“endo” isomers (if the ring junction nitrogens are pyramidalized).

ISSN:0038-7010    

DOI:10.1080/00387019708006754

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The samples from Permian period in east China were investigated by Mössbauer spectroscopy, X-ray powder diffraction and TGA-DTA methods. According to the different valence states of the iron in samples, the divisions of the Permian may also be separated by such methods at first report. The result shows a new approach for the studies in Permian.

ISSN:0038-7010    

DOI:10.1080/00387019708006755

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor