Interactive computer system for the simulation of carbon-13 nuclear magnetic resonance spectra

Small, Gary W.; Jurs, Peter C.

doi:10.1021/ac00258a033

Cited by 48 publications

(36 citation statements)

References 39 publications

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“…No hydrogens were attached to the structures at this time. Other routine, but essential, tasks such as perception of structurally unique carbons, storage of computed models, etc., were performed by use of a set of interactive software tools developed by Small and Jurs (15). Assembly of Data for Modeling.…”

Section: Resultsmentioning

confidence: 99%

Structure elucidation methodology for disaccharides based on carbon-13 nuclear magnetic resonance spectrum simulation

Small¹,

McIntyre²

1989

Anal. Chem.

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Molecular mechanics techniques are used to derive structural parameters that allow carbon-13 nuclear magnetic resonance spectra of disaccharides to be modeled. On the basis of a collection of 40 disaccharide spectra, four linear models are derived that allow complete spectra to be simulated. On the basis of these 40 compounds, the average difference between simulated and observed chemical shifts is +/- 0.45 ppm. The majority of structural parameters used are based on interatomic distances computed from modeled three-dimensional atomic coordinates. Found particularly useful in modeling the disaccharide spectra are the effects of oxygen electron lone pairs and encodings of the structural environments of hydrogens alpha to the carbon whose chemical shift is being predicted. The computed models are examined, and their predictive ability is assessed. The potential application of the methodology to the structure elucidation of disaccharides is demonstrated.

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Section: Resultsmentioning

confidence: 99%

Structure elucidation methodology for disaccharides based on carbon-13 nuclear magnetic resonance spectrum simulation

Small¹,

McIntyre²

1989

Anal. Chem.

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“…The chemical shift models used in generating simulated spectra for comparison with the retrieved chemical shifts were computed by use of a set of software tools developed by Small and Jurs. 23 The MM2(87) molecular mechanics software used in computing threedimensional coordinates for the structures was obtained from the Quantum Chemistry Program Exchange (Department of Chemistry, Indiana University, Bloomington, IN) and was implemented without modification to the force-field parameters.…”

Section: Methodsmentioning

confidence: 99%

Database retrieval techniques for carbon-13 nuclear magnetic resonance spectrum simulation

Small¹

1992

J. Chem. Inf. Comput. Sci.

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“…Subjected to the NMR analysis, a total of 43 resonances with 17 methyl, 17 methylene, 7 methine, and 2 quarternary carbons were observed. A total of 14 compounds were assigned, encompassing T a b l e V. Identification and Q u a n t i t a t i v e A n a l y s i s of P e t r o l e u m F r a c t i o n s I and I 1 by U s i n g S i m u l a t e d Library 11. A total of 20 chromatographic peaks were observed of which 12 major peaks yielded matches of mass spectral search results in the first or second search position that agreed with NMR results.…”

Section: I1 I11mentioning

confidence: 99%

Identification of organic mixture components without separation: quantitative and edited carbon-13 nuclear magnetic resonance spectrometry data for analysis of petroleum distillates

Laude¹,

Wilkins²

1986

Anal. Chem.

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A new method for the analysls of unknown mlxtures whlch Incorporates unlque features of quantitative and edlted ''C nuclear magnetic resonance (NMR) spectra Is descrlbed. Chromatographic separalbn and subsequent ldentlflcatbn by match with a spectroscopic data base spectrum Is not required for quantltative analysts of mixture components. Instead, equlvalent Informath Is obtalned by creating subspectra from resonances with equlvalent peak areas wlthln a quantitative NMR spectrum. IdentHbaUon Is accompRshed by comparison of edited spectra with mu#ipric#y data derlved dlrectly from the chemical structure of potentlal components. Analysis of petroleum drstWlates wlthhr the class of low bofflng (C,-C,) hydrocarbon compounds is Considered here. A 207-component library Is created and utilized In the analysls of two fractlons for which 7 and 14 compounds are successfully identlfied.In general, analysis of organic mixtures is a two-step procedure requiring isolation of mixture components followed by identification of the pure materials. Computer-assisted methods employing chromatographic separation, followed by detection using infrared or mass spectrometers, which provide information-rich spectra for library searches of spectral data bases, are common. However, gas chromatography/mass spectrometry (GC/MS) and gas chromatography/infrared spectrometry (GC/IR), which are among the more successful implentations, suffer from a number of shortcomings. GC separation is not always possible because of sample nonvolatility or lack of sufficient chromatographic selectivity. Furthermore, present spectral libraries are incomplete and often contain spectra obtained under nonstandard conditions. In this paper an alternate approach to mixture analysis, incorporating unique features of 13C nuclear magnetic resonance (NMR) spectrometry to eliminate the need for chromatographic separation and library data bases, is described. Instead, individual components are "separated" within a quantitative 13C NMR spectrum of the mixture and identified by comparison of quantitative and multiplicity-containing 13C NMR data with a library of "predicted" NMR spectra, derived solely from chemical structure. Initial studies of the method as applied to the analysis of petroleum distillates were successful; a total of 7 and 14 components were unambiguously identified for two low-boiling fractions.The separation of components by 13C NMR is dependent upon the equivalent response achieved for all carbon nuclei under quantitative NMR conditions. Under these conditions, peak areas for all resonances within a molecule must equal some integer multiple of the area corresponding to a single nucleus. The minimum number of components in a mixture then quickly can be determined from the quantitative spectrum by counting the number of peak subsets with dissimilar peak intensities. The reliability of such a procedure is dependent upon the accuracy of peak integration and minimization of peak overlap. The contributions to integration error from both spectral and data process...

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Interactive computer system for the simulation of carbon-13 nuclear magnetic resonance spectra

Cited by 48 publications

References 39 publications

Structure elucidation methodology for disaccharides based on carbon-13 nuclear magnetic resonance spectrum simulation

Structure elucidation methodology for disaccharides based on carbon-13 nuclear magnetic resonance spectrum simulation

Database retrieval techniques for carbon-13 nuclear magnetic resonance spectrum simulation

Identification of organic mixture components without separation: quantitative and edited carbon-13 nuclear magnetic resonance spectrometry data for analysis of petroleum distillates

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