Curtis, J
1990
Computerized Analysis of 2D INADEQUATE Spectra
Dunkel, R.; Mayne, C.L.; Curtis, J.; Pugmire, R.J. and Grant, D.M.
Journal of Magnetic Resonance, 90, 290-302, 1990. Funded by ACERC and US Department of Energy.
The extraction of carbon-carbon bond information from two-dimensional INADEQUATE spectra is both time consuming and complex due to the low sensitivity of the method, the incomplete suppression of single-quantum signals, and the large size of the data sets. A computerized analysis technique is introduced which detects bonds through a nonlinear regression analysis of carefully chosen subsets of the spectral data. A quantitative one-dimensional carbon spectrum is used to establish initial values for the regression and to determine the data subsets to be used. Using statistical analysis techniques, bonds are detected with reliability and sensitivity comparable to those of careful manual interpretation.
1989
Distortion in Six-Membered Saturated Rings by Natural Abundance Deuterium NMR
Curtis, J.; Grant, D.M. and Pugmire, R.J.
J. Am. Chem. Soc., 111, 7711, 1989. Funded by National Institutes of Health.
Distortions in six-membered aliphatic ring systems were examined using deuterium chemical shifts and multiple linear regression analysis. A new set of regression parameters has been developed that successfully interprets not only spectra for those methylcyclohexanes with normal chair conformations but also spectra for cis- and trans-decalin and for three highly distorted trimethylcyclohexanes with skew-boat type distortions to their equilibrium conformations. The origin of deformations in the cyclohexane ring and the effect of distortions on ring hydrogen/deuterium chemical shifts are discussed in terms of gauche interactions between vicinal C-C and C-D bonds. The fits for 115 deuterium shifts in these cyclic alkanes exhibited a multiple R = 0.9816 and s = 0.0623 ppm for an overall shift range of about 1.5 ppm. As the 14 structural parameters obtained in this study are very sensitive to distortions and conformational features, the results indicate that ²H NMR methods should be very powerful in those cyclic paraffins in which highly second-order banding is observed in the corresponding H-1 NMR spectrum.
1988
Distortion in Six-Membered Saturated Rings by Natural Abundance Deuterium NMR
Curtis, J. and Grant, D.M.
Submitted to J. Am. Chem. Soc., 1988. Funded by US Department of Energy.
Distortions in six-membered aliphatic ring systems were examined using deuterium chemical shifts and multiple linear regression analysis. A new set of regression parameters has been developed which successfully interprets not only spectra for those methylcyclohexanes with normal chair conformations, but also spectra for cis- and trans-decalin and for three highly distorted trimethylcyclohexanes with skw boat type distortions to their equilibrium conformations. The origin of deformations in the cyclohexane ring and the effect of distortions on ring hydrogen/deuterium chemical shifts are discussed in terms of gauche interactions between vicinal C-C and C-D bonds. The fits for 115 deuterium shifts in these cyclic alkanes exhibited a multiple R-=0.9816 and s=0.0623 ppm for an overall shift range of about 1.5 PPM As the 14 structural parameters obtained in this study are very sensitive to distortions and conformational features, the results indicate that 2H NMR methods should be very powerful in those cyclic paraffins in which highly second-order banding is observed in the corresponding proton NMR spectrum.
Curtis, J
1990
Computerized Analysis of 2D INADEQUATE Spectra
Dunkel, R.; Mayne, C.L.; Curtis, J.; Pugmire, R.J. and Grant, D.M.
Journal of Magnetic Resonance, 90, 290-302, 1990. Funded by ACERC and US Department of Energy.
The extraction of carbon-carbon bond information from two-dimensional INADEQUATE spectra is both time consuming and complex due to the low sensitivity of the method, the incomplete suppression of single-quantum signals, and the large size of the data sets. A computerized analysis technique is introduced which detects bonds through a nonlinear regression analysis of carefully chosen subsets of the spectral data. A quantitative one-dimensional carbon spectrum is used to establish initial values for the regression and to determine the data subsets to be used. Using statistical analysis techniques, bonds are detected with reliability and sensitivity comparable to those of careful manual interpretation.
1989
Distortion in Six-Membered Saturated Rings by Natural Abundance Deuterium NMR
Curtis, J.; Grant, D.M. and Pugmire, R.J.
J. Am. Chem. Soc., 111, 7711, 1989. Funded by National Institutes of Health.
Distortions in six-membered aliphatic ring systems were examined using deuterium chemical shifts and multiple linear regression analysis. A new set of regression parameters has been developed that successfully interprets not only spectra for those methylcyclohexanes with normal chair conformations but also spectra for cis- and trans-decalin and for three highly distorted trimethylcyclohexanes with skew-boat type distortions to their equilibrium conformations. The origin of deformations in the cyclohexane ring and the effect of distortions on ring hydrogen/deuterium chemical shifts are discussed in terms of gauche interactions between vicinal C-C and C-D bonds. The fits for 115 deuterium shifts in these cyclic alkanes exhibited a multiple R = 0.9816 and s = 0.0623 ppm for an overall shift range of about 1.5 ppm. As the 14 structural parameters obtained in this study are very sensitive to distortions and conformational features, the results indicate that ²H NMR methods should be very powerful in those cyclic paraffins in which highly second-order banding is observed in the corresponding H-1 NMR spectrum.
1988
Distortion in Six-Membered Saturated Rings by Natural Abundance Deuterium NMR
Curtis, J. and Grant, D.M.
Submitted to J. Am. Chem. Soc., 1988. Funded by US Department of Energy.
Distortions in six-membered aliphatic ring systems were examined using deuterium chemical shifts and multiple linear regression analysis. A new set of regression parameters has been developed which successfully interprets not only spectra for those methylcyclohexanes with normal chair conformations, but also spectra for cis- and trans-decalin and for three highly distorted trimethylcyclohexanes with skw boat type distortions to their equilibrium conformations. The origin of deformations in the cyclohexane ring and the effect of distortions on ring hydrogen/deuterium chemical shifts are discussed in terms of gauche interactions between vicinal C-C and C-D bonds. The fits for 115 deuterium shifts in these cyclic alkanes exhibited a multiple R-=0.9816 and s=0.0623 ppm for an overall shift range of about 1.5 PPM As the 14 structural parameters obtained in this study are very sensitive to distortions and conformational features, the results indicate that 2H NMR methods should be very powerful in those cyclic paraffins in which highly second-order banding is observed in the corresponding proton NMR spectrum.