Journal of the Chemical Society, Dalton Transactions, 1987
Page 1. J. CHEM. SOC. DALTON TRANS. 1987 795 Menthyl-substituted Organophosphorus Compounds. Part... more Page 1. J. CHEM. SOC. DALTON TRANS. 1987 795 Menthyl-substituted Organophosphorus Compounds. Part 6.' Preparation of P(L-men)RCI and P(L-men)R(S)CI (R = Me, Et, Pr', But, or Ph; men = cyc/oC,H,- 2-Pr'-5-Me) and ...
ABSTRACT The thermodynamic theory of cross-polarization (CP) between one abundant and one rare sp... more ABSTRACT The thermodynamic theory of cross-polarization (CP) between one abundant and one rare spin is well understood and widely applied. CP dynamics between several abundant spin baths has some inherent complications that lead to misinterpretation of the CP rates and relaxation parameters if not properly accounted for. A general thermodynamic description of CP dynamics involving up to six spin baths is developed and implemented with MATLAB. The CP dynamics for a fluorinated polymer, (2-perfluorohexylethyl acrylate)–styrene co-polymer, was analysed as a system with five spin baths—four 19F and one 1H. The CP behaviour was successfully simulated above the glass-transition temperature. The CP rates and T1ρ's are discussed in terms of the structure and dynamic behaviour of the polymer.
The title compound has been synthesised, and characterised by multinuclear magnetic resonance spe... more The title compound has been synthesised, and characterised by multinuclear magnetic resonance spectroscopy, both in solution and in the solid state. The bandshapes of variable-temperature solution-state 19 F NMR spectra have been iteratively fitted to obtain information on the ...
The 1 H, 13 C and 19 F magic-angle spinning NMR spectra have been recorded for Form 1 of flurbipr... more The 1 H, 13 C and 19 F magic-angle spinning NMR spectra have been recorded for Form 1 of flurbiprofen. In the case of 19 F, spinning sideband analysis has produced data for the components of the shielding tensor. The chemical shift of the hydrogen-bonded proton was found to be 14.0 ppm. Shielding parameters for all three nuclei have been calculated using Density Functional Theory (DFT) together with the Gauge Including Projector Augmented Wave (GIPAW) method which takes full allowance for the repetition inherent in crystalline structures. Such computations were made for the reported geometry, for a structure with all the atomic positions relaxed using DFT, and with only the hydrogen positions relaxed. The relationships of the computed shifts to those observed are discussed. In general, the correlations are good.
In order to check the efficiency of high-power decoupling when used with the two-dimensional mult... more In order to check the efficiency of high-power decoupling when used with the two-dimensional multiple-quantum MAS method recently proposed to obtain isotropic spectra from quadrupolar nuclei, we applied this new technique to NMR for a hydrous layered silicate compound, makatite, with and without decoupling. A remarkable improvement of the spectral resolution in the isotropic dimension was observed by the decoupling, showing that it is effective in the 2D MQ-MAS method and suggesting that proton decoupling should be generally applied in experiments concerning these kinds of compound.
Simulations have been carried out on z-magnetizations produced by (and hence of the resulting spe... more Simulations have been carried out on z-magnetizations produced by (and hence of the resulting spectra from) the dipolar filter (DF) and the recently suggested "Discrimination Induced by Variable-Amplitude Minipulses" (DIVAM) pulse sequences [S. Ando et al., Polymer 42 (2001) 8137; Magn. Reson. Chem. 40 (2002) 97]. The strengths of dipolar interactions have been modelled by introducing different values for transverse relaxation times. The DF case has been extended by allowing the pulse angles to be smaller than 90 degrees. The pulse intervals have also been used as variables. For the DIVAM case, the variables are similarly the minipulse nutation angles and minipulse intervals. The computations show that DIVAM is superior to DF in terms of selectivity for spectra of heterogeneous materials such as semi-crystalline polymers. The effects of the pulse sequences on 19F spectra of poly(vinylidene fluoride) (PVDF) and of a copolymer of vinylidene fluoride and trifluoroethylene (p(VDF/TrFE)) are presented, together with fits of the experimental results by the simulations.
Journal of the Chemical Society, Dalton Transactions, 1987
Page 1. J. CHEM. SOC. DALTON TRANS. 1987 795 Menthyl-substituted Organophosphorus Compounds. Part... more Page 1. J. CHEM. SOC. DALTON TRANS. 1987 795 Menthyl-substituted Organophosphorus Compounds. Part 6.' Preparation of P(L-men)RCI and P(L-men)R(S)CI (R = Me, Et, Pr', But, or Ph; men = cyc/oC,H,- 2-Pr'-5-Me) and ...
ABSTRACT The thermodynamic theory of cross-polarization (CP) between one abundant and one rare sp... more ABSTRACT The thermodynamic theory of cross-polarization (CP) between one abundant and one rare spin is well understood and widely applied. CP dynamics between several abundant spin baths has some inherent complications that lead to misinterpretation of the CP rates and relaxation parameters if not properly accounted for. A general thermodynamic description of CP dynamics involving up to six spin baths is developed and implemented with MATLAB. The CP dynamics for a fluorinated polymer, (2-perfluorohexylethyl acrylate)–styrene co-polymer, was analysed as a system with five spin baths—four 19F and one 1H. The CP behaviour was successfully simulated above the glass-transition temperature. The CP rates and T1ρ's are discussed in terms of the structure and dynamic behaviour of the polymer.
The title compound has been synthesised, and characterised by multinuclear magnetic resonance spe... more The title compound has been synthesised, and characterised by multinuclear magnetic resonance spectroscopy, both in solution and in the solid state. The bandshapes of variable-temperature solution-state 19 F NMR spectra have been iteratively fitted to obtain information on the ...
The 1 H, 13 C and 19 F magic-angle spinning NMR spectra have been recorded for Form 1 of flurbipr... more The 1 H, 13 C and 19 F magic-angle spinning NMR spectra have been recorded for Form 1 of flurbiprofen. In the case of 19 F, spinning sideband analysis has produced data for the components of the shielding tensor. The chemical shift of the hydrogen-bonded proton was found to be 14.0 ppm. Shielding parameters for all three nuclei have been calculated using Density Functional Theory (DFT) together with the Gauge Including Projector Augmented Wave (GIPAW) method which takes full allowance for the repetition inherent in crystalline structures. Such computations were made for the reported geometry, for a structure with all the atomic positions relaxed using DFT, and with only the hydrogen positions relaxed. The relationships of the computed shifts to those observed are discussed. In general, the correlations are good.
In order to check the efficiency of high-power decoupling when used with the two-dimensional mult... more In order to check the efficiency of high-power decoupling when used with the two-dimensional multiple-quantum MAS method recently proposed to obtain isotropic spectra from quadrupolar nuclei, we applied this new technique to NMR for a hydrous layered silicate compound, makatite, with and without decoupling. A remarkable improvement of the spectral resolution in the isotropic dimension was observed by the decoupling, showing that it is effective in the 2D MQ-MAS method and suggesting that proton decoupling should be generally applied in experiments concerning these kinds of compound.
Simulations have been carried out on z-magnetizations produced by (and hence of the resulting spe... more Simulations have been carried out on z-magnetizations produced by (and hence of the resulting spectra from) the dipolar filter (DF) and the recently suggested "Discrimination Induced by Variable-Amplitude Minipulses" (DIVAM) pulse sequences [S. Ando et al., Polymer 42 (2001) 8137; Magn. Reson. Chem. 40 (2002) 97]. The strengths of dipolar interactions have been modelled by introducing different values for transverse relaxation times. The DF case has been extended by allowing the pulse angles to be smaller than 90 degrees. The pulse intervals have also been used as variables. For the DIVAM case, the variables are similarly the minipulse nutation angles and minipulse intervals. The computations show that DIVAM is superior to DF in terms of selectivity for spectra of heterogeneous materials such as semi-crystalline polymers. The effects of the pulse sequences on 19F spectra of poly(vinylidene fluoride) (PVDF) and of a copolymer of vinylidene fluoride and trifluoroethylene (p(VDF/TrFE)) are presented, together with fits of the experimental results by the simulations.
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