A two-dimensional Fluorine Detected Local Field (FDLF) NMR experiment is demonstrated on a sample of perfluoropropyl iodide dissolved in the nematic solvent ZLI1132. In analogy to the proton detected local field (PDLF) technique, for each resolved site of the carbon spectrum, a simple map of the heteronuclear coupling network is obtained in the indirect dimension. A full analysis of the FDLF spectrum was achieved with the aid of two-dimensional 19F–13C HETCOR and 13C, D-resolved spectra (with D representing the anisotropic spin–spin coupling). A one-dimensional 19F spectrum was recorded on the same sample at intermediate resolution, and values of the residual spin–spin couplings TCF and TFF obtained from both experiments were combined and used to provide starting parameters for the analysis of a very high resolution 19F spectrum, including the weak satellite lines from single-13C isotopomers. The high-precision, residual, anisotropic couplings were used to explore whether they have an appreciable contribution from the anisotropic electron-mediated spin–spin couplings.
A general strategy for obtaining 19F-19F and 13C-19F residual dipolar couplings in perfluorocarbons from the NMR spectroscopy of liquid crystalline samples
DE LUCA, Giuseppina;
2010-01-01
Abstract
A two-dimensional Fluorine Detected Local Field (FDLF) NMR experiment is demonstrated on a sample of perfluoropropyl iodide dissolved in the nematic solvent ZLI1132. In analogy to the proton detected local field (PDLF) technique, for each resolved site of the carbon spectrum, a simple map of the heteronuclear coupling network is obtained in the indirect dimension. A full analysis of the FDLF spectrum was achieved with the aid of two-dimensional 19F–13C HETCOR and 13C, D-resolved spectra (with D representing the anisotropic spin–spin coupling). A one-dimensional 19F spectrum was recorded on the same sample at intermediate resolution, and values of the residual spin–spin couplings TCF and TFF obtained from both experiments were combined and used to provide starting parameters for the analysis of a very high resolution 19F spectrum, including the weak satellite lines from single-13C isotopomers. The high-precision, residual, anisotropic couplings were used to explore whether they have an appreciable contribution from the anisotropic electron-mediated spin–spin couplings.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
