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Physical Chemistry Chemical Physics

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Phys. Chem. Chem. Phys., 2007, 9, 3098 - 3103, DOI: 10.1039/b700631d


Quantum chemistry-based NMR spin Hamiltonian parameters of GABA for quantitation in magnetic resonance spectroscopy

A. R. Allouche, M. Aubert-Frécon and D. Graveron-Demilly


Chemical shifts and spin–spin coupling constants J have been calculated using quantum chemistry approaches for the -amino butyric acid GABA which is a brain metabolite. Two theoretical methods HF and DFT/B3LYP, two basis sets 6-31G* and 6-311+G(2d,p) and two gauge-invariant methods CSGT and GIAO have been used. From and J values, NMR spectra have been obtained from the strongly coupled spin system Hamiltonian using the NMR-SCOPE package. Solvent effects have been considered within the polarisable continuum model. Comparisons between calculated and experimental NMR spectra at 300 MHz show that our best results correspond to the B3LYP/6-311+G(2d,p)-GIAO calculations. They are seen to be in good agreement with experiment. This demonstrates the usefulness of quantum chemistry methods for estimating NMR spin Hamiltonian parameters involved in specific algorithms used for quantitation of metabolites such as GABA.

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