Computational study of nuclear magnetic resonance shielding constants

• Autores: Abril Carolina Castro Aguilera
• Directores de la Tesis: Marcel Swart (dir. tes.)
• Lectura: En la Universitat de Girona ( España ) en 2017
• Idioma: español
• Tribunal Calificador de la Tesis: David J. Tozer (presid.), Leonardo Belpassi (secret.), Jordi Poater Teixidor (voc.)
• Materias:
  • Física
    • Química física
  • Química
    • Química analítica
      • Espectroscopia de resonancia magnética
• Enlaces
  • Tesis en acceso abierto en: TDX
• Resumen

  • Nuclear Magnetic Resonance (NMR) spectroscopy is an indispensable structural tool in the modern analytical arsenal of chemists and structural biologists. Certainly, the synergy between computational and experimental methods in NMR spectroscopy is a powerful approach since it allows to combine the experimental precision with the predictive and explanatory power of theoretical methods, yielding new insight unachievable by the experimental or theoretical approaches alone. However, despite the advances attained in theoretical chemistry methods, the accuracy with which the NMR shift constants can be obtained depends on several factors and a protocol for these calculations is not always well established and understood.

    The present thesis is a computational study of the NMR shift constants in a number of chemical systems of interest, using both static and dynamic approaches via Density Functional Theory, to predict, confirm the presence of transient species, and/or explain ambiguous signals in the NMR spectra. Special attention was put on cases where there are strong interactions between the solvent and the molecule studied. The most accurate calculations of this type involve the use of molecular dynamics simulations to provide typical solvent configurations in an atomistic and dynamic detail, and it can be combined with quantum mechanical calculations to determine the NMR chemical shifts in liquid state conditions.

    In addition, this thesis addresses other methodological issues that influence the quality of the calculated NMR chemical shifts such as the level of theory, the explicit inclusion of solvent molecules, the choice of the reference molecule, as well as the relativistic effects for heavy element compounds.