Solution State 19F Magnetic Resonance (MR) Account of Molecular Interactions in Solutions.

Abstract

The Thesis aims to explore the potential of ligand-based one dimensional (1D) 19F NMR methods (with 1H, 2H NMR and ODNP: Overhauser Dynamic Nuclear Polarization whenever required) to provide the qualitative and quantitative description of molecular interactions in solutions, for a selected (a) Ligand-Protein (b) Agrochemicals-Humic Acid and (c) Solute-Solvent type fluorinated systems in in vitro fashion. The Thesis illustrates the application of 19F transverse relaxation and diffusion analysis unravelling interaction of organofluorines with (a) serum and digestive proteins, (b) humic acid (HA). Extraction of exchange rate between the free and bound state of the organofluorine is accomplished through 19F constant time fast pulsing CPMG experiments allowing determination of the lifetime of the complex. 19F diffusion measurements are found to be more reliable leading to easier interpretation of kinetic parameters using suitable binding isotherms. 19F-1H and 1H-1H Saturation Transfer Difference measurements enabled prediction of the binding mode. 19F spectral analysis in addition to 1H NMR highlighted the influence of HA on photo-degradation of a fluorinated agrochemical. Further a successful attempt is made to establish a new approach to investigate the trifluoroethanol solvation dynamics inducing structural transition of melittin employing a combination of solvent detected low field 19F relaxation and 19F ODNP. A direct determination of molecular correlation times from low field 19F longitudinal relaxation simplifies the analysis. Further, the preferential solvation of carbohydrates is also investigated in TFE: D2O cosolvent mixture to benchmark the high field 2H and low field 19F NMR relaxation measurements for investigating such processes.