Study of solute-solvent interactions with vibrational CD spectroscopy and DFT calculations

• Author / Creator

  POOPARI, MOHAMMAD REZA

• My PhD thesis work is centered on developing a suitable approach to
  account for solvent effects in solution spectroscopic measurements and on
  providing significant insights into the intermolecular interactions between chiral
  solute and solvent, in particular water, molecules. Vibrational absorption (VA)
  and vibrational circular dichroism (VCD) spectroscopic techniques have been
  used as the main experimental tools to study conformational distributions and
  most importantly solute-solvent interactions of a number of prototype chiral
  molecules in several common solvents. The spectral window from 800 cm-1 to
  1800 cm-1 was used for data acquisition. Aqueous solutions, both normal and
  deuterated water, and organic solvents such as methanol, dimethyl sulfoxide, and
  chloroform were used. Complementary optical rotatory dispersion measurements
  have also been carried out. Density functional theory has been employed to
  perform all calculations for conformational searches, geometry optimizations,
  VA, VCD, UV, and ECD intensities, and spectral simulations. To account for
  effects of water solvent, a clusters-in-a-liquid approach has been proposed.
  Molecular dynamics simulations and radial distribution function calculations have
  also been carried out to identify the representative hydration clusters, i.e. chiral
  solute-(water)N. Initial conformational analyses have been done using small basis
  set like 6-31G(d), which is a compromise between accuracy and computational
  cost. For final calculations, several larger basis set like 6-31++G(d,p), 6-
  311++G(d,p), cc-pVTZ, and aug-cc-pVTZ, have been used and the specific
  choices depend on the size and complexity of systems under the investigation. Geometries of the molecular systems of interest have been evaluated in the gas
  phase and in bulk solvent using the implicit solvation polarization continuum
  model, while the related geometries of the explicit hydration clusters of the
  targeted chiral molecules have been similarly evaluated. My thesis work shows
  that inclusion of both explicit and implicit solvent effects simultaneously is
  essential to interpret the experimental VA and VCD spectra whenever strong
  hydrogen-bonding interactions are expected between chiral solute and solvent
  molecules. When no strong solvent–solute hydrogen-bonding interactions are
  expected, it was found that the gas phase monomer model is adequate but not
  optimal for spectral interpretations and the inclusion of the implicit bulk water
  environment is highly recommended.

• Subjects / Keywords

  • Density Functional Theory
  • Implicit and explicit solvent models
  • Solute-solvent interactions
  • Vibrational Circular Dichroism

• Graduation date

  Spring 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3W950W8F

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.