Computational and experimental studies using absorption spectroscopy and vibrational circular dichroism.

摘要

Chapter one provides an introduction to the general area of study and the general basis for the research to be performed. It concludes with a brief mathematical description of the computational equations used to calculate and measure vibrational circular dichroism (VCD).; Chapter two evaluates four chemically related compounds and provides detailed analyses of the vibrational spectra obtained by performing a combination of experimental and theoretical chemical techniques.; For all compounds, a detailed thermodynamic analysis was performed. Enthalpies, entropies and free energy were derived and compared. It is concluded, both MP2 and DFT/B3LYP yield a good description of the vibrational modes and thermodynamics for the compounds researched.; For chapter three, a detailed analysis of alpha-d-alanine, alpha-l-alanine, beta-l-mannose and alpha-l-mannose were performed using a combination of experimental and theoretical techniques.; Chapter four presents, the first time, VCD for several compounds. Five of the compounds have never before been synthesized. These compounds were measured to determine environmental effects at and around the chiral (stereo) center. It was determined for the first time that the electron influence on the chiral center can be recorded in the VCD. Results warranted the measurement of 25+ additional compounds in an effort to better understand observations from the initial measurements.; Experimental data supports the general conclusion "electron-donating groups intensify the VCD signal by forcing conjugation or electron cloud contribution towards the chiral center."; Finally, chapter five provides a general discussion on where to proceed with this research and provides other systems to consider, which are comparable to carbonyl systems. It is concluded, VCD can be applied to determine fundamental spectra characteristics. Systems considered for continued research are nitrogen oxides, phosphorus oxides, and sulfur oxides. (Abstract shortened by UMI.)