Date of Award
Master of Science (MS)
Molecular Science and Nanotechnology
In the field of green chemistry, deep eutectic solvents (DES) have seen extensive use and research in the last two decades. Two carboxylic acid-choline chloride DESs were studied using experimental Fourier Transform Infrared Spectroscopy (FTIR) and computational Density Functional Theory (DFT). Geometry optimization, vibrational analysis, and assignment of vibrational frequencies were performed using B3LYP with a DNP basis set. The identified experimental FTIR peaks were found to be close to the calculated vibrations. Vibrations that would be impossible to identify and characterize using experimental methods were identified using DFT simulations. The shifts in wavenumber of FTIR vibrational peaks were studied to detect the presence of hydrogen bonds in acetic acid-choline chloride DES (AACC) and formic acid-choline chloride DES (FACC). Atoms in Molecules theory was applied to study hydrogen bonding in these DES. The chlorine ion in choline chloride was found to form a strong hydrogen bond with acetic acid and formic acid in AACC and FACC, respectively. The choline ion was also found to act as a hydrogen bond donor in forming a strong hydrogen bond with acetic acid and formic acid. The interactions between the chlorine ion and methyl groups of the choline ion were found to be van der Waals interactions and not hydrogen bonds. Weaker hydrogen bonds between the oxygen of each carboxylic acid and the methyl groups of choline chloride were also found. These findings hint at the involvement of the chlorine ion in hydrogen bond formation with lignin in the biomass deconstruction process.
Gautam, Ramu, "" (2020). Thesis. 56.