Author

Desmond Khan

Date of Award

August 2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Mark Hoffmann

Second Advisor

Mark Hoffmann

Abstract

This study examines the performance of various quantum chemical methods, particularly density functional theory (DFT), in predicting noncovalent interactions in eleven unnatural amino acids. The research compares five DFT functionals (PBE-D3, B3LYP-D3, HSE06, M06-2X, and ꞷB97XD) and MP2 theory against the benchmark CCSD(T) method, using two Pople basis sets (6-31G* and 6-311++G**). Results highlight ꞷB97XD's superior performance in capturing strong dispersion interactions, especially when paired with the 6-311++G** basis set. Additionally, the study investigates interactions between biomimetic Fe and Mg co-doped montmorillonite clay and the amino acids. It reveals the necessity of employing PBE-GGA + U with U ≥ 4 eV for accurate descriptions of the clay's structural, electronic, and magnetic properties. The research identifies significant electrostatic interactions, primarily involving amino groups, suggesting the potential for designing tailored amino acids for innovative biomaterial composites.Ab initio molecular dynamics simulations confirmed the stability of clay-amino acid systems under ambient conditions, with an implicit water solvent enhancing amino acid binding energy on the clay surface. These findings underscore DFT's utility in understanding and designing noncovalent interactions in complex molecular systems. This research offers valuable insights for materials science and bioengineering applications, paving the way for developing novel biomaterial composites with specific functionalities.

Available for download on Saturday, August 23, 2025

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