UC Davis

The purpose of this dissertation is to showcase the use of computational chemistry to understand and corroborate chemical observations from experiments.This report will begin with highlighting the importance of considering the conformational space of an organic molecule. Instead of a static picture, molecules have degrees of freedom in space and they can equilibrate between different conformations. This flexibility can affect a molecule’s reactivity and spectral properties. Chapter 2 and 3 focus the study of structures. Here, we used computational data to correlate to experimental observations, and subsequently guide decisions on synthesis. Then, we move from the study of structures to mechanisms, highlighting the ability of using quantum chemistry to compare reaction energetics. For example, using transition state theory (TST), we can predict if a chemical transformation is kinetically feasible and which product is favored under the experimental conditions. The final chapter describe a purely computational project which considers the two major assumptions involved in the previous chapters: 1) a chemical reaction obeys conventional TST; 2) the inclusion of implicit solvent environment is sufficient to simulate realistic solvent effect. This chapter will consider the limitations of these two assumptions using a bifurcating pericyclic model reaction, in which the inclusion of explicit solvent molecule affects product selectivity.