Degree Type

Dissertation

Date of Award

2019

Degree Name

Doctor of Philosophy

Department

Chemistry

Major

Organic Chemistry

First Advisor

Brett . VanVeller

Abstract

Fluorescence spectroscopy field has evolved tremendously over the past 50 years and still developing. Now with the advance of computational calculation, we are able to understand more about photophysical processes and invent new ideas and designs. We use the approach of applying aromaticity experimentally and theoretically to understand the chemical processes in the ground state and excited state of chromophores. Chapter 2 of this dissertation focuses on how aromaticity effects the hydrogen transfer in Schiff bases, hence change the enol-keto equilibrium. We created quinoxaline and benzothiadiazole Schiff base systems where competing resonance-assisted hydrogen bonding can happen and that allows us to gauge the effect of aromaticity change to the proton transfer. Our results confirm the dominance of aromaticity in determining the tautomeric equilibrium.

Chapter 3 of this dissertation looks at the less red-shift emission of hydroxy- naphthylbenzoxazoles compared to hydroxy-phenylbenzoxazoles. In contrast to the common notion that expansion of π-conjugation generally leads to a more red-shift absorbance and emission wavelengths, we found that less aromaticity in ground state S0 leads to less antiaromaticity in the first excited state S1, and hence less red-shift emission will happen.

Chapter 4 of this dissertation proposes the combination of Baird’s and Clar’s description of aromaticity to rationalize the different degree in red-shift ESIPT emissions among 2-hydroxy- naphthylbenzoxazole derivatives.

Copyright Owner

Yen Hoang Nguyen

Language

en

File Format

application/pdf

File Size

144 pages

Included in

Chemistry Commons

Share

COinS