Date of Award
2008
Degree Type
Thesis
Degree Name
Master of Science
Program
Chemistry
Supervisor
Dr. Jones
Abstract
Electrochemically-induced light emission from conjugated organic molecules has received intense interest due to its possible application in fast response displays, sensors, chemical imaging and laser technology. The development in the field has been fueled by the search for improved light-emitting organic materials. Taking advantage of the Sharpless “click” reaction, a library of thiophene derivatives have been made from azidothiophenes and various aromatic acetylenes (Series A-D, below). These reactions were moderate to high yielding (60 - 98 %) and offered an alternative to carbon-carbon coupling reactions more traditionally used to make derivatives of thiophene and made purification by column chromatography unnecessary. Electron-donating or withdrawing groups could easily be introduced by the appropriate choice of the acetylene.
Series A Series B
S
Series C
S
N-N
RRR
1 =C6H5 2 = C6H5F 3 = C6H4N(CH3)2 4 = SC4H3 5 = C6H4OCH3
8=C6H5 7 = C6H4F 8 = C6H4N(CH3)2 9 = SC4H3
10 = C6H4OCH3
11 =C6H5 12 = C6H4F 13 = C6H4N(CH3)2 14 = SC4H3 15 = C6H4OCH3
Series D
S
N-N l/ ∖
N1 N=N
19
N=N
20
21
N-N
S
S
S
S
The optical and redox properties of compounds in Series A, B and D were investigated in order to determine the relative effects that their electron-donating and - withdrawing substituents had on the thiophene-containing compounds, and to evaluate their potential for electrochemiluminescence (ECL).
The compounds formed unstable radical ions in solution which could be seen from the non-reversible oxidation and reduction potentials in the cyclic voltammograms,
and also from the low efficiencies in the annihilation experiments (0.5 -1.5 %) relative to 9, 10-diphenylanthracene. However, efficiencies did increase with the use of benzoyl peroxide as coreactant and we were able to achieve efficiencies as high as 17 % for compound 20. Characteristic low wavelength emissions indicated the presence of excimer (excited dimers) in the ECL spectra. It was also possible to tune the amount of excimer formation by pulsing to different potentials.
Recommended Citation
Price, Jacquelyn T., "Electrogenerated Chemiluminescence of New Thiophene-Containing Compounds" (2008). Digitized Theses. 4776.
https://ir.lib.uwo.ca/digitizedtheses/4776