Master of Science
Dr. Brian Pagenkopf
There has been increasing interest in the synthesis of siloles over the past 20 years due to their applications as chemoselective sensors and light emitting diodes. The standard synthesis of siloles involves a one-pot reductive cyclization followed by Negishi cross-coupling, which was modified by the Pagenkopf group to allow the synthesis of dissymmetric siloles. This modified synthesis allows siloles to be tuned to improve their fluorescent properties via varying substituents on the silole. This culminated in the synthesis of a series of 2,5-bis(thiophene)siloles with bulky silyl substituents that displayed excellent electrochemiluminescent properties.
In the past decade there has been a large push for effective synthetic methods for making benzosiloles. The synthetic method developed by the Chatani group is particularly interesting because of the large variety of benzosiloles that could be synthesized in high yields. Combining the Chatani benzosilole synthesis with the Pagenkopf group’s knowledge in tuning siloles should result in new benzosilole chromophores that might have applications as biosensors or in solar cells.
This work describes the synthesis of benzosiloles containing oligothiophenes substituted at the C2 and C3 positions. Benzosiloles are formed in a cycloaddition reaction from 2-silylphenylborates and thiophene-acetylenes with a rhodium catalyst. In total seven benzosiloles were synthesized including those with electron donating and electron withdrawing groups. Their ECL properties were then tested to discover that both highly conjugated bis(2,3-terthiophene)benzosilole and 6-cyano-bis(2,3-terthiophene)benzosilole displayed the best ECL properties of those synthesized.
Day, Tyler J. B., "Synthesis and Electrochemiluminescence of Thiophene Substituted Benzosiloles" (2016). Electronic Thesis and Dissertation Repository. 3709.