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Theses Doctoral

Efforts Towards Greener Photocatalysis and Streamlining Catalyst Design

Karp, Lindsey

Photocatalysis is a robust synthetic tool capable of breaking and assembling chemical bonds using single electron chemistry. This is achieved through the catalytic conversion of light energy to chemical energy in situ, such that the photons being delivered are themselves reagents. Herein, an inexpensive and environmentally-benign platform for scaling up photocatalytic reaction is disclosed, harnessing blue light naturally emitted by deep-sea bioluminescent bacteria. Photobacterium angustum GB-1 was demonstrated to photoexcite both polypyridyl organometallic chromophores and organic dyes at short molecular distances, enabling photocatalysis without any external energy-consuming lamps.While improving the eco-friendliness of photocatalysis itself, we also present a method to use photocatalysis for environmental remediation. Using visible light, a nontoxic organic photosensitizer, and oxygen, we demonstrate the controlled oxidative depolymerization of polystyrene—including polystyrene retrieved from waste receptacles in Havemeyer—to acetophenone. This method is based on results obtained in the controlled aerobic deannulation of cycloalkanes, which is also discussed herein.

Lastly, a means by which catalysis itself can be made more cost, resource, and time effective is presented. An innovative computational platform in development predicts new catalysts for reactions currently energetically inaccessible. In collaboration with the developers, we present experimental validation of their theoretical predictions, as well as perform the synthesis of a de novo fluorinated thiazolium precatalyst calculated to significantly lower the energetic barrier of an otherwise energetically prohibitive Stetter reaction.

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More About This Work

Academic Units
Chemistry
Thesis Advisors
Rovis, Tomislav
Degree
Ph.D., Columbia University
Published Here
September 8, 2021