2024 Theses Doctoral

Development and Application of Low-Energy Photoredox Catalysis Methodologies

Xie, Katherine

The development and application of photoredox methodologies in organic synthesis is a powerful paradigm in the synthesis of value-added products. While conventional methods of photoredox catalysis employ ultraviolet (UV) or blue light (i.e. visible light), the associated high energies can lead to deleterious off-cycle pathways and the formation of undesired byproducts. Transitioning to a low-energy (i.e. red/orange) light manifold can mitigate some of these challenges and promote batch-scale reactivity.

We first show standardized syntheses and photophysical/electrochemical characterizations of a library of Os(II) polypyridyl complexes activatable by red light and demonstrate their application in metallaphotoredox-assisted aryl etherification. Thereafter, we leverage the advantages of spin-forbidden excitation (SFE) in the activation of novel Irⁱⁱⁱ photocatalysts, showing the first known examples of C(sp²)–C(sp³) bond formation with low-energy light.

Finally, we utilize the low triplet energy and high redox versatility of an orange light photocatalyst to enable unified oxidative/reductive pathways in decarboxylative arylation, the first such photoredox system to effect dual catalytic manifolds in this paradigm with broadly similar reaction conditions.