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- All Subjects: Photocatalysis
- Creators: Biegasiewicz, Kyle
- Creators: Alcala-Torano, Rafael de Jesus
Additionally, two different approaches to incorporate non-natural organometallic catalysts into protein matrix are discussed. First, cobalt protoporphyrin IX was incorporated into cytochrome b562 to produce a water-soluble proton and CO2 reduction catalyst that is active upon irradiation in the presence of a photosensitizer. The effect of the porphyrin axial ligands provided by the protein environment has been investigated by introducing mutations into the native scaffold, indicating that catalytic activity of proton reduction is dependent on axial coordination to the porphyrin. It is also shown that effects of the protein environment are not directly transferred when applied to other reactions, such as CO2 reduction.
Inspired by the active site of [FeFe]-hydrogenases, the second approach is based on the stereoselective preparation of a novel amino acid bearing a 1,2-benzenedithiol side chain. This moiety can serve as an anchoring point for the introduction of metal complexes into protein matrices. By doing so, this strategy enables the study of protein interactions with non-natural cofactors and the effects that it may have on catalysis. The work developed herein lays a foundation for furthering the study of the use of proteins as suitable environments for tuning the activity of organometallic catalysts in aqueous conditions, and interfacing these systems with other supporting units into supramolecular assemblies.
This thesis is about how Fe catalysts can be degraded using photocatalysis and how Fe catalysts can degrade small molecules in conjunction with light. The goal of this paper is to look further into more sustainable methods of organic chemistry. Many current organic chemistry practices involve the use of precious metals. Iron is a more sustainable catalyst because it is abundant and inexpensive which is important for preserving the earth and making the organic chemistry more accessible. Along the same lines, light is a renewable energy source and has demonstrated its ability to aid in reactions. Overall, the goal of this paper is to explore the more sustainable alternatives to harsh and toxic organic chemistry practices through the use of Iron and light.
The trifluoromethyl group is an essential chemical motif in pharmaceutical and agrochemical industries. The trifluoromethyl group has similar steric bulk to a methyl group, but exhibits strongly electron withdrawing properties. As a result, a trifluoromethyl group can provide a molecule with enhanced lipophilicity, bioavailability, and metabolic stability, which makes it a commonly used tool to tune activity of agrochemicals and pharmaceutical candidates. There are many methods to generate a new trifluoromethyl moiety, but many of these methods rely on stoichiometric metal reagents or harsh reaction conditions. One strategy to install the trifluoromethyl group under benign conditions is with photoredox catalysis. In the field of photocatalysis, iron has emerged as an alternative for precious metals due to its low cost, earth-abundance, and environmentally benign nature. Methods of trifluoromethylation utilizing iron catalysis do exist, but they often rely on expensive CF3 precursors such as Togni’s Reagent and trifluoromethyl iodide. This thesis demonstrates a method using iron photocatalysis for decarboxylative trifluoromethylation of alkenes using trifluoroacetic acid. We have successfully enabled trifluoromethylation of select methoxy-substituted benzene derivatives as well as a number of alkenes, including those bearing sulfone and ketone groups.