Fluorination of Rubisco-Mimetic CO2 Capture Systems. Theoretical and Experimental Studies of Ammonium Ion Acidity Depression and Carbamylation

<p>"RuBisCO-inspired CO₂ capture and release (CCR) systems featuring amines have been developed for the purpose of reversable CO₂ capture from air. The enzyme active site consists of the tetrapeptide sequence Lys-Asp-Asp-Glu. The Lys sidechain amine undergoes carbamylation and an Mg²⁺ cation stabilizes the resulting carbamate. The N^a-acyl-lysinyl-aspratyl-aspartyl-glutamide (Lys-Asp-Asp-Glu, KDDE) peptide featured maximum capture at pH ≈ 10; a pH region too high for Mg²⁺ ions to remain in solution. This work aims to achieve pKa depression by introducing fluorine in the proximity of the lysine’s sidechain amine. A comparative analysis was made of butylamine, (2,2,2-trifluoroethyl) butylamine, and 2,2-difluoropropylamine to examine fluorination strategies aimed at ammonium ion pK_a depression and carbamylation at reduced pH (CH. 1). CF3-functionalized lysines ^tFK_n were synthesized for the purpose of embedding the amino acids into the larger KDDE tetrapeptide (CH. 2). Two ¹³C NMR rotamer quartet signals were observed for the CF₃ carbon of tert-butyloxycarbonyl (boc) protected intermediates. To understand the rotational dynamics, we analyzed the potential energy surface (PES) of a fluorinated tertiary carbamate model system (CH 3). The rotation-inversion barrier was measured to create a direct connection to experimentation (CH. 4). The CO₂ addition pathway of the fluorinated ^tFLys-Asp-Asp-Glu (^tFKDDE) tetrapeptide was analyzed to understand its carbamylation mechanics (CH. 5). The CF_3-functionalized lysine ^tFK was embedded into the tetrapeptide and its carbamylation, both with and without Mg²⁺, was analyzed as a function of pH to determine maximum carbamylation, the pH of maximum carbamylation, and its Gibbs’ free energy (CH 6)"--Abstract, p. iv</p>

Name thesis:degree_name

Ph. D. in Chemistry

Grantor

Missouri University of Science and Technology

Author dc:creator

• Jameson, Brian Michael

• Carbamylation
• CO2 Capture
• Fluorinated Amines
• pKa Depression
• RuBisCO-mimetic
• Unnatural Amino Acids
• Chemistry
• Physical Chemistry
• Physical Sciences and Mathematics

Repository record dc:identifier

https://scholarsmine.mst.edu/doctoral_dissertations/3275

OAI identifier oai:identifier

oai:scholarsmine.mst.edu:doctoral_dissertations-4280