"Novel synthesis of sulfur based ligands used in modeling biological hy" by Tyler Jesse Jacinto

Date of Award

Spring 2013

Project Type

Thesis

Program or Major

Chemistry

Degree Name

Master of Science

First Advisor

Samuel Pazicni

Abstract

Heme-thiolate proteins are known to have hydrogen bond donors proximal to the axial thiolate ligand. The specific roles of these conserved H-bond donors have not yet been elucidated. However, various sources agree upon the positive influence that increased X-H···S interactions have on protein redox potentials. For example, synthetic modeling studies of the cytochromes P450 show similar positive shifts in potential in iron-porphyrin-thiolate model systems. The ligands used in modeling the H-bonding interactions in the P450 cytochromes included a series of 2,6-substituted thiophenols, -S(2,6-(CX3CONH)2C6H3), where X = H, F, CH3. The current synthetic route to these ligands is vague and employs materials that are no longer commercially available. Seeking a new synthetic route to the precursor to this ligand series, bis(2,6- diaminophenyl)disulfide, 2,6-dinitrophenylsulfonyl chloride (14) has been synthesized and characterized by X-ray diffraction (XRD) and nuclear magnetic resonance (NMR). The steric contributions of these bulky ligands may have an effect on the redox potential and Fe-S bond length of the heme-thiolate complexes. This new idea prompted the synthesis of a putative precursor to the nearly isosteric bis-ester ligand series, -S-(2,6- (CX3COO) 2C6H3), where X is as specified above. Compound 18 and its intermediates were characterized by NMR.

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