Superoxide dismutase enzymes are a major defense against superoxide, which is a potent reactive oxygen species. Misregulation of reactive oxygen species and subsequent neuronal damage are etiological hallmarks of neurodegenerative disease. Macrocyclic small molecules have offered inroads toward functional SOD1 mimics.
View Article and Find Full Text PDFThe abundance of manganese in nature and versatility to access different oxidation states have made manganese complexes attractive as catalysts for oxidation reactions in both biology and industry. Macrocyclic ligands offer the advantage of substantially controlling the reactivity of the manganese center through electronic tuning and steric constraint. Inspired by the manganese catalase enzyme, a biological catalyst for the disproportionation of HO into water and O, the work herein employs 12-membered tetra-aza macrocyclic ligands to study how the inclusion of and substitution to the pyridine ring on the macrocyclic ligand scaffold impacts the reactivity of the manganese complex as a HO disproportionation catalyst.
View Article and Find Full Text PDFA series of Cu(II) complexes with the formula varying in substitution on the pyridine ring were investigated as superoxide dismutase (SOD) mimics to identify the most efficient reaction rates produced by a synthetic, water-soluble copper-based SOD mimic reported to date. The resulting Cu(II) complexes were characterized by X-ray diffraction analysis, UV-visible spectroscopy, cyclic voltammetry, and metal-binding (log β) affinities. Unique to this approach, the modifications to the pyridine ring of the parent system tune the redox potential while exhibiting high binding stabilities without changing the coordination environment of the metal complex within the family of ligands.
View Article and Find Full Text PDFExperiment and computation are used to develop a model to rapidly predict solution structures of macrocycles sharing the same Murcko framework. These 24-atom triazine macrocycles result from the quantitative dimerization of identical monomers presenting a hydrazine group and an acetal tethered to an amino acid linker. Monomers comprising glycine and the β-branched amino acids threonine, valine, and isoleucine yield macrocycles , , , and , respectively.
View Article and Find Full Text PDF12-Membered pyridinophanes are the focus of many studies as biological mimics, chelators, and catalytic precursors. Therefore, the desire to tune the reactivity of pyridinophanes to better control the applications of derivative metal complexes has inspired many structure-activity relationship studies. However, the separation of structural electronic changes imparted by ligand modification has made these structure-activity relationship studies of transition metal catalysts challenging to define.
View Article and Find Full Text PDFGrowing evidence links oxidative stress to the development of a cataract and other diseases of the eye. Treatments for lens-derived diseases are still elusive outside of the standard surgical interventions, which still carry risks today. Therefore, a potential drug molecule PyN was explored for the ability to target multiple components of oxidative stress in the lens to prevent cataract formation.
View Article and Find Full Text PDFIron-catalyzed C-C coupling reactions of pyrrole provide a unique alternative to the traditional Pd-catalyzed counterpart. However, many details regarding the actual mechanism remain unknown. A series of macrocyclic iron(III) complexes were used to evaluate specifics related to the role of O, radicals, and -oxodiiron-complex participation in the catalytic cycle.
View Article and Find Full Text PDFThe number of substituted pyridine pyridinophanes found in the literature is limited due to challenges associated with 12-membered macrocycle and modified pyridine synthesis. Most notably, the electrophilic character at the 4-position of pyridine in pyridinophanes presents a unique challenge for introducing electrophilic chemical groups. Likewise, of the few reported, most substituted pyridine pyridinophanes in the literature are limited to electron-donating functionalities.
View Article and Find Full Text PDFThe use of tetra-aza pyridinophanes is of increasing interest in the fields of bioinorganic modeling, catalysis, and imaging. However, a full study of how modifications to the pyridyl moiety affect the characteristics of the daughter metal complexes, has not been explored. In this study, six tetra-aza macrocyclic ligands were metalated with Fe(iii) and were characterized for the first time.
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