Date of Award
Honors Bachelor of Arts
Laurel Goj Habgood
For thousands of years, silver (Ag) has been widely used for medicinal purposes due to its broad-spectrum antimicrobial properties. While medicinal silver usage declined with the advent of antibiotics, there has been a renewed interest in therapeutic silver coordination compounds to combat the spread of antibiotic resistance. N-heterocyclic carbenes (NHCs) are promising ligands for silver metallodrugs due to their wide structural variety that allows for tunability of the complex’s overall steric and electronic properties and previously established bioactivity against various pathogens and cancer cell lines. There is potential for efficacy against biofilms, a type of microbial growth pattern that is common among numerous pathogens. In order to explore the impact of the steric and electronic properties of certain NHC structural features on the overall activity against Streptococcus mutans, the etiological agent behind cavities, a series of five Ag(I)-NHCs were synthesized over the course of three steps and characterized: [(IMes)AgCl] (1), [(IPr)AgCl] (2), [(IMesMe2)AgCl] (3), [(SIMes)AgCl] (4), [(IMes)AgCl] (5). Challenges occurred while synthesizing complex 3, IPr∙HCl (14), and IMesMe2∙HCl (15). Complex 1 will serve as the baseline that all other complexes will be compared to in future antibacterial studies. The diazabutadiene and imidazolium chloride precursors and Ag(I)-NHCs were synthesized with low to moderate yields. Based on the reaction mechanisms and literature protocols, increasing the amount of the catalytic reagents as well as optimization of the isolation and purification techniques should improve yields. Future work should focus on the syntheses of [(BMes)AgCl] (6) and [(6-Mes)AgCl] (7) which were unable to be completed due to time constraints. Upon successful completion of the syntheses, all will be given to the Santiago lab (Rollins Dept. of Biology) where they will be screened against S. mutans to assess their antibacterial activity.
Malto, Alyssa, "Synthesis of a Series of Ag(I)-NHC Complexes for Future Antibacterial Studies" (2021). Honors Program Theses. 149.