Computational study of interactions between the superoxide radical and thymine

Project Abstract

We report the first computational study of the intermolecular interactions between the hard anion fluoride (F⁻) and the nucleobase thymine. Calculations were performed using density functional theory (DFT) with the B3LYP functional and the aug-cc-pVDZ basis set. The study included geometry optimizations, vibrational frequency analysis, and construction of radial and angular potential energy surfaces. Our results reveal nearly complete selective proton transfer from the N–H groups of thymine to fluoride, accompanied by bond elongation of 0.55 and 0.46 Å, respectively, for each site. This transfer results in the formation of thymine anions and HF units stabilized by strong ionic hydrogen bonds of 0.93 Å; bond dissociation energy = [insert value] kcal·mol⁻¹. Two distinct hydrogen bonded dimer motifs were identified, with the negative charge localized at different thymine nitrogen sites. Comparison of interaction strengths indicates preferential binding at one N–H site, with stabilization energies of –40.69 and –53.66 kcal·mol⁻¹. Vibrational analysis reveals red-shifts of 1030 and 1466 cm⁻¹, consistent with strong hydrogen-bonding interactions. These findings highlight the role of proton acidity and the local chemical environment in determining the site selectivity of F⁻–thymine interactions. Calculated geometrical parameters and vibrational frequencies will be compared to available experimental data. Building on these results, ongoing work is now focused on extending this approach to the radical anion superoxide (O₂⁻) to further probe nucleobase–anion interactions and their implications for oxidative stress and DNA damage.

Conference

Conference Name: Spring American Chemical Society National Meeting & Exposition
Dates: March 23–27, 2025
Location: Atlanta, Georgia
Sponsoring Body: American Chemical Society (ACS)

Funding Type

Travel Grant

Academic College

Jesse D. Jones College of Science, Engineering and Technology

Area/Major/Minor

Chemistry/Mathmatics

Degree

bachelors of science

Classification

Senior

Name

Dr. Wafaa Fawzy

Academic College

Jesse D. Jones College of Science, Engineering and Technology

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