Novel Approach for Predicting Vertical Electron Attachment Energies in Bulk-Solvated Molecules

Area of Science:

• Theoretical Chemistry
• Chemical Physics
• Computational Biology

Background:

• Low-energy electrons form transient anion resonances upon interacting with molecules.
• These resonances can induce DNA damage, necessitating study in biologically relevant environments.
• Previous research focused on gas-phase or microsolvated molecules, leaving a gap in understanding bulk water effects.

Purpose of the Study:

• To develop and apply a novel theoretical-computational approach for studying resonances of bulk-solvated molecules.
• To investigate the impact of bulk water on the vertical electron attachment energies of 1-methyl-5-nitroimidazole (1M5NI).
• To analyze the mutual polarization between 1M5NI resonances and the surrounding water environment.

Main Methods:

• Combined multibasis-set (time-dependent-)density functional theory and self-consistent sequential quantum mechanics/molecular mechanics polarizable electrostatic embedding.
• Prediction of vertical electron attachment energies for 1M5NI in bulk water, microsolvated environments, and in isolation.
• Analysis of polarization effects between solute resonances and the solvent environment.

Main Results:

• The study successfully predicted vertical electron attachment energies of 1M5NI in bulk water.
• Significant impact of water's polarization on vertical electron affinity and attachment energies was observed.
• Bulk water's polarization did not significantly alter the excitation energies of the anion.

Conclusions:

• The developed computational approach effectively models electron resonances in bulk water.
• Solvent polarization plays a critical role in determining electron attachment energies, relevant for radiosensitizer efficacy.
• Understanding these effects is vital for predicting molecular behavior and potential damage in biological systems.