Ultrafast solvent migration in an iron complex revealed by nonadiabatic dynamics simulations
Severin Polonius1,2, Leticia González1,3, Sebastian Mai1
1Institute of Theoretical Chemistry, University of Vienna Währinger Straße 17 1090 Vienna Austria.
Chemical Science
|May 26, 2025
Summary
Photoexcitation triggers rapid solvent shell responses in [Fe(CN)4(bipy)]2-, leading to hydrogen bond reorganization within 100 fs. Nonadiabatic molecular dynamics reveal distinct solvent dynamics for metal-to-ligand charge transfer and metal-centered states.
Area of Science:
- Physical Chemistry
- Computational Chemistry
- Spectroscopy
Background:
- Solvation shell response to photoexcitation is crucial but difficult to resolve experimentally.
- Understanding solvent dynamics, hydrogen bond reorganization, and electronic/nuclear interplay is key.
Purpose of the Study:
- To investigate the ultrafast solvent shell response to photoexcitation of [Fe(CN)4(bipy)]2- in water.
- To elucidate the mechanisms of hydrogen bond reorganization and solvent migration.
Main Methods:
- Large-scale nonadiabatic molecular dynamics simulations.
- Vibronic coupling model potentials with electrostatic embedding (VC/MM).
- Computation of thousands of nonadiabatic excited-state trajectories.
Main Results:
- Observed direct solvent migration within 100 fs, breaking and forming hydrogen bonds.
- Revealed distinct solvent responses for metal-to-ligand charge transfer (MLCT) and metal-centered (MC) states.
- Achieved few-femtosecond and sub-angstrom resolution of solvent distribution dynamics.
Conclusions:
- VC/MM nonadiabatic dynamics simulations can resolve anisotropic solvent dynamics with high detail.
- Provides new insights into ultrafast solvent behavior around photoexcited solutes.
- Stimulates development of advanced time-resolved experimental techniques.
