We investigate what happens after a molecule absorbs light: which excited states become populated, how the excitation energy is dissipated, and under what conditions a chemical reaction competes with relaxation to the ground state. Our work combines electronic-structure calculations, reaction-path analysis and, where appropriate, nonadiabatic molecular dynamics.
A recurring question is how interactions with nearby molecules alter the available pathways. Our studies of adenine–uracil and adenine–thymine base pairs address competition between intramolecular relaxation, electron-driven proton transfer and intersystem crossing (Szkaradek and Góra, 2024). Solvent molecules can also take an active role: the proposed water-to-chromophore electron-transfer pathway in guanosine provides a molecular account of the formation of photodamage products (Janicki et al., 2022).
Chemical substitution and covalently attached groups introduce further possibilities. In thionated nucleosides, ribose changes the photochemical behaviour of the nucleobase and can participate in hydrogen-transfer reactions (Janicki et al., 2021). These mechanistic studies connect our work on origins of life with research on molecular photoswitches and optical properties.
Selected publications
- Szkaradek and Góra. Theoretical insight into photodeactivation mechanisms of adenine–uracil and adenine–thymine nucleobase pairs. Physical Chemistry Chemical Physics 2024, 26, 27807–27816.
- Janicki et al. Photoinduced water–chromophore electron transfer causes formation of guanosine photodamage. Physical Chemistry Chemical Physics 2022, 24, 8217–8224.
- Janicki et al. Ribose Alters the Photochemical Properties of the Nucleobase in Thionated Nucleosides. The Journal of Physical Chemistry Letters 2021, 12, 6707–6713.