Resolving Ultrafast Photoinduced Deactivations in Water-Solvated Pyrimidine Nucleosides.
Ana Julieta PepinoJavier Segarra-MartiArtur NenovRoberto ImprotaMarco GaravelliPublished in: The journal of physical chemistry letters (2017)
For the first time, ultrafast deactivations of photoexcited water-solvated pyrimidine nucleosides are mapped employing hybrid QM(CASPT2)/MM(AMBER) optimizations that account for explicit solvation, sugar effects, and dynamically correlated potential energy surfaces. Low-energy S1/S0 ring-puckering and ring-opening conical intersections (CIs) are suggested to drive the ballistic coherent subpicosecond (<200 fs) decays observed in each pyrimidine, the energetics controlling this processes correlating with the lifetimes observed. A second bright 1π2π* state, promoting excited-state population branching and leading toward a third CI with the ground state, is proposed to be involved in the slower ultrafast decay component observed in Thd/Cyd. The transient spectroscopic signals of the competitive deactivation channels are computed for the first time. A general unified scheme for ultrafast deactivations, spanning the sub- to few-picosecond time domain, is eventually delivered, with computed data that matches the experiments and elucidates the intrinsic photoprotection mechanism in solvated pyrimidine nucleosides.
Keyphrases
- electron transfer
- energy transfer
- diffusion weighted imaging
- molecular docking
- molecular dynamics
- molecular dynamics simulations
- magnetic resonance imaging
- computed tomography
- ionic liquid
- electronic health record
- machine learning
- escherichia coli
- magnetic resonance
- quantum dots
- risk assessment
- blood brain barrier
- subarachnoid hemorrhage