Impact of Solvation on the Photoisomerization Mechanism of Oxindole Switches with Electron-Donating Substituents
Bibliographic record
Abstract
Molecular photoswitches that undergo Z/E photoisomerization are fundamental components of light-driven molecular machines. Their efficiency is determined by ultrafast isomerization dynamics and high quantum yields, both of which are strongly modulated by the solvent environment. In this work, we examine two protonation states of an oxindole-based photoswitch in methanol. Using a combination of quantum mechanics/molecular mechanics (QM/MM) simulations with semi-empirical and high-level electronic structure methods, we compute radial distribution functions, isomerization free energy barriers, absorption spectra, and nonadiabatic dynamics in solution. We find that the deprotonated oxindole establishes stronger hydrogen bonds with methanol, whereas the protonated form adopts a pre-twisted conformation in solution. Nonadiabatic dynamics reveal that the weaker hydrogen bonding of the protonated state permits coherent isomerization, in contrast to the deprotonated form, where solvent fluctuations exert a stronger influence on individual trajectories. These findings clarify how solvent interactions govern the photoisomerization pathways of molecular photoswitches and inform the design of light-driven molecular machines, thereby enabling precise control of their operation in the condensed phase.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".