Electron-Transfer Reactions in Micelles: Dynamics of Psoralen and Coumarin Radical Cations
Bibliographic record
Abstract
Radical cations of several psoralens and coumarins have been generated by photoionization in aqueous micellar solution for a comparison of their dynamic behavior with results observed previously in aqueous solution. The photoionization efficiencies are significantly higher in anionic sodium dodecyl sulfate (SDS) micelles than in aqueous solution as a result of favorable electrostatic effects that lead to rapid ejection of the electron into the aqueous phase. By contrast, much lower quantum yields are measured in neutral and cationic micelles. Experiments with anionic quenchers that are soluble only in the aqueous phase demonstrate that exit of the radical cations from anionic SDS micelles is too slow to measure (<10 5 s -1 ) under our conditions. Exit rate constants from neutral Triton X-100 micelles are approximately an order of magnitude faster. Comparison of equilibrium constants for both triplet and radical cations of 4,5‘,8-trimethylpsoralen demonstrates that electrostatic effects lead to an order of magnitude enhancement of the affinity of the radical cation for the anionic vs neutral micelles, as compared to the triplet of the same substrate. The slow exit of the radical cation from the micelle facilitates the measurement of rate constants for reaction of the micelle-incorporated radical cations with both water soluble quenchers and species for which exchange between micelle and aqueous phases is rapid on the time scale of the radical cation lifetime. This work provides some of the first kinetic data for dynamics of exit of reactive radical cations from micelles and indicates that these species may provide useful probes for studying electron-transfer dynamics in micellar media.
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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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".