Ligand control of hydrocarbon C-H bond functionalization by uranyl photocatalysts
Bibliographic record
Abstract
The aqueous uranyl dication has long been known to facilitate the UV light-induced decomposition of aqueous VOCs (volatile organic compounds), via the long-lived highly efficient, uranyl excited state. However, the lower-energy visible light excited uranyl ion is also able to cleave unactivated hydrocarbon C-H bonds, yet the development of this reactivity into controlled and catalytic C-H bond functionalization is still in its infancy, with almost all studies still focused on uranyl nitrate as the precatalyst. Here, hydrocarbon-soluble, uranyl nitrate and chloride complexes supported by substituted phenanthroline (Ph2phen) ligands are compared to each other, and to the parent salts, as photocatalysts for the functionalization of cyclooctane by H atom abstraction. Analysis of the absorption and emission spectra, and emission lifetimes of Ph2phen-coordinated uranyl complexes demonstrate the utility of the ligand in light absorption in the photocatalysis, which is related to the energy and kinetic decay profile of the uranyl photoexcited state. Density Functional Theory computational analysis of the C-H activation steps in the reaction show how a set of dispersion forces between the hydrocarbon substrate and the Ph2phen ligand provide control over the H atom abstraction, and provide predictions of selectivity of H atom abstraction by the uranyl oxo of the ring CH over the ethyl C-H in an ethylcyclohexane substrate.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".