Synthesis and Properties of π- Extended Phenoxyl Radicals.
Bibliographic record
Abstract
Phenoxyl radicals are a class of π-radicals synthesized by single-electron oxidation of phenols. The spin density from the unpaired electron of a phenoxyl radical is highest at the oxyl position, as well as at the ortho and para positions relative to the oxyl group. The stability of phenoxyl radicals can be improved by substituents at the ortho and para positions, including aromatic, O, N, S-alkyl, and sterically hindered alkyl groups, which compensate for electronic deficiency through resonance or inductive effects. In 2016, Lemaire group reported a crystal structure of the stable phenoxyl radical 2,6-bis(8-quinolylamino)-4-(tert-butyl)phenoxyl (BAQP), which lacks the commonly utilized tert-butyl groups at the ortho position relative to the oxyl group. Moreover, the BAQP radical also showed reversible π-dimerization in solution. This thesis describes the synthesis and characterization of two sets of phenoxyl radicals that lack ortho tert-butyl groups, similar to BAQP. The first set of phenoxyl radicals is ortho-substituted with amino derivatives of large aromatic π-systems, namely pyrene, naphthalene, and phenalenone. The second set is the halogenated derivatives of the BAQP radical. This thesis also explores the stability and the reversible π-dimerization of both of the above-described novel sets of phenoxyl radicals. Notably, one of the radicals synthesized during this work, 5-(tert-butyl)l-2-oxy-1,3,-bis(1- prenylamino)benzene, was proven to be stable as crystal structures were obtained from the pure compound. This particular radical, like BAQP, showed reversible π-dimerization in solution detected by spectroscopic methods such as EPR and 1H-NMR spectroscopy methods. The solid- state properties of this radical were also explored through DC susceptibility measurements and EPR spectroscopy.
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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".