ArOCF <sub>3</sub> , ArOCHF <sub>2</sub> , ArOCH <sub>2</sub> F, and ArOCH <sub>3</sub> : What the F Does to Control the Crystallization of Riluzole and Analogous Fluoromethyl Ethers
Bibliographic record
Abstract
6-(Trifluoromethoxy)benzo[ d ]thiazol-2-amine ( 1a ), known as riluzole, was approved by the U.S. Food and Drug Administration in 1995 for treating amyotrophic lateral sclerosis. A recent study revealed that the compound is polymorphic and showed that all reported forms have similar structures in which molecular organization is controlled primarily by a combination of hydrogen bonding, aromatic interactions, and segregation of fluorous and nonfluorous domains. To assess the relative importance of these effects, we have analyzed the structures of the analogous difluoromethyl ether ( 1b ), monofluoromethyl ether ( 1c ), and methyl ether ( 1d ). These analogues are similar to riluzole in topology and have virtually identical abilities to form hydrogen bonds, but their fluorous character decreases systematically. In all structures observed, the aminothiazole units self-associate by N–H···N hydrogen bonding to form dimers described by the graph set R 2 2 (8). Packing of the dimers varies within the series 1a – 1d, in part because interactions of the groups OCH x F 3– x differ as x is changed from 0 to 3. Although the series 1a – 1d adopts diverse patterns of molecular organization, all pairs of the compounds can nevertheless form mixed crystals containing significant amounts of both components. Together, our results provide a deeper understanding of the polymorphic landscape of riluzole ( 1a ), the associative properties of fluorinated compounds, and the phenomenon of mixed crystallization.
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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) | 0.001 | 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".