Melting Behavior of Crown Thioethers: Correlation of Entropy Changes with Conformational Disorder
Bibliographic record
Abstract
We have examined the following crown thioethers by differential scanning calorimetry from −90 °C, or lower, up to their melting points: 1,4,7-trithiacyclononane (9S3); 1,5,9-trithiacyclododecane (12S3); 1,4,7,10-tetrathiacyclododecane (12S4); 1,4,8,11-tetrathiacyclotetradecane (14S4); 1,4,7,10,13-pentathiacyclopentadecane (15S5); and 1,5,9,13-tetrathiacyclohexadecane (16S4). We have identified new solid−solid phase transitions above room temperature in 12S3, in the α-phase of 14S4, in 15S5, and in both the α-phase and β-phase of 16S4. Of those crown thioethers examined, only 9S3 and 12S4 do not show any solid−solid phase transitions. From an analysis of the entropy of fusion, we find that only the high-temperature solid phase of 16S4 is orientationally disordered. Analysis of the entropy changes associated with the solid−solid phase transitions and with fusion indicate that all except 12S4 have considerably more conformational freedom in the melt than in the room-temperature solid. Insight into these conformational changes is of considerable importance for understanding complexation of thioethers to metals.
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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) | 0.000 | 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 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".