Host–guest complexes of conformationally flexible<i>C</i>-hexyl-2-bromoresorcinarene and aromatic<i>N</i>-oxides: solid-state, solution and computational studies
Bibliographic record
Abstract
Host–guest complexes ofC-hexyl-2-bromoresorcinarene (BrC6) with twelve potential aromaticN-oxide guests were studied using single crystal X-ray diffraction analysis and1H NMR spectroscopy. In the solid state, of the nine obtained X-ray crystal structures, eight were consistent with the formation of BrC6-N-oxideendocomplexes. The lone exception was from the association between 4-phenylpyridineN-oxide and BrC6, in that case the host forms a self-inclusion complex. BrC6, as opposed to more rigid previously studiedC-ethyl-2-bromoresorcinarene andC-propyl-2-bromoresorcinarene, undergoes remarkable cavity conformational changes to host differentN-oxide guests through C–H···π(host)interactions. In solution phase CD3OD/CDCl3(1:1 v/v), all twelveN-oxide guests formendocomplexes according to1H NMR; however, in more polar CD3OD/DMSO-d6(9:1 v/v), only threeN-oxides with electron-donating groups form solution-phaseendocomplexes with BrC6. In solid-state studies, 3-methylpyridineN-oxide+BrC6 crystallises with both the upper- and lower-rim BrC6 cavities occupied byN-oxide guests. Computational DFT-based studies support that lower-rim long hexyl chains provide the additional stability required for this ditopic behaviour. The lower-rim cavity, far from being a neutral hydrophobic environment, is a highly polarizable electrostatically positive surface, aiding in the binding of polar guests such asN-oxides.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".