Cosublimation: A Rapid Route Toward Otherwise Inaccessible Halogen-Bonded Architectures
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Bibliographic record
Abstract
Several synthetic techniques are available for the preparation of halogen-bonded adducts, including traditional solvent-evaporation methods and mechanochemistry. With the intention of reducing solvent usage and experimental times, we establish cosublimation as a synthetic technique for preparing halogen-bonded cocrystals, focusing on the C–I···N motif involving nitrogen-containing heterocycles. We selected four common halogen-bond donors (I2, 1,4-diiodobenzene, 1,4-diiodotetrafluorobenzene, 1,3,5-trifluoro-2,4,6-triiodobenzene) and four halogen-bond acceptors (2,3,5,6-tetramethylpyrazine, 1,4-diazabicyclo[2.2.2]octane, 2,2′-bipyridyl, 1-adamantanecarbonitrile), by virtue of their range in volatility, and explored all 16 combinations via the following methods: solvent evaporation, overnight cosublimation in a sealed glass tube using a two-zone furnace, and expedited cosublimation in a vacuum sublimation apparatus. We show that the raw crystals obtained from overnight cosublimation are of suitable quality for single-crystal X-ray diffraction, resulting in five new crystal structures, two of which are, currently, unobtainable through other methods. Of these new structures, the first halogen bond to the nitrile group of 1-adamantanecarbonitrile is reported, resulting in the formation of a supramolecular rotor in a spinning top configuration as evidenced by 13C and 15N solid-state NMR spectroscopy. Strikingly, the cosublimation approach overcomes an anticooperative halogen-bonding effect to produce fully saturated cocrystals of the tritopic halogen bond donor 1,3,5-trifluoro-2,4,6-triiodobenzene with 1,4-diazabicyclo[2.2.2]octane. Finally, we show that cosublimation can be used to rapidly prepare and purify bulk samples using a vacuum sublimation apparatus, enabling the scalable preparation of halogen-bonded cocrystals within 10 to 30 min using common laboratory equipment. The methods described here enable a broad exploration of the polymorphic landscape and may be extended to the facile preparation of other classes of cocrystals.
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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) | 0.003 | 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 it