Tailoring crystal structures and polymorphs of halogen-bonded supramolecular assemblies: co-crystals of hexahalogenated benzenes and 2,3,5,6-tetramethylpyrazine
Bibliographic record
Abstract
Polymorphism is of significant interest owing to its potential to influence the physiochemical properties of pharmaceuticals and other materials. The high directionality and the intrinsic tunability of the intermolecular halogen bond make it a compelling design element in crystal engineering. In this work, we describe various polymorphs of halogen-bonded co-crystals constructed from 2,3,5,6tetramethylpyrazine with different halogen bond donors (1,4-diiodotetrafluorobenzene, 1,3,5-trifluoro-2,4,6-triiodobenzene, and their bromoand chloro-analogues). Polymorphic cocrystals are obtained from solution-based and solid-based methods. Solution-based methods are implemented by manipulating the solvent system mixture and the mixing temperature while solid-based cocrystals are obtained via cosublimation and mechanochemical techniques. Co-crystal structures are characterized via single crystal X-ray diffraction and powder X-ray diffraction. 13C solid-state nuclear magnetic resonance spectroscopic investigations of cocrystals are used to validate and further probe the polymorphic structures. This study serves as a holistic approach in investigating polymorphism and demonstrates the unquenchable importance of halogen bonding in crystal engineering.
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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) | 0.000 | 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".