Weak Interactions in the Crystal Structures of Tetraacetylenes Derived from Pentaerythrityl Tetraphenyl Ether
Bibliographic record
Abstract
Tetrakis(4-ethynylphenyl)methane ( 7 ) is known to crystallize as an interpenetrated diamondoid network held together in part by weak C⋮C H···C⋮C interactions that define characteristic cyclic quartets of ethynyl groups. To test the ability of this motif to direct the crystallization of more flexible molecules, we synthesized a series of tetraacetylenes derived from pentaerythrityl tetraphenyl ether, and we solved their structures by X-ray diffraction. Pentaerythrityl tetrakis(4-ethynylphenyl) ether ( 4 ) and the more rigid analogue 7 crystallize isostructurally, even though their cores are significantly different in size and flexibility. This observation shows that C⋮C H···C⋮C interactions may have value in engineering molecular crystals. However, widely different structures are obtained by crystallizing pentaerythrityl tetrakis(3-ethynylphenyl) ether ( 5 ) and pentaerythrityl tetrakis(4‘-ethynyl-1,1‘-biphenyl-4-yl) ether ( 6 ), despite their close similarity to tetraacetylene 4 . The unpredictably varied behavior of tetraacetylenes 4 − 7 highlights the difficulty of engineering crystals built from molecules that are flexible and unable to form dominant directional interactions.
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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 | 0.001 |
| 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".