Structural Features in Crystals of Derivatives of Benzene with Multiple Contiguous Phenyl Substituents
Bibliographic record
Abstract
Hexaphenylbenzene and related derivatives of benzene with multiple contiguous phenyl substituents have well-defined nonplanar topologies. Their structures limit conjugation and disfavor intermolecular π−π and C−H···π interactions. Such compounds therefore show higher HOMO−LUMO gaps, lower degrees of self-association, less efficient packing, and higher solubilities than planar analogues. These characteristic properties underlie the growing utility of nonplanar phenyl-substituted benzenes in science and technology. Surprisingly, no systematic structural analysis of compounds of this type has been reported. We have now examined structural features in crystals of hexaphenylbenzene, 1,2,4,5-tetraphenylbenzene, 1,4-dimethyl-2,3,5,6-tetraphenylbenzene, pentaphenylbenzene, 1-methyl-2,3,4,5,6-pentaphenylbenzene, and an octaphenyl- p -quinquephenyl. These compounds tend to crystallize in sheets held together by van der Waals contacts and small numbers of C−H···π interactions. Although the nonplanar topologies of these compounds do not eliminate C···H contacts entirely, the ratios of H···H contacts to C···H contacts greatly exceed those found in analogous aromatic compounds that can assume planar structures. Our structural analyses promise to help explain the characteristic behavior of nonplanar aryl-substituted arenes and to accelerate the discovery of new applications.
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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 | 0.001 |
| 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 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".