Molecular Tectonics. Hydrogen-Bonded Networks Built from Tetra- and Hexaanilines
Bibliographic record
Abstract
A series of compounds with multiple PhNH 2 groups were synthesized and crystallized, and their structures were solved by X-ray diffraction to assess the ability of -NH 2 groups in anilines to direct molecular crystallization. 2,2‘,7,7‘-Tetraamino-9,9‘-spirobi[9 H -fluorene] ( 1c ) forms an inclusion complex held together in part by donation of hydrogen bonds from -NH 2 groups to guest molecules. Surprisingly, the -NH 2 groups do not engage in hydrogen bonding with each other. Tetrakis(4-aminophenyl)methane ( 2c ) crystallizes to form a guest-free close-packed diamondoid network in which each -NH 2 group donates and accepts one N−H···N hydrogen bond. Tetrakis[(4-aminophenoxy)methyl]methane ( 3c ), a more flexible analogue, also crystallizes as a close-packed structure maintained by an extensive network of N−H···N hydrogen bonds. Despite the structural similarity of tetraanilines 2c and 3c, their hydrogen-bonding patterns and network topologies are different. A flexible hexaaniline, 1,1‘-oxybis[3-(4-aminophenoxy)-2,2-bis[(4-aminophenoxy)methyl]]propane ( 4c ), produces a close-packed network joined by both N−H···N and N−H···O hydrogen bonds. Tetrakis(4-aminophenyl)ethylene ( 5 ) crystallizes as a hydrate to yield a structure consisting of layered hydrogen-bonded sheets. The diverse hydrogen-bonding motifs observed show that crystal engineering using direct interactions of the -NH 2 group of anilines is a challenging endeavor, and other intermolecular interactions can compete effectively with N−H···N hydrogen bonds to determine how crystallization occurs.
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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) | 0.003 | 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 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".