Hydrogen Bonds between Acidic Protons from Alkynes (C–H···O) and Amides (N–H···O) and Carbonyl Oxygen Atoms as Acceptor Partners
Bibliographic record
Abstract
Crystals of tert-butyl (2S)-2-(prop-2-yn-1-ylcarbamoyl)pyrrolidine-1-carboxylate (Boc-L-Pro-NHCH2CCH) have been obtained. The title compound crystallizes easily as sharp needles in orthorhombic system, space group P 21 21 21 with a = 9.2890(2), b = 9.7292(2), c = 15.7918(4) Å, V = 1427.18(6) Å3, and Z = 4. The main feature of the structure is the orientation of the carbamate and amide. Their dipoles add up and the molecule displays an electric dipole moment of 5.61 D from B3LYP/6-31G(d) calculations. The antiparallel H bonding of amides and the alignment of dipoles induce columnar stacking (the dipole moment along the columnar a axis is 4.46 D for each molecule). The other components across the other axes are, therefore weaker, (3.17 D and 1.23 D along the b and c axes, resp.). The resulting anisotropic columns pack side by side, in an antiparallel fashion mostly by (alkyne) CH···O=C (carbamate) interactions.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".