Rotational spectra and theoretical study of tetramers and trimers of 2-fluoroethanol: dramatic intermolecular compensation for intramolecular instability
Bibliographic record
Abstract
Using broadband rotational spectroscopy aided by high level ab initio calculations, we probe structural diversity and emerging bulk behavior in trimeric and tetrameric aggregates of the transiently chiral 2-fluoroethanol (FE). One FE tetramer which is homochiral and features a highly compact arrangement that is stabilized by a water tetramer-like H-bond ring and a network of fully bifurcated C-HF H-bonds, and two higher energy FE trimers which feature a water trimer-like H-bond ring, were observed experimentally in a jet expansion. The three most stable FE trimers predicted within a few kJ mol-1 are all made of the most stable FE subunit and are detected experimentally. Unexpectedly, two out of the three most stable FE tetramers exclusively consist of much less stable subunits. For example, one FE tetramer that contains four less stable subunits, which are in total ∼40 kJ mol-1 less stable than their global minimum counterparts, is predicted to be of similar stability as the tetramer containing four global minimum subunits. High level theoretical modeling is essential in providing a comprehensive picture of the energetic and structural landscapes of the FE tetramer, an intriguing system at the interface between gas- and bulk-phase behavior, where the conformational specificity seen in the gas-phase is still experimentally relevant but plays a diminished role relative to the intermolecular topology and cooperative stability.
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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) | 0.001 | 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".