Matrix Isolation‐Vibrational Circular Dichroism Spectroscopy of 3‐Butyn‐2‐ol and its Binary Aggregates
Bibliographic record
Abstract
Vibrational circular dichroism (VCD) spectroscopy has a unique specificity to chirality and is highly sensitive to the conformational equilibria of chiral molecules. On the other hand, the matrix-isolation (MI) technique allows substantial control over sample compositions, such as the sample(s)/matrix ratio and the ratio among different samples, and yields spectra with very narrow bandwidths. We combined VCD spectroscopy with the MI technique to record MI-VCD and MI-vibrational absorption spectra of 3-butyn-2-ol at different MI temperatures, which allowed us to investigate the conformational distributions of its monomeric and binary species. Good mirror-imaged MI-VCD spectra of opposite enantiomers were achieved. The related conformational searches were performed for the monomer and the binary aggregate and their vibrational absorption and VCD spectra were simulated. The well-resolved experimental MI-VCD bands provide the essential mean to assign the associated vibrational absorption spectral features correctly to a particular conformation in case of closely spaced bands. By varying the matrix temperature, we show that one can follow the self-aggregation process of 3-butyn-2-ol and confidently correlate the MI-VCD spectral features with those obtained for a 0.1 M CCl(4) solution and as a neat liquid at room temperature. Comparison of the aforementioned experimental VCD spectra shows conclusively that there is a substantial contribution from the 3-butyn-2-ol aggregate even at 0.1 M concentration. This spectroscopic combination will be powerful for studying self-aggregation of chiral molecules, and chirality transfer from a chiral molecule to an interacting achiral molecule and in electron donor-acceptor chiral complexes.
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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".