Investigation of Barriers To Conformational Interchange in Oligothiophenes and Oligo(Thienyl)furans
Bibliographic record
Abstract
The conformational analysis of unsubstituted and alkyl-substituted oligothiophenes and oligo(thienyl)furans by dynamic NMR (DNMR) spectroscopy and ab initio calculations is described. The DNMR studies of oligothiophenes indicate that the conformational exchange is fast even on the 13 C chemical shift scale and that the barriers are too low to be measured by this technique. Ab initio 6-31G** and MP2/6-31G** calculations are in agreement with these experimental findings. Moreover, it is found that the torsional barriers do not change significantly as the chain length is increased. Torsional parameter sets for the MM2 force field are derived for substituted oligothiophenes and oligo(thienyl)furans using the ab initio torsional energy profiles for the appropriate dimers, with the expectation that these parameter sets will be transferable to larger oligomers.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".