Effects of Hydrogen Bonding on the Acidity of Uracil Derivatives
Bibliographic record
Abstract
The present study uses density functional theory to investigate the effects of hydrogen bonding on the acidity of C5- and C6-substituted uracil derivatives. The proton affinities and acidities of uracil donor and acceptor sites generally decrease and increase, respectively, with an increase in the electronegativity of the uracil substituent. Despite these substituent effects, the binding strengths of small molecules (NH 3, H 2 O, or HF) to the uracil derivatives are relatively independent of the substituent, which indicates that the changes in the uracil proton affinity and acidity effectively cancel. The acidities of substituted uracil complexes increase not only with the electronegativity of the substituent, but also with the acidity of the small molecule bound to the uracil ring. However, the magnitude of the effect of hydrogen bonding on the acidity of uracil derivatives is not dependent on the nature or position of the substituent. Our results lead to a greater fundamental understanding of the effects of substituents on the hydrogen-bonding properties of uracil, which may have implications for understanding biological applications and processes that involve these modified nucleobases.
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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".