Acceptor Influence on Thiolate Sensing by Hemicyanine Dyes
Bibliographic record
Abstract
Promoting selective interactions between a nucleophile and electrophilic dye in complex environments is a central goal in nucleophilic chemosensor development. Commonly employed dyes are hemicyanines containing either the N-methylbenzothiazolium (Btz) or the N-methyl-3,3-dimethylindolium (Ind) acceptors. The dyes are related to α,β-unsaturated carbonyls and contain two sites of reactivity (C2 vs C4) with the C2-site directly attached to the quaternary nitrogen possessing greater electrophilicity. We demonstrate the regioselectivity between reactions of sodium thiomethoxide (NaSMe) with two electrophilic hemicyanine dyes bearing Btz (1) or Ind (2) in dipolar aprotic solvent–water mixtures. Adduct complexation was followed by NMR spectroscopy, and structures were optimized in the gas phase to estimate relative adduct stability. The key results include finding a preference for thiolate attachment at the C4-site to generate an enamine adduct with no evidence for attachment at the more electrophilic C2-position. Equilibration between NaSMe and water also affords NaOH that displays a thermodynamic preference for C2-attachment. Dye 1 containing the Btz moiety exhibits greater selectivity for the thiolate addition, with dye 2 being more reactive toward adventitious water to generate OH-adducts. Our data affords diagnostic 1H/13C NMR adduct signals, regioselectivity for various dye/nucleophile combinations, and suggests use of the Btz acceptor for direct thiolate detection.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".