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 (C 2 vs C 4 ) with the C 2 -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 C 4 -site to generate an enamine adduct with no evidence for attachment at the more electrophilic C 2 -position. Equilibration between NaSMe and water also affords NaOH that displays a thermodynamic preference for C 2 -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 1 H/ 13 C 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 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".