Reichardt’s dye: the NMR story of the solvatochromic betaine dye
Bibliographic record
Abstract
Reichardt’s dye, 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenolate (1), has a very large negative solvatochromism in the long wavelength absorption in the UV–vis spectrum when going from nonpolar to polar solvents. This shift provides the basis of the important and widely used E T (30) scale of solvent polarity. While many papers have investigated the properties of this dye, only a few describe the 1 H and 13 C NMR assignments in any detail. We report herein, our detailed analysis of the proton and carbon chemical shift assignments for this molecule based on 1D and 2D NMR measurements, as well as those of the protonated and methoxy derivatives 2 and 3, respectively. Much to our surprise, some of the critical chemical shift values we observed were significantly different from those previously reported. In addition, we discovered a good correlation not only between the solvent polarity and the chemical shifts of carbons C1 and C4 of Reichardt’s dye (1), but also between the concentration of the dye and these chemical shifts.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".