Red‐Shifting ESIPT Fluorescence by Site‐Specific Functionalization in 2‐(2’‐hydroxyphenyl)benzazole Derivatives
Bibliographic record
Abstract
Abstract We describe the synthesis, full photophysical study, and ab initio calculations of 2‐(2’‐hydroxyphenyl)benzazole (HBX) fluorophores substituted, at the meta position of the phenol group, by pyridine derivatives. HBX are commonly used as model dyes to study the stimuli‐induced modulation of the Excited State Intramolecular Proton Transfer (ESIPT) process. The meta‐substituted fluorophores reported herein, display a photophysical profile different from the previously reported ortho‐ and para‐substituted HBO pyridine isomers. Indeed, while all dyes undergo spontaneous deprotonation in neutral conditions, leading to highly emissive anionic species; upon protonation, ortho‐ and para‐pyridine substitution leads to resonance‐stabilized keto isomers, formed after ESIPT. Protonated meta derivatives, unable to stabilize their excited structure by such electronic delocalization process, display sizable intramolecular charge transfer (ICT) processes, translating into significantly redshifted emission. In addition, all dyes present a strong emission intensity, not only in neutral and acidic solutions, but also in the solid‐state. The nature of the emissive transitions was confirmed in each case by theoretical calculations combining Time‐Dependent Density Functional Theory (TD‐DFT) and second‐order Coupled Cluster (CC2) methods.
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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 | 0.001 |
| 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) | 0.002 | 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".