Revisiting the photochemistry 2,5‐dihydroxy benzoic acid (gentisic acid): Solvent and pH effect
Bibliographic record
Abstract
Abstract In the present study, we have reinvestigated photochemistry of 2,5‐dihydroxy benzoic acid (DHBA) in a series of organic solvents of different polarities and the aqueous solution of varying pH from 1 to 14. The investigation was carried out using steady‐state and nanosecond (ns) time‐domain fluorescence measurement techniques at room temperature. Some hitherto not explored spectral features with new insight on different forms of DHBA are reported. It is found that DHBA exists as monoanionic and neutral forms in various polar protic, aprotic, and nonpolar solvents. In aqueous solution (pH 1 to 14), neutral, monoanionic, and dianion forms are found to be responsible for the observed optical spectral profiles. The observed significant Stokes shift in emission is attributed to species undergoing excited‐state intramolecular proton transfer (ESIPT) in different solvents. The analysis presented in this work elucidates and validate the presence of various species and conformers of DHBA.
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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".