Modulation of the Spiropyran−Merocyanine Reversion via Metal-Ion Selective Complexation: Trapping of the “Transient” <i>cis</i>-Merocyanine
Bibliographic record
Abstract
The effects of molecular structure and metal-ion complexation on the photochromic and thermochromic properties of N-functionalized carboxyl ligands of 6‘-nitrobenzoindolinospiropyrans (6-nitroBIPS) with varying methylene spacers ( n = 2, 4, and 5) were examined. Irradiation of this series of molecules in the presence of Cu 2+ and Zn 2+ produced two species that were spectroscopically distinguishable based on their absorption characteristics and stable toward the thermal reversion process. The two bands were diagnostic of the cis - and trans -MC−M 2+ complexes, with λ cis = 410 nm and λ trans = 490 nm, respectively. It was found that lengthening the N-moiety spacer produced no perturbations in the metal-ion complexation behavior. Addition of an equimolar amount of the chelating agent, EDTA, to these solutions resulted in the disappearance of the cis -MC−M 2+ and trans -MC−M 2+ complex absorptions and a simultaneous increase in free trans -MC which could then be observed to revert back to the SP form by a first-order rate decay process. Thus it is shown that Cu 2+ and Zn 2+ function as traps of the “transient” cis -merocyanine stereoisomer formed upon irradiation of spiropyrans functionalized with carboxyl ligands having two, four, and five methylene spacer units, with the potential to modulate this molecular switch by selection of the appropriate metal.
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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".