Ultrafast signatures of merocyanine overcoming steric impedance in crystalline spiropyran
Bibliographic record
Abstract
Isomerisation through stereochemical changes and modulation in bond order conjugation are processes that occur ubiquitously in diverse chemical systems and for photochromic spirocompounds, it imparts them their functionality as phototransformable molecules. However, these transformations have been notoriously challenging to observe in crystals due to steric hindrance but are necessary ingredients for the development of reversible spiro-based crystalline devices. Here, we report the detection of spectroscopic signatures of merocyanine due to photoisomerisation within crystalline spiropyran following 266 nm excitation. Our femtosecond spectroscopy experiments reveal bond breaking, isomerisation and increase in bond order conjugation towards the formation of merocynine on a sub-2 ps time scale. They further unveil a lifetime of several picoseconds for the initial open ring intermediate with subsequent relaxation to mercocyanine, with established back connversion pathways, which make the system highly reversible in the solid state. Supporting femtosecond electron diffraction studies suggest that lattice strain favours the return of photoproduct to the closed spiroform. Our work thus paves the way for novel ultrafast applications from spiropyran-derived compounds.
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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) | 0.000 | 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".