Insights into the Effect of the Ketylimine Group on the Fluorescence Deactivation of Oligofluorenes
Bibliographic record
Abstract
A series of oligofluorenes containing arylketylimines in the 9-position ranging between 1 and 3 fluorene segments was prepared. The conjugated ketylimines were prepared using dehydration and Lewis acid protocols from the corresponding oligofluorenones. These heteroconjugated oligomers were prepared for examining the effect of the ketylimine moiety on the photophysical properties relative to their ketone counterparts. Both the ketylimine and fluorenone containing oligofluorenes exhibited reduced fluorescence relative to their corresponding all-fluorene analogues. Temperature-dependent emission measurements and steady-state fluorescence quenching confirmed that fluorescence deactivation of the ketylimines occurred predominately by intramolecular photoinduced electron transfer (PET). This is in contrast to their oligofluorenone counterparts that dissipated their singlet excited state energy via both intersystem crossing and nonradiative internal conversion. The measured diffusion controlled fluorescence quenching rate constants (3 × 10 10 M −1 s −1 ) combined with the calculated exergonic energetics ranging from −10 to −116 kJ/mol derived from the Rehm−Weller equation for the oligofluorenyl ketylimines corroborate that the ketylimines’ fluorescence deactivation occurs by intramolecular PET.
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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".