Excimer-Suppressed and Oxygen-Tolerant Photophysics of “Arm-like” Substituted Pyrene Derivatives
Bibliographic record
Abstract
Pyrene-functionalized materials are extensively employed in photoluminescent applications, owing to their extended π-conjugation and favorable photophysical properties. However, their luminescent performance is often attenuated by π–π stacking-driven excimer formation and molecular oxygen quenching. To mitigate these undesirable effects, a novel class of 7- tert -butylpyren-2-ol derivatives with extended “arm-like” substituents at the 1,3-positions have been synthesized and their luminescent properties in solution have been thoroughly investigated. While the 2- and 7-positions of the pyrene core are frequently modified with hydroxyl and tert -butyl groups, this work presents the first introduction of “arm-like” substituents at the 1,3-positions. The stretched-out “arm-like” substituents not only introduce steric bulk to suppress excimer formation but also change the symmetry class of pyrene and modulate electron density at its 1,2,3,7-positions. These effects tune pyrene’s energy levels and result in moderate (0.4) to high (0.7) fluorescence quantum yields and shorter-lived fluorescence lifetimes ranging from ca. 20 to 40 ns. These shorter lifetimes lead to a reduction of the pyrene derivatives’ susceptibility to energy scavenging by molecular oxygen. In addition, the specific form of the “arms” are important. Alkyl-containing arms and alkenyl-containing arms exhibit different decay pathways, which is reflected by their disparate nonradiative rates. Thus, the introduction of “arm-like” modifications represents a promising approach to modulate the photophysical behavior of an important class of polycyclic aromatic hydrocarbons, highlighting their applicability in next-generation electronic and optoelectronic systems.
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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".