Sequential Forward S<sub>2</sub>−S<sub>2</sub> and Back S<sub>1</sub>−S<sub>1</sub> (Cyclic) Energy Transfer in a Novel Azulene−Zinc Porphyrin Dyad
Bibliographic record
Abstract
A covalently tethered dyad containing the azulene (Az) and zinc tetraphenylporphyrin (ZnP) chromophores has been synthesized and its excited-state dynamics investigated, using the tether-substituted monochromophoric species as reference compounds. One photon excitation of the dyad at 270 nm results in selective population of the S 2 state of the azulene moiety, followed by near-quantitative electronic relaxation in the cycle S 2 (Az)−S 2 (ZnP)−S 1 (ZnP)−S 1 (Az)−S 0 . Energy transfer from the S 2 state of the azulene moiety to the S 2 state of the ZnP moiety is ultrafast ( k eet > 2 × 10 12 s -1 ) and quantitative. The ZnP(S 2 ) moiety subsequently undergoes rapid ( k ic = 3 × 10 11 s -1 ), quantitative internal conversion to its S 1 state. Thereafter, the excitation residing on the S 1 state of the ZnP is returned to the Az moiety via an efficient (ca. 90%) back S 1 −S 1 energy transfer process ( k eet = 2.8 × 10 9 s -1 ). Ultimately the system returns to the electronic ground state via conical intersection of the azulene S 1 and S 0 surfaces in ca. 1 ps. The cyclic interchromophoric energy transfer rates are nearly the same in both acetonitrile and cyclohexane, suggesting that the conformation of the tether is similar in both solvents. Förster theory is inadequate in explaining the efficient energy transfer dynamics, and other processes such as the Dexter mechanism must be invoked.
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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".