Intersystem crossing and intramolecular triplet excitation energy transfer in spiro[9,10-dihydro-9-oxoanthracene-10,2′-5′,6′-benzindan] investigated by DFT/MRCI methods
Bibliographic record
Abstract
Recent experimental studies of a spiro-linked anthracenone (A)–naphthalene (N) compound (AN) in butyronitrile (BuCN) solution (Dobkowski et al., J. Phys. Chem. A 2019, 123, 6978) proposed an excited-state energy dissipation pathway [1ππ* (N) + 1ππ*(A)]↝1 nπ* (A)↝3 nπ* (A)↝3ππ*(N). However, a detailed theoretical study employing combined density functional theory and multireference configuration interaction methods, performed in the present work, suggests that the photoexcitation decay follows a different pathway. In BuCN solution, the intersystem crossing (ISC) follows the well-established El-Sayed rule and involves the 3ππ*(A) state which is found to be the lowest excited triplet state localized on the anthracenone moiety. Because the Dexter triplet excitation energy transfer (TEET) to the first excited triplet state of the naphthalene subunit is forbidden in C2 v symmetry, it is mandatory to go beyond the Condon approximation in modeling this process. Nonadiabatic coupling matrix elements were computed to obtain a TEET rate different from zero. Our calculations yield time constants of 5 ps for the 1 nπ* (A)↝3ππ* (A) ISC and of 3 ps for the subsequent 3ππ* (A)↝3ππ* (N) TEET in BuCN whereas the energy dissipation involving the 3 nπ*(A) state as an intermediate occurs on a much longer time scale.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".