Optical Intramolecular Electron Transfer in Opposite Directions through the Same Bridge That Follows Different Pathways
Bibliographic record
Abstract
The electrochemical and spectroscopic properties of eight bis(tridentate) cyclometalated Ru II compounds covalently linked by a phenyl- or xylyl-thiophene bridge to a pendant triphenylamine (TPA) were characterized in fluid solution and immobilized on metal oxide surfaces. Upon surface immobilization, the TPA +/0 reduction potentials of the phenyl-bridged compounds exhibited large changes, ±100 mV, relative to solution-based values, yet those observed for the xylyl-bridged compounds were relatively unchanged. The highest occupied molecular orbital of the surface-immobilized compounds was associated with either TPA or Ru II, enabling the study of the electron transfer in opposite directions. Electron transfer in the mixed-valent states of the compounds was found to proceed by different optical pathways for Ru II → TPA + relative to TPA → Ru III . Mulliken–Hush analysis of intervalence charge transfer bands for the phenyl-bridged compounds revealed that the electronic coupling matrix element, H DA, was ∼950 cm –1 for Ru II → TPA +, while H DA for TPA → Ru III appeared to be 2500 cm –1 . In contrast, the xylyl-bridged compounds were weakly coupled. A superexchange analysis, where unoccupied bridge orbitals were taken directly into account, led to a very different conclusion: H DA did not depend on the charge-transfer direction or path. The results imply that the electron-transfer direction can alter optical charge transfer pathways without influencing the electronic coupling.
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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 | 0.001 | 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".