Ruthenium bistridentate complexes with non-symmetrical hexahydro-pyrimidopyrimidine ligands: a structural and theoretical investigation of their optical and electrochemical properties
Bibliographic record
Abstract
Six ruthenium complexes were synthesized based on three non-symmetrical tridentate ligands bearing the strongly electron-donating group 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-α]pyrimidine (hpp), bpyG (bpyG = 2,2'-bipyridyl-6-hpp), phenG (phenG = 2-hpp-1,10-phenanthroline) and QpyG (QpyG = 2-hpp-6-quinolylpyridyl). The fac-/mer-conformation of the homoleptic species has a dramatic effect on the optical properties, where the fac-isomer absorption is red-shifted by 150 nm, thus reaching the near-IR at approximately 850 nm. Owing to the interesting structural effect on the optical properties, density functional theory (DFT) and time-dependent DFT calculations have been implemented to enlighten the experimental data and prove that exciton coupling is at the origin of the observed shift. The electronic properties have been investigated and, as corroborated by electrochemical data, the presence of the hpp ligand strongly affects the oxidation potential of the ruthenium metal ion, which allows facile fine-tuning of the electronic properties. The luminescence properties of all the compounds have also been investigated (λmax emission = 781-817 nm) and the complexes have longer excited-state lifetimes at room temperature than the parent bis(2,2':6',2''-terpyridine)ruthenium(ii) by 10 to 30 times.
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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".