Pressure-Induced Enhancements of Luminescence Intensities and Lifetimes Correlated with Emitting-State Distortions for Thiocyanate and Selenocyanate Complexes of Platinum(II) and Palladium(II)
Bibliographic record
Abstract
The luminescence properties of thiocyanate and selenocyanate platinum(II) and palladium(II) complexes show strong variations with temperature and pressure. The d-d luminescence band maxima for [Pt(SCN)(4)](PPh(4))(2) (1), [Pt(SCN)(4)](n-Bu(4)N)(2) (2), and [Pt(SeCN)(4)](n-Bu(4)N)(2) (4) complexes are centered at ca. 14500 cm(-1) whereas those of the [Pd(SCN)(4)](n-Bu(4)N)(2) (3) and [Pd(SeCN)(4)](n-Bu(4)N)(2) (5) complexes are approximately 2000 cm(-1) lower in energy. Low-temperature luminescence spectra from single-crystal samples have broad bands with highly resolved vibronic structure indicating large displacements of the emitting-state potential energy minimum along several metal-ligand normal coordinates. The largest displacements involve the totally symmetric (a(1g)) stretching modes with frequencies of 295 cm(-1) (1), 303 cm(-1) (2), 274 cm(-1) (3), 195 cm(-1) (4), and 185 cm(-1) (5). The lower frequencies of these dominant progression-forming modes for the selenocyanate complexes lead to luminescence bands that are narrower by ca. 500 cm(-1) (fwhm) than those observed from the thiocyanate complexes. Under external pressures, the room-temperature luminescence intensities and lifetimes show considerable enhancement at pressures up to 40 kbar. This effect is largest for the palladium(II) complexes with lifetimes increasing from approximately 350 ns at ambient pressure up to 62 micros at 30 kbar, an increase by more than 2 orders of magnitude. The platinum(II) complexes exhibit a significant, but noticeably lesser increase of luminescence lifetimes and intensities with increasing pressure. The temperature- and pressure-dependent luminescence decay behavior is rationalized using the emitting-state molecular geometry determined from the resolved low-temperature luminescence spectra combined with the strong-coupling limit of radiationless decay theory.
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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 | 0.001 |
| 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) | 0.002 | 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".