In Pursuit of Low Energy Phosphorescence: Late Metal Coordination Complexes of the Planar, π‐extended Bipyridyl Ligand 6,6′,7,7′‐Biphenanthridine
Bibliographic record
Abstract
Abstract The coordination chemistry of the planar, doubly π‐extended bipyridine analog, 6,6′,7,7′‐biphenanthridine ( p ‐biphe), is presented. The phenanthridine units in p ‐biphe are fused together at the 6‐ and 7‐ positions, and the resulting rigid ligand is compared with the more flexible parent “biphe” fused only at the 6‐positions. p ‐Biphe is intensely fluorescent in solution with a much higher quantum yield, but, unlike biphe, at 77 K the fluorescence is not accompanied by any significant phosphorescence. Two four‐coordinate Cu(I) complexes and pseudo‐octahedral Ru(II) and Ir(III) complexes are described: [Cu( p ‐biphe) 2 ] + , [(P^P)Cu( p ‐biphe)] + , [Ru(bpy) 2 ( p ‐biphe)] 2+ , and [Ir(ppy) 2 ( p ‐biphe)] + , isolated as PF 6 salts (P^P = 4,5‐ bis (diphenylphosphino)‐9,9‐dimethylxanthene; bpy = 2,2′‐bipyridine; ppy = 2‐phenylpyridine). The complexes are strongly coloured due to intense low‐energy absorption to charge‐transfer excited states based on TDDFT calculations. The acceptor nature of the p ‐biphe ligand is clear from multiple reduction events observed electrochemically. The Ir(III) complex displays remarkably low‐energy phosphorescence (λ max = 812 nm) in solution at room temperature with a vibrational progression evident extending into the near IR, with no contamination from visible light emission. While the heteroleptic Cu(I) complex is phosphorescent at 77 K, no emission is detectable from [Cu( p ‐biphe) 2 ] + or [Ru(bpy) 2 ( p ‐biphe)] 2+ , likely due to competitive nonradiative decay.
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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".