Switchable Ambient‐Temperature Singlet–Triplet Dual Emission in Nonconjugated Donor–Acceptor Triarylboron–Pt<sup>II</sup> Complexes
Bibliographic record
Abstract
Abstract Double the fun! Singlet–triplet dual emission at ambient temperature has been achieved in compounds containing a triarylboron acceptor and an N ‐(2′‐pyridyl)‐7‐azaindolyl donor group bridged by a tetrahedral Si linker (see figure). Pt II chelation and chelate‐mode switching from N , N to N , C have been found to greatly enhance phosphorescent emission. Furthermore, both singlet and triplet emission bands are responsive to fluoride ions. magnified image A triarylboron compound Si‐BNPA ( 1 ) containing a BMes 2 acceptor and an N ‐(2′‐pyridyl)‐7‐azaindolyl (NPA) donor linked by a tetrahedral silane group has been synthesised. This molecule displays unusual white singlet–triplet dual emission at 77 K, with an exceptionally long phosphorescent decay time (2.2 s). Fluoride titration experiments established that the singlet and triplet emission peaks are due to acceptor‐based Mes→B charge transfer and donor‐based 3 π→π* transitions, respectively. This dual emission was found to be persistent and observable at ambient temperature in its Pt II complex [Pt( N , N‐ Si‐BNPA)Ph 2 ] ( 2 a ). Furthermore, 2 a was found to undergo intramolecular “roll‐over” CH activation to produce the N , C ‐chelate complex [Pt( N , C ‐Si‐BNPA)(SMe 2 )Ph] ( 2 b ). This compound also displays ambient temperature singlet–triplet dual emission, but with a much greater phosphorescent efficiency than 2 a due to the formation of a more stable chelate ring. Addition of fluoride was found to have little impact on the phosphorescent emission of 2 a , but resulted in a large enhancement of the phosphorescent emission intensity of 2 b . To establish the impact of donor–acceptor geometry on this singlet–triplet dual emission, the properties of linearly conjugated donor–acceptor complexes [Pt( N , N‐ BNPA)Ph 2 ] ( 3 a ) and [Pt( N , C ‐BNPA)Ph 2 ] ( 3 b ) were also examined. Consistent with 2 a and 2 b , the N , C ‐chelate complex 3 b has a much higher phosphorescent efficiency than the N , N ‐chelate 3 a . Although 3 a and 3 b show bright and fluoride‐switchable phosphorescence at ambient temperature, they are not dual emissive and show only metal‐to‐ligand chage‐transfer‐based phosphorescence. The non‐conjugated donor–acceptor geometry and the overlap of the donor and acceptor singlet and triplet excitation bands in Si‐BNPA and its Pt II complexes may thus be the key for achieving singlet–triplet dual emission on two separated chromophores in a single molecule.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 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 | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 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 teacher head, 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".