Conjugated Triarylboryl Donor−Acceptor Systems Supported by 2,2′-Bipyridine: Metal Chelation Impact on Intraligand Charger Transfer Emission, Electron Accepting Ability, and “Turn-on” Fluoride Sensing
Bibliographic record
Abstract
To investigate the impact of metal-chelation on intraligand charge transfer emission involving a triarylboron group, three 2,2'-bipyridine derivative molecules, 5,5'-bis(BMes(2))-2,2'-bipy (B2bpy), 5-(BMes(2))-5'-(NPh(2))-2,2'-bipy (BNbpy), and 5,5'-bis(NPh(2))-2,2'-bipy (N2bpy) have been synthesized, which can be described as donor-only, donor-acceptor, and acceptor-only systems. Each of these molecules displays distinctive electrochemical and photophysical properties with BNbpy and N2bpy being bright emitters and B2bpy being a strong electron acceptor. In addition, BNbpy displays a "turn-on" fluorescent response while B2bpy has a "turn-off" response upon binding with fluoride ions. These molecules can readily chelate to a PtPh(2) or a PtCl(2) group, producing square planar complexes Pt(B2bpy)Ph(2) (Pt-1), Pt(B2bpy)Cl(2) (Pt-1a), Pt(BNbpy)Ph(2) (Pt-2), Pt(BNbpy)Cl(2) (Pt-2a), and Pt(N2bpy)Ph(2) (Pt-3) that have significantly altered electrochemical and photophysical properties from those of the free ligands. Metal chelation has been found to greatly enhance the electron accepting ability of the three ligands, especially B2bpy and BNbpy. The Ph and Cl auxiliary ligands have also been found to have a significant impact on the electrochemical and photophysical properties of the complexes. B2bpy complexes Pt-1 and Pt-1a are not luminescent at ambient temperature while BNbpy complexes Pt-2 and Pt-2a display room temperature phosphorescence in solution under air that has a similar "turn-on" response toward fluoride ions as the free BNbpy does but with a much more dramatic color switch (orange or red to blue-green). The persistent intraligand N-->B charge transfer transition in the BNbpy complexes is believed to play a key role in their unique phosphorescent response toward fluorides. The complex Pt-3 displays a bright blue-green phosphorescence in solution at ambient temperature. Density functional theory computations established that the lowest electronic transition in the Pt(II) complex is from the Pt(II) d orbital and the auxiliary ligand to the pi* orbital of the 2,2'-bipy derivative ligand.
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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".