Cu@Core in the Cu <sub>3</sub> C <sub>3</sub> Ring with 2-bdppmapy: A High-Quantum-Yield Planar Hexagonal Cu(I) Metallacycle
Bibliographic record
Abstract
Despite the potential of Cu(I) complexes in optoelectronics, their practical application is hindered by their susceptibility to oxidation and low photoluminescence quantum yields (PLQYs). While phosphine–alkynyl coligation strategies have improved stability, structural distortions in conventional open-cube Cu 4 clusters limit PLQYs to an unsatisfactory level. Herein, we address this challenge via ligand engineering with a bidentate diphosphine (2-bdppmapy = N,N -bis((diphenylphosphino)methyl)-2-pyridinamine). This design enables the synthesis of planar tetranuclear clusters [(2-bdppmapy) 3 Cu 4 (μ 3 -PhC≡C) 3 ]X (X – = I –, Br –, ClO 4 –, BF 4 –, Cl – ) featuring a near-perfect coplanar Cu 3 C 3 @Cu hexagonal ring. Single-crystal X-ray diffraction reveals exceptional planarity (mean deviation: 0.025 Å) and strong cuprophilic interactions (Cu···Cu: 2.387–2.441 Å). These complexes achieve an unprecedented solid-state PLQY of up to 93% with turquoise emission, attributed to their rigid planar architecture, which maximizes electronic delocalization. Spectroscopic analysis reveals a structured emission band with a maximum at 483 nm and a pronounced shoulder at 526 nm, which arise from ν(C═C) and ν(C≡C) stretching vibrations localized on the phenylacetylene ligands. Notably, the emissions exhibit microsecond-scale lifetimes (τ ≈ 22 μs), indicative of long-lived triplet phosphorescence. Theoretical calculations further confirm that the vibronically structured emission originates from T 1 triplet excited states derived from hybrid metal-to-ligand charge transfer and intraligand charge transfer transitions within the phenylacetylene framework.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.000 | 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".