Probing Optical Anisotropy and Polymorph‐Dependent Photoluminescence in [Ln<sub>2</sub>] Complexes by Hyperspectral Imaging on Single Crystals
Bibliographic record
Abstract
Abstract Two homodinuclear and one heterodinuclear lanthanide (Ln)‐based complexes of the general formula [Ln 2 (bpm)(tfaa) 6 ] (Ln=Eu ( 1 ), Tb ( 2 ), Eu−Tb ( 3 ), bpm=2,2′‐bipyrimidine, tfaa − =1,1,1‐trifluoroacetylacetonate) were synthesized and characterized by single‐crystal photoluminescence spectroscopy and hyperspectral imaging. Complexes 1 and 2 crystallize in two polymorphic structures, while three polymorphs were isolated for 3 , namely having needle‐, plate‐, and block‐like morphologies. Single‐crystal photoluminescence spectroscopy and imaging on Eu 3+ ‐containing 1 and 3 revealed polymorph‐dependent J ‐splitting of the hypersensitive 5 D 0 → 7 F 2 Eu 3+ transition as well as electric‐to‐magnetic dipole emission intensity ratios. According to these observations, the lowest symmetry chemical environment was attributed to the Eu 3+ ions present in the needle‐like polymorph, also in agreement with single‐crystal X‐ray diffraction analysis. More importantly, hyperspectral imaging on all three single‐crystal polymorphs of 3 exhibits optical anisotropy with photoluminescence enhancement at specific crystallographic faces. This behavior was ascribed to the distinct molecular packing of the Ln−Ln dimers in each polymorphic crystal as well as to face‐specific local symmetry of the Eu 3+ centers. Overall, opto‐structural relationships of three Ln−Ln dimers and their single‐crystal polymorphs were established as a particularly promising avenue for control of photoluminescence by chemical crystal engineering.
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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 | 0.000 |
| 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) | 0.000 | 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".