H<sub>4</sub>HBEDpa: Octadentate Chelate after A. E. Martell
Bibliographic record
Abstract
H4HBEDpa, a new octadentate chelator inspired by the 1960s ligand HBED of Arthur E. Martell, has been investigated for a selection of trivalent metal ions useful in diagnostic and therapeutic applications (Sc3+, Fe3+, Ga3+, In3+, and Lu3+). Complex formation equilibria were thoroughly investigated using combined potentiometric and UV–vis spectrophotometric titrations which revealed effective chelation and high metal-sequestering capacity, in particular for Fe3+, log KFeL = 36.62, [Fe(HBEDpa)]−. X-ray diffraction study of single crystals revealed that the ligand is preorganized and forms hexa-coordinated complexes with Fe3+ and Ga3+ at acidic pH. Density functional theory (DFT) calculations were applied to probe the geometries and energies of all the possible conformers of [M(HBEDpa)]− (M = Sc3+, Fe3+, Ga3+, In3+, and Lu3+). DFT calculations confirmed the experimental findings, indicating that [Fe(HBEDpa)]− is bound tightly in an asymmetric pattern as compared to the symmetrically bound and more open [Ga(HBEDpa)]−, prone to hydrolysis at higher pH. DFT calculations also showed that a large metal ion such as Lu3+ fully coordinates with HBEDpa4–, forming a binary octadentate complex in its lowest-energy form. Smaller metal ions form six or seven coordinate complexes with HBEDpa4–.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.018 | 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".