H<sub>2</sub>ampa─Versatile Chelator for [<sup>203</sup>Pb]Pb<sup>2+</sup>, [<sup>213</sup>Bi]Bi<sup>3+</sup>, and [<sup>225</sup>Ac]Ac<sup>3+</sup>
Bibliographic record
Abstract
A new decadentate chelator, H2ampa, was designed to be a potential radiopharmaceutical chelator component. The chelator involves both amide and picolinate functional groups on a large non-macrocyclic, ether-bridged backbone. With its large scaffold, H2ampa was paired with [nat/203Pb]Pb2+, [nat/213Bi]Bi3+, and natLa3+/[225Ac]Ac3+ ions. Nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry were used to study the non-radioactive metal complexes. A single crystal of [Bi(ampa)](NO3) was obtained; its asymmetric, 10-coordinate complex structure was revealed by X-ray diffraction. Optimal conformations of the metal complexes were assessed by density functional theory studies to provide further structural information. Solution studies providing thermodynamic insights into metal complex formation revealed H2ampa coordinated Bi3+, Pb2+, and La3+ ions to obtain pM values of 26, 14.8, and 15.1, respectively. Preliminary concentration-dependent radiolabeling experiments were carried out between H2ampa and three different radiometals to evaluate their compatibility for radiopharmaceutical applications. The chelator radiolabeled [203Pb]Pb2+, [213Bi]Bi3+, and [225Ac]Ac3+ in short reaction times (7–30 min), at dilute concentrations, and under mild conditions. Thus, H2ampa was proven to be a versatile chelator able to well coordinate a small range of radiometals frequently considered to be alpha therapeutic candidates.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.004 | 0.005 |
| Meta-epidemiology (broad) | 0.005 | 0.002 |
| Bibliometrics | 0.001 | 0.004 |
| Science and technology studies | 0.003 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.004 | 0.003 |
| Research integrity | 0.003 | 0.007 |
| Insufficient payload (model declined to judge) | 0.011 | 0.001 |
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; both teacher heads agree on what is shown here.
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".