Hydrolytic Synthesis and Structural Characterization of Lanthanide Hydroxide Clusters Supported by Nicotinic Acid
Bibliographic record
Abstract
Polynuclear lanthanide hydroxide complexes featuring the cubane-like [Ln(4)(mu(3)-OH)(4)](8+) [Ln = Eu(III), Gd(III)] cluster core have been synthesized by controlled hydrolysis of the lanthanide ions using nicotinic acid as the ancillary ligand. The synthetic procedure has been found to significantly influence the nature of the resulting cluster species. In a one-pot synthesis, adjusting the pH of the reaction mixture containing Ln(ClO(4))(3) and nicotinic acid afforded tetranuclear complexes of the general formula [Ln(4)(mu(3)-OH)(4)(Hnic)(5)(H(2)O)(12)](ClO(4))(8) with the [Ln(4)(mu(3)-OH)(4)](8+) (Ln = Eu, Gd) cluster core encapsulated by zwitterionic nicotinate ligands. In stark contrast, mixing aqueous solutions of Ln(ClO(4))(3) and nicotinic acid whose pH had been preadjusted produced assemblies composed of two of the cubane-like cluster cores that are related by a crystallographic inversion center and are doubly bridged by nicotinate ligands using both the carboxylate group and pyridyl N atom for coordination. The influences of pH conditions and synthetic procedures on the identity of the resulting cluster species are discussed, so is the structural relevance of the low-pH complexes to their cluster analogues obtained under higher-pH conditions.
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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 | 0.000 | 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 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".