Synthesis, characterization, and X-ray crystal structures of Co(II) and La(III) complexes of a pyridine containing self-assembling system and solution studies of the Co(II) complex
Bibliographic record
Abstract
The complexes [pyda.H]2[Co(pydc)2]·H2O (I) and [pyda·H]2[La2(pydc)4(H2O)4].2H2O (II) were prepared from the complexation of a novel pyridine containing self-assembling system LH2, ([pyda·H2]2+[pydc]2) (pyda = 2,6-pyridinediamine and pydc·H2 = 2,6-pyridinedicarboxylic acid), with cobalt(II) and lanthanum(III) salts in 82% and 74% yields, respectively. The characterizations were performed using elemental analysis, ESI mass spectroscopy as well as 1H and 13C solution NMR spectroscopy, and X-ray crystallography. The crystal systems I and II are monoclinic and triclinic with space groups P21/n and P[Formula: see text] respectively. Coordination number around each Co atom is six with distorted octahedral geometry, while coordination number around each La atom is nine with highly distorted tricapped trigonal prism geometry. The paramagnetic Co(II) and diamagnetic La(III) complexes show 1H NMR resonances of both anionic [pydc]2- and cationic counter ion [pyda·H]+ in DMSO-d6. The complexation reactions of the complex I in aqueous solution were investigated by potentiometric pH titrations and the equilibrium constants for all major complexes formed are described. The results are presented in the form of distribution diagrams revealing the concentrations of individual complex species as a function of pH. The results revealed that at a pH range 4.04.5 the major complex species is [(pyda·H)]2[Co(pydc)2].Key words: self-assembly, X-ray crystal structure, Co(II) complex, La(III) complex, 2,6- pyridinedicarboxylic acid, 2,6-pyridinediamine, hydrogen bonding.
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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) | 0.001 | 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".