Complexation of the La(III) cation by <i>p</i>-sulfonatocalix[4]arene A <sup>139</sup>La NMR study
Bibliographic record
Abstract
The complexation of La(III) by the water-soluble p-sulfonatocalix[4]arene was thermodynamically characterized by 139 La NMR. The 139 La NMR data are consistent with the formation of a 1:1 complex resulting from electro static interactions between the sulfonato groups and La(III). The complexation is entropy-driven and is characterized by a positive standard enthalpy (Δ r H° = 11.0 ± 0.5 kJ mol 1 ) and a positive standard entropy (Δ r S° = 108 ± 2 J K 1 mol 1 ), which are in very good agreement with the ones determined previously by microcalorimetry. The linear relationship between the 139 La NMR linewidth of the free and of the complexed cation, obtained at temperatures ranging from 290 to 340 K, excludes the formation of complexes or aggregates other than the 1:1 complex. It shows also that upon complexation, the effective radius of La(III) undergoes an increase of 50%, related to the replacement of water molecules of the hydrated cation by sulfonato groups of the ligand.Key words: complexation, water-soluble calixarene, p-sulfonatocalix[4]arene, 139 La NMR, lanthanum.
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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 | 0.000 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".