Synthesis and ESI-MS Alkali Metal Ion Binding Selectivities of Cone, Partial Cone, and 1,3-Alternate 1,3-Bis(α-picolyloxy)-p-tert-butylcalix[4]arene Crown-6 and 1,1'-Binaphthalene-2,2'-diyl Crown-6 Conformers
Bibliographic record
Abstract
The syntheses of 1,3-bis(α-picolyloxy)-p-tert-butylcalix[4]arene crown-6 and 1,1'-binaphthalene-2,2'-diyl crown-6 title conformers have been achieved by two complementary synthetic strategies, which differ in the order in which the polyether loop and the pendant picolyl groups are introduced. The structure and conformation of all new compounds have been firmly established by NMR spectroscopy, and further proven by X-ray analysis for the intermediate p-tert-butyl-25,27-(1,1'-binaphthalene-2,2'-diyl-crown-6)-26,28-dihydroxycalix[4]arene. Within each set of conformers, the nature of the polyether chain has little or no influence on the overall conformation of the calixarene platform. The alkali metal ion binding selectivities of the two series of calixarenes have been evaluated in competitive complexation experiments by electrospray ionization mass spectrometry. In the p-tert-butylcalix[4]arene crown-6 series, partial cone and 1,3-alternate conformers show a peak selectivity for the larger Cs+ ions, while the cone one preferentially binds the smaller Na+ ions. On the other hand, the cone and 1,3-alternate binaphthyl-containing analogues show a preference for Na+ ions, the partial cone being quite unselective.
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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) | 0.002 | 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".