A solid-state <sup>35/37</sup>Cl NMR study of a chloride ion receptor and a GIPAW-DFT study of chlorine NMR interaction tensors in organic hydrochlorides
Bibliographic record
Abstract
The results of a 35/37Cl solid-state nuclear magnetic resonance (SSNMR) study of the 1-butyl-3-methylimidazolium chloride complex of meso-octamethylcalix[4]pyrrole (1) are reported. Line shapes obtained from magic-angle-spinning and stationary powder samples collected at 9.4 and 21.1 T are analyzed to provide the 35/37Cl quadrupolar tensor and chemical shift (CS) tensor and their relative orientation. The relatively high symmetry of the chloride ion coordination environment is manifested in the small value of the quadrupole coupling constant, CQ(35Cl) = 1.0 MHz. The isotropic chemical shift of 120 ppm (with respect to NaCl(s)) is at the upper edge of the typical range seen for organic hydrochlorides. Consideration of chemical shift anisotropy (span, Ω = 50 ppm) and non-coincidence of the quadrupolar and CS tensors were essential to properly simulate the experimental spectra. The utility of gauge-including projector-augmented wave density functional theory (GIPAW-DFT) calculations of chlorine quadrupolar and CS tensors in organic chlorides was explored by validation against available benchmark experimental data for solid amino acid hydrochlorides. The calculations are shown to systematically overestimate the value of the 35Cl quadrupole coupling constant. Additional calculations on various hydrated and solvated models of 1 are consistent with a structure in which solvent and water of hydration are absent.
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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 | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".