Solid-State <sup>51</sup>V NMR Investigation of the Intercalation of Alkylamines into Layered α-Vanadyl Phosphate
Bibliographic record
Abstract
The intercalation behavior of layered alpha-phase vanadyl phosphate, alpha-VOPO(4).2H(2)O (alpha-VP), with alkylamine was investigated by (51)V solid-state NMR in combination with powder XRD. The XRD results show that the amines form bimolecular layers upon intercalation. For the intercalation with short chain amines (propylamine, pentylamine, and hexylamine), the C-C chain of the amines is tilted with respect to the inorganic basal plane. The amines with a longer alkyl chain (dodecylamine and hexadecylamine) tend to adopt an orientation where the C-C chain direction is perpendicular to the VP layer. For the amine with eight carbon atoms (octylamine), the intercalation results in two coexisting phases with different chain orientations. (51)V solid-state NMR was used to directly probe the effect of intercalation on the metal center environments. Both (51)V magic-angle spinning and static spectra of alpha-VP intercalated with different amines were obtained at different magnetic fields, and they are sensitive to intercalation. The intercalation induces the (51)V isotropic chemical shift to move toward deshielded direction. (51)V chemical shielding parameters such as the span are sensitive to the orientation of the amine chain with respect to the VP basal plane. For the V centers interacting with the amines having a tilted orientation, the (51)V span gradually decreases with increasing alkyl chain length. However, the span of the (51)V atoms interacting with the amines perpendicular to the VP layer is larger and independent of the length of the alkyl chain. The (51)V NMR data indicate that for the alpha-VPs intercalated with long-chain amines, such as dodecylamine and hexadecylamine, the amines can assume both tilted and perpendicular orientations.
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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".