Thermal Behavior of a Self-Assembled Silver <i>n</i>-Dodecanethiolate Layered Material Monitored by DSC, FTIR, and <sup>13</sup>C NMR Spectroscopy
Bibliographic record
Abstract
The thermal behavior of a self-assembled silver alkanethiolate layered material (AgSC n, n = 12) has been explored using two spectroscopic techniques: 13 C CPMAS NMR ( 13 C cross-polarization magic angle spinning NMR) and FTIR (Fourier transform infrared) spectroscopy. The goal was to correlate structural changes monitored by spectroscopy with the phase transition detected by DSC (differential scanning calorimetry). Variable-temperature 13 C CPMAS NMR was used for the first time to study silver alkanethiolates in order to obtain conformational and structural information about each of the C positions in the alkyl chain as a function of the temperature. In the low-temperature domain, a subtle change in the chain packing is observed, as evidenced by the chemical shift of the internal methylenes in the 13 C CPMAS NMR spectra. A remarkable degree of conformational order is observed, which is retained up to 120 °C. A sharp phase transition between 125 and 130 °C is associated with conformational changes, from all-trans to gauche containing bonds, as detected by IR and 13 C CPMAS NMR. The complete reversibility of these structural changes indicates that the alkyl chains remain anchored to the Ag−S backbone above the transition. The key determinants of the thermal behavior of the layered system are the strong Ag−S bonding and the high conformational degree of order conferred by the polymeric character of the compound.
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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".