Conformational Changes of <i>trans</i>-1,2-Dichlorocyclohexane Adsorbed in Zeolites Studied by FT-Raman Spectroscopy and Molecular QM/MM Simulations
Bibliographic record
Abstract
The conformational behavior of trans -1,2-dichlorocyclohexane (T12D) adsorbed inside zeolites with Faujasite structure (FAU) including sodium Y (Na–Y) and siliceous Y (Si–Y) was investigated by FT-Raman spectroscopy and molecular simulations. The results have clearly shown that the conformational and dynamic properties of T12D strongly depend on the presence of charge-balancing cations as well as Si/Al ratio. Upon loading into Na–Y, the population of the diequatorial ( ee ) conformer increases compared with pure T12D liquid due to the strong interaction with the extra-framework Na + ions. Molecular simulations of T12D in Na–Y and Si–Y have also been carried out. The T12D molecule was modeled by quantum and semiempirical quantum chemistry methods and embedded in a zeolite framework that was described by empirical force field. Conformational changes were sampled using quantum mechanics/molecular mechanics molecular dynamics and replica exchange molecular dynamics. Molecular simulations revealed that the ee conformer is preferable versus the diaxial ( aa ) conformer in both Na–Y and Si–Y frameworks. However, in the Na–Y supercage environment, the Na + ions polarize the ee conformer stronger than in Si–Y. This leads to a larger shift of the conformational equilibrium in favor of the ee component in Na–Y relative to Si–Y. Computations of the equilibrium population of aa and ee conformers using the dihedral Cl–C–C–Cl angle distributions of aa and ee showed good quantitative agreement with the experimental findings with respect to the dominant ee conformer in both Na–Y and Si–Y.
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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) | 0.001 | 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".