Deducing CO<sub>2</sub>motion, adsorption locations and binding strengths in a flexible metal–organic framework without open metal sites
Bibliographic record
Abstract
Microporous metal-organic frameworks (MOFs) have high surface areas and porosities, and are well-suited for CO2 capture. MIL-53 features corner-sharing MO4(OH)2 (M = Al, Ga, Cr, etc.) octahedra interconnected by benzenedicarboxylate linkers that form one-dimensional rhombic tunnels, and exhibits an excellent adsorption ability for guest molecules such as CO2. Studying the behavior of adsorbed CO2 in MIL-53 via solid-state NMR (SSNMR) provides rich information on the dynamic motion of guest molecules as well as their binding strengths to the MOF host, and sheds light on the specific guest adsorption mechanisms. Variable-temperature (13)C SSNMR spectra of (13)CO2 adsorbed within various forms of MIL-53 are acquired and analyzed. CO2 undergoes a combination of two motions within MIL-53; we report the types of motion present, their rates, and rotational angles. (1)H-(13)C CP SSNMR experiments are used to examine the proximity of (1)H atoms in the MOF to (13)C atoms in CO2 guests. By replacing (1)H with (2)H in MIL-53, the location of the CO2 adsorption site in MIL-53 is experimentally confirmed by (1)H-(13)C CP SSNMR. The binding strength of CO2 within these MIL-53 MOFs follows the order MIL-53-NH2 (Al) > MIL-53-NH2 (Ga) > MIL-53 (Al) > MIL-53 (Ga).
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 teacher head, 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".