Two open metal sites on the same metal: Dynamics of CO2 in MOF UTSA-74
Bibliographic record
Abstract
Metal-organic frameworks (MOFs) are an emerging class of porous materials with many unique properties that make them promising candidates for carbon dioxide (CO 2 ) capture and storage. A better understanding of the behavior of CO 2 adsorbed inside MOF will enable researchers to develop the ability of designing new MOF based materials with high CO 2 adsorption capabilities. It is well known that presence of open metal sites (OMSs) can greatly enhance the gas adsorption capability of MOFs. MOF UTSA-74, a framework isomer of well-known MOF-74 has a unique feature that upon activation, a single metal ion has two OMSs. Therefore, it presents a unique opportunity to probe the dynamics of CO 2 molecules adsorbed on these OMSs. In this work, the CO 2 adsorptive properties of MOF UTSA-74 are examined with particular attention being paid to the dynamics of the CO 2 adsorbed on these OMSs. Specifically, variable temperature 13 C static solid-state nuclear magnetic resonance (SSNMR) experiments were conducted to directly monitor the behavior of 13 CO 2 in UTSA-74 at different loadings. All CO 2 molecules undergo localized wobbling. At low loadings, some CO 2 molecules jump among three OMSs from three different Zn atoms in the cross-section of the channel. Others hop back and forth between the two neighboring OMSs. At high loading, the three-site jump has ceased, but two-site hopping persists. The dynamical behavior of CO 2 in UTSA-74 results from the unique Zn coordination environment. It was discovered that CO 2 is less mobile in UTSA-74 than in its framework isomer, MOF-74-Zn.
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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 | 0.000 |
| 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 | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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".