A Theoretical Study of Cohesion, Structural Deformation, Inclusion, and Dynamics in Porous Hydrogen-Bonded Molecular Networks
Bibliographic record
Abstract
Molecules with multiple sites of hydrogen bonding attached to suitable cores tend to crystallize as open networks. The resulting crystals can have the following unusual properties: They can include significant amounts of guest molecules; the guests are typically located in channels and can be exchanged without loss of crystallinity; and the geometry of the networks can change in response to new guests. We have found that DFT calculations can provide accurate simulations of the unusual structure and properties of such materials, represented by crystals of prototypic tetrapyridinone 1. These calculations have yielded three key insights that cannot be obtained directly from experiments. (1) The hypothetical porous network obtained by removing guests from crystals of compound 1 is highly flexible, and its deformations are inherently anisotropic, leading to lengthening or shortening of the channels along the c axis and no significant changes along the a and b axes. (2) Quantitative analysis of the total cohesive energy has revealed that hydrogen bonding within the network makes a dominant contribution, along with interactions of guests with the network. (3) Differences in the overall stability of crystals of compound 1 as the guests are varied do not arise primarily from significant changes in the cohesive energy of the network itself; instead, differences in guest-guest interactions play a key role, resulting from the nature of the guests and constraints imposed by the surrounding network. These insights, together with the results of ab initio molecular dynamics, help explain how hydrogen-bonded networks can be robust yet permit molecular movement that underlies the exchange of guests and adaptive porosity. These insights promise to be of general value to scientists studying ordered molecular materials in which strong directional interactions are prominent.
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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 | 0.001 | 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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".