Hydrogen-bonded networks in crystals built from bis(biguanides) and their salts
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Bibliographic record
Abstract
Biguanide groups and biguanidinium cations incorporate multiple sites that can donate or accept hydrogen bonds. To assess their ability to associate and to direct the formation of extended hydrogen-bonded networks, we examined the structure of crystals of four compounds in which two neutral biguanide groups or the corresponding cations are attached to the 1,4- and 1,3-positions of phenylene spacers. As expected, all four structures incorporate extensive networks of hydrogen bonds and reveal other reliable features. In particular, (1) neutral biguanide groups favor a roughly planar conformation with an intramolecular hydrogen bond, and they associate as hydrogen-bonded pairs, (2) despite coulombic repulsion, biguanidinium cations can also associate as hydrogen-bonded pairs, and (3) the 1,3-phenylenebis(biguanidinium) dication favors a pincerlike conformation that allows chelation of suitable counterions. However, the precise patterns of hydrogen bonding in the structures vary substantially, limiting the usefulness of biguanide and biguanidinium as groups for directing supramolecular assembly.Key words: bis(biguanide), bis(biguanidinium), structure, hydrogen-bonded network, noncovalent interaction, supramolecular chemistry, crystal engineering.
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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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 it