Molecular Networks Created by Charge-Assisted Hydrogen Bonding in Phosphonate, Phosphate, and Sulfonate Salts of Bis(amidines)
Bibliographic record
Abstract
Two bis(amidines), 2,2′-bi-2-imidazoline (BI) and fluoflavin (FF), were treated with phosphonic, phosphoric, and sulfonic acids in an effort to produce crystalline salts composed of ions linked by networks of charge-assisted hydrogen bonds. As intended, mixing bis(amidine) BI with 1,4-benzenediphosphonic acid and 1,3,5-benzenetriphosphonic acid yielded crystals of phosphonate salts of dication H 2 BI +2 . Structural analyses showed that such salts tend to incorporate tapes composed of alternating dications and anions linked by multiple charge-assisted N–H···O hydrogen bonds of type R 2 2 (9) and R 2 1 (7). Typically, the ionic tapes are further connected to form sheets or other assemblies by additional O–H···O hydrogen bonds involving phosphonate anions. An analogous reaction of the more weakly basic bis(amidine) FF with 1,4-benzenedisulfonic acid yielded only a sulfonate salt of monocation HFF +; however, diprotonation could be achieved by phosphoric acid to produce a crystalline salt built from stacks of H 2 FF +2 dications linked to phosphate anions by charge-assisted N–H···O hydrogen bonds of type R 2 2 (8). Together, these results demonstrate that acids with multiple PO(OH) 2 and SO 2 OH groups can react with bis(amidines) to produce salts with structural features resulting predictably from the geometry of the ions and their ability to engage in multiple charge-assisted hydrogen bonds according to standard patterns.
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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".