Salts of maleic and fumaric acids with organic polyamines: comparison of isomeric acids as building blocks in supramolecular chemistry
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Bibliographic record
Abstract
Maleic acid and fumaric acid both readily form adducts with organic diamines: maleic acid usually forms 2:1 adducts with bases, while fumaric acid usually forms 1:1 adducts, and the supramolecular structures within the two series are not simply related. The 1:2 adducts formed by 1,2-bis(4-pyridyl)ethane and by 4,4'-bipyridyl, respectively, with maleic acid, compounds (1) and (2), are salts [(diamine)H(2)(2+)].[(C(4)H(3)O(4))(-)](2) in which the cations lie across a centre of inversion and a twofold rotation axis, respectively. The ions are linked by N-H...O hydrogen bonds into three-ion aggregates, which are further linked by C-H...O hydrogen bonds into two- and three-dimensional arrays, respectively. In the fumarate salts formed by 2,2'-dipyridylamine (1:1) and 1,4-diazabicyclo[2.2.2]octane (1:2), compounds (3) and (4), the ionic components are linked into molecular ladders. The 1:1 adduct of 4,4'-bipyridyl and fumaric acid, compound (5), contains two neutral components, both of which lie across centres of inversion; these components are linked into chains by a single O-H...N hydrogen bond and thence into sheets by C-H...O hydrogen bonds. The corresponding adduct formed by 1,4-diazabicyclo[2.2.2]octane, compound (6), is a salt that again contains chains linked into sheets by C-H...O hydrogen bonds. In the 1:1 adducts, compounds (7), (8) and (10), that are formed between 1,2-bis(4-pyridyl)ethane, 4,4'-trimethylenedipyridine and hexamethylenetetramine, respectively, with fumaric acid, and in the 1:2 adduct, compound (9), of 2,2'-dipyridylamine and maleic acid, the chains that are generated by the hard hydrogen bonds are linked by C-H...O hydrogen bonds to form, in each case, a single three-dimensional framework. In the 1:1 adduct, compound (11), of 2,2'-bipyridyl and fumaric acid the hydrogen bonds generate two interwoven three-dimensional frameworks.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.003 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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 it