Chiral <i>versus</i> racemic building blocks in supramolecular chemistry: malate salts of organic diamines
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Bibliographic record
Abstract
(S)-Malic acid forms a salt with N,N'-dimethylpiperazine, [MeN(CH(2)CH(2))(2)NMe]H(2)(2+) x 2C(4)H(5)O(5)(-) (1) (triclinic, P1, Z' = 1), in which the cations link pairs of hydrogen-bonded anion chains to form a molecular ladder. With 4,4'-bipyridyl, (S)-malic acid forms a 1:1 adduct which crystallizes from methanol to yield two polymorphs, (2) (triclinic, P1, Z' = 1) and (3) (monoclinic, C2, Z' = 1), while racemic malic acid with 4,4'-bipyridyl also forms a 1:1 adduct, (4) (monoclinic, P2(1)/c, Z' = 1). In each of (2), (3) and (4) the components are linked by O[bond]H...N and N[bond]H...O into chains of alternating bipyridyl and malate units, which are linked into sheets by O[bond]H...O hydrogen bonds. In each of the 1:1 adducts (5) and (6), formed by, respectively, (S)-malic acid and racemic malic acid with 1,2-bis(4'-pyridyl)ethene, the diamine is disordered over two sets of sites, related by a 180 degrees rotation about the N...N vector. In (5), (C(12)H(10)N(2))H(+) x C(4)H(5)O(5)(-) (triclinic, P1, Z' = 1), the components are again linked by a combination of N[bond]H...O and O[bond]H...O hydrogen bonds into sheets, while in (6) (triclinic, P1;, Z' = 0.5) there is only partial transfer of the H atom from O to N and the malate component is disordered across a centre of inversion. With 1,4-diazabicyclo[2.2.2]octane, racemic malic acid forms a 1:2 salt, [(C(6)H(12)N(2))H(2)](2+).2C(4)H(5)O(5)(-) (7) (monoclinic, P2(1)/c, Z' = 2), while (S)-malic acid forms a 1:1 adduct, (8) (monoclinic, P2(1), Z' = 3). There are thus six independent molecular components in each. In (7) the ions are linked by an extensive series of N[bond]H...O and O[bond]H...O hydrogen bonds into a three-dimensional framework, but in (8) there is extensive disorder involving all six components, and no refinement proved to be feasible.
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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 | 0.003 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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