Further investigation on the nitration of BODIPY with cupric nitrate: crystal structures of 4,4-difluoro-1,3,5,7,8-pentamethyl-2-nitro-4-bora-3a,4a-diaza-<i>s</i>-indacene, 4,4-difluoro-3-nitro-8-phenyl-4-bora-3a,4a-diaza-<i>s</i>-indacene, and 3-chloro-6-ethyl-5,7,8-trimethyl-2-nitro-4,4-diphenyl-4-bora-3a,4a-diaza-<i>s</i>-indacene
Bibliographic record
Abstract
The treatment of non-fully substituted 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) with cupric nitrate leads to the introduction of a nitro group at different positions of the BODIPY core, depending on the substitution pattern. This methodology complements the treatment of fully substituted BODIPY with cupric nitrate that was previously reported. The crystal structures of 4,4-difluoro-1,3,5,7,8-pentamethyl-2-nitro-4-bora-3a,4a-diaza-s-indacene, C14H16BF2N3O2 (5a) 4,4-difluoro-3-nitro-8-phenyl-4-bora-3a,4a-diaza-s-indacene, C15H10BF2N3O2 (5b) and 3-chloro-6-ethyl-5,7,8-trimethyl-2-nitro-4,4-diphenyl-4-bora-3a,4a-diaza-s-indacene, C26H25BClN3O2 (5d) are presented. In all three structures, the fused ring system is in a very flattened `V-shape', with dihedral angles between the two outer five membered rings of 8.12 (14), 6.67 (9) and 12.30 (18) Å for 5a, 5b and 5d, respectively. In each case, the central six-membered ring is in a flattened sofa conformation. In the crystal of 5a, molecules are linked by weak C—H...O and C—H...F hydrogen bonds forming sheets parallel to (10-1). In the crystal of 5b molecules are linked by weak C—H...O and C—H...F hydrogen bonds and π–π interactions forming sheets parallel to (001). In the crystal of 5d, weak C—H...O hydrogen bonds link molecules into chains along [001]. In compound 5d, the atoms of the nitro group were refined as disordered over two sets of sites with occupancies 0.618 (12) and 0.382 (12).
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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 | 0.001 | 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 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".