A New Bridging Chelating Ligand for Crystal Engineering: Synthesis, Polymorphism, and Two Modes of Assembly of 1,4-Bis(3-phenyl-1,3-propanedion)benzene with Metal Cations Resulting in Either Discrete or Polymeric Complexes
Bibliographic record
Abstract
This work introduces a new ligand (H 2 L, PhCOCH 2 COPhCOCH 2 COPh) bearing two β-diketonate functions separated by a phenylene ring. The free ligand was synthesized and isolated in two polymorphic modifications. The ligand exhibits a preference for one of two basic conformational types where β-diketonate functions are approximately coplanar and directed either on opposite sides (trans) or on the same side ∼60° to each other (cis). In the free form, the ligand exists as 100% enol; in the solid state, it adopts a trans conformation. In a one-dimensional (1D) coordination polymer [ZnPy 2 L] n *nPy, the ligand adopts the trans conformation and chelates to two zinc(II) centers bridging them at 11.3 Å. In three of the crystals studied, another structure was observed with an ideal formula [M 3 Py 6 L 3 ]*5(CHCl 3 ). In this case, the ligand adopts a cis conformation and chelates to two metal centers bridging them at 10.7 Å, to produce a trinuclear macrocyclic species. In the crystal, these triangles pack to create channels that accommodate chloroform as a guest. The specific crystals studied had the following overall compositions: [Co 3 Py 6 L 3 ]*4.84(CHCl 3 ), [Co 3 Py 6 L 3 ]*4.11(CHCl 3 ), and [Ni 3 Py 6 L 3 ]*4.68(CHCl 3 ). The architecture displays flexibility and zeolite-like behavior.
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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".