Orthogonalization of Polyaryl Linkers as a Route to More Porous Phosphonate Metal‐Organic Frameworks
Bibliographic record
Abstract
Abstract The coordinative pliancy of the phosphonate functional group means that metal‐phosphonate materials often self‐assemble as well‐packed structures with minimal porosity, as efficient inter‐ligand packing is enabled. Here, we report a multistep synthesis of a novel aryl‐phosphonate linker with an orthogonalized ligand core, 1,3,5‐tris(4’‐phosphonophenyl)‐2,4,6‐trimethylbenzene (H 6 L2) designed to form more open structures. A series of crystalline metal‐phosphonate frameworks (CALF‐35 to ‐39) have been assembled by coordinating to divalent metals (Ba, Sr, Ca, Mg, Zn). H 6 L2 is unable to pack efficiently and, as a consequence, yields several distinct microporous structures. The resulting structures are discussed in detail, with a focus on the solid‐state packing of the sterically rigidified linker. Combined with larger cations (Sr, and Ba), H 6 L2 packs in a parallel‐offset manner, yielding isomorphous and microporous metal‐organic frameworks (CALF‐35 (Sr), and (Ba)). When coordinated to smaller metals (Ca, Mg, Zn), H 6 L2 forms four new structures. Two Ca MOFs of different stoichiometry, (CALF‐36 and 37) and a Mg MOF CALF‐38 show narrow pores and have high selectivities for CO 2 over N 2 and CH 4 . Finally, in CALF‐39 (Zn), H 6 L2 linkers pack in a herringbone fashion, resulting in a material with 10.9×10.1 Å 2 square channels. The stability of all structures was tested, and the most porous structure, CALF‐39 (Zn), was found to retain its structure and gas adsorption after immersion in water over pH 3–11.
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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".