Five New Cobalt(II) and Copper(II)-1,2,4,5-benzenetetracarboxylate Supramolecular Architectures: Syntheses, Structures, and Magnetic Properties
Bibliographic record
Abstract
1,2,4,5-Benzenetetracarboxylic acid (H 4 btec) and a combination of N -donor coligands, such as 4-aminopyridine (4-apy), pyrazine (pyz), 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz), and 4,4‘-bipyridine (4,4‘-bipy) with transition metal ions Co(II) and Cu(II), give rise to five coordination complexes namely, [{Co(H 2 btec)(H 2 O) 4 }·4-apy·(H 2 O) 2 ] n ( 1 ), [{Cu(btec)(4-apy) 2 }·(4-Hapy) 2 ·(H 2 O) 4 ] n ( 2 ), [{Cu(H 3 btec) 2 (pyz)·(H 2 O) 2 }·H 2 O] n ( 3 ), [Co(tptz)(H 2 O) 2 (H 2 btec)]·(H 2 O) 2 ( 4 ), and [{Co 2 (4,4‘-bipy) 2 (H 2 O) 8 }·(btec)·(H 2 O) 2 ] n ( 5 ). All these complexes form supramolecular frameworks through ligand-based hydrogen bonding interactions. They have been characterized by a combination of analytical, spectroscopic, and crystallographic methods. These highly crystalline complexes have been obtained under different pH conditions at room temperature and the btec binding mode differs in these five complexes. Complex 1 is a one-dimensional (1D) layered solid consisting of alternating neutral metal−organic coordination polymeric chains, [Co(H 2 btec)(H 2 O) 4 ] n, and amines whereas the molecular structure of 2 is made up of alternating layers of anionic [Cu(btec)(4-apy) 2 ] 2- n coordination polymers and 4-apy cations (4-Hapy). In both 1 and 2, btec links the metal centers. Complex 3 is composed of zigzag 1D copper chains, and complex 4 is a mononuclear cobalt complex. In both 3 and 4, btec binds as a monodentate ligand. In the crystal structure of 5, btec 4- is present unbound in the lattice and linked to 1D chains of [Co(4,4‘-bipy)(H 2 O) 4 ] 2+ through strong hydrogen bonding interactions. The magnetic properties of the polymers were investigated in the temperature range 300−2 K. The values for the spin coupling constant J were estimated to be −0.60, −0.50, −0.79, and −5.72 cm -1 for 1 − 3 and 5, respectively, indicative of antiferromagnetic interactions.
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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".