A Leap Forward in the Coordination Chemistry of <i>N</i>-hydroxy-1,8-naphthalimide Chelate: New {Dy<sub>2</sub>} and {Dy<sub>5</sub>} Single-Molecule Magnets and the Structure-Directing Role of Supporting β-Diketonate Ligands
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide The employment of the organic chelating/bridging ligand N -hydroxy-1,8-naphthalimide (hynadH) in Dy III chemistry, combined with various β-diketones, such as 2,2,6,6-tetramethyl-3,5-heptanedione (dpmH), 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (ttaH), and 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (hfacH), as ancillary/supporting ligands, has facilitated the isolation of dinuclear complexes [Dy 2 (hynad) 2 (dpm) 4 ] ( 1 ) and [Dy 2 (hynad) 4 (tta) 2 ] ( 2 ), as well as a highly symmetric [Dy 5 (OH) 3 (hynad) 6 (hfac) 3 (O 2 CCF 3 ) 3 ] ( 3 ) cluster. The CF 3 CO 2 – groups have been probably derived from a retro-Claisen condensation reaction of the hfac – groups under the prevailing basic conditions. The R-substituents on the external α-carbons of the β-diketonate ligands, with their varying electron-withdrawing or donating abilities, significantly impacted the nuclearity of the inorganic compounds and the resulting hynad – /β-diketonate ratio of the coordinated groups. Owing to the distinct steric and electronic effects of the diketones, the Dy III coordination polyhedra in 1 - 3 also differed, including the triangular dodecahedron ( 1 ), spherical tricapped trigonal prismatic ( 2 ), and biaugmented trigonal prismatic and spherical tricapped trigonal prismatic geometries ( 3 ). Interestingly, complexes 1 and 2 exhibited well-resolved out-of-phase (χ M ″) ac signals, which were both frequency- and temperature-dependent, thereby acting as single-molecule magnets (SMMs). In contrast, the polynuclear compound 3 displayed only weak tails of ac signals. The dpm-containing complex 1 demonstrated the highest energy barrier ( U eff = 100.27(7) K) for the magnetization reversal, a result attributed to the interplay between weaker transverse coordination effects and stronger axial crystal field effects at the Dy III ions. This is further supported by the variations in Dy–O axial versus equatorial bond lengths. The combined results reinforce the reactivity of coordinated ligands as a fruitful strategy for the preparation of new molecule-based magnetic materials through the stepwise modification of the ancillary capping groups.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
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".