From Coordination to π‐Hole Chemistry of Transition Metals: Metalloporphyrins as a Case of Study
Bibliographic record
Abstract
Abstract Herein we have evidenced the formation of favorable π‐hole Br⋅⋅⋅metal noncovalent interactions (NCIs) involving elements from groups 9, 11 and 12. More in detail, M (M=Co2+, Ni2+, Cu2+ and Zn2+) containing porphyrins have been synthesized and their supramolecular assemblies structurally characterized by means of single crystal X‐ray diffraction and Hirshfeld surface analyses, revealing the formation of directional Br⋅⋅⋅M contacts in addition to ancillary hydrogen bond and lone pair‐π bonds. Computations at the PBE0‐D3/def2‐TZVP level of theory revealed the π‐hole nature of the Br⋅⋅⋅M interaction. In addition, the physical nature of these NCIs was studied using Quantum Chemistry methodologies, providing evidence of π‐hole Spodium and Regium bonds in Zn2+ and Cu2+ porphyrins, in addition to unveiling the presence of a π‐hole for group 9 (Co2+). On the other hand, group 10 (Ni2+) acted as both electron donor and acceptor moiety without showing an electropositive π‐hole. Owing to the underexplored potential of π‐hole interactions in transition metal chemistry, we believe the results reported herein will be useful in supramolecular chemistry, organometallics, and solid‐state chemistry by i) putting under the spotlight the π‐hole chemistry involving first row transition metals and ii) unlocking a new tool to direct the self‐assembly of metalloporphyrins.
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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".