Halogen Bonding to Carbon: a Directional Interaction for the Reliable Design of Supramolecular Architectures Based on Non-derivatized Aromatic Carbon Systems
Bibliographic record
Abstract
Carbon, although the central element in organic chemistry has been traditionally neglected as a target for directional supramolecular interactions. The design of supramolecular structures involving carbon-rich molecules, such as arenes, has almost exclusively been limited to π-stacking of aromatic systems, or derivatization with heteroatoms as sites for molecular recognition. Here, we demonstrate that C-I···Cπ halogen bonds to carbon-based π-systems can be reliably used as direction-al interactions for the creation of extended structures based on planar, as well as curved aromatic systems, without any need for derivatization or π-stacking. Specifically, we describe the first systematic study of a series of cocrystals containing non-derivatized carbon-only aromatic systems of different sizes and shapes, including polycyclic aromatic hydrocarbons (PAHs) and fullerene C60, which are held together by directional halogen bonds to aromatic carbon atoms. In a large majority (~90%) of structures, the C-I···Cπ halogen bonding with PAHs leads to a supramolecular ladder-like motif, in which the PAHs act as the rungs and halogen bond donors as rails, demonstrating this motif as the first example of a supramolecular synthon based on carbon. These results, supported by novel cocrystal structures, theoretical calculations, and a systematic analysis of the Cambridge Structural Database, offer a new, previously overlooked paradigm for the assembly of carbon-only aromatic systems, not based on π-stacking, but via specific, directional halogen bonding. This new ability to use a car-bon-based supramolecular synthon to direct the assembly aromatic systems provides an exciting opportunity to create materials with new and modified properties based on non-derivatized aromatic systems, as seen from large red and blue shifts in solid-state luminescence for cocrystals of pyrene, coronene and perylene, as well as the appearance of room-temperature phosphorescence upon cocrystal formation.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".