Weakly Bonded Molecular Networks Built from Tetranitro- and Tetracyanospirobifluorenes
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Three tetranitro and three tetracyano derivatives of 9,9‘-spirobifluorene were synthesized and crystallized, and their structures were determined by X-ray crystallography. 2,2‘,7,7‘-Tetranitro-9,9‘-spirobi[9 H -fluorene] ( 4 ) self-associates via C−H···O interactions to give an open supramolecular network, with 31% of the total volume of the crystal available for including guests. Tetracyano analogue 5 also crystallizes to give a porous network, but no significant C−H···N interactions are present; instead, molecular association is directed primarily by π-stacking. An extended tetranitro analogue, 2,2‘,7,7‘-tetrakis(4-nitrophenyl)-9,9‘-spirobi[9 H -fluorene] ( 6 ), crystallizes as a nearly close-packed structure held together by a combination of C−H···O interactions and π-stacking. Tetracyano analogue 7 crystallizes to form an open structure maintained by π-stacking, without significant C−H···N contacts. Extended meta-substituted analogues, 2,2‘,7,7‘-tetrakis(3-nitrophenyl)-9,9‘-spirobi[9 H -fluorene] ( 8 ) and 2,2‘,7,7‘-tetrakis(3-cyanophenyl)-9,9‘-spirobi[9 H -fluorene] ( 9 ), were also synthesized and crystallized. The two structures are closely similar and show close-packed architectures involving mainly π-stacking. Together, these observations suggest that cyano groups are not effective acceptors for the formation of C−H···N interactions strong enough to direct molecular association in competition with aryl−aryl interactions, at least in the spirobifluorene system. In contrast, nitro groups can be used to help direct association via C−H···O interactions, either in competition with or in cooperation with other weak interactions.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| 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) | 0.002 | 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 it