Liquid crystals with axially chiral 3,3′-dinitro-2,2′,6,6′-tetramethylbiphenyl cores: the lateral shielding effect of bicyclo[2.2.2]octane-1-carboxylate terminal chains
Bibliographic record
Abstract
Calamitic mesogens with axially chiral 3,3′-dinitro-2,2′,6,6′-tetramethylbiphenyl cores and combinations of 4-alkoxybenzoate and 4-pentyl- or 4-alkoxybicyclo[2.2.2]octane-1-carboxylate terminal chains were synthesized and characterized. The results suggest that the bicyclo[2.2.2]octane segment is effective in shielding the unfavorable lateral bulk of the axially chiral biphenyl core and imparting mesogenic properties to the calamitic structures. Most of the compounds reported herein form a chiral nematic (N*) phase with a pitch in the submicron range that increases with temperature. Two homologues with the longest alkoxy terminal chains form a chiral smectic A (SmA*) phase. Two symmetrical derivatives with either 4-octyloxybenzoate terminal chains (3(8)) or 4-octyloxybicyclo[2.2.2]octane-1-carboxylate terminal chains (5(8)), and one unsymmetrical derivative with 4-octyloxybenzoate and 4-octyloxybicyclo[2.2.2]octane-1-carboxylate terminal chains (7(8,8)) were doped in the liquid crystal host 2-(4-butyloxyphenyl)-5-octyloxypyrimidine (PhP). Ferroelectric polarization powers (δp) and helical pitch induced by the three dopants in both the SmC* and N* phases were measured. The results show that the polarization power at T–TC = −10 K decreases in the order 3(8) > 7(8,8) > 5(8), whereas the induced SmC* pitch at a constant dopant mole fraction xd = 0.015 increases in the same order, which suggests that the shielding effect of the bicyclo[2.2.2]octane segment hinders chirality transfer in the SmC* phase.
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.
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) | 0.000 | 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 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".