Diastereomeric preference of a triply axial chiral binaphthyl based molecule: a concentration dependent study by chiroptical spectroscopies
Bibliographic record
Abstract
We have examined the effects of environmental perturbations, specifically solvents and concentrations, on axial chirality of a recently synthesized axially chiral binaphthyl fluorene based salen ligand, named AFX-155, {[2,2'-(1E,1'E)-(R)-1,1'-binaphthyl-2,2'-diylbis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)bis(4-((7-(diphenylamino)-9,9-dihexyl-9H-fluoren-2-l)ethynyl)-phenol)]}. Chirality and dominant conformations of AFX-155 in CDCl3 solvent have been characterized using vibrational absorption (VA) and vibrational circular dichroism (VCD) spectroscopy in combination with DFT calculations. AFX-155 exhibits triple axial chirality: one is at the binaphthyl ring and the other two are related to the axes of chirality along the -C-N bonds where Cs are part of the binaphthyl group. To evaluate solvent and concentration dependence, complementary VA and VCD experiments in both THF-d8 and CDCl3 have been performed, as well as the optical rotatory dispersion (ORD) and electronic CD (ECD) measurements in CDCl3 under much diluted conditions. While the binaphthyl chirality is determined by the synthetic route, the results show that the latter two axial chirality labels of the dominant diastereomers are concentration dependent. Under much diluted conditions, R-binaphthyl, R_intra_HB//R_extra_HB (R-RR) is favoured, whereas R-binaphthyl, S_intra_HB//S_extra_HB (R-SS) is the dominant species in a concentrated solution. This diastereomeric interconversion is found to be independent of the two solvents used. To provide insights into this interesting finding, conformational searches and the related spectral simulations have been carried out at the DFT/B3LYP/6-31G(d) level.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| 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 | 0.001 | 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".