Chiral X-ray internal reference

FIGURE 55.4. A general procedure for determining AC by X-ray crystallography using a chiral X-ray internal reference (CXR). 

CEC capillary electrochromatography chiral X-ray internal reference reagent... 

FIGURE 55.6. Absolute configuration of chiral Cgo-fullerene cis-3 bisadduct 9 by X-ray internal reference method. 

The results obtained by the internal reference method are clear and reliable, even when the final R-value is not small enough as a result of the poor quality of the single crystal. The next is a striking example showing this advantage, where the AC of chiral Ceo fuUerene cis-3 bisadduct 9 was determined by X-ray crystallography (Figure 55.6). ... 

The story of a hght-powered chiral molecular motor originates from the smdy how to determine the AC of chiral olefin [CD(- -)239.0]-45, which also takes a similar twisted structure and, hence, shows a strong positive CD band at 239.0 nm. To determine the AC of [CD(- -)239.0]-45, we first tried to prepare derivatives containing a heavy atom, but aU attempts were unsuccessful. So we adopted the next strategy, where the methyl group at the chiral position was used as an internal reference of AC in X-ray crystallography. 

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