rowlesmr
Is it possible to study chiral compounds by powder diffraction?
Are there any differences to be seen between racemic mixtures and pure L- and R-enantiomers?
I've just been given two "enantiometrically pure" compounds, and their powder patterns are completely different. Just wondering if that is normal/possible or that there are different polymorphs going on.
Thanks
Matthew
rowlesmr
Apparently, they were a bit loose with terminology. They reckon they are stereoisomers (from NMR), not necessarily enantiomers.
johnsoevans
"Is it possible to study chiral compounds by powder diffraction?"
You know I'm going to say that you can study anything by powder diffraction, you just might not get any useful answers!
I guess you answered your own question in the second post - enantiomers are a subset of stereoisomers.
If you are interested in absolute configuration the information comes from the (usually very small) difference in intensity of hkl and -h-k-l in single crystal experiments and is monitored via a refinable Flack parameter. If you do a google for "Flack parameter" you'll find lots of nice discussion about when you can/can't trust the parameter. Howard Flack died a few years ago, so there were some nice general summaries of this work published at about that time.