As far as I know (from a crystallographer point of view) chemical synthesis usually produces 50% of each enantiomer and the real problem is to **separate** them to get an enantiomer-pure solution/crystal.

My 2 cents.

Dear Dinsefa,

                               I agree with Sabino's answer. No specific method exists to produce one out of the two enantiomers of a given crystal phase.

Nevertheless, there is a general way to "favor" the nucleation of one enantiomer. It is well known that if the epitaxial adsorption of polar compounds  occur s on a given face of a given enantiomer, the same adsorption "cannot" occur on the corresponding face of the opposite enantiomer. The problem is to find the molecule to be adsorbed... I'll send you, in the attached file a recent paper we published, in order to more deeply explain this concept.

All the best

Dino

For proteins, there is at least one 3D structure of a D-protein (D-monellin) that was solved. Structure of an Enantiomeric Protein, D-Monellin at 1.8 A Resolution.

(1998) Acta Crystallogr.,Sect.D 54: 494-500.

If I remember correctly, the protein was produced by chemical synthesis (a small protein) using only D-amino-acids. I do not know if there are other such examples of 3D structures of D-proteins.

You can surely solve racemic structures by x-ray diffraction, i.e., distinguish between the two enantiomorphs of a chiral crystal structure, provided that:

1. you are able to separate the two enantiomers;

2. substitute one (or more) light atom with an heavy atom, which shows a larger anomalous dispersion effect.

Sometimes, if you are lucky, from a racemate (mixture of enantiomers), the two enantiomers will crystallize into separate crystals if the conditions are just right.

"Racemic acid is an old name for an optically inactive or racemic form of tartaric acid. It is an equal mixture of two mirror-image isomers (enantiomers), optically active in opposing directions.

Its sodium-ammonium salt is unusual among racemic mixtures in that during crystallization it can separate out into two kinds of crystals, each composed of one isomer, and whose macroscopic shapes are mirror images of each other. Thus, Louis Pasteur was able to separate the two enantiomers by picking apart the crystals.[1][2]

In a modern-time re-enactment of the Pasteur experiment,[3][4] it was established that the preparation of crystals was not very reproducible. The crystals deformed, but they were large enough to inspect with the naked eye (microscope not required)." https://en.wikipedia.org/wiki/Racemic_acid