- Mechanism of preferential enrichment, an unusual enantiomeric resolution phenomenon caused by polymorphic transition during crystallization of mixed crystals composed of two enantiomers. Tamura, R., Fujimoto, D., Lepp, Z., Misaki, K., Miura, H., Takahashi, H., Ushio, T., Nakai, T., Hirotsu, K. J. Am. Chem. Soc. (2002)