Stereospecific Polymerization and Chiral Crystallization

Configurationally and conformationally specific polymerization processes which lead to helical macromolecules can be successfully carried out when monomer structure, polymerization mechanism, and spatial restrictions for monomer addition are all carefully considered. Under certain conditions, optically active polymers having a single helical screw sense can be prepared. Surprisingly, the chiral crystallization of certain inorganic salts has much in common with stereospecific polymerization mentioned above. Achiral sodium chlorate and sodium bromate can crystallize spontaneously from aqueous solutions to give a mixture of pure levorotatory and pure dextrorotatory isotropic crystals. The crystallization of these salts can also be nucleated with traces of levo- or dextro- rotatory crystals to furnish new crystals with a high degree of chiroptical purity. Our varied efforts within the confines of these two related fields are summarized.