Crystal Morphology Control with Tailor-Made Additives; A Stereochemical Approach

Abstract

Crystals and the crystallization process from solutions play an important role in pure and applied sciences. However, the ability to design crystals with desired properties and the control over crystallization, based on structural understanding, are still limited when compared with the controlled crystal growth provided in bio-mineralization processes. Tailor-made molecules are designed and used as additives in crystallization processes from solution to control the nucleation and growth of molecular crystals. These additives can be either inhibitors or promoters of crystal growth. These additives bind at the growing crystal surfaces via two-step stereo-specific mechanism, followed by inhibition of growth perpendicular to these faces. This mechanism has found application in a variety of molecular crystals including α -amino acids, di-peptides, primary and secondary amides, carboxylic acids, sugars, and steroids. This chapter explains that a variety of crystal properties can be controlled and modified with the use of tailor-made additives, including growth and dissolution, morphology, crystal texture and polymorphism.