Polymorphisms of Crystalline Solids :: Chemistry Engineering Science Essays

Polymorphisms of Crystalline Solids Polymorphism is the phenomenon where a compound can precipitate to form numerous crystal structures. Due to space and time limitations, we have decided to confine the scope of this paper to only include polymorphisms of crystalline solids and not include polymorphisms associated with DNA and genetic related topics. It is important in many areas of technology, that people are aware of the presence of polymorphisms and the properties of the different polymorphisms. The different crystalline structures each have different physical properties, which can change the use of the chemical. The physical properties that may differ from one polymorphism to another include: solubility, density, melting point and even color. One of the variables that affect the crystallization process is the solvent that is used in the precipitation. The solvent may cause less stable polymorphisms to form instead of those that are more stable. Predictions can be made as to which polymorphism wil l be formed based on the solvent and its properties. The mixing conditions also have an affect on the formation of various polymorphisms. (Meyerson) Different polymorphisms can also be formed by manipulating the solute concentrations, flows rates, and equipment configurations. Research involving polymorphisms is becoming increasingly important to the pharmaceutical industry due to the number of pharmaceuticals that are prone to polymorphisms, patents on certain polymorphisms, the differing bioavailability of the polymorphisms and the differing effects of the polymorphisms on the body. (Meyerson) During the 1970’s, G.M.J. Schmidt coined the term crystal engineering and defined it as predicting the crystal structure of solid-state organic molecules (Sharma). In 1989, G.R. Desiraju revised the meaning as the â€Å" ‘the understanding of intermolecular interactions in the context of crystal packing and in the legalization of such understanding and the design of new solids with desired physical and chemical properties’ † (Sharma). Crystal engineering has grown to encompass the study of the hardness and color of solids, nanotechnology, protein receptor binding, pharmaceutical development, and polymorphisms (Sharma). Crystals are used in many areas of science, pharmaceuticals, and materials engineering. Crystals differ from many other organic and inorganic materials because of their ability to form polymorphisms.