Inorganic Chemistry

Structure and Bonding

Can more than one packing arrangement exist for a given chemical molecule?

Yes—this is referred to as polymorphism, and examples are known for most types of crystalline materials—organic and inorganic molecules, polymers, and metals. The way in which molecules pack in the solid state can actually alter some of its properties. Some pharmaceutically active molecules have more than one solid-state structure, or polymorphs. Sometimes certain polymorphs of drugs can be more useful. For example, a specific arrangement could be more soluble, making it more active in the human body. A second polymorph of aspirin (acetylsalicylic acid) was discovered in 2005, but it’s only stable at -180 °C.


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