The Third Ambient Aspirin Polymorph

Abstract

Polymorphism of aspirin (acetylsalicylic acid), one of the most widely consumed medications, was equivocal until the structure of a second polymorph II, similar in structure to the original form I, was reported in 2005. Here, the third ambient polymorph of aspirin is described. It was crystallized from the melt, and its structure was determined using a combination of X-ray powder diffraction analysis and crystal structure prediction algorithms.