Isomorphism and Polymorphism of the Crystal Structures of Cholesterol Derivatives

Department of Chemistry, Sookmyung Women's University
â—‹Young-Ja Park

We have undertaken 25 crystal structure analyses of cholesteryl ethers, esters and carbonates. Among these crystal structures, (1)cholesteryl ethyl ether, isopropyl ether, hexanoate, heptanoate, pentyl carbonate and hexyl carbonate are isostructural each other, (2)cholesteryl ethyl carbonate(two forms), propyl carbonate, crotonate and crotyl carbonate are isostructural each other, (3)cholesteryl isobutyrate and isobutyl carbonate are isostructural, (4)cholesteryl phenyl acetate and cholesteryl isopropyl carbonate are also isomorphic each other. The cholesteryl 2,4-dichlorobenzoate, ethyl carbonate and butyl carbonate have been crystallized in two polymorphic forms, respectively. The crystal structures of cholesteryl formate, hemisuccinate, aniline, 2,4-dichlorobenzoate, hydrocinnamate, butyl carbonate, methyl ether, methyl carbonate and pentanoate do not belong to any typical packing group and do not show any isomorphism.
Most of crystal structures of cholesterol derivatives are remarkable in forming layer structures, so called monolayer type 1, 2, 3 and bilayer. Typical packing modes will be discussed in terms of isomorphism and polymorphism.