Hierarchical Prediction Process of Cholic Acid Crystal Structures Based on Characteristic Helical Assemblies

ABSTRACT

We describe here a hierarchical prediction process for crystal structures of inclusion compounds of cholic acid through a right-handed 2₁ helical assembly. This helical assembly is predictable from the distribution of three hydroxyl groups on the steroidal skeleton and can be regarded as the inherent structural unit of cholic acid. Subsequently, the carboxyl group of the side chain links neighboring 2₁ helical assemblies by means of the various hydrogen-bonding arrangements to form the corresponding structural motifs. These motifs can be built up more diversely using various guest molecules.

Keywords:

• cholic acid
• helical assembly
• hierarchical structure
• hydrogen bonds
• steroidal inclusion crystals

Acknowledgments

This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports, and Culture, Japan.