Bile acid-derived mono- and diketals--synthesis, structural characterization and self-assembling properties

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Bile acids are natural steroids with diverse biological roles.
• Chemical modification of bile acids can lead to novel materials with unique properties.
• Ketals are versatile functional groups formed from ketones and alcohols.

Purpose of the Study:

• To synthesize novel bile acid monoketals and diketals using catechol, naphthalenediol, and pentaerythritol.
• To investigate the self-assembly and material properties of these novel bile acid derivatives.
• To determine the solid-state structures of selected bile acid ketals.

Main Methods:

• Synthesis of bile acid methyl ester oxo-derivatives.
• Ketalization reactions with 1,2-benzenediol, 2,3-naphthalenediol, and pentaerythritol.
• Characterization of synthesized compounds using techniques including X-ray crystallography.
• Solvent-based gelation and film formation studies.

Main Results:

• Bile acid monoketals with pentaerythritol formed thermoreversible gels in aromatic solvents.
• One methyl lithocholate derivative acted as a supergelator, forming gels at 0.5% w/v.
• Catechol ketals rapidly crystallized, yielding X-ray quality single crystals.
• The X-ray structure of a dehydrocholate monoketal revealed an unusual packing pattern.
• Separation and X-ray structure determination of pentaerythritol diketal diastereomers were achieved.

Conclusions:

• Novel bile acid ketals exhibit diverse material properties, including gelation and crystallization.
• The structural features of bile acid ketals influence their solid-state packing and self-assembly behavior.
• These findings contribute to the development of new functional materials derived from bile acids.