Formation of molecular hydrogels from a bile acid derivative and selected carboxylic acids

摘要

Bile acids are natural compounds that can be made into dimers by covalently linking two of them through diethylenetriamine. A cholic acid dimer of this kind is synthesized and is found to form thermally reversible hydrogels with selected carboxylic acids through combined hydrogen bonding and ionic interactions. The gelation and viscoelastic properties of the hydrogels may be varied by judicious choice of the carboxylic mono- and diacids. The total organic content (the dimer and carboxylic acid) represents about 2% or less by weight in the ternary mixture. The molecular arrangement between the dimer and carboxylic acid is proposed to illustrate the formation mechanism of the hydrogels. The marginal solubility of the dimer–acid mixtures seems to be the deciding factor in obtaining the hydrogels.