Remarkable isomer-selective gelation of aromatic solvents by a polymorph of a urea-linked bile acid–amino acid conjugate

Abstract

A urea-linked bile acid–amino acid conjugate was developed as a remarkable isomer-selective gelator for various disubstituted aromatic solvents. Polymorphism shown by the urea derivative was studied in detail which showed that only the amorphous polymorph acts as a gelator, but not the crystalline one.

Bile salts and derivatives: Rigid unconventional amphiphiles as dispersants, carriers and superstructure building blocks

“…predominantly apolar moieties were recently tested [19**, [53][54][55]). For compounds 1-3, belonging to a series of bile acid hydrazides [55], reversible sol-gel transitions were highlighted by both sonication, shaking and heating of the samples.…”

“…Compound 4 bears urea-linked phenylalaninemethyl esters [53]. Both the D-and L-phenylalanine-cholic acid conjugates were synthesized and found to show polymorphism.…”

Physiology and Physical Chemistry of Bile Acids

“…Several BAs functionalized at the carboxylic groups to form different species like hydrazide [ 204 ] and aminoacid [ 205 ] esters [ 206 ] and conjugate [ 207 , 208 ] have also been widely investigated for their organo- or hydro-gelation properties. The importance of the hydrophobic/hydrophilic balance of the derivatives on their gelation ability was clearly illustrated.…”

“…Exploiting the cross-linking action of cations [202], stable gels of helical ribbons closed into hollow cylinders have been reported to form by calcium ions and phenylalanine substituted deoxycholate at high pH [203]. Several BAs functionalized at the carboxylic groups to form different species like hydrazide [204] and aminoacid [205] esters [206] and conjugate [207,208] have also been widely investigated for their organo-or hydro-gelation properties. The importance of the hydrophobic/hydrophilic balance of the derivatives on their gelation ability was clearly illustrated.…”

Supramolecular Self-Assembly Based on Natural Small Molecules

“…Galantini 等 [115] 13 Hydrogel and nanotubes formed by 95 in acidic aqueous solution [115] 除了对胆甾酸的 3 位羟基进行修饰外, 在羧基上修 饰芳香基团也可以增强分子间的作用力. Maitra 等 [116] 15 Schematic illustration of the vesicles and amphiphilic pockets assembled from compounds 98 and 99 [118] 除了胆固醇和胆甾酸以外, 雌二醇衍生物也是一类 很好的凝胶因子. Sierra 等 [119] 随后, 他们发现未经任何修饰的白桦脂酸 106 [122] 、 甘草次酸 107 [123] 和齐墩果酸 108 [124] [129] .…”