Synthesis of low molecular weight organogelators and their physical gelation

This article describes the low molecular weight gelators which were reported since 1996. Alkylamides and alkylureas derived from trans-1,2-diaminocyclohexane are excellent organogelators which can gelate a wide variety of organic solvents, from protic polar solvents to aprotic non-polar ones. The results of gelation test of di-urea derivatives indicate that the intermolecular hydrogen bonding between ureylene units is as very useful as the intermolecular hydrogen bonding between amides for molecular design of gelators. Tridodecyl-1,3,5-benzenetricarboxamide is found to act as thickener, because the addition of the small amount of this compound causes a marked rise of viscosity of hydrocarbons and oils. On the other hand, trioctadecyl-cis-1,3,5-cyclohexanetricarboxamide, which is structurally related to tridodecyl-1,3,5-benzenetricarboxamide, can cause physical gelation of hydrocarbons and oils. Bolaform amides derived from L-valine or L-isoleucine are excellent organogelators for a wide variety of organic solvents, although they contain neither an aromatic moiety nor a long methylene segment. The bolaform amides are expected to be smoothly-biodegradable organogelators. Besides the above gelators, this article deals with the following compounds; 4,4',4 "-tris(stearoylamino)triphenylamine, an equimolar mixture of isocyanuric acid and triaminopyrimidine containing a cholesterol segment, gamma-alkoxybutyrolactone, quaternary ammonium halide salts, p-toluenesulfonic acid salt of L-leucine alkyl eater, fluoroalkylated oligomers, a 24-residue peptide, a biotin derivative, a cholic acid derivative, an N-alkylgluconamide derivative, and an L-isoleucine derivative.