Remarkable influence of the preparation method on the gelation ability of a cholesterol-based isocyanuric acid-2,4,6-triaminopyrimidine pair. Does the formation of a `molecular tape' contribute to the gelation?

The gelation system of a 1:1 mixture of cholesterol-containing isocyanuric acid (1) and cholesterol-containing 2,4,6-triaminopyrimidine (2) in organic fluids was investigated to understand the gelation mechanism. A series of gelation tests have shown that the gelation is remarkably dependent upon the cooling rate of the mixture solution as well as the nature of solvents and concentrations. The investigation using FT-IR revealed that the mismatched hydrogen-bonding interaction between (1) and (2) is responsible for the gelation and well defined hydrogen-bonding interaction such as a `molecular tape' rather results in coprecipitation. It was confirmed by the gelation test of two-faced (1) and (2) with the complementary single-faced compounds that the gel is constructed by the three-dimensional network through an irregular hydrogen-bonding interaction.