Cholesterol-Appended Aromatic Imine Organogelators: A Case Study of Gelation-Driven Component Selection

This letter describes a novel approach for developing organogelators through the formation of reversible imine bonds from two molecular components and the enriching behavior of the gelating imines. Cholesterol-appended aniline 1 and 4-substituted benzaldehydes 2a-d did not gelate any solvents. Their condensation products, imines 3a-d, however, could gelate alcohols because of the enhanced stacking interaction of the imine unit. For a further component selectivity test, the reactions of the mixture of 1, 2b-d, and cholesterol-free aniline 7 (1:1:1) in different solvents were performed. The resulting imines were reduced to the corresponding amines and analyzed with H-1 NMR. It was revealed that, for the reactions resulting in no formation of the gel phase, imines 8a-c formed from 2b-d and 7 were obtained as the major product (64-76%) and all of the reactions that led to the formation of the gel phase gave rise to 3b-d as the major product (55-61%).