Cholesteryl derivatives as phase-selective gelators at room temperature

One cholesterol-based ALS and two dimeric cholesterol-based A(LS)2 low-molecular-mass organic gelators (LMOGs) containing phthaloyl, isophthaloyl, and terephthaloyl moieties, respectively, were prepared. Gelation test revealed that 2 and 3 are more efficient gelators than 1. Interestingly, 2 and 3 can gel several solvents spontaneously at room temperature and these gels posses thixotropic properties as revealed by rheological studies. More interestingly, 2 and 3 show selective gelation of the solvents from their mixtures with water. The network structures of some gels were investigated by SEM measurements, and the molecular packing mode of the LMOGs in the gel was studied by XRD analysis. Temperature- and concentration-dependent 1H NMR measurements revealed that hydrogen bonding between the gelator molecules is an important driving force for the gel formation.