Synthesis and gelation behaviors of five new dimeric cholesteryl derivatives

Abstract

Five new diacid amides of di-cholesteryl L-glycinates were designed and prepared. The compounds with linkers containing 0, 1, 2, 3, or 4 methylene units are denoted as 1, 2, 3, 4, and 5, respectively. Their gelation behaviors in 25 solvents were tested as novel low-molecular-mass organic gelators (LMOGs). It was shown that the length of the linker connecting the two-cholesteryl residues in a gelator plays a crucial role in the gelation behavior of the compound. 1 gels 11 of the 25 solvents tested at a concentration lower than 1.0%, while 2 gels 17 of the solvents tested. 4 and 5, however, gel only 2 and 4 of them, respectively. SEM observation reveals that the lengths of the linkers and the identity of the solvents are the main factors affecting the structures of the aggregates in the gels. Experimentally, a clear linker effect on the microstructures of the gels was observed. As example, the aggregates of 1, 2 and 3 in benzene or 1-heptanol adopt structures of thin fibers, rods or lamellas, respectively. Furthermore, it was found that the gelation and aggregation behaviors of 2, 3, 4, and 5 in DMSO showed an even-odd effect. organogelators, cholesterol, linker effect, solvent effect

Recent advances in steroidal supramolecular gels

“…The length of the linker connecting the two cholesteryl residues was shown to play a crucial role in the gelation behavior of the compounds and in the nature of the microstructures of the gels. 45 As the first example of cholesterol derivatives, compound 17 (Fig. 11) was shown to form a water-in-oil type gel emulsion by agitating the system at room temperature.…”