title: Novel dimeric cholesteryl derivatives and their smart thixotropic gels.
abstract: Three novel LS(2)-type dimeric-cholesteryl derivatives (1-3), where S is a steroidal residue and L stands for a linker connecting the two S residues and contains three benzene rings and two amide and two carbamate groups, were designed and prepared. The compounds can gel a wide variety of organic solvents via three different ways, including mixing at room temperature, a heating-cooling cycle, and ultrasound treatment. SEM measurements revealed that the structures and the concentrations of the gelators, the nature of the solvent, and the preparation method employed have a great effect on the morphologies of the gel networks. It was revealed that 1 is a supergelator for DMSO (cgc = 0.04% w/v) and that the 1/DMSO gel can be prepared via any of the three methods mentioned above. Furthermore, the gel possesses excellent mechanical strength and a very smart thixotropic property. FT-IR and temperature- and concentration-dependent (1)H NMR spectroscopy studies revealed that hydrogen bonding and π-π stacking among the molecules of 1 are two important driving forces for the physical gelation of DMSO. In addition, XRD analysis confirmed the layered packing structure of 1 in its DMSO gel.
authors.affiliation: Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Hou
authors.forename: Di
authors.initials: D
authors.lastname: Gao
authors.forename: Junlin
authors.initials: J
authors.lastname: Yan
authors.forename: Ying
authors.initials: Y
authors.lastname: Ma
authors.forename: Kaiqiang
authors.initials: K
authors.lastname: Liu
authors.forename: Yu
authors.initials: Y
authors.lastname: Fang