Novel Vesicular Aggregates of Crown-Appended Cholesterol Derivatives Which Act as Gelators of Organic Solvents and as Templates for Silica Transcription

• DOI: 10.1021/ja001623f
• Publication Date: 2002-07-26T05:57:48Z
• Authors: Jong Hwa Jung; Yoshiyuki Ono; Kazuo Sakurai; Masahito Sano; Seiji Shinkai
• Keywords: 02 engineering and technology; 0210 nano-technology

New diazacrown-appended cholesterol gelators 1 and 2 were synthesized, and their gelation ability was evaluated in organic solvents. Very surprisingly, 1 + acetic acid gel results in spherical vesicles with two distinct sizes 200 and 2500 nm in diameter. In particular, the smaller vesicles are linked linearly, which is considered to serve as a driving-force for gelation. In contrast, 2 has a multilayered tubular structure. To characterize their aggregation modes in the gel phase, the organogels were observed by CD spectroscopy. The CD spectrum of 1 + acetic acid gel exhibits a negative sign for the first Cotton effect, indicating that the dipole moments in the gelator aggregate orient into an anticlockwise direction. On the other hand, 2 exhibits a positive sign for the first Cotton effect, indicating that they orient into a clockwise direction. The results indicate that the aggregate of 2 is stabilized by intermolecular cholesterol−cholesterol and azobenzene−azobenzene interactions, whereas the CD sign f...