Solid Molecular Mono- and Bilayer Twisted

5 Solid Molecular Mono- and Bilayer Twisted Ribbons and Tubules 

Spherical micelles and vesicles are formed from amphiphiles and bolaamphi-philes by the solvophobic effect and are protected against crystallization by head group repulsion. What happens if the head groups carry secondary amide groups which have an inborn and irresistible drive to form linear hydrogen bond chains in polar and apolar environments (see section 5.4) Chains will be formed, of course. The usual result will be vesicular tubules, as in the case of amphiphiles with a low cmc (typically 10 M) and thinner micellar rods in the case of amphiphiles with a relatively high cmc (typically 10 -10 M). 

An L-glutamic triamide with a pyridinium head group and two 2,4-hexadie-noyl groups also produced twisted ribbons which, with ageing, closed to tubules. Similar tubules were also obtained upon UV irradiation and polymerization. The CD spectrum of surface adsorbed methyl orange , however, 

Takafuji, C. Hirayama, D.F. O Brien, Langmuir, 1992, 8, 1548 N. Nakashima, H. Fukushima, T. Kunitake, Chem. Lett., 1981, 1207 

Single chain amides with amino acid head groups and alkyl chains of various lengths have also been shown to form helical rods, twisted ribbons and straight tubules. These assemblies show no regular pitch in electron micrographs and 

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