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Updated: Aug 14, 2026

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
Synthesis and molecular geometry of an achiral 30-crown-12 polyacetal from alpha-cyclodextrin
1Institut fur Organische Chemie, Technische Universitat Darmstadt, Germany.
Abstract:
Periodate oxidation of alpha-cyclodextrin followed by borohydride reduction readily provided an octadeca-hydroxymethyl-substituted 30-crown-12 polyacetal 1, its 30-membered macrocycle being composed of six meso-butanetetrol/glycolaldehyde acetal units, which is, consequently, optically inactive. Its solid-state molecular geometry emerged from the X-ray structural analysis of the well-crystallizing octadeca-acetate 2, which revealed the undulated macrocycle to be molded into three loops with a unique order of succession of the -CHR-CHR-O-CHR-O- units: alternating gauche- and anti-conformations of the meso-butanetetrol portions and consecutive disposition of the glycolaldehyde-acetoxymethyl groups above and below the mean-plane of the macrocycle. In solution, however, as evidenced by 1H- and 13C-NMR spectra, the macrocycle is highly flexible at ambient and higher temperatures, its mobility becoming distinctly restricted only below -20 degrees C.
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