Cooperative Self-Assembly of Pyridine-2,6-Diimine-Linked Macrocycles into Mechanically Robust Nanotubes
Journal
Angewandte Chemie International Edition
Journal Volume
58
Journal Issue
41
Start Page
14708
End Page
14714
ISSN
1433-7851
1521-3773
Date Issued
2019-09-13
Author(s)
Strauss, Michael J.
Asheghali, Darya
Evans, Austin M.
Chavez, Anton D.
Sun, Chao
Becker, Matthew L.
Dichtel, William R.
Abstract
Nanotubes assembled from macrocyclic precursors offer a unique combination of low dimensionality, structural rigidity, and distinct interior and exterior microenvironments. Usually the weak stacking energies of macrocycles limit the length and mechanical strength of the resultant nanotubes. Imine-linked macrocycles were recently found to assemble into high-aspect ratio (>103), lyotropic nanotubes in the presence of excess acid. Yet these harsh conditions are incompatible with many functional groups and processing methods, and lower acid loadings instead catalyze macrocycle degradation. Here we report pyridine-2,6-diimine-linked macrocycles that assemble into high-aspect ratio nanotubes in the presence of less than 1 equiv of CF3CO2H per macrocycle. Analysis by gel permeation chromatography and fluorescence spectroscopy revealed a cooperative self-assembly mechanism. The low acid concentrations needed to induce assembly enabled nanofibers to be obtained by touch-spinning, which exhibit higher Young's moduli (1.33 GPa) than many synthetic polymers and biological filaments. These findings represent a breakthrough in the design of inverse chromonic liquid crystals, as assembly under such mild conditions will enable the design of structurally diverse and mechanically robust nanotubes from synthetically accessible macrocycles.
Subjects
organic nanotubes
self-assembly
stimuli responsive materials
supramolecular chemistry
touch-spinning
Publisher
Wiley
Type
journal article