Cooperative Self‐Assembly of Pyridine‐2,6‐Diimine‐Linked Macrocycles into Mechanically Robust Nanotubes
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 13, 2019
- Source ID
- 10.1002/ange.201907668
Entities
People
- Anton D. Chavez
- Austin M Evans
- Chao Sun
- Darya Asheghali
- Matthew L. Becker
- Michael J Strauss
- Rebecca L Li
- William Dichtel
Organizations
- Army Research Office
- Cornell University
- National Science Foundation
- Northwestern University
- United States Department of Energy
- University of Akron