Equilibration of Imine-Linked Polymers to Hexagonal Macrocycles Driven by Self-Assembly

Anton D Chavez; Austin M Evans; Nathan C Flanders; Ryan P Bisbey; Edon Vitaku; Lin X Chen; William R Dichtel

doi:10.1002/chem.201800459

Equilibration of Imine-Linked Polymers to Hexagonal Macrocycles Driven by Self-Assembly

Chemistry. 2018 Mar 15;24(16):3989-3993. doi: 10.1002/chem.201800459. Epub 2018 Feb 26.

Authors

Anton D Chavez^{1

2}, Austin M Evans¹, Nathan C Flanders¹, Ryan P Bisbey^{1

2}, Edon Vitaku¹, Lin X Chen^{1

3}, William R Dichtel¹

Affiliations

¹ Department of Chemistry, Northwestern University, Evanston, Illinois, 60208, USA.
² Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, 14853, USA.
³ Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois, 60439, USA.

PMID: 29388270
DOI: 10.1002/chem.201800459

Abstract

Macrocycles based on directional bonding and dynamic covalent bond exchange can be designed with specific pore shapes, sizes, and functionality. These systems retain many of the design criteria and desirable aspects of two-dimensional (2D) covalent organic frameworks (COFs) but are more easily processed. Here we access discrete hexagonal imine-linked macrocycles by condensing a truncated analogue of 1,3,5-tris(4-aminophenyl)benzene (TAPB) with terephthaldehyde (PDA). The monomers first condense into polymers but eventually convert into hexagonal macrocycles in high yield. The high selectivity for hexagonal macrocycles is enforced by their aggregation and crystallization into layered structures with more sluggish imine exchange. Their formation and exchange processes provide new insight into how imine-linked 2D COF simultaneously polymerize and crystallize. Solutions of these assembled macrocycles were cast into oriented, crystalline films, expanding the potential routes to 2D materials.

Keywords: covalent organic frameworks; dynamic covalent chemistry; imines; self-assembly; supramolecular chemistry.