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

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.

Supramolecular polymerization provides non-equilibrium product distributions of imine-linked macrocycles

“…2C, D, F and G) (see ESI †). 31,33 The assembly of MC 2 into nanotubes under conditions typical for its synthesis was also observed in the presence of other acids (HCl, p-toluenesulfonic acid, and methanesulfonic acid) capable of protonating the pyridine ring ( Fig. S40 †).…”

“…At longer times, the GPC signal of the MC 1 experiment narrowed, indicating successful macrocycle formation (see ESI †), which is consistent with our previous study on how neutral macrocycles form via linear polyimines. 33 Characterization of the resulting macrocycles by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) revealed single peaks corresponding to the target macrocycles ( Fig. S4 and S24 †).…”

Cooperative Self‐Assembly of Pyridine‐2,6‐Diimine‐Linked Macrocycles into Mechanically Robust Nanotubes

“…A bifunctional aryl amine, containing a solubilizing decyloxy side chain, was condensed with both 2,6‐pyridinedicarboxaldehyde ( MC 1 ) and isophthalaldehyde ( MC 2 ) to yield [3+3] macrocycles in high yields (91 % and 80 %, respectively) with smaller pore sizes than previous reports (Figure , Scheme S8 and S9) . Both macrocycles exhibit single narrow peaks in the gel permeation chromatography (GPC) traces, as well as peaks in the matrix assisted laser desorption ionization mass‐spectrometry (MALDI‐MS) spectra corresponding to the desired [3+3] product (See Supporting Information).…”

Cooperative Self-Assembly of Pyridine-2,6-Diimine-Linked Macrocycles into Mechanically Robust Nanotubes

“…[4] Previously,S hionoya and co-workers and Tanaka and coworkers synthesized macrocycles containing 1,10-phenanthroline and bis(salicylidene)-o-phenylenediamine moieties, respectively,w hich assembled into nanotubes upon binding transition metals. [10,11] One of the unique aspects of this system is that al arge excess of CF 3 CO 2 Hi nduced assembly,y et lower acid loadings catalyzed macrocycle hydrolysis.H owever, these characteristics are detrimental to accessing functionalized structures,a sw ell as processing and aligning the nanotubes. [10,11] One of the unique aspects of this system is that al arge excess of CF 3 CO 2 Hi nduced assembly,y et lower acid loadings catalyzed macrocycle hydrolysis.H owever, these characteristics are detrimental to accessing functionalized structures,a sw ell as processing and aligning the nanotubes.…”

“…[16,17] Then anotubes reported here fulfill both of these criteria, while at the same time developing ag eneral synthetic strategy to form nanostructures with designed and dynamic emergent functions. [10,11] Both macrocycles exhibit single narrow peaks in the gel permeation chromatography (GPC) traces,aswell as peaks in the matrix assisted laser desorption ionization mass-spectrometry (MALDI-MS) spectra corresponding to the desired [3+ +3] product (See Supporting Information). [10,11] Both macrocycles exhibit single narrow peaks in the gel permeation chromatography (GPC) traces,aswell as peaks in the matrix assisted laser desorption ionization mass-spectrometry (MALDI-MS) spectra corresponding to the desired [3+ +3] product (See Supporting Information).…”