Two‐Dimensional Supramolecular Polymerization of a Bis‐Urea Macrocycle into a Brick‐Like Hydrogen‐Bonded Network

Abstract

We report on a dendronized bis‐urea macrocycle 1 self‐assembling via a cooperative mechanism into two‐dimensional (2D) nanosheets formed solely by alternated urea‐urea hydrogen bonding interactions. The pure macrocycle self‐assembles in bulk into one‐dimensional liquid‐crystalline columnar phases. In contrast, its self‐assembly mode drastically changes in CHCl3 or tetrachloroethane leading to 2D hydrogen‐bonded networks. Theoretical calculations, complemented by previously reported crystalline structures, indicate that the 2D assembly is formed by a brick‐like hydrogen bonding pattern between bis‐urea macrocycles. This assembly is promoted by the swelling of the trisdodecyloxyphenyl groups upon solvation, which frustrates, due to steric effects, the formation of the thermodynamically more stable columnar macrocycle stacks. This work proposes a new design strategy to access 2D supramolecular polymers by means of a single non‐covalent interaction motif, which is of great interest for materials development.

Pathway-dependent supramolecular polymerization by planarity breaking

“…The obtained energy difference between the two assembled states lies within the range of systems to be considered supramolecular polymorphs (approximately 10 kJ mol −1 ). 64–66,68…”

Two-Dimensional Molecular Architectonics through Controlled Noncovalent Interactions: Structure, Functional Properties, and Applications

“…Another study described the preparation of 2D hydrogen bonded supramolecular polymers of a bis-urea macrocycle functionalized with two exterior bulky 3,4,5tris(dodecyloxy)phenyl substituents (97). 115 The macrocycle is organized into 1D columnar structures in a liquid-crystalline (LC) state. The molecular assembly of 97 resulted a welldefined nanosheet with a thickness of ∼2−3 nm in CHCl 3 or tetrachloroethane (TCE) solvents by a brick-like hydrogen bonding between bis-urea macrocycles (Figure 11f,g).…”

“…Under acidic conditions, these vesicles can be reversibly transformed to sheet architectures through protonation of acceptor moieties. Another study described the preparation of 2D hydrogen bonded supramolecular polymers of a bis-urea macrocycle functionalized with two exterior bulky 3,4,5-tris­(dodecyloxy)­phenyl substituents ( 97 ) . The macrocycle is organized into 1D columnar structures in a liquid-crystalline (LC) state.…”

“…(a) Schematic representation of a nanocapsule and free-standing thin lamella film formation by molecular assembly of 94 ; (b) TEM image of free-standing thin lamella film formed by molecular assembly of 94 ; (c) schematic illustration of the molecular assembly structures formed by coassembly of 95 and 96 ; (d, e) TEM and AFM images (inset shows the height profile) of a 2D membrane sheet formed by the coassembly of 95 and 96 ; (f, g) AFM images (inset shows the height profile) of the sheet formed by 97 in tetrachloroethane solution; TEM images of molecular assembly architectures of (h) 98 , (i) 99 , and (j) 100 . Panels (a, b) and (f, g) were adapted with permission from ref and ref , respectively. Copyright of 2016 and 2023, respectively, Wiley-VCH.…”