Hexagonal Molecular Tiling by Hexagonal Macrocycles at the Liquid/Solid Interface: Structural Effects on Packing Geometry

Abstract

We present here hexagonal tiling using hexagonal phenylene-ethynylene and phenylene-butadiynylene macrocycles attached by alkyl ester groups, PEM-C6 and PBM-C8, respectively, or triethylene glycol ester groups, PEM-TEG and PBM-TEG, respectively, at each vertex of the macrocyclic periphery at the liquid/solid interface. In this study, we focused on the effects of macrocyclic core size and the chemical properties of side chains attached to macrocyclic cores as well as solute concentrations on the hexagonal geometry of self-assembled monolayers. STM observations at the 1,2,4-trichrolobenzene/graphite interface revealed that PEM-C6 formed a honeycomb structure by van der Waals interactions between the interdigitated alkyl chains. However, upon increasing solute concentration, it changed to more dense hexagonal structure (tentatively called loose hexagonal structure I). In contrast, PBM-C8 formed loose hexagonal structure II of a slightly different packing mode at low concentration, while at high concentration it formed a high-density hexagonal structure in which alkyl chains are not adsorbed on the surface (dense hexagonal structure). In the dense hexagonal structure, macrocyclic cores are linked by hydrogen bonds between the ester carbonyl oxygen and the aromatic hydrogen atoms of the neighboring macrocycles. The packing geometries of loose hexagonal structures of PEM-C6 and PBM-C8 are different due to the different distance between the attachment of the alkyl ester groups which are located in confined space. On the other hand, PEM-TEG and PBM-TEG formed dense hexagonal structures, similar to PBM-C8 at high concentration, with their TEG units not adsorbed on the surface.

Electrostatically Driven Guest Binding in Self-Assembled Molecular Network of Hexagonal Pyridine Macrocycle at the Liquid/Solid Interface: Symmetry Breaking Induced by Coadsorbed Solvent Molecules

“…For 2D host-guest chemistry using a macrocycle as a host, packing patterns of the host network affect the 2D space arrangement of co-adsorbed guests. In this respect, control of the molecular tiling of the surfaces by triangular, [49][50][51][52] square, 29,34,53 and hexagonal 35,[54][55][56] macrocycles is an important issue.…”

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

“…

Macrocyclesb ased on directional bonding and dynamic covalentb ond exchange can be designed with specificp ore shapes, sizes, andf unctionality.T hese systems retain many of the design criteria and desirablea spects of two-dimensional (2D) covalent organic frameworks (COFs)b ut are more easily processed. [8,9] The rigidity and planarity of macrocycles lead to assemblies such as 2D networks, [10] liquid crystals, [11] or nanotubes with well-defined channels. The monomers first condense into polymers bute ventually converti nto hexagonal macrocycles in high yield.

…”

“…Solutions of thesea ssembled macrocycles were cast into oriented, crystalline films, expanding the potential routes to 2D materials.The precise chemical structures and nanometer-scale internal cavities of shape-persistent macrocyclesa nd cages have shown promise for applications in optoelectronics, [1][2][3] ion binding, [4,5] sensing, [6] ionic conductivity, [7] and templates for nanoparticles ynthesis. [8,9] The rigidity and planarity of macrocycles lead to assemblies such as 2D networks, [10] liquid crystals, [11] or nanotubes with well-defined channels. [12] The solid-state ordering of shape-persistent macrocycles mimics that of 2D covalent organic frameworks (COFs), whicha re extended, periodics tructures with permanent porositya nd high internal surface areas.…”

Separation of Arylenevinylene Macrocycles with a Surface‐Confined Two‐Dimensional Covalent Organic Framework

“…STM characterization of the self‐assembled AVMs reveals the coexistence of AVMs and linear by‐products (Figure ; see Figure S1 in the Supporting Information). However, the self‐assembly of AVM1 and AVM2 show different concentration dependences . When a saturated solution of AVM1 was deposited onto the bare HOPG surface, we observed a monolayer composed merely of linear by‐products (see Figure S1a), while with the decrease of the concentration, the assembly of AVM1 soon became dominant.…”