Selective binding in different adsorption sites of a 2D covalent organic framework

Abstract

This study shows that surface-supported two-dimensional (2D) porous covalent organic frameworks (COFs) can selectively bind different molecules at specific sites via different types of interactions. Scanning tunneling microscopy (STM) images collected at the liquid/solid interface reveal the adsorption of 1,2,4-trichlorobenzene (TCB) in the hexagonal pore of a COF-1 template. A well-defined loop boundary formed by a chain of pentagonal and heptagonal pores allowed the investigation of the effect of pore shape and size on TCB adsorption, suggesting that both geometrical and size effects are important in binding TCB.When both C 60 and TCB are present at the solution/solid interface, the TCB molecules are selectively trapped in the pore-site, whereas fullerenes are adsorbed on the top-site of COF-1. While the former structure is stabilized by Cl⋯H hydrogen bonds, the latter is controlled by van der Waals interactions.These results suggest that COFs may offer a powerful platform for the recognition and patterning of guest molecules.

Probing functional self-assembled molecular architectures with solution/solid scanning tunnelling microscopy

“…The adsorption of solvent molecules in the host lattice can be used to control the adsorbed site of guest molecules. 111 Fullerenes adsorb on the top-site of COF-1 (Fig. 3j) when both C 60 and TCB are present at the TCB/HOPG interface since the pore-site is blocked by the adsorption of TCB molecule.…”

Covalent organic frameworks from a monomer with reduced symmetry: polymorphism and Sierpiński triangles

“…Our results suggest that the confinement of reactions on a crystalline substrate may be an efficient way to select the desired polymorph. In future investigations host-guest chemistry for ST 41,[44][45][46] and the elucidation of the electronic properties 26,27 in such fractal confinements may reveal intriguing phenomena.…”

Planar Anchoring of C70 Liquid Crystals Using a Covalent Organic Framework Template

“…These results reveal the stepwise breakdown in ordering caused by the anisotropy and suggest that using a surface‐confined template to anchor the initial layer of LC molecules could be a modular and potentially broadly applicable approach to organizing molecular mesogens to form new LCs. Moreover, our previous work has shown that solvents can be used to select the adsorption sites of guest molecules in similar systems . Even though several C 70 mesophases were observed in heptanoic acid, exploiting a different solvent molecule, such as 1,2,4‐trichlorobenzene, may selectively form a single phase.…”

“…Small 2019, 15,1903294 of guest molecules in similar systems. [23,51] Even though several C 70 mesophases were observed in heptanoic acid, exploiting a different solvent molecule, such as 1,2,4-trichlorobenzene, may selectively form a single phase. The combination of template, solvent, and anisotropy of building blocks implies an effective approach to controlling molecular packing from 2D to 3D, which has the potential to provide structural control over properties in device-relevant films.…”