Electrostatically Driven Guest Binding in a Self-Assembled Porous Network at the Liquid/Solid Interface

Abstract

We present here the construction of a self-assembled two-dimensional (2D) porous monolayer bearing a highly polar 2D space to study guest co-adsorption through electrostatic interactions at the liquid/solid interface. For this purpose, a dehydrobenzo[12]annulene (DBA) derivative, DBA-TeEG, having tetraethylene glycol (TeEG) groups at the end of the three alternating alkoxy chains connected by p-phenylene linkers was synthesized. As a reference host molecule, DBA-C10, having nonpolar C alkyl chains at three alternating terminals, was employed. As guest molecules, hexagonal phenylene-ethynylene macrocycles (PEMs) attached by triethylene glycol (TEG) ester and hexyl ester groups, PEM-TEG and PEM-C6, respectively, at each vertex of the macrocyclic periphery were used. Scanning tunneling microscopy observations at the 1,2,4-trichlorobenzene/highly oriented pyrolytic graphite interface revealed that PEM-TEG was immobilized in the pores formed by DBA-TeEG at higher probability because of electrostatic interactions such as dipole-dipole and hydrogen bonding interactions between oligoether units of the host and guest, in comparison to PEM-C6 with nonpolar groups. These observations are discussed based on molecular mechanics simulations to investigate the role of the polar functional groups. When a nonpolar host matrix formed by DBA-C10 was used, however, only phase separation and preferential adsorption were observed; virtually no host-guest complexation was discernible. This is ascribed to the strong affinity between the guest molecules which form by themselves densely packed van der Waals networks on the surface.

Engineering porous two-dimensional lattices via self-assembly of non-convex hexagonal platelets

“…The design of two-dimensional (2D) ordered nanoporous networks, with pore sizes between 1 and 10 nm, has received significant attention in supramolecular chemistry due to their current and potential applications in areas such as guest molecule adsorption and immobilization of functional guest molecules in spatially ordered arrangements, [1][2][3][4] enantioselective adsorption, 5 fabrication of hyperthin membranes, 6 sensory devices and substrate-specific tailor-made catalysts. 7 These systems are typically formed at liquid/solid interfaces where the regular and open structures formed by certain molecules allow the exposure of actives sites on the substrate selectively on the nanoscale.…”

One-shot preparation of topologically chimeric nanofibers via a gradient supramolecular copolymerization

“…Although the segregated organization of molecular components into two-dimensional (2D) and threedimensional (3D) nanostructures can be guided by differences in the molecular surface energy and interactions with substrates ( Fig. 1a) [11][12][13][14][15][16][17][18][19][20][21][22][23] , 1D nanostructures are generally prepared via selfassembly in solution, which allows individual molecular components to self-nucleate and elongate into self-sorted fibers (narcissistic self-sorting) [24][25][26][27][28] . Accordingly, in most cases, the synthesis of such multicomponent 1D nanostructures with segregated molecular domains, i.e., block supramolecular copolymers, relies on seeded-growth approaches, wherein kinetically inert seeds have to be prepared in advance from one monomer, whereas the other has to be co-assembled in a kinetically controlled manner in order to avoid self-nucleation [1][2][3][4][5][6][29][30][31][32][33][34][35][36] .…”

Host–Guest Chemistry in Integrated Porous Space Formed by Molecular Self-Assembly at Liquid–Solid Interfaces

“…For the first two purposes, we used a principle similar to that above to functionalize the inner rim of the nanowell with fluoroalkane or oligoethylene glycol units. We synthesized DBA-F 94 bearing C 8 F 17 chains and GBA-TeEG 95 bearing tetraethylene glycol (TeEG), respectively. The functional chains are linked by a p-phenylene unit at three alternating alkyl chain terminals (Figure 19a).…”