On-Surface Synthesis of Novel Kagome Lattices Coordinated via Four-Fold N–Ag Bonding

Abstract

The Kagome lattice structures based on metal–organic coordination have garnered widespread interest because of their topologically Dirac/flat bands and other exotic electronic structures. However, the experimental fabrication of large-area two-dimensional (2D) Kagome lattice structures of metal–organic frameworks (MOFs) via on-surface synthesis remains limited. Herein, we successfully construct two kinds of large-scale 2D Kagome-type lattices stabilized by 4-fold N–Ag coordination on the Ag(111) surface. With the aid of scanning tunneling microscopy (STM) and synchrotron radiation photoemission spectroscopy (SRPES), we clearly elucidate the reaction pathway and mechanism of fabrication of the two Kagome lattices. This work provides a novel platform for investigating related intriguing physical properties.

Surface-supported metal−organic frameworks with geometric topological diversity via scanning tunneling microscopy

“…A inspiring strategy for on-surface synthesis was employed to construct two large-scale SMOFs consisting of 4-fold N−Ag bonds on the Ag(111) substrate. 91 For example, the quasi-Kagome lattice with two different size nodes and the Kagome lattice was formed by covalent trimers ( Figure 11 A). The excellent selective construction of Kagome lattice was a thermodynamically controlled reaction process.…”

“… (I) Large-scale STM image of Kagome lattice after annealing at 520 K. Figures reproduced from: Xiong et al. 91 Copyright 2023 American Chemical Society. …”

From Short‐ to Long‐Range Chiral Recognition on Surfaces: Chiral Assembly and Synthesis

“…A great number of chiral assemblies have been studied on metal surfaces, including 0D chiral clusters, [24][25][26][27] 1D chiral chains, stripes or lines, filaments, wires [28][29][30][31][32][33][34] and 2D chiral islands, lamellas structures and honeycomb or more complex nontrivial architectures (chiral Kagome networks, quasicrystals, Sierpiński triangle fractals and semi-regular Archimedean tilings) that may possess intriguing physical and chemical properties. Most of these chiral nanostructures are achieved through shortrange chiral recognition induced by non-covalent intermolecular interactions, such as hydrogen bonding, [24,28,30,31,[34][35][36][37][38][39][40][41][42] halogen bonding, [33,[43][44][45][46] van der Waals (vdW) forces, [47] dipoledipole interactions, [48] metal-organic coordination [33,[49][50][51] or cooperative interactions of two or more sorts of intermolecular forces. [27,29,34,40,[52][53][54][55] In addition, the competition between molecule-molecule an...…”

Chiral Honeycomb Lattices of Nonplanar π-Conjugated Supramolecules with Protected Dirac and Flat Bands

“…These Dirac and flat bands are under intensive investigations because of rich topological and/or many-body phenomena, − but most of them are based on naturally grown inorganic materials and thus lack controllability of model parameters. One of the promising methods for extending the research realm is the usage of molecular assembly such as supramolecules − and metal–organic/covalent-organic frameworks, − where 2D electronic lattices are defined by intermolecular networks ,− or localized Schockley surface states coupled through molecular potential barriers. ,, This approach is based on the rational design of molecules and thus can be very flexible and powerful. However, intermolecular coupling is often very weak, and the general strategy for the formation of a molecular-based honeycomb lattice has not been established yet.…”