On-Surface Synthesis: A New Route Realizing Single-Layer Conjugated Metal–Organic Structures

Abstract

Recently, both experimental and theoretical advances have demonstrated that two-dimensional conjugated metal-organic frameworks (2D-cMOFs) exhibit interesting electronic and magnetic properties, such as high conductivity and ferromagnetism. Theoretical studies have predicted that exotic quantum states, including topological insulating states and superconductivity, emerge in some 2D-MOFs. The high design tunability of MOFs' structure and composition provides great opportunities to realize these structures. However, most of conventional synthesis methods yield multi-layer structures of the 2D-cMOFs, in which the predicted exotic quantum phases are often quenched due to inter-layer interactions. It is highly desirable to synthesize single-layer cMOFs.

Electronic structure and magnetic properties of transition metal kagome metal–organic frameworks

“…52–54 Since 2D MOFs can be prepared from the direct synthesis of their metal nods and organic ligands, so-called bottom-up synthesis, MOFs are considered a suitable platform for studying 2D properties. 55,56…”

“…[52][53][54] Since 2D MOFs can be prepared from the direct synthesis of their metal nods and organic ligands, so-called bottom-up synthesis, MOFs are considered a suitable platform for studying 2D properties. 55,56 The metal sites in these M 3 L 2 -type MOFs have a local structure of four neighboring atoms in a planar configuration regardless of the type of ligand molecules. For example, the Fe atom in Fe 3 (C 6 S 6 ) 2 (Fig.…”

Electronic band structure of 1D π–d hybridized narrow-gap metal–organic polymers

“…10,11 The fabrication of such nanostructures via traditional hydro-/solvothermal methods, as well as interface-assisted synthesis methods has turned out to be a real challenge. [12][13][14][15][16] In contrast, the on-surface synthesis route enables the formation of solvent-free and single-layer MO nanostructures. 15 The general approach taken towards achieving chemical bonds and efficient electron delocalization in such MO nanostructures, being a prerequisite to obtain the aforementioned emergent properties, focuses on enhancing metal-ligand interactions.…”

On-Surface Design of a 2D Cobalt-Organic Network Preserving Large Orbital Magnetic Moment

“…Such metal–organic nanomaterials are built from the packing of layers formed by transition metal ions coordinated to −NH 2 , −OH, −SH, or −SeH functional groups with single/polyaromatic cores and predominantly crystallize in porous hexagonal honeycomb lattices, while there are only a handful of examples of dense Kagome networks with benzene- and coronene-based ligands. From a physical standpoint, chemical control of these systems can allow for the augmented mobility of charge carriers due to extended intralayer conjugation − or the expression of novel quantum phases of matter. − The possibility of confining their growth to just atomically thick 2D layers by an on-surface chemistry approach offers exciting opportunities for investigating their electronic and magnetic properties at the ultimate spatial resolution, − which now we contribute to extend to the assembly of topologies and metal coordination indexes only accessible in solvent-free environments. − …”