Recent Progress in the Fabrication of Low Dimensional Nanostructures via Surface-Assisted Transforming and Coupling

Abstract

Polymerization of functional organics into covalently cross-linked nanostructures via bottom-up approach on solid surfaces has attracted tremendous interest recently, due to its appealing potentials in fabricating novel and artificial low dimensional nanomaterials. While there are various synthetic approaches being proposed and explored, this paper reviews the recent progress of on-surface coupling strategies towards the synthesis of low dimensional nanostructures ranging from 1D nanowire to 2D network and describes their advantages and drawbacks during on-surface process and phase transformations, for example, from molecular self-assembly to on-surface polymerization. Specifically, Ullmann reaction is discussed in detail and the mechanism governing nanostructures' transforming effect by surface treatment is exploited. In the end, it is summarized that the hierarchical polymerization combined with Ullmann coupling makes it possible to realize the selection of different synthetic pathways and phase transformations and obtain novel organometallic nanowire with metalorganic bonding.

Controlling a Chemical Coupling Reaction on a Surface: Tools and Strategies for On-Surface Synthesis

“…On-surface synthesis is a newly developing field of research that aims at making use of well-defined solid surfaces as confinement templates to initiate chemical reactions. − The concepts of supramolecular chemistry are applied here to provide well-defined functional surfaces from the “bottom-up” self-assembly of nanometer-sized elementary building-blocks . On-surface synthesis represents in a sense an extension of heterogeneous catalysis whereby the initial precursors, the intermediate states, and the reaction products all remain in an adsorbed state, usually in the submonolayer regime.…”

Recent Advances of Hierarchical and Sequential Growth of Macromolecular Organic Structures on Surface

“…On-surface chemistry is an emerging field of research and optimization of the reaction conditions to elaborate well-defined nanostructures constitutes the major focus of researchers. Since the first reports mentioning the elaboration of sCOFs, Ullmann coupling of halogenated aromatic rings [ 31 , 82 ] have undoubtedly been one of the most commonly used coupling mode. As mentioned previously, the sequential growth of covalent networks is mainly based on the attachment of two different types of functional groups onto the same monomer.…”

“…Since the first reports mentioning the elaboration of sCOFs, condensation of boronic acids to form boroxines [ 92 , 93 ] and the Ullmann coupling of halogenated aromatic rings [ 31 , 82 ] have been widely used as coupling modes. Considering that these two on-surface reactions are now a mature field of research with regards to the number of publications, a combination of these two reactions was logical to create 2D covalent networks.…”

“…At present, possibilities offered by organic chemistry to form covalent bonds between molecular tectons have only been scarcely explored by physicists with regards to the number of existing coupling modes [ 30 , 31 ] and the reactions of cyclodehydrogenation [ 32 , 33 ], dehydration of boronic acids [ 34 , 35 , 36 , 37 , 38 , 39 ], esterification of boronic acids [ 40 ], Bergman cyclization [ 41 ], Glaser coupling [ 42 , 43 ], Wurtz reaction [ 44 ], dehydrogenative coupling of terminal alkenes [ 45 ], dehydrogenative coupling of porphyrines [ 46 ], aryl–aryl coupling via a C–H activation [ 47 ], formation of triple bonds by coupling of trichloromethyl groups [ 48 ], cyclotrimerization of acetyls [ 49 ], formation of imines [ 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ], esters [ 59 ], imides [ 60 , 61 ], amides [ 62 , 63 ], or the Ullmann coupling between halogenated aromatic rings [ 18 , 64 ] can be cited as examples of reactions already examined on surface (see Figure 3 ). Parallel to known reactions, unprecedented coupling modes were also discovered in the context of the surface-mediated reactions, as exemplified with the oxidative coupling of activated methylene groups [ 65 , 66 , 67 ], the polymerization of alkanes [ 68 ], or the aryl–aryl coupling of none halogenated polyaromatics […”

Two‐Sidedness of Surface Reaction Mediation

“…Studies of surface reactions based on the SPM technique have triggered intense interest. To date, many excellent reviews have been published on the reactions on various solid surfaces from various angles …”