Porous Self-Assembled Molecular Networks as Templates for Chiral-Position-Controlled Chemical Functionalization of Graphitic Surfaces

Abstract

Controlled covalent functionalization of graphitic surfaces with molecular scale precision is crucial for tailored modulation of the chemical and physical properties of carbon materials. We herein present that porous self-assembled molecular networks (SAMNs) act as nanometer scale template for the covalent electrochemical functionalization of graphite using an aryldiazonium salt. Hexagonally aligned achiral grafted species with lateral periodicity of 2.3, 2.7, and 3.0 nm were achieved utilizing SAMNs having different pore-to-pore distances. The unit cell vectors of the grafted pattern match those of the SAMN. After the covalent grafting, the template SAMNs can be removed by simple washing with a common organic solvent. We briefly discuss the mechanism of the observed pattern transfer. The unit cell vectors of the grafted pattern align along non-symmetry axes of graphite, leading to mirror-image grafted domains, in accordance with the domain-specific chirality of the template. In case a homochiral building block is used for SAMN formation, one of the 2D mirror image grafted patterns is cancelled. This is the first example of a nearly crystalline one-sided or supratopic covalent chemical functionalization. In addition, the positional control imposed by the SAMN renders the functionalized surface (homo)chiral reaching a novel level of control for the functionalization of carbon surfaces, including surface-supported graphene.

Self-limiting covalent modification of carbon surfaces: diazonium chemistry with a twist

“…We have employed STM to image grafted aryl groups on the surface of graphite and single layer graphene in the recent past. 17,41,42 STM measurements provide nanoscale insight in to the efficiency of the grafting process. Figure 3 shows representative large-and small scale STM images of covalently modified graphite using the different precursors.…”

Iodide mediated reductive decomposition of diazonium salts: towards mild and efficient covalent functionalization of surface-supported graphene

“…Using appropriate design of aryldiazonium salts, we have recently demonstrated precise control over the density of covalent grafting onto the surface of HOPG. [16][17][18][19] Both the approaches described above have progressed substantially in the past few years. In contrast to the bulk approach, which allows functionalization on a gram scale, the electrochemical approach is limited to surface functionali-zation with areas extending only up to a few square centimetres.…”

Multicomponent Covalent Chemical Patterning of Graphene

“…Facilitated by the characteristic Moiré pattern of graphene on Ir(111), the chemisorption of hydrogen was found to open a band gap in graphene . We have demonstrated the covalent patterning of graphene and graphite via electrochemical diazonium chemistry using physisorbed self-assembled monolayers of organic molecules as sacrificial templates bringing the patterning dimensions within the sub 10 nm realm. , The light induced decomposition of dibenzoylperoxide was recently used to demonstrate laser-based writing, reading, and erasing of information stored in the form of covalent chemical patterns on graphene …”

“…12 We have demonstrated the covalent patterning of graphene and graphite via electrochemical diazonium chemistry using physisorbed self-assembled monolayers of organic molecules as sacrificial templates bringing the patterning dimensions within the sub 10 nm realm. 13,14 The light induced decomposition of dibenzoylperoxide was recently used to demonstrate laserbased writing, reading, and erasing of information stored in the form of covalent chemical patterns on graphene. 15 A combination of conventional lithography with chemical functionalization is being actively explored to combine the best of both worlds.…”