Spatially Resolved Covalent Functionalization Patterns on Graphene

Abstract

Spatially resolved functionalization of 2D materials is highly demanded but very challenging to achieve.T he chemical patterning is typically tackled by preventing contact between the reagent and material, which brings various accompanying challenges.P hotochemical transformation on the other hand inherently provides remote high spatiotemporal resolution using the cleanest reagent-a photon. Herein, we combine two competing reactions on ag raphene substrate to create functionalization patterns on amicrometer scale via the Mitsunobu reaction. The mild reaction conditions allow introduction of covalently dynamic linkages,w hichc an serve as reversible labels for surface-or graphene-enhanced Raman spectroscopyc haracterization of the patterns prepared. The proposed methodology thus provides ap athwayf or local introduction of arbitrary functional groups on graphene.Graphene holds ap rominent position among two-dimensional (2D) materials owing to its unique properties, [1][2][3] which can be further tuned for particular applications [4][5][6] by several methods.Among them, chemical functionalization offers the broadest variety of possibilities. [7][8][9] Although several approaches for covalent grafting have been reported, [10][11][12][13][14][15] only recently has the advancement towards specific applications revealed the need for spatially resolved methods that would provide patterned surface functionalization on the 2D material, [16][17][18] aiming at sophisticated sensor arrays or device mass production. [19] This non-trivial task has been approached from several directions,u sing for instance photolithography, [20] dip-pen lithography [21][22][23] or various writing techniques. [24][25][26] Using covalent modification for spatially resolved functionalization typically relies on preventing contact of the reagents with graphene,t hus implying the use of ar esist mask [27] or controlled deposition [28,29] at the nanoscale,w hich either adds more steps (with concomitant contamination [30] ) or severely limits the processing speed, respectively.P hotochemical reactions represent au nique alternative to the abovementioned two approaches [31] because photochemistry responds to illumination patterns without the need for aresist or spatially confined reagent deposition.Thec ritical challenge for the surface functionalization of the 2D materials is unambiguous characterization of the reaction products facing the detection and resolution limits of many methods due to the strict monolayer nature of the materials. [32] Ty pical methods such as Raman spectroscopy [33][34][35] and X-ray photoelectron spectroscopy [36] (XPS) provide only limited insight into the actual chemistry taking place at the surface,anissue which has been tackled recently by the use of surface-and graphene-enhanced Raman spectroscopy (SERS and GERS,r espectively) [14,37] and also by other methods. [38,39] Application of SERS/GERS allows direct assignment of characteristic vibrational modes to particular species and thus provides solid evidence for species...

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

“…These species form covalent adducts with graphene via free radical addition, CH insertion or cycloaddition reactions. [2][3][4] Amongst the different strategies, diazonium chemistry has been particularly popular for the covalent attachment of aryl groups to the basal plane of graphene. The usefulness of aryldiazonium salts for covalent modification of carbon surfaces has been known since the early 1990s.…”

Synthesis and characterization of tannic acid–PEG hydrogel via Mitsunobu polymerization

“…S2a †), the single peak at 3.60 ppm was belonging to CH 2 CH 2 O group, the multiple peaks at 7.55 ppm and 7.62 ppm were assignable to aromatic protons. As to 13 C NMR spectrum (Fig. S2b †), the strong single peak at 70 ppm typical of PEG backbone was assigned to (CH 2 CH 2 O) n .…”

“…[7][8][9] Consequently, Mitsunobu reaction is mainly employed either as an intermediate step for the synthesis of functional organic small molecules, or as a post-polymerization functionalization route. [10][11][12][13][14] Illuminated by the work of Chong-Bok Yoon and Hong-Ku Shim 15,16 in which polyimides were obtained via Mitsunobu polycondensation, it is believed that Mitsunobu polymerization or Mitsunobu polycondensation is a potential method to simplify the separation process as well as a promising way leading to a bunch of brand-new polymers due to its wide scope. Rather than synthesis of linear polyimides, crosslinked bulk polymers obtained via Mitsunobu polymerization are promising since the properties of nucleophiles (carboxylic acids, phenols, thiols, imines, purine/pyrimidine bases and so on) and substrates can be integrated together without tedious column chromatography separation process.…”

Evolution of Graphene Patterning: From Dimension Regulation to Molecular Engineering

“…Recently, this UV photolithography approach allowed for carboxylate groups being pattered onto graphene as well. [ 181 ] Initially, an oxygen plasma was applied to introduce hydroxyl‐ and epoxy‐groups to the surface of graphene deposited on a Si/SiO 2 substrate. Afterward, these introduced hydroxyl‐ and epoxy‐groups were converted into easily leaving groups via a Mitsunobu reaction and then substituted by nucleophilic azodicarboxylate species.…”