Mono‐ and Ditopic Bisfunctionalization of Graphene

Abstract

For the first time, the bisfunctionalization of graphene by employing two successive reduction and covalent bond forming steps is reported. Bulk functionalization in dispersion and functionalization of individual sheets deposited on surfaces have both been carried out. Whereas in the former case attacks from both sides of the basal plane are possible and can lead to strain-free architectures, in the latter case, retrofunctionalizations can become important when the corresponding anion of the addend is a sufficiently good leaving group.

Degree of functionalisation dependence of individual Raman intensities in covalent graphene derivatives

“…Methods) to cover a wide range of θ . Figure 1a depicts the schematic representation of these derivatives: pristine CVD graphene (CVD-G), hexylated (hexyl-G)24, mixed functionalised (hexyl/aryl-G)24, reduced oxo-graphene (r-oxo-G)2526, arylated (aryl-G)27 as well as oxo-graphene (oxo-G)2526 (Supplementary note 1). In order to eliminate the impact of the addends on the optoelectronic response, the chemical moieties used were either non-Raman active28 or showed a Raman response far from the dominant graphene peak positions29.…”

“…Hexylated CVD graphene (hexyl-G), hexylated and arylated CVD graphene (hexyl/aryl-G): were synthesized according to Ref. 24. Laser-induced thermal defunctionalisation of hexyl-G was carried out with the laser line 532 nm and a power of 15 mW.…”

“…We selected Raman spectroscopy, including a combined in situ Raman-spectroscopy and dry electrostatic doping method, as a principally non-invasive method for probing the (localized) sp 2 areas of differently functionalised graphene derivatives24252627. Here we show that for monolayer functionalised graphene, the increase in optical response with θ is directly associated with the presence of photoluminescent C(sp 2 ) domains in the material.…”

Highly Regioselective Alkylation of Hexabenzocoronenes: Fundamental Insights into the Covalent Chemistry of Graphene

“…Another highly appealing aspect of covalent graphene functionalization is the desire to discover fundamental reactivity principles within the largely unexplored realm of 2D chemistry.T he most efficient method for covalent graphene functionalization is the treatment of negatively charged graphenide sheets with electrophiles,amethod we introduced afew years ago, [11] and which since then, has been continuously improved. [12][13][14][15][16][17][18][19][20][21] This reductive approach allows the generation of alarge variety of covalent adducts,including alkylated, arylated, and hydrogenated graphene derivatives, which exhibit comparatively high degrees of addition. Together with the reductive bulk functionalization, the addition chemistry of graphenides deposited on surfaces [18][19][20][21] has been investigated.…”

“…[12][13][14][15][16][17][18][19][20][21] This reductive approach allows the generation of alarge variety of covalent adducts,including alkylated, arylated, and hydrogenated graphene derivatives, which exhibit comparatively high degrees of addition. Together with the reductive bulk functionalization, the addition chemistry of graphenides deposited on surfaces [18][19][20][21] has been investigated. Thek ey point is the use of negatively charged graphites,t he so called graphite intercalation compounds (GICs), as starting materials.InGICs,alkaline metals, such as potassium, are placed between the individual carbon sheets and the graphene layers are reductively activated by electron transfer from the metal intercalates.Ageneral feature of reductive graphene functionalization protocols seems to be an inhomogeneous distribution of addends on the surface and leads to the formation of islands of highly functionalized areas next to intact nanographenes.T his distribution has been demonstrated, for example,b yh ighresolution transmission-electron microscopy (HRTEM) of polyarylated graphene, [11] and fluorescence spectroscopy of hydrogenated graphene.…”