Herein, we report on a significant discovery, namely, the quantitative discharging of reduced graphite forms, such as graphite intercalation compounds, graphenide dispersions and graphenides deposited on surfaces with the simple solvent benzonitrile. Because of its comparatively low reduction potential, benzonitrile is reduced during this process to the radical anion, which exhibits a red colour and serves as a reporter molecule for the quantitative determination of negative charges on the carbon sheets. Moreover, this discovery reveals a very fundamental physical–chemical phenomenon, namely a quantitative solvent reduction induced and electrostatically driven mass transport of K+ ions from the graphite intercalation compounds into the liquid. The simple treatment of dispersed graphenides suspended on silica substrates with benzonitrile leads to the clean conversion to graphene. This unprecedented procedure represents a rather mild, scalable and inexpensive method for graphene production surpassing previous wet-chemical approaches.
Hexa‐peri‐hexabenzocoronides (HBC) was successfully used as a model system for investigating the complex mechanism of the reductive functionalization of graphene. The well‐defined molecular HBC system enabled deeper insights into the mechanism of the alkylation of reductively activated nanographenes. The separation and complete characterization of alkylation products clearly demonstrate that nanographene functionalization proceeds with exceptionally high regio‐ and stereoselectivities on the HBC scaffold. Experimental and theoretical studies lead to the conclusion that the intact basal graphene plane is chemically inert and addend binding can only take place at either preexisting defects or close to the periphery.
A systematic screening study of the exohedral reactivity of the reduced fullerenes (fullerenides) C602− and C60⋅− is reported. These doubly and singly negatively charged carbon cages were prepared by two‐fold reduction of C60 with potassium, leading to K2C60, or by in situ monoreduction with the radical anion of benzonitrile PhCN⋅−, respectively. Several series of electrophiles, including geminal and distant dihalides, benzyl bromides, and diazonium compounds, were employed as addition partners. In general, the investigated bromides proved to be the most suitable reaction partners. A series of fullerene adducts and cycloadducts involving either 1,2‐ or 1,4‐addition patterns, depending on the precise architecture and the steric demand of the addends, were synthesized and fully characterized. Some of the reaction products are unprecedented and inaccessible forms of neutral C60. The fullerenide chemistry presented here closely resembles related reactions of graphenides and carbon nanotubides, which are the most powerful methods for the functionalization of these macromolecular forms of synthetic carbon allotropes (SCAs). Activation of C60 by negative charging represents a little explored concept of fullerene chemistry, providing both new insights of fullerene reactivity itself and new types of exohedral derivatives.
We report on the synthesis and the structure elucidation of the elusive azafullerene pentachloride C NCl , which was obtained by high temperature halogenation of (C N) . The exceptionally strong host-guest interaction of the title compound in the solid is discussed.
Hexa-peri-hexabenzocoronides (HBC) was successfully used as am odel system for investigating the complex mechanism of the reductive functionalization of graphene.The well-defined molecular HBC system enabled deeper insights into the mechanism of the alkylation of reductively activated nanographenes.The separation and complete characterization of alkylation products clearly demonstrate that nanographene functionalization proceeds with exceptionally high regio-and stereoselectivities on the HBC scaffold. Experimental and theoretical studies lead to the conclusion that the intact basal graphene plane is chemically inert and addend binding can only take place at either preexisting defects or close to the periphery.The chemistry of two-dimensional (2D) materials is currently an emerging field located at the interface between chemistry,p hysics,a nd materials science.T he archetype of such planar architectures is graphene, [1] as ingle sheet of graphite,w hich represents ah exagonal network of sp 2 -configured carbon atoms.C ovalent functionalization [2][3][4][5][6][7][8] of graphene allows the combination of its unique properties [9,10] with those of other classes of compounds.T he chemical consequence of the covalent addend binding is the rehybridization of the carbon atom, to which the addend is bound, from its initial sp 2 to an sp 3 configuration. This process can also be considered as an introduction of basal plane defects which lead to the modification of the electronic (band structure), optical, and mechanical properties.I nc ontrast, the covalent addition chemistry offers the opportunity to improve the solubility and processability,thus facilitating the manufacturing processes required for practical applications.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. 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 o...
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