Nanographenes from Distinct Carbon Sources

Matsumoto, Ikuya; Sekiya, Ryo; Haino, Takeharu

doi:10.1246/bcsj.20200381

Cited by 16 publications

(20 citation statements)

References 23 publications

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“…H 2 SO 4 and 60 % HNO 3 (3 : 1, v/v) at 120 °C for 24 h followed by deionization with dialysis membranes with a pore size of 2 kDa to remove inorganic salts and graphene fragments smaller than the pore size [29, 30] . This procedure was found to produce NGs with a less oxidized surface, [29, 31] as evidenced by a 13 C NMR spectrum of NG‐ 2 in [D 2 ]water, which showed sp 2 carbons and carboxy groups, while oxidized sp 3 carbons on the basal plane were not observed (Figure S11 in the Supporting Information). The size separation of NGs with a dialysis membrane (pore size: 15 kDa) to remove NGs larger than the pore size afforded NG‐ 2 .…”

Section: Figurementioning

confidence: 98%

Electrochromism of Nanographenes in the Near‐Infrared Region

et al. 2022

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Nanographene (NG) is a potential candidate for organic EC materials because of its large πconjugated system, chemical stability, absorption band covering the visible region, and tunable optical properties by postsynthetic modification. We show that NGs carrying redox-active triphenylamine (TPA) units covalently linked to the NG edge function as EC materials in the NIR region. The hybrid materials can be obtained by the installation of TPA units onto the NG edge and display changes in the absorption spectrum in the NIR region extending to a wavelength of over 2000 nm upon one-electron oxidation and reduction at low potentials (< 1.1 V). Time-dependent unrestricted density functional theory calculation of a model NG at the UB3LYP/6-31G(d,p) level of theory suggests that a narrow energy gap between the basal plane and the oxidized TPA unit is responsible for the observed EC function in the NIR region.

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Section: Figurementioning

confidence: 98%

Electrochromism of Nanographenes in the Near‐Infrared Region

et al. 2022

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“…[43] The amount of acids and the reaction time affect the PL properties of NGs. [42] The nonstoichiometric mixture of NGs inevitably lowers the reproducibility of their properties, in particular, optical spectra; the optical properties are the sum of those of individual NGs. For example, Matsuda et al reported that the chromatographic separation of NGs yielded NGs with distinct PL properties.…”

Section: Production Of Nanographenesmentioning

confidence: 99%

“…The produced NGs are the mixture of NGs with a few to tens of nanometers and are black to dark blown solids depending on their size distributions [43] . The amount of acids and the reaction time affect the PL properties of NGs [42] …”

Section: Functionalization Of Nanographenesmentioning

confidence: 99%

“…Our group has obtained NGs from graphite or finely crushed graphite by top-down methods (Scheme 1). [33,42] Acidassisted oxidative cleavage of graphite with a mixture of concentrated sulfuric acid and nitric acid (3 : 1, v/v) at 120 °C offers a mixture of NGs and inorganic salts. Neutralization of the solution with sodium carbonate (pH ~9) followed by deionization with dialysis membranes (2 kDa) affords NGs.…”

Section: Production Of Nanographenesmentioning

confidence: 99%

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Nanographene – A Scaffold of Two‐Dimensional Materials

Sekiya

Haino

2021

The Chemical Record

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Substances can be divided into 0D to 3D species based on the number of repeating units (atom, ion, and molecule) and their arrangements in space (point, linear, layer, and solid). Discrete substances belong to 0D species, polymers are examples of 1D species, and molecular crystals are 3D species. Most of the substances belong to one of these species. On the other hand, those categorized into 2D species wherein the repeating units organize a layer are less explored. 2D species have a surface and edges. The incorporation of these structural features into a molecular design can realize multifunctionalized systems that are difficult to achieve by conventional organic synthesis. The development of 2D species is, therefore, the frontier of organic, inorganic, and polymer chemistry. Nanographenes (NGs) are suitable scaffolds for realizing 2D species due to several factors, such as chemical stability and oxygen-containing functional groups on the surface and on the edge, allowing postsynthetic modifications. Our group has utilized NGs with tens of nanometers in diameters for developing 2D species. Carboxy groups on the edge enable us to install various substituents into NGs, offering NG-based functional materials. These studies demonstrate that the integration of NGs with organic chemistry can widen the scope of their applications other than optical materials that are a main application of NGs. We introduce our recent studies on the development of NG-based functional materials realized by postsynthetic modifications. We hope that this account will contribute to the development of the chemistry of 2D species.

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“…The oxidative cleavage of carbon (2 g) with a mixture of concentrated sulfuric acid (60 mL) and nitric acid (20 mL) for 12 h at 120 8C followed by neutralization with Na 2 CO 3 afforded a nanographene mixture (Scheme 1 a). [22] The mixtures were subjected to deionization with dialysis membranes with a pore size of 2 kDa. Nanographenes smaller than the pore size were removed by dialysis.…”

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confidence: 99%

Self‐Assembly of Nanographenes

2021

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Suitably decorated small aromatic systems can organize stacked structures that display interesting properties arising from their unique morphologies. Although nanographenes produced by top‐down methods have graphitic domains and can in principle be applied for such supramolecular systems, to our knowledge, no such example has been reported thus far. This is partly because of their limited solubility in organic solvents and partly because of their wide lateral size distribution. To realize nanographene‐based supramolecular aggregates, nanographenes carrying alkyl chains with narrow lateral size distributions are employed. We find that the nanographenes undergo self‐assembly and that self‐assembly is regulated by concentration, solvent polarity, temperature, and sonication. Optical measurements and AFM images indicate that stacked structures are possible candidates for aggregates. A molecular mechanics calculation models the interactions in the aggregates. The nanographenes showed concentration‐dependent morphologies on mica, stacked structures at low concentrations and polymer‐like network structures on mica at higher concentrations.

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Nanographenes from Distinct Carbon Sources

Cited by 16 publications

References 23 publications

Electrochromism of Nanographenes in the Near‐Infrared Region

Electrochromism of Nanographenes in the Near‐Infrared Region

Nanographene – A Scaffold of Two‐Dimensional Materials

Self‐Assembly of Nanographenes

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