Functionalized fullerenes in water. The first 10 years of their chemistry, biology, and nanoscience

Beneficial Influence of Water-Soluble PEG-Functionalized C60 Fullerene on Human Osteoblast Growth In Vitro

The purpose of this study was to make an initial assessment of new PEG (polyethylene glycol)-functionalized C₆₀ fullerene derivative for potential bone tissue engineering applications. Thus, Fourier Transform Infrared spectroscopy analysis, thermogravimetric analysis, and cyclic voltammetry measurement were performed. Moreover, cell culture experiments in vitro were carried out using normal human osteoblasts. Cell viability and proliferation were evaluated using colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test as well as by fluorescent staining. It was demonstrated that resultant derivative possessed good solubility in water, high temperature stability, and retained favorable electron accepting properties of C₆₀ fullerene core. Most important, new fullerene derivatives at low concentrations did not exhibit cytotoxic effect and supported osteoblast proliferation compared to control. Thanks to all mentioned properties of new PEG-functionalized C₆₀ fullerene derivative, it seems that it could be used as a component of polymer-based bone scaffolds in order to enhance their biological properties.

[2 + 1] Cycloaddition reactions of fullerene C60 based on diazo compounds

The most common variant of fullerene core functionalization is the [2 + 1] cycloaddition process. Of these, reactions leading to methanofullerenes are the most promising. They are synthesized in two main reactions: nucleophilic cyclopropanation according to the Bingel method and thermal addition of diazo compounds. This present review summarizes the material on the synthesis of monofunctionalized methanofullerenes - analogues of [60]PCBM - based on various diazo compounds. The main cyclopropanating agents for the synthesis of monosubstituted methanofullerenes, the optimal conditions and the mechanism of the [2 + 1] cycloaddition, as well as the practical application of the target products are analyzed.

Metal-Free-Catalyzed Three-Component [2+2+2] Annulation Reaction of [60]Fullerene, Ketones, and Indoles: Access to Diverse [60]Fullerene-Fused 1,2-Tetrahydrocarbazoles

The first example of metal-free-catalyzed multicomponent annulation reaction of [60]fullerene has been developed for concise and efficient construction of novel [60]fullerene-fused 1,2-tetrahydrocarbazoles. Using inexpensive and readily available I₂ as a catalyst, [60]fullerene, ketones, and indoles undergo a formal [2+2+2] annulation process to conveniently assemble diverse 1,2-tetrahydrocarbazoles. Mechanistic studies indicate that this reaction proceeds through I₂-promoted generation of a 3-vinylindole structure with the characteristics of a conjugated diene followed by cycloaddition to [60]fullerene.

Biogenic fenton-like reaction involvement in aerobic degradation of C60 by Labrys sp. WJW

Buckminster fullerene (C₆₀), the most representative type among fullerenes, has attracted widely attentions because of its many potential applications. The increasing application of fullerene and limited knowledge of its environmental fate are required concerns. Herein, the biotransformation of C₆₀ by Labrys sp. WJW was investigated. Cell numbers reached 25.76 ± 1.85 folds within 8 days using 100 mg/L C₆₀ as sole carbon source. The biotransformation of C₆₀ by Labrys sp. WJW was analyzed by various characterization methods. Raman spectra indicated that strain WJW broke the soccer ball like structure of C₆₀. After 12 days, over 60% of C₆₀ was degraded evidenced by UV-vis spectrophotometry and liquid chromatography-mass spectrometry. The underlying biotransformation mechanism of C₆₀ through an extracellular Fenton-like reaction was illustrated. In this reaction, the ^•OH production was mediated by reduction of H₂O₂ involving a continuous cycle of Fe(II)/Fe(III). Bacterial transformation of C₆₀ will provide new insights into the understanding of C₆₀ bioremediation process.

Preparation, Functionalization, Modification, and Applications of Nanostructured Gold: A Critical Review

Gold nanoparticles (Au NPs) play a significant role in science and technology because of their unique size, shape, properties and broad range of potential applications. This review focuses on the various approaches employed for the synthesis, modification and functionalization of nanostructured Au. The potential catalytic applications and their enhancement upon modification of Au nanostructures have also been discussed in detail. The present analysis also offers brief summaries of the major Au nanomaterials synthetic procedures, such as hydrothermal, solvothermal, sol-gel, direct oxidation, chemical vapor deposition, sonochemical deposition, electrochemical deposition, microwave and laser pyrolysis. Among the various strategies used for improving the catalytic performance of nanostructured Au, the modification and functionalization of nanostructured Au produced better results. Therefore, various synthesis, modification and functionalization methods employed for better catalytic outcomes of nanostructured Au have been summarized in this review.

An "Umpolung Relay" Strategy: One-Pot, Twice Polarity Inversion Cascade Synthesis of Diversified [60]Fulleroindoles

An "umpolung relay" strategy, which includes an one-pot, twice polarity inversion cascade of C₆₀ via carbanion and carbocation polarity reversed relay pathway, has been developed for the synthesis of a diverse range of novel [60]fulleroindole derivatives.

A copper-promoted synthesis of epoxy-bridged [60]fullerene-fused lactones and further derivatization

A facile copper-promoted decarboxylative annulation of [60]fullerene (C60) with two identical α-oxocarboxylic acids via an unprecedented cascade addition pathway has been exploited to synthesize the unique epoxy-bridged C60-fused lactones for the first time. Further transformations into the rare epoxy-bridged C60-fused hemiacetals and bicyclic-fused 1,2,3,4-adducts as well as application in a perovskite solar cell device of the obtained products have also been demonstrated. The structures of the epoxy-bridged C60-fused lactones and derived reductive products have been unequivocally established by single-crystal X-ray crystallography. Plausible reaction mechanisms leading to the observed products are proposed.

One-pot, three-component regioselective coupling reaction of triphenylamine/carbazole derivatives with [60]fullerene and indoles via an “umpolung relay” strategy

An “umpolung relay” three-component regioselective coupling reaction of triphenylamine/carbazole derivatives with C60 and indoles was developed, which features high regioselectivity, broad substrate scope, and excellent functional group tolerance.

Water-soluble host-guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

A sugar-functionalized water-soluble tribenzotriquinacene derivative bearing six glucose residues, TBTQ-(OG) 6 , was synthesized and its interaction with C60 and C70-fullerene in co-organic solvents and aqueous solution was investigated by fluorescence spectroscopy and ultraviolet-visible spectroscopy. The association stoichiometry of the complexes TBTQ-(OG) 6 with C60 and TBTQ-(OG) 6 with C70 was found to be 1:1 with binding constants of K a = (1.50 ± 0.10) × 105 M-1 and K a = (2.20 ± 0.16) × 105 M-1, respectively. The binding affinity between TBTQ-(OG) 6 and C60 was further verified by Raman spectroscopy. The geometry of the complex of TBTQ-(OG) 6 with C60 deduced from DFT calculations indicates that the driving force of the complexation is mainly due to the hydrophobic effect and to host-guest π-π interactions. Hydrophobic surface simulations showed that TBTQ-(OG) 6 and C60 forms an amphiphilic supramolecular host-guest complex, which further assembles to microspheres with diameters of 0.3-3.5 μm, as determined by scanning electron microscopy.

Sonochemical synthesis of novel C60 fullerene 1,4-oxathiane derivative through the intermediate fullerene radical anion

We have discovered a selective and efficient method for the synthesis of previously unknown 1,9-(1',4'-oxathiano)-1,9-dihydro-(C₆₀-I_h)[5,6]fullerene, a compound with the direct attachment of the sulfur atom to the fullerene core. The method is based on the reaction of C₆₀ with 1,2-hydroxythiols in the presence of inorganic bases in air under ultrasonication. The significance of ultrasound has been exemplified with the comparative conventional methods. The title compound has been identified with mass-(MALDI TOF/TOF), one- and two-dimensional NMR ¹H and ¹³C (COSY, HSQC, HMBS), IR, UV-Vis spectroscopic techniques. Using the direct EPR method, we have detected radical anion C₆₀^- (g = 2.0046 and ΔH = 2 G) as a key reaction intermediate of the sonochemical reaction. Based on the experimental results and quantum chemical calculations, we have proposed a mechanism for the conversion of C₆₀ and 2-mercaptoethanol to the C₆₀-1,4-oxathiane adduct.

Facile access to amino-substituted cyclopentafullerenes: novel reaction of [60]fullerene with β-substituted propionaldehydes and secondary amines in the absence/presence of magnesium perchlorate

A series of scarce amino-substituted cyclopentafullerenes instead of the expected N-alkyl-2,5-disubstituted fulleropyrrolidines were synthesized in moderate to excellent yields via the simple one-step reaction of [60]fullerene with cheap and easily available β-substituted propionaldehydes and secondary amines in the absence/presence of magnesium perchlorate. The in situ generation of allylic amines from β-substituted propionaldehydes and secondary amines played a crucial role in the successful preparation of amino-substituted cyclopentafullerenes without additional carbons. With the addition of magnesium perchlorate, secondary amines containing ethyl group(s) could produce novel amino-substituted cyclopentafullerenes with two additional carbons. All the obtained cyclopentafullerenes displayed high stereoselectivity with cis isomers as the exclusive or major products. Plausible reaction mechanisms are proposed to elucidate the above-mentioned reaction process.

Iron-Catalyzed Redox-Neutral Radical Cascade Reaction of [60]Fullerene with γ,δ-Unsaturated Oxime Esters: Preparation of Free (N-H) Pyrrolidino[2',3':1,2]fullerenes

Herein an unprecedented iron(II)-catalyzed redox-neutral radical cascade reaction of [60]fullerene with γ,δ-unsaturated oxime esters is reported for the preparation of novel free (N-H) pyrrolidino[2',3':1,2]fullerenes. The transformation undergoes an intramolecular cyclization/intermolecular cyclization/oxidation/hydrolysis cascade, and features simple operation, broad substrate scope/high functional group compatibility as well as suitable for scale-up synthesis, providing a facile and practical access to a range of free pyrrolidino[2',3':1,2]fullerenes.

Carbon-based antiviral nanomaterials: graphene, C-dots, and fullerenes. A perspective

The appearance of new and lethal viruses and their potential threat urgently requires innovative antiviral systems. In addition to the most common and proven pharmacological methods, nanomaterials can represent alternative resources to fight viruses at different stages of infection, by selective action or in a broad spectrum. A fundamental requirement is non-toxicity. However, biocompatible nanomaterials have very often little or no antiviral activity, preventing their practical use. Carbon-based nanomaterials have displayed encouraging results and can present the required mix of biocompatibility and antiviral properties. In the present review, the main candidates for future carbon nanometric antiviral systems, namely graphene, carbon dots and fullerenes, have been critically analysed. In general, different carbon nanostructures allow several strategies to be applied. Some of the materials have peculiar antiviral properties, such as singlet oxygen emission, or the capacity to interfere with virus enzymes. In other cases, nanomaterials have been used as a platform for functional molecules able to capture and inhibit viral activity. The use of carbon-based biocompatible nanomaterials as antivirals is still an almost unexplored field, while the published results show promising prospects.

Electrochemical regioselective alkylations of a [60]fulleroindoline with bulky alkyl bromides

Electrochemical alkylations of a [60]fulleroindoline with different bulky alkyl bromides exhibit different reaction behaviors. The hydroalkylation and dialkylation of the electrochemically generated dianionic [60]fulleroindoline with bulky 2,4,6-tris(bromomethyl)mesitylene give rise to 1,2,3,16-adducts. In comparison, the hydroalkylation of the dianionic [60]fulleroindoline with bulkier diphenylbromomethane still affords a 1,2,3,16-adduct, while the corresponding dialkylation provides a sterically favoured 1,4,9,12-adduct, which is scarcely investigated, as the major product along with the isomeric 1,2,3,16-adduct as the minor product. The structures of these products have been determined by spectroscopic data and single-crystal X-ray diffraction analysis. A plausible reaction mechanism has been proposed to explain the formation of the observed products.

Self-Stabilized Giant Aggregates in Water from Room-Temperature Ionic Liquids with an Asymmetric Polar-Apolar-Polar Architecture

We report the assembly of four imidazolium bromides, each of which bears a naphthyl on one side of the imidazolium cation and a branched alkyl chain on the other. This design creates a new type of amphiphilic ionic liquid with an apolar-polar-apolar structure and a low melting point (m_p, <-20 °C), which has not been achieved by reported counterparts bearing linear alkyl chains. In solvent-free states, microphase segregation occurs where polar and apolar domains arrange bicontinuously as proved by molecular dynamics (MD) simulations. When dispersed in water, self-stabilized giant aggregates formed with ultrahigh colloidal stability (up to years). MD simulations provide clues of discrete bicontinuous phases within the giant aggregates. These newly discovered self-assemblies provide a heterogeneous reservoir that can accommodate guest molecules including the highly apolar fullerene C₆₀, paving the way for a wide range of potential applications.

Intrinsic Enzyme-like Activities of Cerium Oxide Nanocomposite and Its Application for Extracellular H2O2 Detection Using an Electrochemical Microfluidic Device

Artificial enzyme mimics have gained considerable attention for use in sensing applications due to their high stability and outstanding catalytic activity. We show that cerium oxide nanosheets (NSs) exhibit triple-enzyme mimetic activity. The oxidase-, peroxidase-, and catalase-like activities of the proposed nanoparticles are demonstrated using both colorimetric and electron paramagnetic resonance (EPR) spectroscopy. On the basis of the excellent catalytic activity of cerium oxide NSs toward hydrogen peroxide, an electrochemical approach for the high-throughput detection of H₂O₂ in living cells was established. This report presents an analytical microfluidic chip integrated with a cerium oxide NS mimic enzyme for the fabrication of a simple, sensitive, and low-cost electrochemical sensor. Three Au microelectrodes were fabricated on a glass substrate using photolithography, and the working electrode was functionalized using cerium oxide NSs. The operation of this biosensor is based on cerium oxide NSs and presents a high sensitivity over a wide detection range, between 100 nM and 20 mM, with a low detection limit of 20 nM and a high sensitivity threshold of 226.4 μA·cm^-2·μM^-1. This microfluidic sensor shows a strong response to H₂O₂, suggesting potential applications in monitoring H₂O₂ directly secreted from living cells. This sensor chip provides a promising platform for applications in the field of diagnostics and sensing.

A facile approach to hydrophilic oxidized fullerenes and their derivatives as cytotoxic agents and supports for nanobiocatalytic systems

A facile, environment-friendly, versatile and reproducible approach to the successful oxidation of fullerenes (oxC₆₀) and the formation of highly hydrophilic fullerene derivatives is introduced. This synthesis relies on the widely known Staudenmaier’s method for the oxidation of graphite, to produce both epoxy and hydroxy groups on the surface of fullerenes (C₆₀) and thereby improve the solubility of the fullerene in polar solvents (e.g. water). The presence of epoxy groups allows for further functionalization via nucleophilic substitution reactions to generate new fullerene derivatives, which can potentially lead to a wealth of applications in the areas of medicine, biology, and composite materials. In order to justify the potential of oxidized C₆₀ derivatives for bio-applications, we investigated their cytotoxicity in vitro as well as their utilization as support in biocatalysis applications, taking the immobilization of laccase for the decolorization of synthetic industrial dyes as a trial case.

Unraveling Chiral Selection in the Self-assembly of Chiral Fullerene Macroions: Effects of Small Chiral Components Including Counterions, Co-ions, or Neutral Molecules

Lactic acid-functionalized chiral fullerene (C₆₀) molecules are used as models to understand chiral selection in macroionic solutions involving chiral macroions, chiral counterions, and/or chiral co-ions. With the addition of Zn²⁺ cations, the C₆₀ macroions exhibit slow self-assembly behavior into hollow, spherical, blackberry-type structures, as confirmed by laser light scattering (LLS), transmission electron microscopy (TEM), and atomic force microscopy (AFM) techniques. Chiral counterions with high charge density show no selection to the chirality of AC₆₀ macroions (LAC₆₀ and DAC₆₀) during their self-assembly process, while obvious chiral discrimination between the assemblies of LAC₆₀ and DAC₆₀ is observed when chiral counterions with low charge density are present. Compared with chiral counterions, chiral co-ions show weaker effects on chiral selection with larger amounts needed to trigger the chiral discrimination between LAC₆₀ and DAC₆₀. However, they can induce a higher degree of discrimination when abundant chiral co-ions are present in solution. Furthermore, the self-assembly of chiral AC₆₀ macroions is fully suppressed by adding significant amounts of neutral molecules with opposite chirality. Thermodynamic parameters from isothermal titration calorimetry (ITC) reveal that chiral selection is controlled by the ion pairing and the destruction of solvent shells between ions, and meanwhile originates from the delicate balance between electrostatic interaction and molecular chirality.

Functionalization of Gold Nanoparticles by Inorganic Entities

The great affinity of gold surface for numerous electron-donating groups has largely contributed to the rapid development of functionalized gold nanoparticles (Au-NPs). In the last years, a new subclass of nanocomposite has emerged, based on the association of inorganic molecular entities (IME) with Au-NPs. This highly extended and diversified subclass was promoted by the synergy between the intrinsic properties of the shell and the gold core. This review-divided into four main parts-focuses on an introductory section of the basic notions related to the stabilization of gold nanoparticles and defines in a second part the key role played by the functionalizing agent. Then, we present a wide range of inorganic molecular entities used to prepare these nanocomposites (NCs). In particular, we focus on four different types of inorganic systems, their topologies, and their current applications. Finally, the most recent applications are described before an overview of this new emerging field of research.

A [60]fullerene nanoconjugate with gemcitabine: synthesis, biophysical properties and biological evaluation for treating pancreatic cancer

Background

The first-line chemotherapy drug that is used to treat pancreatic ductal adenocarcinoma is gemcitabine. Unfortunately, its effectiveness is hampered by its chemo-resistance, low vascularization and drug biodistribution limitations in the tumor microenvironment. Novel nanotherapeutics must be developed in order to improve the prognosis for patients with pancreatic cancer.

Results

We developed a synthetic methodology for obtaining a water-soluble nanoconjugate of a [60]fullerene-glycine derivative with the FDA-approved drug gemcitabine (nanoC60GEM). The proposed synthetic protocol enables a highly water-soluble [60]fullerene-glycine derivative (6) to be obtained, which was next successfully conjugated with gemcitabine using the EDCI/NHS carbodiimide protocol. The desired nanoconjugate was characterized using mass spectrometry and DLS, IR and XPS techniques. The photogeneration of singlet oxygen and the superoxide anion radical were studied by measuring 1O2 near-infrared luminescence at 1270 nm, followed by spin trapping of the DMPO adducts by EPR spectroscopy. The biological assays that were performed indicate that there is an inhibition of the cell cycle in the S phase and the induction of apoptosis by nanoC60GEM.

Conclusion

In this paper, we present a robust approach for synthesizing a highly water-soluble [60]fullerene nanoconjugate with gemcitabine. The performed biological assays on pancreatic cancer cell lines demonstrated cytotoxic effects of nanoC60GEM, which were enhanced by the generation of reactive oxygen species after blue LED irradiation of synthesized fullerene nanomaterial.

Stereoselective synthesis of amino-substituted cyclopentafullerenes promoted by magnesium perchlorate/ferric perchlorate

A facile one-step reaction of [60]fullerene with cinnamaldehydes and amines promoted by magnesium perchlorate/ferric perchlorate under air conditions afforded a series of rare amino-substituted cyclopentafullerenes in moderate to good yields. Stereoselectivity was readily achieved. Secondary amines exclusively produced N,N-disubstituted cyclopentafullerenes as cis isomers, while arylamines gave N-monosubstituted cyclopentafullerenes with a preference of cis isomers as major products. N-Monosubstituted cyclopentafullerenes could be further converted into other scarce cyclopentafullerenes in the presence of acid chloride or paraformaldehyde. A possible reaction pathway was proposed to elucidate the formation of amino-substituted cyclopentafullerenes.

Direct arylation of C60Cl6 and C70Cl8 with carboxylic acids: a synthetic avenue to water-soluble fullerene derivatives with promising antiviral activity

We report unprecedented Friedel-Crafts arylation of chlorofullerenes C60Cl6 and C70Cl8 with unprotected carboxylic acids as an efficient single-step synthesis of the inherently stable water-soluble fullerene derivatives. Using this method, a series of previously unaccessible compounds was obtained without chromatographic purification in almost quantitative yields. Promising anti-HIV activity comparable to characteristics of commercial drugs was demonstrated for some of these compounds.

Synthesis and Photophysical Study of [60]Fullerene-Maleimide Dyads

Novel [60]fullerene-maleimide dyads were synthesized by covalent linking of maleimide fluorophore to the [60]fullerene (C₆₀) via Bingel reaction. The dyads were well characterized and studied for their absorption and emission properties. The fluorescence quenching of maleimide moiety by C₆₀ was observed, indicating the intramolecular energy transfer from maleimide fluorophore to C₆₀ moiety.

Regioselective electrosynthesis of tetra- and hexa-functionalized [60]fullerene derivatives with unprecedented addition patterns

The efficient and regioselective electrosynthesis of tetra- and hexa-functionalized [60]fullerene derivatives with unprecedented addition patterns has been achieved. The tetra-functionalized [60]fullerene derivative with an intriguing 1,2,4,17-addition pattern is regioselectively obtained by cyclization reaction of the dianionic species generated electrochemically from a [60]fulleroindoline with 1,2-bis(bromomethyl)benzene at 0 °C, and can be converted to the more stable 1,2,3,4-adduct at 25 °C. Furthermore, the hexa-functionalized [60]fullerene derivative with the 1,2,3,4,9,10-addition pattern displaying a unique "S"-shaped configuration can be synthesized by protonation of the electrochemically generated dianion of the obtained tetra-functionalized 1,2,4,17-adduct. The structures of the tetra- and hexa-functionalized products have been determined by spectroscopic data and single-crystal X-ray analysis.

Potassium salt promoted regioselective three-component coupling synthesis of 1,4-asymmetrical [60]fullerene bisadducts with superior electron transport properties

An efficient one-pot three-component domino coupling reaction of phenols, C₆₀, and bromoalkanes was developed, resulting in the highly regioselective synthesis of 1,4-asymmetrical C₆₀ bisadducts.

Precise synthesis of double-armed polymers with fullerene C60 at the junction for controlled architecture

We report the first successful synthesis of the polymer-attached 1,2-hydrofullerene and the double-armed 1,4-bisadducts in a regioselective manner via controlled radical reactions.

Base-iodine-promoted metal-catalyst-free reactions of [60]fullerene with β-keto esters for the selective formation of [60]fullerene derivatives

In this study, methanofullerenes and 2′,3′-dihydrofuran C₆₀ derivatives were selectively synthesized in high yields via the reactions of C₆₀ with β-keto esters under mild conditions by controlling the addition sequence and molar ratio of iodine and base. The structures of the products were determined by spectroscopic characterization. Moreover, a possible reaction mechanism for the selective formation of fullerene derivatives was proposed.

In this study, methanofullerenes and 2′,3′-dihydrofuran C₆₀ derivatives were selectively synthesized in high yields via the reactions of C₆₀ with β-keto esters under mild conditions by controlling the addition sequence and molar ratio of iodine and base.

Successively Regioselective Electrosynthesis and Electron Transport Property of Stable Multiply Functionalized [60]Fullerene Derivatives

With the recent advance in chemical modification of fullerenes, electrosynthesis has demonstrated increasing importance in regioselective synthesis of novel fullerene derivatives. Herein, we report successively regioselective synthesis of stable tetra- and hexafunctionalized [60]fullerene derivatives. The cycloaddition reaction of the electrochemically generated dianions from [60]fulleroindolines with phthaloyl chloride regioselectively affords 1,2,4,17-functionalized [60]fullerene derivatives with two attached ketone groups and a unique addition pattern, where the heterocycle is rearranged to a [5,6]-junction and the carbocycle is fused to an adjacent [6,6]-junction. This addition pattern is in sharp contrast with that of the previously reported biscycloadducts, where both cycles are appended to [6,6]-junctions. The obtained tetrafunctionalized compounds can be successively manipulated to 1,2,3,4,9,10-functionalized [60]fullerene derivatives with an intriguing "S"-shaped configuration via a novel electrochemical protonation. Importantly, the stability of tetrafunctionalized [60]fullerene products allows them to be applied in planar perovskite solar cells as efficient electron transport layers.

Low-temperature synthesis of sp2 carbon nanomaterials

sp² carbon nanomaterials are mainly composed of sp²-hybridized carbon atoms in the form of a hexagonal network. Due to the π bonds formed by unpaired electrons, sp² carbon nanomaterials possess excellent electronic, mechanical, and optical properties, which have attracted great attention in recent years. As the advanced sp² carbon nanomaterials, graphene and carbon nanotubes (CNTs) have great potential in electronics, sensors, energy storage and conversion devices, etc. The low-temperature synthesis of graphene and CNTs are indispensable to promote the practical industrial application. Furthermore, graphene and CNTs can even be expected to directly grow on the flexible plastic that cannot bear high temperature, expanding bright prospects for applications in emerging flexible nanotechnology. An in-depth understanding of the formation mechanism of sp² carbon nanomaterials is beneficial for reducing the growth temperature and satisfying the demands of industrial production in an economical and low-cost way. In this review, we discuss the main strategies and the related mechanisms in low-temperature synthesis of graphene and CNTs, including the selection of precursors with high reactivity, the design of catalyst, and the introduction of additional energy for the pre-decomposition of precursors. Furthermore, challenges and outlooks are highlighted for further progress in the practical industrial application.

Functionalization of Carbon Nanomaterials for Biomedical Applications

Over the past decade, carbon nanostructures (CNSs) have been widely used in a variety of biomedical applications. Examples are the use of CNSs for drug and protein delivery or in tools to locally dispense nucleic acids to fight tumor affections. CNSs were successfully utilized in diagnostics and in noninvasive and highly sensitive imaging devices thanks to their optical properties in the near infrared region. However, biomedical applications require a complete biocompatibility to avoid adverse reactions of the immune system and CNSs potentials for biodegradability. Water is one of the main constituents of the living matter. Unfortunately, one of the disadvantages of CNSs is their poor solubility. Surface functionalization of CNSs is commonly utilized as an efficient solution to both tune the surface wettability of CNSs and impart biocompatible properties. Grafting functional groups onto the CNSs surface consists in bonding the desired chemical species on the carbon nanoparticles via wet or dry processes leading to the formation of a stable interaction. This latter may be of different nature as the van Der Waals, the electrostatic or the covalent, the π-π interaction, the hydrogen bond etc. depending on the process and on the functional molecule at play. Grafting is utilized for multiple purposes including bonding mimetic agents such as polyethylene glycol, drug/protein adsorption, attaching nanostructures to increase the CNSs opacity to selected wavelengths or provide magnetic properties. This makes the CNSs a very versatile tool for a broad selection of applications as medicinal biochips, new high-performance platforms for magnetic resonance (MR), photothermal therapy, molecular imaging, tissue engineering, and neuroscience. The scope of this work is to highlight up-to-date using of the functionalized carbon materials such as graphene, carbon fibers, carbon nanotubes, fullerene and nanodiamonds in biomedical applications.

Interfacial Chemistry of Conical Fullerene Amphiphiles in Water

Amphiphiles are used for a variety of applications in our daily life and in industrial processes. They typically possess hydrophobic and hydrophilic moieties within the molecule, thereby performing a myriad of functions through the formation of two- and three-dimensional assemblies in water, such as Gibbs monolayers and micelles. However, these functions are often inseparable because they emerge from the same structural feature of the molecule, and are difficult to control because the structural diversity is limited to either long-chain hydrocarbons bearing a polar end group(s) or polymers bearing polar groups exposed to the exterior surface. In this Account, we describe the chemistry of a new class of amphiphiles, conical fullerene amphiphiles (CFAs), utilizing a superhydrophobic [60]fullerene group as a nonpolar apex with added structural features to make it soluble in water. By selective functionalization of only one side of the fullerene molecule, the CFA molecules spontaneously assemble in water through strong hydrophobic interactions among the fullerene apexes and exhibit unusual supramolecular and interfacial behavior. They form unilamellar micelles and vesicles at a critical aggregation concentration as low as micromolar, not showing any air-water and oil-water interfacial activity. The strong preference for self-assembly in water over monolayer formation at an air-water interface makes CFAs unique among conventional nonpolymeric surfactants. The CFA assemblies are often so mechanically robust that they can be transferred to the surface of a solid substrate and analyzed by high-resolution microscopy. Because of this rigid conical structure of a few nanometers in size, CFA molecules aggregate readily in water to form a hierarchical assembly with biomolecules and nanomaterials while maintaining the structural integrity of the CFA aggregate to form multicomponent agglomerates of controllable structural features. For instance, tissue-selective in vivo transport of DNA and siRNA has been achieved. Hybridization of a CFA vesicle with a transition metal catalyst enables the construction of a structurally defined nanospace and an interface for precise control of the nanoscale morphology of polymers. Solubilization of hydrophobic nanocarbons and nanoparticles is also achieved through hemimicelle formation on solid surfaces. The examples reported here illustrate the potential of the conical fullerene motif for the design of amphiphiles as well as supramolecular structures at molecular and tens of nanometers scale.

Copper-Catalyzed N-H/C-H Sequential Relay Oxidative Radical Carboannulation: Construction of Diversely Substituted [60]Fullerene-Fused Tetrahydrocyclopenta[b]indoles

Reported herein is a new copper-catalyzed N-H/C-H sequential relay oxidative radical carboannulation of [60]fullerene with C2-functionalized free indoles for the direct construction of novel [60]fullerene-fused tetrahydrocyclopenta[b]indoles. The transformation shows high regioselectivity and atom economy, broad substrate scope, and good functional group tolerance, providing an efficient and practical approach to access diversely substituted fullerene-fused polycyclic derivatives from simple hydrocarbons.

Site-Selectivity of Prato Additions to C70: Experimental and Theoretical Studies of a New Thermodynamic Product at the dd-[5,6]-Junction

Three Prato monoadduct isomers were synthesized and structurally characterized by ¹H, ¹³C NMR spectra and single-crystal X-ray diffraction, and one adduct on the dd-[5,6]-bond was found as the first example of a Prato [5,6]-adduct of C₇₀. To investigate the mechanism in the generation of this dd-[5,6]-adduct, computational studies were employed to show that it was thermodynamically obtained by sigmatropic rearrangement from the presumed initial kinetic product de-[6,6]-adduct.

Competition and Cooperation among Different Attractive Forces in Solutions of Inorganic-Organic Hybrids Containing Macroionic Clusters

Hybrids composed of nanoscale inorganic clusters and organic ligands are ideal models for understanding the different attractive forces during the self-assembly processes of complex macromolecules in solution. The counterion-mediated attraction induced by electrostatic interaction from the large, hydrophilic macroionic clusters can compete or cooperate with other types of attractive forces such as hydrophobic interactions, hydrogen bonding, π-π stacking, and cation-π interactions from the organic ligands, consequently determining the solution behaviors of the hybrid molecules including their self-assembly process and the final supramolecular structures. The incorporation of organic ligands also leads to interesting responsive behaviors to external stimuli. Through the manipulation of the hybrid composition, architecture, topology, and solution conditions (e.g., solvent polarity, pH, and temperature), versatile self-assembled morphologies can be achieved, providing new scientific opportunities and potential applications.

Aggregation Behavior and Antioxidant Properties of Amphiphilic Fullerene C60 Derivatives Cofunctionalized with Cationic and Nonionic Hydrophilic Groups

Amphiphilic derivatives of fullerene C₆₀ are attractive from viewpoints of supramolecular chemistry and biomedicine. The establishment of relationships among the molecular structure, aggregation behavior and properties such as scavenging radicals of the amphiphilic C₆₀ derivatives is the key to push these carbon nanomaterials to real applications. In this work, six monosubstituted C₆₀ derivatives were synthesized by a one-step quaternization of their neutral precursors, which bear Percec monodendrons terminated with oligo(poly(ethylene oxide)) (o-PEO) chain(s). The main difference among the C₆₀ derivatives lies in the number and substituted position of the o-PEO chain(s) within the Percec monodendron. Derivative with a 4-substitution of the o-PEO chain still showed limited solubility in water. Other derivatives possessing two or three o-PEO chains exhibited much improved solubilities and rich aggregation behavior in water. It was found that the formation of aggregates is regulated both by the number and the substituted pattern of the o-PEO chains. Typical morphologies include nanosheets, nanowires, vesicles, nanotubes, and nanorods. Although the structures of the C₆₀ derivatives are different from those of traditional surfactants, their aggregation behavior can be also well explained by applying the theory of critical packing parameter. Interestingly, the capabilities of the C₆₀ derivatives to scavenge the hydroxyl radicals (OH^·-) followed the same order of their solubility in water, where the compound bearing three o-PEO chains with a 2,3,4-substitution got the champion quenching efficiency of ∼97.79% at a concentration of 0.15 mg·mL^-1 (∼0.11 mmol·L^-1).

Fabrication of a novel biosensor for biosensing of bisphenol A and detection of its damage to DNA

In this work, a novel electrochemical biosensor has been fabricated based on step-by-step modification of a glassy carbon electrode (GCE) with methylene blue (MB)-DNA/multiwalled carbon nanotubes (MWCNTs)-chitosan (CS)/palladium nanoparticles (Pd NPs)/fullerene C₆₀ (C₆₀) for voltammetric and impedimetric detection of DNA damage induced by bisphenol A (BPA). Modifications applied to the GCE were characterized by cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy. The EIS and DPV responses of the biosensor were increased and decreased, respectively, by the DNA damage induced by BPA which led us to develop novel systems for detection of DNA damage. Our records confirmed that the biosensor was able to rapid and sensitive detection of DNA damage induced by BPA. Finally, according to the developed systems for detection of DNA damage, we have developed voltammetric and impedimetric methods for determination of BPA.