Aqueous dispersions of C<Subscript>60</Subscript> fullerene

Stable aqueous colloidal dispersions of C₆₀ fullerene are prepared. A solvatochromic effect is revealed upon the addition of C₆₀ solution in chlorobenzene to a water-acetone mixture.     

Solution ozonolysis of C<Subscript>70</Subscript>: stable products and chemiluminescence

For the first time the total and relative contents of the stable ozonolysis products of fullerene C₇₀ solutions were identified by IR spectroscopy and elemental and chemical analyses. At the 100% conversion of C₇₀ a mixture of products corresponding to the empirical formula C₇₀O_14.3H_0.21 (epoxides: polyketones: polyesters: secondary fullerene ozonides (SFOZ): acids = 1.07: 6: 6: 0.21: 1.02) is formed. The content of polyketones, polyesters, acids, and SFOZ increases during the whole ozonolysis time (1 h). The number of oxygen atoms in epoxides C₇₀O _n (n = 1–4) is lower than that in epoxides C₆₀O _n (n = 1–6) formed by the ozonolysis of fullerene C₆₀. The kinetic curve of accumulation of epoxides C₇₀O _n (n = 1–4) passes through a maximum, which is observed 0.5 min after the beginning of ozonolysis. No epoxides were identified among the products 3.5 min after the ozonolysis. The photoluminescence (PL) (λ_max = 645 and 685 nm) of fullerene polyketones in glassy EtO₂/EtOH solutions frozen at 77 K was observed. This PL is much brighter, than that of polyketones formed upon the ozonolysis of fullerenes C₆₀. For the first time the chemiluminescence (CL) was detected and studied upon the ozonolysis of C₇₀ solutions at 300 K. The CL emitters are excited states of fullerene polyketones. The CL spectrum is partially overlapped with the known CL spectrum appeared upon the ozonolysis of C₆₀ (λ_max = 685 nm) but contains the greater number of maxima (λ_max = 645 and 685 nm), which is related to a lower symmetry of the C₇₀ oxidation products.     

Spectroscopic characteristics of gold nanoparticles synthesized in an aqueous solution of a micelle-forming surfactant (AOT)

Gold nanoparticles were synthesized in aqueous solutions of AOT using hydrazine as the reducing agent and characterized by spectrophotometry, transmission electron microscopy, and photon-correlation spectroscopy. The effect of gold (C_Au = 10^–4–10^–3 mol/L) and AOT (C_AOT = 5 × 10^–4–2.5 × 10^–2 mol/L) concentrations on the formation of stable gold sols (λ_max = 520 nm) was studied. According to transmission electron microscopy data, the average size of gold nanoparticles in the dispersions was ~10 nm, which was in good agreement with the n-averaged hydrodynamic diameter determined by the photon correlation spectroscopy.     

Chemiluminescence produced by oxidation of fullerene hydride C60H36 with oxygen in solution

It was found that the oxidation of fullerene hydride C₆₀H₃₆ with oxygen in solution is accompanied by chemiluminescence (CL). The CL spectrum maxima are assigned to the emission by the oxidation products of C₆₀H₃₆, namely, the excited hydride C₆₀H₁₈* (495, 535 nm) and singlet-excited fullerene ¹C₆₀* (720—750 nm).     

Preparation of Aqueous Colloidal Dispersion of C<Subscript>60</Subscript> Fullerene

A method for preparing aqueous colloidal dispersions of C₆₀ fullerene free of organic solvents is proposed. The size of dispersed particles is determined using the turbidity spectra. A solvatochromic effect is observed upon the addition of a C₆₀ solution in toluene to a water-acetone mixture.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 4, 2005, pp. 575–576.Original Russian Text Copyright © 2005 by Tseluikin, Tolstova, Gun’kin, Pankst’yanov.     

Effect of lipophilicity of C60 fullerene derivatives on their ability to inhibit peroxide oxidation of lipids in aqueous medium

The aqueous solutions of C₆₀ fullerene derivatives were studied by means of dynamic light scattering, their effect on the peroxide oxidation of lipids (POL) in aqueous solutions was investigated via chemiluminescence method. It was shown that the colloidal solubility in water, which defines the antioxidant activity of C₆₀ fullerene derivatives during POL, is controlled by the chemical structure of the addend added to C₆₀ fullerene. For the studied derivatives, the direct dependence of the efficiency of POL inhibition on the lipophilicity was established.     

Interaction of shungite carbon nanoparticles with blood protein and cell components

We have analyzed and compared the effects of aqueous dispersion of shungite carbon nanoparticles, fullerene C₆₀, and nanodiamonds on structure, dynamics, and thermodynamic and redox properties of blood proteins (serum albumin and hemoglobin), proteins of erythrocyte ghost membranes as well as on erythrocyte integrity and aggregation.. All the nanomaterials dispersions have induced similar effects; however, nanodiamonds have not influences the redox properties. Basing on the results, the experimental and theoretical approaches presented can be employed to estimate the effects of biological structures contact with the nanoparticles on the bioreactivity.     

Near-Infrared-Absorbing Chiral Open [60]Fullerenes

Though [60]fullerene is an achiral molecular nanocarbon with I_h symmetry, it could attain an inherent chirality depending upon a functionalization pattern. The conventional chiral induction of C₆₀ relies mainly upon a multiple addition affording a mixture of achiral and chiral isomers while their chiral function would be largely offset by the existence of pseudo-mirror plane(s). These are major obstacles to proceed further study on fullerene chirality and yet leave its understanding elusive. Herein, we showcase a carbene-mediated synthesis of C₁-symmetric chiral open [60]fullerenes showing an intense far-red to near-infrared absorption. The large dissymmetry factor of |g_abs|=0.12 was achieved at λ=820 nm for circular dichroism in benzonitrile. This is, in general, unachievable by other small chiral organic molecules, demonstrating the potential usage of open [60]fullerenes as novel types of chiral chromophores.     

Chemiluminecsence in the oxidation of Na2C60 by the (NH4)2Ce(NO3)6 complex in THF

Chemiluminescence (_max = 790 nm) in the oxidation of fulleride Na₂C₆₀ by the (NH₄)₂Ce(NO₃)₆ complex in THF was found. The ³C₆₀* triplet of fullerene formed in the transfer of an electron from the intermediate C₆₀ ^– anion to Ce^IV was suggested to be the chemiluminescence emitter.     

Synthesis of VO2 Nanopowders. Part II. Hydrolysis of Vanadium Alkoxide/Citric Acid Premixes: VO2 Nanostructures of Controlled Shape

Reaction of VO(OiPr)₃/citric acid premixes with excess water produces stable, blue dispersions of V_xO_y gel nanoparticles (5–100 nm in diameter) that can be isolated via acetone precipitation. Annealing under reducing conditions transforms these gel particles into crystalline, faceted VO₂ nanoparticles of similar size. Larger V_xO_y gel particles (75–200 nm in diameter) form when V_xO_y nanogel dispersions are aged with aqueous ammonia. Upon annealing, these larger gel particles transform into crystalline VO₂ rods of 50 nm–10 μm in length. Hysteresis loops confirming a semiconductor-to-metal phase transition near 68 °C expected for crystalline VO₂ particles are recorded by variable-temperature electrical resistance and powder X-ray diffraction measurements.     

Inertness of C<Subscript>60</Subscript> fullerene toward RO<Subscript>2</Subscript><Superscript>·</Superscript> peroxy radicals

The reactivity of fullerene C₆₀ toward peroxy radicals RO₂ ^· was tested by the chemiluminescence method. A comparison of the influence of C₆₀ and known inhibitors on the kinetics of liquid-phase chemiluminescence (CL) during oxidation of a series of hydrocarbons (ethyl-benzene, cyclohexane, n-dodecane, and oleic acid) shows that the fullerene does not react with the RO₂ ^· radicals. A sharp decrease in the CL intensity observed upon C₆₀ addition is caused by the quenching of CL emitters with fullerene but not by inhibition of hydrocarbon oxidation. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1808–1811, August, 2005.     

Red to Blue High Electrochromic Contrast and Rapid Switching Poly(3,4‐ethylenedioxypyrrole)–Au/Ag Nanocomposite Devices for Smart Windows

Poly(3,4‐ethylenedioxypyrrole) (PEDOP)–Ag and PEDOP–Au nanocomposite films have been synthesized for the first time by electropolymerization of the conducting‐polymer precursor in a waterproof ionic liquid, 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, followed by Ag/Au nanoparticle incorporation. That the Ag/Au nanoparticles are not adventitious entities in the film is confirmed by a) X‐ray photoelectron spectroscopy, which provides evidence of Ag/Au–PEDOP interactions through chemical shifts of the Ag/Au core levels and new signals due to Ag–N(H) and Au–N(H) components, and b) electron microscopy, which reveals Au nanoparticles with a face‐centered‐cubic crystalline structure associated with the amorphous polymer. Spectroelectrochemistry of electrochromic devices based on PEDOP–Au show a large coloring efficiency (η_max=270 cm² C^?1, λ=458 nm) in the visible region, for an orange/red to blue reversible transition, followed by a second, remarkably high η_max of 490 cm² C^?1 (λ=1000 nm) in the near‐infrared region as compared to the much lower values achieved for the neat PEDOP analogue. Electrochemical impedance spectroscopy studies reveal that the metal nanoparticles lower charge‐transfer resistance and facilitate ion intercalation–deintercalation, which manifests in enhanced performance characteristics. In addition, significantly faster color–bleach kinetics (five times of that of neat PEDOP!) and a larger electrochemical ion insertion capacity unambiguously demonstrate the potential such conducting‐polymer nanocomposites have for smart window applications.     

Effect of the medium on the reactivity of fullerene N60 with respect to the peroxide radicals RO2 ·. Chemiluminescence in the C60—AIBN—O2—C2H5Ph—PhH system

Chemiluminescence (CL), HLPC, and volumetry were used to demonstrate that fullerene N₆₀ exerts no inhibiting effect on the liquid-phase chain oxidation of hydrocarbons. Peroxide radicals RO₂ · do not add to N₆₀ in hydrocarbons with active C—H bond, because the reaction is suppressed by the competing addition of RO₂ · to the hydrocarbon. The addition of RO₂ · radicals to N₆₀ does occur in benzene (a solvent with strong C—H bonds) in the presence of low concentrations of the hydrocarbon oxidized. Fullerene N₆₀ is found to exhibit a new type of liquid_phase CL, which is presumably generated upon thermal decomposition of fullerene peroxides formed by adding peroxy radicals to fullerene in the C₆₀—AIBN—O₂—C₂H₅Ph—PhH system. The CL spectrum exhibits long-wavelength maxima at 645 and 685 nm. The supposed CL emitters are keto derivatives of fullerene N₆₀.     

Synthesis of highly stable silver nanoparticles using imidazolium-based ionic liquid

Highly stable, aqueous dispersions, and hydrophilic ionic liquid-capped silver nanoparticles with positive surface charge were synthesized by in situ reduction of AgNO₃ with NaBH₄ in the presence of an imidazolium-based ionic liquid, viz., 1-dodecyl-3-methylimidazolium chloride ([C₁₂mim][Cl]) at room temperature. Prepared silver nanoparticles were characterized by UV–vis spectra, transmission electron microscopy (TEM), and zeta potential. UV–visible spectrum of the aqueous medium peaked at 407 nm corresponding to the plasmon absorbance of silver nanoparticles. TEM analysis revealed the spherical shape of the particles with sizes about 9 nm and low polydispersed. The surface charge of the synthesized silver nanoparticles was determined as +5.0 mV. The ionic liquid ([C₁₂mim][Cl]) capped silver nanoparticles were stable for at least 8 months.     

Interaction between gaseous ozone and crystalline potassium bromide

The formation of nonvolatile products of the oxidation of a bromide ion during the interaction between gaseous ozone and powdered crystalline KBr is studied. It is found that potassium bromate KBrO₃ is the main product of the reaction. The influence of major experimental factors (the duration of ozonation, the concentration of ozone, the humidity of the initial gas, and the temperature) on the rate of formation of bromate is studied. The effective constants of the formation of bromate during the interaction between O₃ and Br^– in a heterogeneous gas–solid body system and in a homogeneous aqueous solution are compared.     

Dynamic Crystals: Visually Detected Mechanochemical Changes in the Luminescence of Gold and Other Transition‐Metal Complexes

Back to the grindstone : Certain crystalline complexes of gold, platinum, and vanadium undergo dramatic changes in their luminescence or their color upon grinding. The picture shows the transformation of colorless crystals of [(F₅C₆Au)₂(μ‐1,4‐CN₂C₆H₄)] powder from a blue‐emitting form (λ_max=415 nm) to a yellow/green‐emitting form (λ_max=533 nm) on grinding with a pestle. The process is reversible.

     

Laser flash photolysis of fullerols of C60 and of C70 in aqueous solutions

Fullerols of C₆₀ and of C₇₀ [C₆₀(OH)_n, C₇₀(OH)_m], water-soluble fullerene derivatives, unlike some other fullerene derivatives (such as C₆₀ (C₄H₆O), C₆₀ (C₃H₇N) and C₆₀ [C(COOEt)₂]_x), do not result in excited triplet state but in ionization via monophotonic process in aqueous solutions with 248 nm laser. The quantum yields of formation of hydrated electron (Φ_e ⁻) are determined to be 0.08 and 0.11 for fullerols of C₆₀ and of C₇₀ respectively at room temperature (ca. 15°C) with KI solution used as reference. By laser flash photolysis and oxidation of sulfate radical anion SO₄ ⁻, the fullerol radical cation or neutral radical of C₆₀ is confirmed to be existent and the transient absorption spectra of fullerol radical cation of C₇₀ are observed for the first time. Project supported by the National Natural Science Foundation of China     

Fullerene Derivatives Functionalized with Diethylamino‐Substituted Conjugated Oligomers: Synthesis and Photoinduced Electron Transfer

Diethylamino‐substituted oligophenylenevinylene (OPV) building blocks have been prepared and used for the synthesis of two [60]fullerene–OPV dyads, F‐D1 and F‐D2 , which exhibit different conjugation length of the OPV fragments. The electrochemical properties of these acceptor–donor dyads have been studied by cyclic voltammetry. The first reduction is always assigned to the fullerene moiety and the first oxidation centered on the diethylaniline groups of the OPV rods, thus making these systems suitable candidates for photoinduced electron transfer. Both the OPV and the fullerene‐centered fluorescence bands are quenched in toluene and benzonitrile, which suggests the occurrence of photoinduced electron transfer from the amino‐substituted OPVs to the carbon sphere in the dyads in both solvents. By means of bimolecular quenching experiments, transient absorption spectral fingerprints of the radical cationic species are detected in the visible (670 nm) and near‐IR (1300–1500 nm) regions, along with the much weaker fullerene anion band at λ_max=1030 nm. Definitive evidence for photoinduced electron transfer in F‐D1 and F‐D2 comes from transient absorption measurements. A charge‐separated state is formed within 100 ps and decays in less than 5 ns.     

Fullerene C<Subscript>60</Subscript> in copolymerization of allyl chloride with methyl methacrylate

The effect of fullerence C₆₀ on the copolymerization of allyl chloride and methyl methacrylate has been studied. With the use of UV spectroscopy, it has been shown that, with an increase in the conversion, the redistribution of optical densities of two π-π* absorption maxima due to fullerene at λ_max = 407 and 330 nm is observed. A difference in the kinetics of copolymer’s formation in the absence and presence of fullerene has been found.     

Effect of nature of organic solvent on the absorption spectrum of C60 fullerene

Absorption spectrums of C₆₀ fullerene in 10 various organic solvents in the range of 300–620 nm was studied. In all the solvents the C₆₀ fullerene has four absorption maxima in the range under study. When an aromatic solvent has an ionization potential of 8.1 eV or lower a new additional absorption band appears in the absorption spectrum of C₆₀ fullerene, caused by the formation of a charge-transfer complex (CTC) of the solvent and C₆₀ fullerene.