Synthesis and photovoltaic properties of novel monoadducts and bisadducts based on amide methanofullerene

Four new [6,6]-phenyl-C(61) and C(71) butylsaure n-dibutyl amides (PCBDBA) with mono- and bis-adduction on C(60) and C(70) cages, respectively, have been synthesized as models to study the effect of the mono- and bis-adduction on fullerene cages on device performance when used as electron acceptors with the donor of regioregular P3HT in bulkheterojunction organic photovoltaics (BHJ-OPV). The optoelectronic, electrochemistry, and photovoltaic properties of these mono- and bis-products were fully investigated. The best device performance of these fullerene derivatives were obtained from the two monoadducts with power conversion efficiency (PCE) of 1.77% for C(60) derivative and 1.90% for C(70) derivative, respectively, which are close to PCBM's 2.43%. The results revealed the structure-function relationship among the monoadduct and bisadduct derivatives of C(60) and C(70) with the BHJ-OPV performance.     

Chromatographic separation and identification of a water-soluble dendritic methano[60]fullerene octadecaacid

The chromatographic separation of a highly water-soluble dendritic monoadduct methano[60]fullerene octadecaacid (dendrofullerene) with octadecylsilica bonded phases has been studied. It has been found that the RP-HPLC behavior of this dendrofullerene obeys the general rules of stationary-phase and mobile-phase selection for controlling the separation of usually acidic compounds. An RP-HPLC-ESI-MS analysis confirms the identity of the dendrofullerene and allows characterization of the molecular weights of the main impurities contained in the sample. The described methods can control the synthesis and efficiently purify this fullerene derivative, which has been previously shown to be active against mutant infectious clones of HIV-1, which are resistant to AZT and 3TC, drugs that are widely used in AIDS therapy.     

Study of nanoscale photopolymerized fullerene clusters in solution droplets using an ultrasonic nebulizer unit

In a designed and developed ultrasonic nebulizer system for obtaining macroscopic-quantity photopolymerized fullerene (C60) clusters, a C60 solution was vaporized to several micro-sized droplets in vacuum, resulting in the formation of C60 aggregates by evaporating the solvent (toluene). The system was invented to produce nanoscale photopolymerized carbon clusters through the irradiation of ultraviolet (UV) light on the C60 aggregates in vacuum. The products, photopolymerized C60 clusters obtained from the system using UV-visible (UV-Vis) absorption and high-performance (or high-pressure) liquid chromatography (HPLC) spectra, were characterized. Compared with the non-irradiating C60 solution, the UV-Vis absorption spectrum of the irradiated C60 solution was drastically decreased, especially at lambda = 335 nm and in the visible region from lambda = 450-650 nm. As such, the UV-Vis absorption spectra provide information about the polymerization of C60 molecules. These photopolymerized C60 clusters can be detected as having a heavy molecular mass order through the HPLC system, and the C60 and photopolymerized C60 cluster can be extracted from the trapped solution on the molecular mass. Although there is a possibility that the products include various forms of C60 clusters, the results suggest that the products obtained from the system using a vaporizer establish a new method of obtaining macroscopic-quantity C60 clusters.     

Poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene)(MEH-PPV) /Nitrogen Containing Derivatives of Fullerene Composites: Optical Characterization and Application in Flexible Polymer Solar Cells

New soluble organofullerenes were synthesized by the reaction of organic amines and azides with the [60]fullerene. The comparative investigations of the IR- and optical absorption spectra of blends MEH-PPV/fullerene derivative in solutions and in films showed no ground-state interaction between the components. Photoluminescence (PL) experiments, and photocurrent-voltage measurements were performed on model photovoltaic (PV) cells. We found that PL of MEH-PPV is completely quenched by a small admixture of fullerene derivative which assumes a high efficiency of charge separation in the composite material. The photocurrent in the PV device containing fullerene derivative is two orders of magnitude higher than that in pure MEH-PPV. An attempt to observe the magnetic field spin effect (MFSE) on the photocurrent in MEH-PPV/fullerene composites was made.     

Poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene)(MEH-PPV)/Nitrogen containing derivatives of fullerene composites: Optical characterization and application in flexible polymer solar cells

New soluble organofullerenes were synthesised by the reaction of organic amines and azides with the [60]fullerene. The comparative investigations of the IR- and optical absorption spectra of blends MEH-PPV/fullerene derivative in solutions and in films showed no ground-state interaction between the components. Photoluminescence (PL) experiments, and photocurrent-voltage measurements were performed on model photovoltaic (PV) cells. We found that PL of MEH-PPV is completely quenched by a small admixture of fullerene derivative which assumes a high efficiency of charge separation in the composite material. The photocurrent in the PV device containing fullerene derivative is two orders of magnitude higher than that in pure MEH-PPV. An attempt to observe the magnetic field spin effect (MFSE) on the photocurrent in MEH-PPV/fullerene composites was made.     

Large optical nonlinearities of new organophosphorus fullerene derivatives

Optical nonlinearities of five new organophosphorus fullerene derivatives with similar structures were determined by the Z-scan method by use of a nanosecond-pulse laser at 532 nm. The experimental results demonstrate that the five derivatives have much larger excited-state absorption and nonlinear refraction than C60. The excited-state absorption cross sections are nearly two to three times that of C60. Using a five-level model to fit the experimental data, we obtained some parameters such as excited-state absorption and refraction cross sections. A simple analysis of correlations between molecular structure and nonlinear properties is given. Optical nonlinearities of the five new organophosphorus fullerene derivatives were compared with those of some other kinds of fullerene derivatives, and the results show that the nonlinearities of the new derivatives are the larger.     

Ferrocene Derivatives in Diels-Alder [4+2] Cycloaddition Reactions to Fullerenes C60 and C70

The synthesis and characterization of adducts of C₆₀ and C₇₀ with diene 5 is described. When 5 was reacted with fullerene C₆₀, a mixture of mono 7 and bisadduct 8 was found, while with C₇₀ a novel monoadduct 9 was formed.     

Synthesis of alkyl sulfonated fullerenes without catalyst: improved water solubility by the sulfonate groups

Two new alkyl sulfonated fullerene (C60) derivatives C60(O)14(OH)4(OCH2CH2CH2SO3Na)5 (2), C60(O)15(OSO3Na)5(OCH2CH2CH2SO3Na)6 (4) with high water-solubility were synthesized by different routes. One derivative (4) was facilely synthesized from a sulfonated C60 derivative C60(O)11(OH)4(OSO3Na)8 (3) in aqueous phase without the addition of any catalyst and has the highest water solubility (118 mg/mL) and smallest aggregation size (49.2 nm) in neutral aqueous solution (0.1 wt%). Derivative 2 was synthesized from fullerenol C60(O)8(OH)13 (1) directly in DMF affording enhanced water solubility compared to 1. The estimated average molecular formulae of these new alkyl sulfonated C60 derivatives were determined by XPS spectroscopy and confirmed by FTIR and 1H NMR spectroscopies. The measured water solubility of the sulfonated C60 derivatives follows the order of 3 < 2 < 4, suggesting that the larger number of functional groups is directly correlated to the higher water solubility, and the sulfonate groups can improve the water solubility greatly. The aggregation size of 2-4 measured by dynamic light scattering (DLS) is all smaller than that of fullerenol 1, indicating that more functional groups result in the improvement of the dispersion of fullerenol in water. ESR study indicates that 2-4 have the ability to produce stable radicals, and the intensity of the ESR signal decreases evidently with the increase of the number of functional groups from 3 to 2 to 4.     

Can apomyoglobin form a complex with a spherical ligand? Interactions between apomyoglobin and [C60] fullerene derivative

The preparation and characterization of the stable equine skeletal muscle apomyoglobin and eee-isomer of tris-malonic acid [C60] fullerene complex is reported. For this new bio-nanomaterial preparation, a procedure of complexation-during-protein-refolding was used and the obtained compound sustained separation by gel-filtration and ion-exchange chromatography. The apomyoglobin-tris-malonic acid [C60] fullerene complex was characterized by UV-vis spectroscopy, steady state fluorescence, time-resolved fluorescence, and circular dichroism spectroscopies. Important information provided by this study, regarding the stability and properties of new material, may lead to a better understanding of the apomyoglobin protein binding characteristics, as well as to development of novel antioxidant and photodynamic therapeutic agents and components for bioelectronic devices.     

Ordered fullerene nanocylinders in large-diameter carbon nanotubes

A new ordered fullerene phase encapsulated by large-diameter CNTs is systematically investigated by combining a growth technique by chemical vapour deposition, high-resolution transmission electron microscopy and molecular-dynamics simulations. In contrast to fullerenes in smaller (1-2?nm) diameter CNTs, where fullerenes are packed in linear or helical chains, fullerenes form a nanoscale cylinder in double-walled CNTs with diameters of ～4?nm. The fullerenes were shown to form a nanocylinder with a side wall that resembled the (111) plane of solid C(60). This ordered phase is different from peapods or fullerene solids known so far, and a result of the interaction between the CNT wall and fullerenes. This finding will open up a new field of fullerene science.     

New graphene technologies of manipulation with molecular objects

A new technique of manipulating with fullerene C₆₀ over graphene on a SiO₂ substrate is proposed. To stop the chaotic motion of molecules and limit its range, it is suggested to use a corrugated substrate. The study has shown that, at the corrugation wavelength of 3.4 nm and depth of 1.6 nm, the fullerene motion becomes directed with a deviation within 0.5 nm. The fullerene motion becomes even more definite, with a deviation from a straight line within tenths of an angstrom by the action of an external electric field, which allows one to manipulate the motion along the bottom of a groove. The method proposed can serve as a basis for the controlled assembly of molecules to supermolecular structures of given configurations, which can be applied in bio- and nanoelectronics.     

Application of the multifractal concept to characterization of the structure of composite films of fullerene C<Subscript>60</Subscript> doped with CdTe

Peculiarities in the surface morphology of fullerene C₆₀ based composite films containing various amounts of CdTe (0 to 100 mass %) were studied using methods of information theory. The characteristic size of the surface structure elements for these films amounts to 150–200 nm. It is shown that the concept of multifractals and the methods of multifractal analysis can be used for a quantitative comparison of the surface topography of such composite films. The multifractal analysis reveals the interval of fullerene based film compositions containing 15–20% CdTe, which corresponds to the most equilibrium conditions of film formation and provides for the most ordered material configuration. It was established that, using films with such compositions, fullerene-containing network nanostructures with a lateral resolution of 250 nm can be obtained by direct electron-beam lithography.     

Synthesis and characterization of hybrid materials formed by C60 in situ decorating copper clusters

Hybrid materials (Cu–C₆₀) formed by C₆₀ decorating the surface of copper clusters were prepared through pulsed laser ablation at the interface between copper solid target and a flowing fullerene solution of hexane. UV–Vis shows that the feature absorption intensity of C₆₀ in the copper–fullerene–hexane sol decreases, and the increased absorption band of copper-cluster sol can also be found between 190 nm and 240 nm. Element analysis indicates that copper clusters in the sample (Cu–C₆₀) are decorated mainly by C₆₀. HRTEM identified that copper clusters are decorated by C₆₀; XRD reveals that the diffraction peaks of the sample have lower value and broader width than pure copper, indicating the surface of copper clusters is decorated by an amorphous material. Magnetism tested by VSM indicated that the sample has one Curie point at 203 K, suggesting that high temperature, high pressure and very rapidly cooled microarea in the method of PLA/ISFL are of importance in affecting the magnetic property of the hybrid material.     

Synthesis of mono-dispersed nano-scale fullerene (C60) crystals

Fullerene (C60), which has a unique molecular structure, was used in the preparation of crystalline organic nano-crystals. Fullerene was dissolved in toluene and this fullerene solution was mixed with water drastically. During this process, fullerene transferred from toluene to water phase. The significantly different solubility of fullerene in a toluene/water solvent system played an important role in the self-assembly of single fullerene nano-crystals, as it is called drowning-out crystallization. In addition, pH of water was controlled to carry out the interfacial transference of fullerene. An optical spectrum analysis showed that the fullerene was transferred by a hydrolysis reaction from toluene to water, depending on the pH and toluene involved in the crystal structure. During the interfacial transference, the growth of nano-scale fullerene occurred at pH > 7. Importantly, fullerene nanocrystals were formed with a mono-dispersed square structure on a nano-scale (104 nm average size and 1.03 +/- 0.24 aspect ratio) at pH 10.     

Growth of fullerene nanoparticles prepared by the gas-evaporation technique

C60 and C70 fullerene nanoparticles prepared by evaporating their powders in inert gas were investigated by electron microscopy and X-ray diffraction. Crystal structures of the particles were face centred cubic (fcc) which is a stable phase at high temperature, with lattice parameters of a=1.42 nm for C60 and a=1.499 nm for C70. Nanoparticles with definite crystal habits were sometimes observed among those with irregular ones. For the C70 nanoparticles, the higher the source temperature was, the better-defined the crystal habits were.     

Effect of C60(Oh)18 on Membranes of Rat Liver Microsomes During Photosensitization

We have examined the ability of a water-soluble derivative of fullerene C₆₀, C₆₀(OH)₁₈, to induce alterations in rat liver microsomes during photosensitization. When it was exposed to UV (330-370 nm), it induced significant membrane damage in terms of (i) lipid peroxidation as assayed by various products and (ii) damage to proteins as assessed by protein carbonyls and loss of the membrane-bound enzymes. The damage induced was both time and concentration-dependent and seems to be predominantly due to radicals and to a lesser extent singlet oxygen.     

Synthesis of [60]fullerene-ZnO nanocomposite under electric furnace and photocatalytic degradation of organic dyes

Zinc oxide (ZnO) nanoparticles were synthesized by a reaction between an aqueous-alcoholic solution of zinc nitrate and sodium hydroxide under ultrasonic irradiation at room temperature. The morphology, optical properties of the ZnO nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis spectroscopy. The [60]fullerene and zinc oxide nanocomposite were synthesized in an electric furnace at 700 degrees C for two hours. The [60]fullerene-ZnO nanocomposite was characterized by XRD, SEM and TEM. In addition, the [60]fullerene-ZnO nanocomposite was investigated as a catalyst in the photocatalytic degradation of organic dyes using UV-vis spectroscopy. The photocatalytic activity of the [60]fullerene-ZnO nanocomposite was compared with that of ZnO nanoparticles, heated ZnO nanoparticles after synthesis, pure [60]fullerene, and heated pure [60]fullerene in organic dyes such as methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) under ultraviolet light at 254 nm.     

Cross-linking of C60 films with 1,8-diaminooctane and further decoration with silver nanoparticles

We applied the direct solvent-free functionalization of fullerene C60 with aliphatic bifunctional amine, 1,8-diaminooctane, to prepare chemically cross-linked C60 thin films capable of binding silver nanoparticles. The gas-phase diamine treatment of C60 reduced dramatically the fullerene solubility in toluene, indicating the transformation of pristine C60 into a different solid phase with cross-linked fullerene molecules. Compared to the spectra of pristine C60 film and powder samples, Fourier-transform infrared, UV-Visible, Raman, and 13C nucleic magnetic resonance spectra of the functionalization products exhibited new features, which point to a breaking of C60 ideal structure during the formation of new covalent bonds and to the appearance of sp3 hibridization. The covalent functionalization with 1,8-diaminooctane allowed for a stable and homogeneous deposition of silver nanoparticles of ca. 5-nm diameter onto the functionalized films through the coordination bonding between metal atoms and nitrogen donor atoms of the fullerene derivatives. The proposed mechanism of Ag nanoparticle binding was supported by density functional theory calculations using the hybrid BLYP functional in conjunction with the double numerical basis set DND.     

Water‐Dispersible Fullerene Aggregates as a Targeted Anticancer Prodrug with both Chemo‐ and Photodynamic Therapeutic Actions

Prodrug therapy is one strategy to deliver anticancer drugs in a less reactive manner to reduce nonspecific cytotoxicity. A new multifunctional anticancer prodrug system based on water‐dispersible fullerene (C60) aggregates is introduced; this prodrug system demonstrates active targeting, pH‐responsive chemotherapy, and photodynamic therapeutic (PDT) properties. Incorporating (via a cleavable bond) an anticancer drug, which is doxorubicin (DOX) in this study, and a targeting ligand (folic acid) onto fullerene while maintaining an overall size of approximately 135 nm produces a more specific anticancer prodrug. This prodrug can enter folate receptor (FR)‐positive cancer cells and kill the cells via intracellular release of the active drug form. Moreover, the fullerene aggregate carrier exhibits PDT action; the cytotoxicity of the system towards FR‐positive cancer cells is increased in response to light irradiation. As the DOX drug molecules are conjugated onto fullerene, the DOX fluorescence is significantly quenched by the strong electron‐accepting capability of fullerene. The fluorescence restores upon release from fullerene, so this fluorescence quenching–restoring feature can be used to track intracellular DOX release. The combined effect of chemotherapy and PDT increases the therapeutic efficacy of the DOX–fullerene aggregate prodrug. This study provides useful insights into designing and improving the applicability of fullerene for other targeted cancer prodrug systems.     

Structural Characterization of the New Fullerene-Rare Gas Compound Ar1C60

We communicate how C₆₀ Hot Isostatically Pressed (HIPed) at 200° or 400°C with a pressure of 1.7 kbar of Ar produces the new fullerene-rare gas compound Ar₁C₆₀. We have shown, using Xray powder diffraction and subsequent Rietveld analysis, that this solid can be characterised stoichiometrically as Ar₁C_60- The stoichiometry has also been confirmed by thermal gravimetric analysis (TGA) showing 5% by weight to be Ar (expected=5.25%). The presence of Ar is confirmed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). This material is found to be remarkably stable to loss of Ar over several weeks at room temperature. This represents the first full characterisation of an interstitial rare gas fullerene compound.