Band gap and density of states of the hydrated C60 fullerene system at finite temperature

We examine the electronic properties of the hydrated C60 fullerene under ambient conditions using a sequential Monte Carlo/density functional theory scheme. In this procedure, the average electronic properties of the first hydration shell of C60 equilibrate for ca. 40 uncorrelated configurations of the fullerene aqueous solution. We obtain a systematic red-shift of 0.8 eV in the band gap of the hydrated system, which is mainly attributed to the thermal fluctuations of the aqueous environment.     

C60 fullerene promotes lung monolayer collapse

Airborne nanometre-sized pollutants are responsible for various respiratory diseases. Such pollutants can reach the gas-exchange surface in the alveoli, which is lined with a monolayer of lung surfactant. The relationship between physiological effects of pollutants and molecular-level interactions is largely unknown. Here, we determine the effects of carbon nanoparticles on the properties of a model of lung monolayer using molecular simulations. We simulate phase-separated lipid monolayers in the presence of a model pollutant nanoparticle, C₆₀ fullerene. In the absence of nanoparticles, the monolayers collapse only at very low surface tensions (around 0 mN m⁻¹). In the presence of nanoparticles, instead, monolayer collapse is observed at significantly higher surface tensions (up to ca 10 mN m⁻¹). Collapse at higher tensions is related to lower mechanical rigidity of the monolayer. It is possible that similar mechanisms operate on lung surfactant in vivo, which suggests that health effects of airborne carbon nanoparticles may be mediated by alterations of the mechanical properties of lung surfactant.     

Dispersed state of C60 fullerene in some polymers

The character of C₆₀ fullerene dispersion and its temperature dependence in various polymer matrices has been studied by UV-Vis spectroscopy and thermodesorption mass spectrometry. It is established that the degree of fullerene aggregation in these composites varies from molecular-dispersed state to largesize clusters. For the polymers studied, the initial dispersed state is most stable with respect to temperature in the case of poly-α-methylstyrene.

     

Charge-transfer interaction between C60 fullerene and alkylnaphthalenes

A series of alkylnaphthalenes, namely 1,4-dimethylnaphthalene, 2,6-diethylnaphthalene, 2-ethylnaphthalene and pure naphthalene are not able to form Diels-Alder adducts with C₆₀ fullerene but produce a series of 1:1 charge-transfer complexes (CTC) where the aromatic compounds act as donor and C₆₀ as acceptor. The spectrophotometric analysis of these CTC has permitted to determine the equilibrium constants of the CTC formation at four different temperatures and the relative enthalpies and entropies of formation. The C₆₀-alkylnaphthalenes and C₆₀-naphthalene were identified as weakly bound CTC. Using the Mulliken theory of the CTC also the degree of charge transfer α was determined, confirming the results already suggested by the equilibrium constants, i.e., the weakly interaction between the donor and the acceptor considered.     

Electronic structure and electrical transport characteristics of C60, 2C60 and 4C60 fullerene molecules

The extended H?ckel method and the Green s function method were used to calculate the electronic structure and electrical transport of Au electrode-C₆₀, 2C₆₀ or 4C₆₀ fullerene-Au electrode systems. Furthermore, their electronic structure and electrical transport characteristics were compared and analyzed. The results show that (i) owing to the contact with the Au electrodes, the C₆₀, 2C₆₀ and 4C₆₀ molecules change in their electronic structures significantly, and their energy gaps between LUMO and HOMO are narrow; (ii) the bonding between C₆₀, 2C₆₀ or 4C₆₀ fullerene and Au electrodes is partially covalent and partially electrovalent; and (iii) the conductance of the three fullerenes conforms to the order of C₆₀>2C₆₀>4C₆₀.     

The effect of fullerene on the temporal characteristics of a nematic liquid crystal-polyaniline-fullerene C60 system

The temporal characteristics of a nematic liquid crystal-polyaniline-fullerene (NLC-PANI-C₆₀) system have been studied with a view to the new field of application of PANI-containing structures: display and optoelectronic technologies. It is shown that the complexation between PANI and fullerene stimulates a transition of the liquid crystal (LC) from the nematic to a smectic phase. The response time of the NLC-PANI-C₆₀ system is two orders of magnitude shorter than that in fullerene-free LC cells of comparable thickness fabricated using the same technology. Thus, the use of fullerenes ensures the transition from the milli-to microsecond range of switching parameters.     

Trapping of solvent by a C60 fullerene film

Mass spectrometry was used over a wide temperature range to compare processes of solvent (toluene) release and desorption of C₆₀ fullerene molecules from a fullerite film formed from solution on an oxidized metal substrate. It is shown that toluene is strongly retained in the fullerite film and that it is almost impossible to remove the toluene from the film without damaging its structure. Quantitative characteristics of the toluene retention and trapping effect are determined. Pis’ma Zh. Tekh. Fiz. 24, 23–29 (December 12, 1998)     

C60、Si@C60及Ge@C60富勒烯分子的电子传输特性

采用扩展的Hückel方法与格林函数方法,分析了双Au电极作用下,C60、Si@C60以及Ge@C60富勒烯分子的电子结构与导电性,并对三种富勒烯分子的电子结构与电子输运特性进行了对比.研究结果表明,C60、Si@C60或Ge@C60分子与Au电极"接触"后,其最高占据分子轨道与最低未占据分子轨道间的能隙减小,它们与Au电极之间的结合既有共价键的成分,又有离子键的成分;三种富勒烯分子的电子输运性能依次具有Ge@C60＞Si@C60＞C60的顺序.     

Organic fractal nano-dimensional structures based on fullerene C60

The ways for a synthesis of nanoporous and close-packed types of fullerene C₆₀ aggregates in two-component organic solvents (toluene?+?tetrahydrofuran) were established as well as their structural and dimensional features - were studied by high-resolution transmission electron microscopy and atomic-force microscopy methods. The physical features and regularities that characterize the processes of self-organization of fullerene molecules in the initial molecular solution were determined. The method for producing nanoscale fullerene C₆₀ fractal coatings (thickness up to ～1200?nm) on a flat dielectric glass surface was proposed.     

Photolytic breakdown of fullerene C60 cages in an aqueous suspension

Fullerene C60, a class of carbon nanomaterials, is widely used and is likely to reach the environment. The degradation and transformation of C60 aqueous suspensions exposed to simulated sunlight were studied. C60 aqueous suspensions prepared by stirring pristine C60 in water under sunlight exposure undergo breakdown with formation of a mixture of compounds with unknown chemical structure. The mass and infrared spectrometric analysis of the breakdown products shows the presence of broken C60 cages, as well as of oxygen and hydrogen atoms in their structure. The presence of oxygen in the breakdown products indicates a possible interaction of C60 molecule with oxygen from the air as well as with water. Interaction with water could also explain the presence of H atoms in the breakdown products. This demonstrates that fullerenes C60 are not stable in the environment and that the breakdown products should be considered when evaluating the environmental impact of fullerenes C60.     

Influence of C60 fullerene on fretting wear of metals

The potential usefulness of C₆₀ as additives in lubricating oils and as coatings under fretting conditions is demonstrated by tribological techniques. Pis’ma Zh. Tekh. Fiz. 23, 1–6 (August 12, 1997)     

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.     

Modification of fullerene nanocolumn structure by accelerated C60 ions

Crystalline C60 and amorphous graphite-like films of nanocolumn arrays fabricated by glancing angle deposition of C60 fullerene at substrate temperatures of -425 K were studied by transmission electron microscopy (TEM) and atomic-force microscopy (AFM). Characteristic dimension of columns is 200-400 nm. We used co-deposition of C60 molecules and accelerated C60 ions to modify the structure and properties of nanocolumn arrays. Influence of incidence angle for C60 ions on formation of film morphology was revealed. Raman spectrum analysis showed that amorphous carbon nanocolumns consist of nanographite areas with average size of -1.5 nm. The films have high conductivity (close to graphite) and have no mechanical stresses. The carbon films were applied in all-solid-state rechargeable thin-film battery as an anode layer. The nanocolumn amorphous carbon film as anode electrode showed the discharge capacity of about 50 microAh cm(-2)microm(-1) and good cycling ability over 100 times in full cell system.     

C60,C180,C60@C180富勒烯分子的压缩力学特性与电子结构

采用分子动力学方法模拟了C60,C180,C60@C180富勒烯分子的压缩过程,用PM3半经验量子力学方法计算了压缩C60,C180,C60@C180分子的电子结构,讨论了C60,C180,C60@C180分子压缩力学特性的差异,以及电子结构在压缩过程中的变化．结果表明,由于分子几何构形上的差异,C60分子的承载与吸收能量能力显著高于C180和C60@C180分子,而CC60@C180分子略高于C180分子;C60分子具有最高的化学稳定性,而C60@C180分子的稳定性最低;C60和C60@C180分子的压缩变形越大,越容易失去电子,稳定性越低;C180分子在加载点处发生压缩“塌陷”时,化学活性明显增加．     

C60 fullerene nanocolumns--polythiophene heterojunctions for inverted organic photovoltaic cells

Inverted organic photovoltaic cells have been fabricated based on vertical C(60) nanocolumns filled with spin-coated poly[3-(4-carboxybutyl)thiophene-2,5-diyl] (P3CBT). These C(60) nanocolumns were prepared via glancing angle deposition (GLAD), an efficient synthetic approach that controls the morphology of the resulting film, including intercolumn spacing, nanostructure shapes, and overall film thickness, among others. Intercolumn spacing was tuned to better match the expected P3CBT exciton diffusion length while simultaneously increasing heterointerface area. Due to observed in situ dissolution of the C(60) nanocolumns in solvents typically used to spin-coat polythiophene-based polymers (i.e., chloroform and chlorobenzene), the carboxylic acid-substituted polythiophene, P3CBT, was used as it is soluble in dimethyl sulfoxide (DMSO), a solvent that did not affect the structure of the GLAD-produced C(60) nanostructures. Preservation of the C(60) nanocolumnar structure in the presence of DMSO, with and without P3CBT, was verified by absorbance spectroscopy and SEM imaging. Incorporating these nanostructured C(60)/P3CBT films into photovoltaic devices on indium tin oxide (ITO) showed that the engineered nanomorphology yielded a 5-fold increase in short-circuit current and a power conversion efficiency (PCE) increase from (0.2 ± 0.03)% to (0.8 ± 0.2)% when compared to a planar device. When compared to a standard bulk heterojunction (BHJ) device based upon the same materials, the C(60)-GLAD device outperformed fully solution-processed bulk heterojunctions, which were observed to have PCEs of (0.49 ± 0.03)%.     

C60 fullerene derivatized nanoparticles and their application to therapeutics

Fullerenes can be formed into many new materials and devices. They have a wide range of applications in medicine, electronics, biomaterials, and energy production. An overview of the nanostructure and the physical and chemical characteristics of fullerene-drug derivatives is given. The biological behavior of fullerene derivatives shows their potential to medical application fields because C(60) is rapidly absorbed by tissues and is excreted through urinary tract and enterons, which reveals low toxicity in vitro and in vivo studies. Nanomedicine has become one of the most promising areas of nanotechnology, while many have claimed its therapeutic use against cancer, human immunodeficiency virus (HIV), and neurodegenerative disorders. Water-soluble C(60) fullerene derivatives that come from chemical modification largely enhance the biological efficacy. The blood-brain barrier (BBB) is a physical barrier composed of endothelial tight junctions that restrict the paracellular permeability. A major challenge facing neuropharmacology is to find compounds that can be delivered into the brain through the bloodstream. Fullerene C(60) was demonstratively able to cross the BBB by hybridizing a biologically active moiety dyad, which provides a promising clue as a pharmacological therapy of neural disorders.     

Langmuir-Blodgett films made from C60 fullerene with grafted macromolecules

Langmuir-Blodgett films made from C₆₀ fullerene with grafted polymer chains —polystyrene and polyethylene oxide — are obtained for the first time. The Langmuir-Blodgett films are obtained by the transfer of Langmuir films onto substrates of single-crystal silicon. The Langmuir films and the single-layer Langmuir-Blodgett films of C₆₀ with grafted polystyrene are nonuniform over their thickness and form a network consisting of aggregates with a size of ≤6 μm. The Langmuir films of C₆₀ with grafted polyethylene oxide are much more uniform. They can easily be used to obtain Langmuir-Blodgett films containing up to 20 layers and having a surface that appears smooth under an optical microscope. Pis’ma Zh. Tekh. Fiz. 24, 88–94 (June 26, 1998)     

Mechanism for thermal destruction of polystyrene grafted to fullerene C60

A model is proposed for the thermal destruction of polystyrene covalently bonded to C₆₀ and this is used to explain various characteristics of its experimental mass thermograms. Pis’ma Zh. Tekh. Fiz. 25, 25–30 (October 26, 1999)