Nanoscale Fullerene Research Articles

Synthesis of Nanoscale Fullerene C60 Filaments in the Volume of an Evaporating Drop of a Molecular Solution and Preparation of Thin Nanostructured Coatings on Their Basis

The features of nucleation and the mechanisms of further growth of nano- and microsized filamentary crystals (so-called whiskers) of fullerene in the volume of an isolated evaporating drop of a C60 molecular solution in ortho-xylene on a smooth surface of silicon and glass substrates have been studied for the first time. The morphological features and the exact dimensional characteristics of nanostructured mC60 fullerene filamentary crystals (where m is the number of spherical C60 macromolecules in the synthesized whisker) that are promising for the creation of nano- and micro-dimensional photoelectric converters in solar energy were determined by high-resolution scanning electron microscopy. When a drop of a molecular solution of C60 in ortho-xylene is transferred onto the surface of an optically smooth glass substrate, filamentary crystalline structures (nanowhiskers) with sizes of ∼250–700 nm in length and ∼50 nm wide were synthesized in the process of natural thermal evaporation of an organic solvent at room temperature (T ≈ 25°С). In this case, the surface of the resulting mC60 nanowhiskers is molecularly smooth, and the roughness does not exceed ∼5 nm. It has been found that at a temperature of silicon substrate T ≈ 35°С, not only the nucleation and growth of crystalline structures of filamentary nanocrystals in a volume of evaporating drop of C60 solution are accelerated, but there is also a significant (more than two orders of magnitude) increase in the final geometric dimensions of the synthesized whiskers. The ratio of the length (L ≈ 80 μm) to width (D ≈ 7.0 μm) of the filamentary crystals is approximately 11 : 1. A nanostructured organic semiconductor coating with a thickness of 10 μm, consisting of closely spaced mC60 filamentary crystals and a molecular layer of fullerene C60 on the smooth surface of a plane silicon substrate has been obtained for the first time.

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.

Novel fullerene-based ferrocene dyad and diferrocene triad: Synthesis and effects of introduction of fullerene[60] and phenyl linker on the thermodynamic stability, the magnetic properties and the band structure

In this paper, two nanoscale fullerene[60]-based compounds, N-methyl-2-(ferrocenyl) (phenyl) fulleropyrrolidine (C60-ph-Fc) and N-methyl-2-(diferrocenyl propane) fulleropyrrolidine (C60-diFc) were synthesized and characterized. The effects of the covalent linkage of fullerene[60] and the insertion of a phenyl group between fullerene[60] and diferrocenyl propane (diFc) moiety on the thermodynamic stability, the magnetic properties and the band structure were studied through measurements of the temperature-dependent magnetic susceptibility and cyclic voltammetry. The results show that both the covalent linkage of fullerene[60] and the insertion of a phenyl linker between fullerene[60] and diferrocenyl propane moiety lead to a weakness in the antiferromagnetic interaction between the two ferrocenyl entities. The introduction of C60 leads to an increase in the thermodynamic stability of the diferrocenyl propane moiety. The insertion of phenyl group between C60 and diFc or between C60 and Fc decreases the thermodynamic stability, and result in an increase in the HOMO orbital energies, but lead to a decrease in the HOMO-LUMO gap. The above experimental results lay the foundation for the future design of novel functional materials that can be applied to molecular devices.

Investigation of mode localization in hybrid periodic/quasiperiodic heterostructures containing nano-scale fullerene layers

In this paper, by using the theoretical model based on the transfer matrix method, we theoretically study the optical properties of electromagnetic waves in one-dimensional hybrid periodic/quasiregular heterostructures containing nano-scale fullerene and semiconductor layers. The results show that a hybrid configuration is a promising candidate for resonant cavities with strong mode localization. A future application of these structures can be realized in the field of random lasers where the quasiregular structures, acting like defects in the hybrid systems, could serve as a new type of complex cavity that provides the feedback for laser action.

Polarization-sensitive optical phase modulators based on aperiodic multilayers containing nano-scale fullerene and semiconductor layers

The band characteristics and the phase shift of electromagnetic waves in one-dimensional Fibonacci photonic structures composed of nano-scale fullerene and semiconductor layers are investigated theoretically in detail for both TE and TM polarizations and for different incident angles. We adopt the transmission matrix method to analyze the transmission properties of supposed sub-wavelength structure. We observe that within the stop band, the reflection phase difference changes smoothly and increases with the increasing of the incident angle. Furthermore, the phase shift decreases with the incident angle increasing for TE mode, and increases with the incident angle increasing for TM mode. Especially, at both the edges of the gap, the reflection phase difference keeps zero in spite of the change of incident angle. Based on our results, the supposed structure provides a convenient way to design very compact phase controllers such as phase retarders.

Molecular Electrostatic Potential Analysis of Nano-Scale Fullerene (C60) Crystals and Some Specific Derivatives: DFT Approach

Molecular Electrostatic Potential Analysis of Nano-Scale Fullerene (C60) Crystals and Some Specific Derivatives: DFT Approach Nano-scale fullerene (C60) crystals and its derivatives have been proven to make contributions in many types of applications. The molecular electrostatic potential of C60 doped with elements of Group III and Group V were studied by technical DFT-B3LYP /3- 21G** molecular modelling. The molecular electrostatic potential map (MEP) for substituting Fullerene by Group III and Group V, was painted on the surface using a red to blue scale. Results dedicate the substituted Fullerene to many important applications depending on the type of metal.

PHOTONIC ANALYSIS OF SEMICONDUCTOR FIBONACCI SUPERLATTICES: PROPERTIES AND APPLICATIONS

Abstract—In this paper, we theoretically study the phase treatment of reflected waves in onedimensional Fibonacci photonic quasicrystals composed of nano-scale fullerene and semiconductor layers. The dependence of the phase shift of reflected waves for TE mode and TM mode on the wavelength and incident angle is calculated by using the theoretical model based on the transfer matrix method in the infrared wavelength region. In the band gaps of supposed structures, it is found that the phase shift of reflected wave changes more slowly than within the transmission band gaps. Furthermore, the phase shift decreases with the incident angle increasing for TE mode, and increases with the incident angle increasing for TM mode. Also, for the supposed structures it is found that there is a band gap which is insensitive to the order of the Fibonacci sequence. These structures open a promising way to fabricate subwavelength tunable phase compensators, very compact wave plates and phase-sensitive interferometry for TE and TM waves.

Adsorption of fullerene nC60 on activated sludge: Kinetics, equilibrium and influencing factors

The increasing production and use of fullerene C60 nanomaterials raises concerns about environmental risks and human health. However, the materials’ behavior and fate during wastewater treatment are still unclear. We investigated the adsorption of aqueous nanoscale fullerene (nC60) on activated sludge by analysis of adsorption kinetics and equilibrium. The adsorption process closely followed the pseudo-second-order kinetics model, and the adsorption isotherm was well described by the Freundlich model. The adsorption process depended strongly on the activated sludge concentration and pH, but there was no significant effect by the temperature and low ionic strength. The dissolved organic matter in wastewater could obviously inhibit the adsorption process. At mixed liquor suspended solids concentrations of 1000 and 2000mg/L after 1h mixing, nC60 removal by adsorption reached 47% and 74%, respectively. Thus, adsorption could play an important role in the fate of nC60 during conventional biological wastewater treatment. The analysis of factors influencing the adsorption amounts indicated that the nC60 adsorption behavior on activated sludge was affected by the combined forces of the hydrophobic attraction, electrostatic repulsion and steric interaction.

Nanoscale Fullerene Compression of an Yttrium Carbide Cluster

The nanoscale parameters of metal clusters and lattices have a crucial influence on the macroscopic properties of materials. Herein, we provide a detailed study on the size and shape of isolated yttrium carbide clusters in different fullerene cages. A family of diyttrium endohedral metallofullerenes with the general formula of Y(2)C(2n) (n = 40-59) are reported. The high field (13)C nuclear magnetic resonance (NMR) and density functional theory (DFT) methods are employed to examine this yttrium carbide cluster in certain family members, Y(2)C(2)@D(5)(450)-C(100), Y(2)C(2)@D(3)(85)-C(92), Y(2)C(2)@C(84), Y(2)C(2)@C(3v)(8)-C(82), and Y(2)C(2)@C(s)(6)-C(82). The results of this study suggest that decreasing the size of a fullerene cage with the same (Y(2)C(2))(4+) cluster results in nanoscale fullerene compression (NFC) from a nearly linear stretched geometry to a constrained "butterfly" structure. The (13)C NMR chemical shift and scalar (1)J(YC) coupling parameters provide a very sensitive measure of this NFC effect for the (Y(2)C(2))(4+) cluster. The crystal structural parameters of a previously reported metal carbide, Y(2)C(3) are directly compared to the (Y(2)C(2))(4+) cluster in the current metallofullerene study.

Synthesis of Mono-Dispersed Nano-Scale Fullerene (C<SUB>60</SUB>) 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.

Transport and Retention of Fullerene Nanoparticles in Natural Soils

Commercial production and use of fullerene (C60) nanomaterials will inevitably lead to their release into the environment, where knowledge of C60 fate and transport is limited. In this study, a series of one-dimensional column experiments was conducted to assess the transport and retention of nanoscale fullerene aggregates (nC60) in water-saturated soils. Under the experimental conditions, complete retention of nC60 was observed in columns (2.5 cm inside diameter x 11 cm length) packed with Appling or Webster soil, which contain 0.75 and 3.33% organic carbon by weight, respectively. When the volume of aqueous nC60 suspension (approximately 4.5 mg L(-1)) applied to Appling soil was increased from 5 to 65 pore volumes, the travel distance increased from 3 to 8 cm, and the retention capacity approached a limiting value of 130 microg g(-1), although nC60 was not detected in the column effluent. The addition of 20 mg C L(-1) Suwannee River humic acid to the influent suspension increased the nC60 transport in Appling soil but did not resul in breakthrough. Attempts to simulate the experimental data using clean-bed filtration theory were not satisfactory, yielding retention profiles that failed to match observed data. Subsequent incorporation of a limiting retention capacity expression into the mathematical model resulted in accurate predictions of the measured nC60 retention profiles and transport behavior. The sizable retention capacities observed in this study suggest that transport of nC60 is limited in relatively fine-textured soils containing appreciable amounts of clay minerals and organic matter, with substantial accumulation of nC60 aggregates near the point of release.

Influence of electrolyte species and concentration on the aggregation and transport of fullerene nanoparticles in quartz sands

The potential toxicity of nanoscale particles has received considerable attention, but the fate of engineered nanomaterials in the environment has been studied only under a limited set of conditions. In the present study, batch and column experiments were performed to assess the aggregation and transport of nanoscale fullerene (nC60) particles in water-saturated quartz sands as a function of electrolyte concentration and species. As the electrolyte concentration increased from 1 to 100 mM, the change in nC60 particle diameter was minimal in the presence of NaCl but increased by more than sevenfold in the presence of CaCl2. The latter effect was attributed to the agglomeration of individual nC60 particles, consistent with a net attractive force between particles and suppression of the electrical double layer. At low ionic strength (3.05 mM), nC60 particles were readily transported through 40- to 50-mesh quartz sand, appearing in the column effluent after introducing less than 1.5 pore volumes of nC60 suspension, with approximately 30% and less than 10% of the injected mass retained in the presence of CaCl2 or NaCl, respectively. At higher ionic strength (30.05 mM) and in finer Ottawa sand (100-140 mesh), greater than 95% of the introduced nC60 particles were retained in the column regardless of the electrolyte species. Approximately 50% of the deposited nC60 particles were recovered from 100- to 140-mesh Ottawa sand after sequential introduction of deionized water adjusted the pH to 10 and 12. These findings demonstrate that nC60 transport and retention in water-saturated sand is strongly dependent on electrolyte conditions and that release of deposited nC60 requires substantial changes in surface charge, consistent with retention in a primary energy minimum.

Investigation of the Transport and Deposition of Fullerene (C60) Nanoparticles in Quartz Sands under Varying Flow Conditions

A coupled experimental and mathematical modeling investigation was undertaken to explore nanoscale fullerene aggregate (nC60) transport and deposition in water-saturated porous media. Column experiments were conducted with four different size fractions of Ottawa sand at two pore-water velocities. A mathematical model that incorporates nonequilibrium attachment kinetics and a maximum retention capacity was used to simulate experimental nC60 effluent breakthrough curves and deposition profiles. Fitted maximum retention capacities (S(max)), which ranged from 0.44 to 13.99 microg/g, are found to be correlated to normalized mass flux. The developed correlation provides a means to estimate S(max) as a function of flow velocity, nanoparticle size, and mean grain size of the porous medium. Collision efficiency factors, estimated from fitted attachment rate coefficients, are relatively constant (approximately 0.14) over the range of conditions considered. These fitted values, however, are more than 1 order of magnitude larger than the theoretical collision efficiency factor computed from Derjaguin-Landau-Verwey-Overbeek (DLVO) theory (0.009). Data analyses suggest that neither physical straining nor attraction to the secondary minimum is responsible for this discrepancy. Patch-wise surface charge heterogeneity on the sand grains is shown to be the likely contributor to the observed deviations from classical DLVO theory. These findings indicate that modifications to clean-bed filtration theory and consideration of surface heterogeneity are necessary to accurately predict nC60 transport behavior in saturated porous media.

Transport and Retention of Nanoscale C60Aggregates in Water-Saturated Porous Media

Experimental and mathematical modeling studies were performed to investigate the transport and retention of nanoscale fullerene aggregates (nC60) in water-saturated porous media. Aqueous suspensions of nC60 aggregates (95 nm diameter, 1 to 3 mg/L) were introduced into columns packed with either glass beads or Ottawa sand at a Darcy velocity of 2.8 m/d. In the presence of 1.0 mM CaCl2, nC60 effluent breakthrough curves (BTCs) gradually increased to a maximum value and then declined sharply upon reintroduction of nC60-free solution. Retention of nC60 in glass bead columns ranged from 8 to 49% of the introduced mass, while up to 77% of the mass was retained in Ottawa sand columns. When nC60 suspensions were prepared in deionized water alone, effluent nC60 BTCs coincided with those of a nonreactive tracer (Br-), with minimal nC60 retention. Observed differences in nC60 transport and retention behavior in glass beads and Ottawa sand were consistent with independent batch retention data and theoretical calculations of electrostatic interactions between nC60 and the solid surfaces. Effluent concentration and retention profile data were accurately simulated using a numerical model that accounted for nC60 attachment kinetics and a limiting retention capacity.

Covalent Formation of Nanoscale Fullerene and Dendrimer Patterns

Localized patterns of amine-terminated monolayers obtained via the surface modification of a monolayer with the biased probe of an atomic force microscope were used to covalently attach buckminsterfullerene or dendrimers to the surface, affording lines as narrow as 20 nm.