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.     

Aqueous fullerene C60 solution suppresses herpes simplex virus and cytomegalovirus infections

Abstract

Fullerene C₆₀ is known as a promising therapeutic agent due to its antioxidant, anti-inflammatory and other properties, along with the lack of noticeable toxicity. In this article, we describe antiviral properties of aqueous fullerene C₆₀ dispersion (ndC₆₀) produced by biocompatible diafiltration technology and C₆₀ amino derivatives against Herpes simplex virus type 1 (HSV-1) and Human cytomegalovirus (HCMV) infections. Their activity in vitro was evaluated by a plaque reduction assay using Vero and HF cells in pre- and post-treatment modes. Therapeutic efficacy of dnC₆₀ and C₆₀ derivatives was studied in DBA mice using cutaneous model of HSV-1 infection. Data obtained indicated low cytotoxicity of all used compounds for both cell lines (CC₅₀ > 1?mg/ml). The antiviral activity of dnC₆₀ in most tests exceeded the activity of both C₆₀ amino adducts and acyclovir (ACV), and it demonstrated significant therapeutic effect against HSV-1 skin infection in mice.     

Synthesis of Calix[4, 5, 6] Resorcinarenes Using Fullerene C60 as Template

Abstract

We present a new use of fullerene C₆₀ as a template for the synthesis of cyclic resorcinarenes, The cyclocondensation of 2‐methyl‐resorcinol with benzaldehyde and hexanal in THF, catalyzed by AlCl₃, in the presence of 1%, 5%, and 10% fullerene C₆₀, produces calix[4], [5], and [6] resorcinarenes, with the pentamer and hexamer as the major products. The resorcinarenes were characterized by ¹H, ¹³C NMR, FTIR, FAB⁺ mass spectrometry, and elemental analysis.     

Complexation of free-base and 3d transition metal(II) phthalocyanines with fullerene C60: A dispersion-corrected DFT study

We performed a systematic comparative theoretical study of noncovalent interactions of free-base H₂Pc and a series of 3d transition metal(II) phthalocyanines (where the transition metals included manganese, iron, cobalt, nickel, copper and zinc) with fullerene C₆₀, by employing a DFT technique accounting for vdW interactions (PBE GGA functional with a dispersion correction by Grimme). We observed four different types of Pc interaction with fullerene cage, depending on central metal atom. Upon complexation with C₆₀, the macrocyclic plane undergoes distortion in all cases, to a different degree. Some correlation was observed between the calculated formation energies for Pc–fullerene complexes and intermolecular separations in them, where stronger binding is generally associated with shorter M^…C_C60 and N^…C_C60 distances. Despite of considerable differences in the structure of Pc–fullerene complexes, the latter do not exhibit notable variations in the distribution of electrostatic potential, contrary to spin density plots for open-shell species. Similarly, HOMO and LUMO distribution can vary within some limits.     

ON THE ABSORPTION SPECTRUM OF C60 IN THE VISIBLE SPECTRAL REGION

ABSTRACT

A complete (720–380?nm), strong visible absorption spectrum (OD₅₉₈=1.6) for C₆₀ in a decalin/methylcyclohexane inert matrix at 77?K is reported for the first time. The structure of this spectrum allows one to construct an acceptable approximation to the gas-phase spectrum for this substance at a low temperature. The 0–0 component of the S₀→S₁ transition in the gas phase at a low temperature was estimated to be at about 635?nm.     

C60H18, C60H36 and C70H36 Fullerene Hydrides: Study by Methods of IR,NMR, XPS,EELS and Magnetochemistry

Abstract

Fullerene hydrides of C₆₀H₁₈, C₆₀H₃₆ and C₇₀H₃₆ are studied by using IR, ¹H and ¹³C NMR, X-ray photoelectron and electron energy loss spectroscopies, and magnetochemistry. The comparison of IR and solid state ¹H and ¹³C NMR data for C₆₀H₃₆ with the theoretical ones allows the suggestion that fullerene hydride has a T symmetric structure and contains 4 isolated benzenoid rings located at tetrahedral positions on the surface of a closed skeleton of the molecule. The EELS revealed that the transition from fullerene to the hydride is accompanied by the decrease of the density of valence electrons. Magnetization measurements showed C₆₀H₃₆ to be a ferromagnet. The hydrogenated fullerenes were prepared by transfer hydrogenation procedures involving 9,10-dihydroanthracene. The compositions of the hydrides are determined by field desorption mass-spectral analysis.     

Reactions of microcrystalline fullerene C60 with amino and aza macrocyclic ligands under solvent-free conditions

We evaluated the reactivity under solvent-free conditions of 2-aminomethyl-15-crown-5 (AM15C5), 2-aminomethyl-18-crown-6 (AM18C6), 1,4,8,12-tetraazacyclopentadecane (TACPD) and rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (tet b) with microcrystalline fullerene C₆₀. The reactions of nucleophilic addition were carried out at temperatures of about 160°C for 5 h in the case of crown ethers and TACPD, and at 180–190°C for 24 h in the case of tet b. Characterization of the products obtained was performed by using Fourier-transform infrared (FTIR) and Raman spectroscopy, laser desorption/ionization time-of-flight (LDI-TOF) mass spectroscopy, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). To provide an additional insight into the reactivity of macrocyclic compounds with C₆₀ molecules, we employed theoretical calculations in the frame of density functional theory (DFT). According to the results of SEM imaging, macrocyclic reagents are generally unable to deeply penetrate into the bulk of fullerene microcrystals (with a possible exception of TACPD). According to TGA measurements, the reaction efficiency is very low for tet b, whereas the average content of organic fraction in C₆₀-AM15C5 and C₆₀-AM18C6 reaches about 29%, and in C₆₀-TACPD, almost 40%. According to LDI-TOF mass spectral analysis, the products of TACPD, tet b and AM15C5 reactions with fullerene have oligomeric or polymeric structure. By using DFT theoretical calculations, the latter observation was explained by enhanced reactivity of secondary amino groups toward nucleophilic addition onto fullerene cage.     

Noncovalent interactions of amino acids with fullerene C60: A dispersion-corrected DFT study

By using the general gradient approximation functional PBE with Grimme's empirical dispersion correction in conjunction with the double numerical basis set DNP, we studied the noncovalent interaction of twenty proteinogenic l-amino acids (AAs) with fullerene C₆₀. The calculations were performed both under vacuum conditions and in aqueous medium. We analyzed the calculated geometries and binding energies for AA+C₆₀ complexes, the shape of HOMO and LUMO orbitals and the corresponding gap energies. Generally, we found a poor correlation between binding energies calculated for AA+C₆₀ complexes in aqueous medium and hydrophobicity scales proposed by other other authors. Despite of C₆₀ cage can be envisioned as a typical hydrophobic surface, the AA adsorption apparently takes place according to a mechanism different from classical hydrophobic interactions, or due to a combination of several types of interactions with a limited contribution of hydrophobic mechanism.     

Preparation and characterization of fullerene (C60)-modified BiVO4/Fe3O4 nanocomposite by hydrothermal method and study of its visible light photocatalytic and catalytic activity

In this study, BiVO₄/Fe₃O₄/C₆₀ nanocomposite has been synthesized for the first time using a facile and feasible hydrothermal method. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), vibrating sample magnetometer (VSM), and N₂ adsorption-desorption analysis were utilized to analyze the structure, morphology, size, and the magnetic property of the synthesized nanocomposite. The photocatalytic activity of the magnetic BiVO₄/Fe₃O₄/C₆₀ nanocomposite was investigated for the degradation of methylene blue. The results showed that 84% degradation of methylene blue (MB) (25 mg/L) solution within 5 h with a rate constant equal to 0.0049 min^?1 in the presence of BiVO₄/Fe₃O₄/C₆₀ nanocomposite and H₂O₂ (1 mL, 30%) under visible light irradiation. The effects of BiVO₄/Fe₃O₄/C₆₀ dosage, H₂O₂ amount dye initial concentration and C₆₀ amount on the efficiency of degradation process were investigated. Furthermore, the catalytic activity of the magnetic BiVO₄/Fe₃O₄/C₆₀ nanocomposite was investigated for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using sodium borohydride (NaBH₄) in the aqueous solution and at room temperature. The results showed that BiVO₄/Fe₃O₄/C₆₀ nanocomposite exhibited an excellent performance for the reduction of 4-NP with 97% conversion into its corresponding amino derivative within 38 min with a constant rate equal to 0.0775 min^?1. As indicated by the results, the magnetic BiVO₄/Fe₃O₄/C₆₀ nanocomposite exhibited much higher photocatalytic and catalytic activity than BiVO₄/ C_60, BiVO₄/Fe₃O_4, and pure BiVO₄. Moreover, the BiVO₄/Fe₃O₄/C₆₀ nanocomposite could be magnetically separated from the reaction mixture due to the presence of the Fe₃O₄ and reused without any change in structure.     

C60 thin-film transistors with high field-effect mobility,fabricated by molecular beam deposition

We report performance of C₆₀ thin-film field-effect transistors and characterizations of C₆₀ thin-films on SiO₂ substrates fabricated by molecular beam deposition. Devices, fabricated and characterized under high vacuum without exposing to air, routinely showed current on/off ratios >10⁸ and field-effect mobility in the range of 0.5–0.3 cm²/V s. The obtained mobility is comparable to the highest value among n-type organic thin-film transistors and close to that derived from the photocurrent measurements on C₆₀ thin-films.The grain size of C₆₀ thin-film, condensed in an fcc solid, increases with the substrate temperature, while themobility did not exhibit a clear relation with substrate temperature.

© 2003 Elsevier Ltd. All rights reserved.     

CHROMATOGRAPHIC PURIFICATION OF Kr@C60

Unusual compounds have been reported to form by the incorporation of atoms into fullerene cages. The compounds in which a noble gas atom is trapped into a C₆₀ cage are very stable and only van der Waals interactions occur between the noble gas and the fullerene cage. The study of these compounds requires efficient chromatographic (or other) separations. We performed the isolation of Kr@C₆₀ and a study of its chromatographic separations on several HPLC columns using toluene : hexane mixtures as solvent. We found that the separation factor is small (1.09 to 1.12) with the highest separation factor on a Buckyprep column.     

Fullerene C60 Complexed with Poly(N-Vinyl-pyrrolidone) (C60/PVP) Prevents the Disturbance of Long-Term Memory Consolidation Induced by Cycloheximide

Abstract

It is shown that fullerene C₆₀/water‐soluble complex with PVP molecular mass of 10,000 injected in the dorsal hippocampus completely prevents the development of amnesia caused by cycloheximide, the inhibitor of protein synthesis. With the increased PVP molecular mass up to 25,000 the complex does not produce protective effect disturbance of learning.     

Bromination of [60]Fullerene. II. Crystal and Molecular Structure of [60]Fullerene Bromides,C60Br6, C60Br8, and C60Br24

Abstract

The crystal and molecular structures of the bromofullerene solvates C₆₀Br₆·0.5C₆H₅Cl·0.5Br₂, C₆₀Br₈·1.5(o‐C₆H₄Cl₂), C₆₀Br₈·Br₂, C₆₀Br₈·0.5C₆H₅Br·0.5Br₂, and C₆₀Br₂₄·2Br₂ have been determined by single crystal X‐ray diffraction. The molecular species C₆₀Br₆, C₆₀Br₈, and C₆₀Br₂₄ which have idealized C _s , C _2v  , and T _h symmetries, respectively, have several different types of C?Br and C?C bonds. A comparison between different solvates of the same bromofullerenes revealed a larger stability of the packing modes for the C₆₀Br₆ and C₆₀Br₂₄ solvates, whereas the C₆₀Br₈ solvates showed different packing motifs dependent on the nature and amount of the solvent molecules.     

Star‐like Fullerene Containing Poly(Vinylpyrrolydone) Derivatives: Chloroform Solution Properties

Abstract

Star‐like fullerene C₆₀ derivatives with different branch number, synthesized by the reaction of fullerene with poly(vinylpyrrolydone) (PVP) macromolecules bearing the terminal amino‐groups, were investigated in solution by the viscometry, dielectric, and electrooptical Kerr‐effect methods in comparison with the ordinary linear PVPs of the same molecular mass. It was shown that covalent linkage of branches to fullerene through amino‐groups leads to appearance of a polar and optically anisotropic nanoparticle (amine‐substituted C₆₀) in the center of the coil of star‐like polymers that radically changes dielectric and electrooptical properties of the initial polymer. Effect of fullerene on the dimension of polymer coil had been detected also.     

On the Effect of the Rotational State of C60 Molecules on Electronic Transport in the C60 Fullerite

Abstract

A phenomenological scenario is suggested in an attempt to explain controversies in the published data concerning the effect of orientational order on electronic transport in solid C₆₀. The main factor of crucial importance is the dependence of the charge hop probability on the mutual orientation of the molecules. Magnitude and the sign of the conductivity response to the changes in the rotational state of C₆₀ across the orientational phase transition are the results of the interplay between the changes in dynamic and static disorder that accompany the transition and may vary in the samples with different structure perfection.     

STM study of C60 overlayers on Pt(111) surfaces

We present a scanning tunnelling microscopy (STM) characterization of C₆₀ layers grown on a Pt(111) substrate at room temperature. Fullerenes diffuse on the surface until finding steps in which they remain anchored forming one-dimensional molecular lines. These rows are seed for the growth of ordered islands, which expand on the Pt atomic terraces with two different orientations: either parallel to main crystallographic direction of the substrate, or rotated by 30°. For coverages near to the monolayer a second layer appears before completing the first one.     

An overview of fullerene chemistry

Fullerenes which were thought to be ‘superaromatics’ are actually ‘superalkenes’. Reactions in fullerenes are varied, ranging from the addition of simple molecules like H₂ to large molecules like dendrimers. The synthesis, structure, characterization, along with simple reactions like halogenation, oxygenation, metalation, cycloaddition, polymerization and dendrimer addition are discussed.     

Synthesis of bipyramidal gold nanoparticle-[C60]fullerene nanowhisker composites and catalytic reduction of 4-nitrophenol

The seed solution was prepared by dissolving hydrogen tetrachloroaurate(III) trihydrate (HAuCl₄·3H₂O), trisodium citrate dihydrate (C₆H₅Na₃O₇·2H₂O), and sodium borohydride (NaBH₄) in distilled water. The resulting reddish-purple seed solution was stirred for 3 h at room temperature. The growth solution was prepared by mixing hydrogen tetrachloroaurate(III) trihydrate (HAuCl₄·3H₂O), cetyltrimethylammonium bromide (CTAB, (C₁₆H₃₃)N(CH₃)₃Br), silver nitrate (AgNO₃), hydrochloric acid (HCl), and ascorbic acid (C₆H₈O₆) in distilled water. Subsequently, 100 μL of this seed solution was transferred into 10 mL of the growth solution. The mixed solution was maintained at 30 °C for 3 h to obtain a solution of bipyramidal gold nanoparticles. The bipyramidal gold nanoparticle-[C₆₀] fullerene nanowhisker composites were synthesized by applying the liquid-liquid interfacial precipitation (LLIP) method to a saturated solution of C₆₀ in toluene, the solution of bipyramidal gold nanoparticles, and isopropyl alcohol. The prepared bipyramidal gold nanoparticle-[C₆₀] fullerene nanowhisker composites were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. The catalytic activity of these composites was confirmed in the reduction of 4-nitrophenol by UV-Vis spectroscopy.     

Optical and photoelectrical studies of gold nanoparticle-decorated C60 films

Optical and photoelectrical studies were performed on octane-1,8-dithiol cross-linked fullerene films, with supported gold nanoparticles (C₆₀-DT-Au). According to high-resolution transmission electron microscopy observations, the average size of obtained gold nanoparticles was about 5 nm, and the shape was spherical. The comparative investigation of optical properties of pristine and cross-linked with octane-1,8-dithiol C₆₀ films, decorated with gold nanoparticles, found the difference in the extinction coefficient spectra, which was observed also in the photocurrent spectra of barrier heterostructure Au/C₆₀/Si. The analysis of dark current-voltage characteristics for Au/C₆₀/Si heterostructures showed that the model for them includes the barrier at the C₆₀/Si interface and internal barriers in the C₆₀ layer, caused by the trapping centers. The hopping mechanism of the current transport in the C₆₀ layer was supplemented with the Poole-Frenkel emission process on these centers, with the barrier height greater for the fullerene C₆₀ film cross-linked with octane-1,8-dithiol.