Synthesis,Spectral Investigations,and Thermal Stability of [60]Fullerene Complexes with TMTSF: 2(C60) · 2(TMTSF) · (C6H6), C60 · TMTSF · 2(CS2), and 2(C60) · 2(TMTSF) · (C6H5Cl)

Abstract

Molecular complexes of [60]fullerene with tetramethyltetraselenafulvalene (TMTSF): C₆₀ · (TMTSF) · 2(CS₂) (1), 2(C₆₀) · (2(TMTSF) · (C₆H₆) (2), and 2(C₆₀) · (2(TMTSF) · (C₆H₅Cl) (3) have been synthesized and their thermal stability and IR spectra vs. light polarization and temperature have been performed.     

Structure and Photoluminescence of Single‐Emulsion C60 and Cu‐C60 Films

Abstract

The phase composition of single‐emulsion C₆₀ and Cu‐C₆₀ films and their photoluminescence were studied and analyzed in detail.     

Singlet‐Triplet Transition in the C60 2− Dianion

Abstract

The C₆₀ complexes with decamethylcobaltocene: (Cp*₂Co)₂C₆₀(C₆H₄Cl₂, C₆H₅CN)₂ (1) and [K · (18‐crown‐6)]₂ · C₆₀ · (DMF)₄ (2) have been obtained as single crystals by the diffusion method. The IR‐ and UV‐VIS‐NIR‐spectra justify the formation of the C₆₀ ^2? dianions in these salts. EPR measurements show that the low temperature signals of 1 in the 4–140 K range and 2 in the 4–60 K range have intensity corresponding only to 0.4% and 3.5% from total C₆₀. Because of this, most of the complexes are EPR silent, and, consequently, C₆₀ ^2? has a diamagnetic singlet (S = 0) state in these temperature ranges. The appearance of a broad EPR signal in the spectum of 1 above 140 K and 2 above ～60 K is assigned to a thermal population of a close lying excited triplet (S = 1) state. The singlet–triplet energy gap for C₆₀ ^2? in solid 1 and 2 was estimated to be 730 ± 10 and 300 ± 10 cm^?1.     

In the Chase of Mixed Halofullerenes: Remarkable Transformation of C60Cl n (n = 6, 8, 12, 14) to C60Br24

Abstract

Chlorofullerenes C₆₀Cl _n (n = 6, 8, 12, 14) were found to react with bromine yielding C₆₀Br₂₄ as a single product. No intermediates containing both bromine and chlorine atoms attached to the cage were detected in the course of transformation.     

Bromination of [60]Fullerene. I. High‐Yield Synthesis of C60Br x (x=6, 8, 24)

Abstract

The systematic study of the bromination of C₆₀ was performed under various experimental conditions. Application of some chloroarenes as reaction media resulted in the high‐yield (70–96%) selective synthesis of C₆₀Br₆ and C₆₀Br₈. Direct bromination of fullerene yielded either C₆₀Br₈, C₆₀Br₁₄, or C₆₀Br₂₄ depending on the reaction time. Possible pathways of bromination of C₆₀Br₈ were analyzed using semiempirical (AM1) calculations, two most probable molecular structures are conjectured for the first isolated C₆₀Br₁₄.     

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.     

Some New Aspects of Chlorination of Fullerenes

Abstract

The effect of the reagent ratio, reaction time and power of the reagent on the product composition in chlorination of [60]fullerene was studied. Chlorofullerenes C₆₀Cl₆, C₆₀Cl₈, C₆₀Cl₁₀, C₆₀Cl₁₂, C₆₀Cl₁₄, and C₆₀Cl₂₆ were synthesized and characterized by chemical analysis, FTIR, ¹³C NMR, and MALDI TOF mass spectrometry. The experimental data supported the coexistence of several isomers of C₆₀Cl _n (n = 8, 10, 12, 14, 26); the mixtures were not separated so far. Semiempirical calculations (AM1, PM3) were used to analyze the addition patterns and resulted in the most favorable structures of C₆₀Cl_8–26. Chlorination of C₇₀ under various conditions invariably yielded C₇₀Cl₁₀.     

The New Method for the Synthesis of Fullerols Based on Radical Reaction

Abstract

The method for the synthesis of fullerols C₆₀(OH) _x was developed, allowing to obtain products with low number of hydroxy groups attached to fullerene molecule. At the first stage, product C₆₀(tert‐BuO) _x was obtained by the radical reaction of C₆₀ with tert‐butyl‐peroxide under heating or UV‐irradiation. At the second stage, fullerol C₆₀(OH) _x was synthesized after the elimination of tert‐butyl groups by acid treatment. Several samples C₆₀(OH) _x containing different numbers (x = 2–5) of hydroxy groups were obtained, the main product had x = 2. The structure of the fullerols was confirmed by UV‐ and Fourier‐transform infrared (FTIR)‐spectroscopy and MALDI‐TOF mass‐spectrometry.     

Trifluoromethylated [60]Fullerenes: Synthesis and Characterization

Abstract

The high temperature reaction of C₆₀ with silver(I) trifluoroacetate followed by 500°C sublimation and HPLC purification has led to the characterization of the trifluoromethyl‐[60]fullerenes 1,4‐C₆₀(CF₃)₂, C _s‐C₆₀(CF₃)₄, C ₁‐C₆₀(CF₃)₄, and C ₁‐C₆₀(CF₃)₆ by EI‐MS and ¹⁹F NMR. The compounds C ₁‐C₆₀(CF₃)₄ and C ₁‐C₆₀(CF₃)₆ were obtained with 90+% compositional purity. A sample of C₆₀(CF₃)₂ also contained ca. 15–20% of a C _s‐symmetry isomer of C₆₀(CF₃)₄. The structural assignments are based on calculations at the AM1 and DFT levels of theory.     

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.     

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.     

Photoluminescence Study of the Two‐Dimensional Tetragonal and Rhombohedral Polymers of C60 at High Pressure

Abstract

The pressure behavior of the photoluminescence (PL) spectra of the planar polymeric phases of C₆₀ have been studied at pressure up to 4 GPa. The PL spectra and the pressure‐induced shift of the principal bands differ considerably for the pristine C₆₀, two‐dimensional tetragonal (2D‐T) and rhombohedral (2D‐R) polymers of C₆₀. The changes in the PL spectra may be related with the transformation of the electron energy spectrum of polymers.     

Degradation of fullerene C60 by human myeloperoxidase and some reaction products

Abstract

The biodegradation of the fullerene molecule C₆₀ under the action of the human myeloperoxidase enzyme accompanied by a complete loss of the topology of the fullerene core. Analysis of this reaction mixture using UV and FTIR spectroscopy, chromatographic and mass spectrometry methods showed that the degradation proceeds without the formation of significant amounts of hydroxylated compounds. Among other intermediate compounds aromatic compounds were detected.     

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.     

GENERATION OF HIGHER FULLERENES FROM LASER ABLATION OF CARBYNE AND C60 PHOTOPOLYMER ASTROCHEMICAL IMPLICATIONS

ABSTRACT

Laser ablation of targets of carbonaceous matter containing carbyne nanodomains (the sp hybridised carbon chains) or targets of C₆₀ photopolymer produced carbon clusters which have been detected by FT-ICR (Fourier-Transform Ion Cyclotron Resonance) mass spectrometer. When the carbonaceous matter containing carbyne has been employed as laser target, no C₆₀ has been generated but only fullerene cages from C₇₄ up to C₁₂₄. Larger cages were also obtained but with odd number. Starting from C₆₀ photopolymer, laser ablation regenerates free C₆₀ and creates a sequence of C₆₀ superior homologues all possessing even number and each member of the series is separated from the preceding and the following member by the loss or by the addition respectively of a C₂ unit. Fullerenes up to C₁₆₂ have been recorded. The implications about the presence of free C₆₀ fullerene in the interstellar and circumstellar space, its formation from carbyne chains and its stability towards its photopolymerization tendency and its regeneration from the photopolymer together with its superior homologues have been discussed thoroughly in the present paper.     

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.     

New Polymeric Phase in Low‐Doped Lithium Intercalated Fullerides

Abstract

The low‐doped Li _x C₆₀ compounds (x≤6) were investigated using laboratory X‐ray and synchrotron radiation diffraction, ¹³C NMR and Raman spectroscopy. Li₄C₆₀ shows an unusual 2D polymerisation in which the C₆₀ units are connected both by [2+2] cycloaddition and by single carbon–carbon bonds, a unique feature among the known polymerised fullerene compounds. This picture is fully supported also by static NMR and Raman measurements. The charge transfer to C₆₀ in the polymeric phase was evaluated from the shift of the A_g(2) mode. The depolymerisation process was investigated as well; despite the presence of two different bonds, the polymer‐to‐monomer transition induced by thermal treatments is a single‐step phenomenon.     

Photo‐Induced Polymerization and Stress Effects in Fullerite C60

Abstract

Modifications of the structure and hardness of fullerite C₆₀ crystals under stresses generated during photo‐induced polymerization are investigated.     

Fullerane,the Hydrogenated C60 Fullerene: Properties and Astrochemical Considerations

Abstract

Hydrogenated C₆₀ fullerene, C₆₀H₃₆ was prepared in different solvents using Zn/HCl as reducing agents. The structure of C₆₀H₃₆ was confirmed both by electronic and FT‐IR spectroscopy and the purity of the reaction product was checked by HPLC analysis. It has been confirmed that C₆₀H₃₆ is not stable in air, especially in presence of light which enhances the oxidation. The oxidation of C₆₀H₃₆ was studied by FT‐IR spectroscopy and by differential scanning calorimetry (DSC) in air; the formation of hydroxyl groups on the fullerene cage and ketonic groups (involving cage breakdown) have been detected. Furthermore, the action of O₃ on C₆₀H₃₆ was investigated and it has been found that O₃ exerts practically the same effect of air but causing an enhanced cage breakdown. The thermal stability of C₆₀H₃₆ was checked by a thermogravimetric analysis (TGA) coupled with a differential thermal analysis (DTA) under N₂ flow. The vaporization of C₆₀H₃₆ occurs at very high temperature: the DTA trace has shown an endothermic peak at 540°C (at a heating rate of 20°C/min). C₆₀H₃₆ shows an electronic absorption spectrum with a maximum at about 217 nm and it is able to match both in position and in half width the peak at 217.5 nm observed in the spectrum of the interstellar extinction of light which was attributed to hydrogenated, radiation processed and thermally annealed carbon dust. Similarly, the absorption spectrum of C₆₀H₃₆ is able to match several infrared emission bands (called UIBs) detected from certain astrophysical objects like the protoplanetary nebulae (PPNe). It is proposed that hydrogenated fullerenes can be used as model compounds in the laboratory simulation studies of interstellar carbon dust.