Production of carbon soot with a high content of C60 and C70 fullerenes by electric arc

The effect of the parameters of the electric arc (helium pressure, current and voltage, clearance between electrodes) and of the peculiarities of the setup design (arrangement of electrodes, distance between the arc and the cooling surface, temperature of the soot condensation surface) on the yield of fullerenes has been studied. Conditions for producing soot with a C₆₀ and C₇₀ content up to 43% (toluene extract) have been found.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 805–809, May, 1994.The authors are grateful to N. G. Spitsyna and A. V. Dubovitskii for the determination of the content of C₆₀ and C₇₀ fullerenes in the extract.The work was financially supported by the Russian Foundation for Basic Research (Project 93-03-18705).     

Intermediates in the photochemical reaction for the formation of 2,7-dimethylacridine from ditolylamine and bromoform

The reaction of the photochemical synthesis of 2,7-dimethylacridine from di(para-tolyl)amine and bromoform was studied utilizing the method of microsecond impulse photolysis. The proposed new scheme for the formation of acridine assumes the recombination of the primary alkyl radicals at the nitrogen atom of the cation radical and/or the radical of the amine as the main route of the reaction. The data obtained indicate the common character of the nature of some intermediate stages and the structures of the intermediates in the photochemical formation of acridine compounds and triphenylmethane dyes from aromatic amines and halogenomethanes.Institute of Chemical Physics, Chernogolovka, Russian Academy of Sciences, 142432 Chernogolovka. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2044–2052, September, 1992.     

Study of the thermal stages of the photoinitiated cyclization of diarylamines with polyhalogenated methanes

On the basis of a study of the kinetics of the dark stages of the photoinitiated formation of acridines from substituted diphenylamines and bromoform the ionic nature of these stages was confirmed. Quantum chemical calculations confirmed the assumption of the dependence of the efficiency of cyclization on the charge state of the reacting molecules.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 564–569, March, 1991.     

Linked crystallites in the conducting topmost layer of polymer bilayer films controlled by temperature: from micro- to nanocrystallites.

Temperature has great impact on the structure and size of the linked crystallites of the conducting topmost layer formed at the surface of a polycarbonate film via the reaction BEDT-TTF+IBr [BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene]. We show that fine temperature control permits formation of a semiconducting topmost layer of alpha'-(BEDT-TTF)(2)(I(x)Br(1-x))(3) crystallites with either micro- or nanometre size, a result that opens a route to miniaturized conducting plastic materials.     

Structure of the neutral metal complex Pt(dddt)2

A neutral metal complex, [Pt(dddt)₂]° (1), has been obtained by oxidation of the [Pt(dddt)₂]^– anion with excess (Bu₄N)AuBr₄ in nitrobenzene. Crystallographic data for 1a=17.854(9) Å,b=18.409(9) Å,c=4.717(5) Å, =68.83(2)°, space group P2₁/n,Z=4,d _calc=2.55 g/cm³. In1 two independent centrosymmetric [Pt(dddt)₂]° molecules are packed in stacks that form layers parallel to the (110) plane. The molecules of1 in the layers have shortened S...S contacts 3.491(9) Å, and 3.594(10) Å. The average bond lengths Pt-S 2.242(7) Å, S-C 1.71(2) Å and C=C 1.40(3) Å, together with the square-planar coordination of Pt in PtS₄, suggest considerable conjugation in the metal cycles.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1207–1209, July, 1993.     

Visible and near-IR spectroscopy of endohedral Gd@C82(C 2v ) and Ho@C82(C 2v ) metallofullerenes and their monoanions

Solutions of endohedral Gd@C₈₂(C _2v ) and Ho@C₈₂(C _2v ) metallofullerenes are studied by means of visible and near-IR spectroscopy upon their conversion from neutral to the anionic form via a redox reaction with the electron donor potassium perchlorotriphenylmethide K(18-crown-6)[C(C₆Cl₅)₃]. The concentrations of the studied solutions of endohedral Gd@C₈₂(C _2v ) and Ho@C₈₂(C _2v ) metallofullerenes in o-dichlorobenzene were determined from the spectroscopic data, and their molar extinction coefficients are calculated.

     

Extraction of C60 from fullerene-containing carbon soots

Extraction of fullerene-containing carbon soots with various organic solvents has been studied at room temperature. Yields and compositions of toluene-soluble carbon soot fractions have been determined. Extracts of different carbon soot samples treated according to the toluene—trichlorobenzene—nitrobenzene scheme are studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1223–1225, July, 1995.The authors are grateful to E. B. Yagubskii and I. S. Krainskii for helpful discussion and help in the work.The work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-18705).     

Photochemical reaction oftrans-di(α-naphthyl)ethylene with diphenylamine

Diphenylamine adds to the ethylene bond of excitedtrans-di(α-naphthyl)ethylene (1). Dependence of the quantum yields of mono- and bi-molecular reactions of1,cis-di(α-naphthyl)ethylene2, and dihydropicene3 on amine concentration was studied. On this basis and theoretical analysis of the kinetic scheme a conclusion was drawn that amine interacts with excited1 with a diffusion-limited rate but has no effect on the photochemical activity of2 and3. The reaction mechanism was discussed.     

Preparation and investigation of the crystals formed in the buckminsterfullerene-tetraselenotetracene-carbon disulfide system

Crystals containing up to 30 wt. % CS₂, according to the data of IR and X-ray photoelectron spectroscopy, were isolated from the C₆₀-TSeT-CS₂ (TSeT is tetraselenotetracene) system. The unusually high concentration of carbon disulfide results in the complete sublimation of the crystals at a relatively high temperature (520 °C). The electron energy loss spectra of the crystals obtained were measured and analyzed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 845–848, May, 1995.This work was financially supported by the Russian Foundation for Basic Research (Projects No. 93-03-18002, 93-03-18705, and 93-03-5650).     

Photophysical properties of the extract of endometallofullerenes La@C2n inortho-dichlorobenzene. Picosecond laser photolysis

The kinetics of relaxation of optical anisotropy induced by polarized light in endometallofullerenes La@C_2n inortho-dichlorobenzene was studied by picosecond laser photolysis. Decay of the optical absorption signal due to the excited states of La@C_2n follows the biexponential law with two values of relaxation time:t ₁=35±3 ps andt ₂=1100±200 ps. The lifetimet or decay of the optical anisotropy is 19±5 ps and determined by the orientational diffusion of La@C_2n . The experimentally determined lifetime of optical anisotropy agrees satisfactorily with the value yielded by the theoretical model of orientational diffusion under slip boundary conditions at the interface of the La@C_2n molecule with the solvent. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya No. 10, pp. 1921–1923, October, 1999.