Vitaliy A. Ioutsi

Mass spectrometric identification of multicage fullerene cycloadducts

Multicage fullerene cycloadducts have been detected by MALDI mass spectrometry; they have been found as admixtures in the products of reactions of the trifluoromethylation of fullerene samples doped with metallic sodium, the reaction between fullerenes and a mixture of trifluoromethylfullerenes, and the synthesis of fulleroproline esters. As a result, over 75 new compounds of this type have been identified. The optimization of the synthesis procedures and chromatographic fractionation allowed us to extract five compounds in the pure form: (C60)2(CF2)2(CF3)8, (C60)2(CF2)2(CF3)3C2F5, (C60)2(CF2)2(CF3)5C2F5, (C60)2(CF2)2(CF3)2O, and C60CH2N(CH2C60)CCOOtBu. Chemical structures of two of them, proposed on the basis of post source decay mass spectra, have been further confirmed by NMR spectra.

Pyrrolizidine and cyclobutane bridged double-caged fullerene derivatives

Novel types of double-caged [60]fullerene derivatives containing adjacent pyrrolizidine and cyclobutane bridges have been synthesized and characterized by MALDI MS, UV/VIS, 1H and 13C NMR spectroscopy, and cyclic voltammetry.

Fullerene as Photocatalyst: Visible-Light Induced Reaction of Perfluorinated α,ω-Diiodoalkanes with C60

Solution phase photochemical reaction of fullerene with perfluorinated alkyldiiodides I-RF-I can be efficiently initiated by visible range irradiation that targets solely the fullerene component. Photoinduced electron transfer from fullerene onto the diiodide component effects dissociative formation of alkyl radicals RFI• subsequently consumed by C60 to give the principal detectable radical intermediate C60RFI•. Experimentally established second-order kinetics with respect to the fullerene concentration evidence that fullerene plays its two roles of photocatalyst and reactant in a decoupled fashion, which suggests its catalytic ability to be of potential use in more complex photochemical systems. The main final product of the photochemical transformation observed is the singly linked dimer of the intermediates, I-RF-C60-C60-RF-I. Side reactions of C60RFI• with the environment lead to quenching of the unpaired electron density by ortho- or para- attachment of hydrogen or iodine. The outlined kinetic findings are discussed in detail.

Standard enthalpy of β-alanine formation

In an isoperibolic calorimeter with a stationary bomb, the value of the combustion energy of crystalline β-alanine (ΔcU0) was determined at 298.15 K, from which standard enthalpies of combustion (ΔcU0) and formation (ΔcU0) have been calculated. The obtained results are compared with literature data.

Standard enthalpy of formation of fullerene bromide C60Br24

The enthalpy of the combustion of C60Br24 · 2Br2 has been measured using a rotating-bomb calorimeter as follows: ΔcH0(C60Br24 · 2Br2, cr) = (−25986 ± 166) kJ/mol. The result has been used to calculate the standard enthalpy of formation, ΔfH0(C60Br24 · 2Br2, cr) = (2375 ± 166) kJ/mol. The enthalpies of formation of C60Br24 (cr) and dissociation of the C-Br bond have been estimated. The latter value has been compared with enthalpies for the C-X (X = H, F, Cl, Br) bonds in fullerene derivatives and organic compounds.

Evaporation Study of an Ionic Liquid with a Double-Charged Cation

The evaporation of a dicationic ionic liquid, 1,3-bis(3-methylimidazolium-1-yl)propane bis(trifluoromethanesulfonyl)amide ([C3(MIm)22+][Tf2N-]2), was studied by Knudsen effusion mass spectrometry. Its evaporation is accompanied by a partial thermal decomposition producing monocationic ionic liquids, 1,3-dimethylimidazolium and 1-(2-propenyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)amides, as volatile products. This decomposition does not affect the vaporization characteristics of [C3(MIm)22+][Tf2N-]2, which were established to be as follows. The vaporization enthalpy (550 K) is equal to (155.5 ± 3.2) kJ·mol-1; the saturated vapor pressure is described by the equation ln( p/Pa) = -(18699 ± 381)/( T/K) + (30.21 ± 0.82) in the range of 508-583 K. 1,3-Bis(3-methylimidazolium-1-yl)propane bis(trifluoromethanesulfonyl)amide is the first dicationic ionic liquid, the vaporization characteristics of which were determined with an acceptable accuracy.

Tightly bound double‐caged [60]fullerene derivatives with enhanced solubility: structural features and application in solar cells

A series of novel highly soluble double-caged [60]fullerene derivatives were prepared by means of lithium-salt-assisted [2+3] cycloaddition. The bispheric molecules feature rigid linking of the fullerene spheres through a four-membered cycle and a pyrrolizidine bridge with an ester function CO2 R (R=n-decyl, n-octadecyl, benzyl, and n-butyl; compounds 1 a-d, respectively), as demonstrated by NMR spectroscopy and X-ray diffraction. Cyclic voltammetry studies revealed three closely overlapping pairs of reversible peaks owing to consecutive one-electron reductions of fullerene cages, as well as an irreversible oxidation peak attributed to abstraction of an electron from the nitrogen lone-electron pair. Owing to charge delocalization over both carbon cages, compounds 1 a-d are characterized by upshifted energies of frontier molecular orbitals, a narrowed bandgap, and reduced electron-transfer reorganization energy relative to pristine C60 . Neat thin films of the n-decyl compound 1 a demonstrated electron mobility of (1.3±0.4)×10-3  cm2  V-1  s-1 , which was comparable to phenyl-C61 -butyric acid methyl ester (PCBM) and thus potentially advantageous for organic solar cells (OSC). Application of 1 in OSC allowed a twofold increase in the power conversion efficiencies of as-cast poly(3-hexylthiophene-2,5-diyl) (P3HT)/1 devices relative to the as-cast P3HT/PCBM ones. This is attributed to the good solubility of 1 and their enhanced charge-transport properties - both intramolecular, owing to tightly linked fullerene cages, and intermolecular, owing to the large number of close contacts between the neighboring double-caged molecules. Test P3HT/1 OSCs demonstrated power-conversion efficiencies up to 2.6 % (1 a). Surprisingly low optimal content of double-caged fullerene acceptor 1 in the photoactive layer (≈30 wt %) favored better light harvesting and carrier transport owing to the greater content of P3HT and its higher degree of crystallinity.