Quasi one-dimensional electroconducting compounds from dibenzote trathiafulvalene and metal halides

Conclusions The coordination compounds of some metal halides with dibenzotetrathiafulvalene were obtained, which have high conductivity values.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 940–942, April, 1978.     

Tetrathiafulvalene-based organic conductors with Pb-containing anions

Hybrid compounds containing organic layers composed of tetrathiafulvalenes (BEDT-TTF, BETS, BEDO-TTF) and inorganic layers consisting of anions based on lead bromide were synthesized. The crystal structure of (BEDT-TTF)₆Pb₃Br₁₀(PhBr) was determined. The temperature dependences of electrical conductivity for the synthesized compounds were measured and the EPR spectra of these compounds were recorded. In the structure of (BEDT-TTF)₆Pb₃Br₁₀(PhBr), the organic conducting layers of BEDT-TTF molecules alternate with non-conducting layers composed of infinite chains of bromoplumbate anions [Pb₃Br₉]^3–, solvent molecules, and Br^– anions. The newly synthesized BEDT-TTF bromoplumbates have similar linewidths of EPR signals, which indicate that their conducting layers have similar structures. The BEDT-TTF bromoplumbates are semiconductors, while temperature-dependent electrical resistivity measurements show the metallic behavior for BEDO-TTF and BETS bromoplumbates.     

Chlorofullerene C60Cl6: a precursor for straightforward preparation of highly water-soluble polycarboxylic fullerene derivatives active against HIV

We report for the first time the application of chlorofullerene C60Cl6 as a substrate for straightforward preparation of highly water-soluble fullerene derivatives, promising compounds for investigation of the biological action of fullerenes in vitro and in vivo. Methyl esters of phenylacetic and benzylmalonic acids were used as reagents in the Friedel-Crafts arylation of C60Cl6 that resulted in the corresponding C60(Ar)5Cl compounds with 50-60% yields. The following cleavage of ester groups in phenylacetic and benzylmalonic residues was accomplished almost quantitatively to yield the corresponding fullerene-based acids bearing 5 and 10 carboxylic groups, respectively. The relatively-low solubility of these acids in water can be strongly enhanced (up to 150-200 mg ml(-1)) by their conversion to salts with alkali metal cations. These fullerene salt derivatives showed pronounced anti-HIV action and low toxicity; these two findings point to the necessity for further investigation of the biological properties of the here-reported compounds.     

Electronic and electron-phonon phenomena in low-dimensional BEDT-TTF-based organic conductors and superconductors

Two related groups of k-phase ion-radical salts (BEDT-TTF) with different electrical properties, namely, superconductors with different transition temperatures and conductors, which transfer to insulating state with decreasing temperature, have been studied by micro-optic spectroscopy. Polarized reflectance spectra of microcrystals have been measured for the three principal crystallographic directions within the 700–40000 cm⁻¹ region, and the corresponding spectra of the optical functions obtained. The anisotropy of the electronic system in the crystals has been established as two-dimensional. The spectra obtained were quantitatively analyzed, the key parameters of the electronic structure and the vibronic coupling constants determined. It is concluded that the conductors have smaller vibronic coupling constants, more narrow allowed electronic bands, and stronger electron-electron interaction compared to those of the superconductors, and that vibronic coupling is the necessary condition for the onset of superconductivity in the superconductors studied. Fiz. Tverd. Tela (St. Petersburg) 41, 897–899 (May 1999)     

Donor–acceptor interaction of fullerene C60 with triptycene in molecular complex TPC·C60

A molecular complex of fullerene C₆₀ with triptycene, TPC·C₆₀ is obtained. The complex has a three-dimensional packing of C₆₀ molecules. According to the IR spectra, the freezing of free rotation of C₆₀ molecules in the complex is maintained up to 360 K. The XP-spectra of TPC·C₆₀ show the suppression of π–π^* transitions of TPC phenylene rings. The separation of C₆₀ molecules by TPC ones in TPC·C₆₀ results in low intensity of the C₆₀ transitions in the 420–500 nm range in an optical spectrum. This absorption is assumed as that attributed to intermolecular transitions between adjacent C₆₀ molecules.     

Effect of Pressure on the Interlayer Charge Transport and the Electronic Structure of the Metallic Layers in the Organic Two-Dimensional Bilayer Metal (BETS)4CoBr4(DCB)

Journal of Experimental and Theoretical Physics - The resistance and magnetoresistance of the organic (BETS)4CoBr4(DCB) metal are studied at atmospheric pressure and a hydrostatic pressure of up to...