Biomedical subjects

Vladislava Tkacheva

Publications and source records attributed to Vladislava Tkacheva.

3 recordsLinked to original sources

PubMed2006

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.

Crystallization↗

PubMed2005

Harnessing ICl reduction processes for synthesis of different BEDT-TTF-based molecular conductors.

Both calculations and experimental data, showing the possibility of formation of I3-, I2Cl-, and ICl2- anions through ICl reduction processes, are described in detail. The above processes were used successfully for the preparation of different molecular conductors based on trihalide anions and bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF). The reaction between ICl and BEDT-TTF occurring in a strong polar reaction media (epsilon > or = 34.8 D) results in the formation of novel molecular conductors containing different sets of the I3-, I2Cl-, and ICl2- anions: beta-(BEDT-TTF)2[(I3)0.4(I2Cl)0.6], beta'BEDT-TTF)2[(I2Cl)0.2(ICl2)0.8], and beta' '-('-(BEDT-TTF)2[(I3)0.075(I2Cl)0.150(ICl2). These molecular conductors reveal semiconducting (beta'-phase) as well as metallic (beta- and beta' '-phases) transport properties. It is also shown that in the reaction media with polarity less than 18.4 D only the I3- anion is incorporated in the BEDT-TTF-based molecular crystals. This fact is an unexpected outcome of our study.

Journal Article↗

PubMed2003

Multistability in a BEDT-TTF based molecular conductor.

The low dimensional organic conductor (BEDT-TTF)(2)Br(1.3)I(1.1)Cl(0.6) [BEDT-TTF = bis(ethylenedithio)tertathiafulvalene] is shown to be a unique molecular solid that exists in three crystalline polymorphic forms (alpha'-, alpha' "-, beta' '-phase) and, surprisingly, is able to adopt the same metal-like beta' '-phase at both low (T < 185 K) and high (T > 395 K) temperatures. Several crystals of the alpha'- and alpha' "-phases have been studied using three different techniques: dc-conductivity measurements, ESR spectroscopy, and X-ray diffraction analysis. All these techniques show the existence of the reversible semiconductor <--> metal (alpha' " <--> beta' ') phase transition at both high and low temperatures as well as the alpha' <--> alpha' " phase transition at high temperatures. The phase transitions of these polymorphs are characterized by huge hysteresis and dramatic changes in the transport and magnetic properties. Based on ab initio calculations, it is suggested that dipole-dipole interactions can play a key role in the rich polymorphism of this molecular solid.

Journal Article↗