G. G. Abashev

New carbazole-containing chalcones and pyrimidines based thereon: Synthesis and electrochemical study

Condensations of aromatic carbo- and heterocyclic ketones and aldehydes in methanol gave new chalcones containing carbazole fragments, 1,3-diaryl(9-R-9H-carbazol-3-yl)prop-2-en-1-ones. Some of the synthesized chalcones reacted with guanidine sulfate to produce 2-amino-4,6-diarylpyrimidines that are promising materials for the design of light emitting diodes. Study on electrochemical polymerization of both chalcones and pyrimidines derived therefrom showed that almost all the examined substrates give rise to stable colored conjugated polymer films on the surface of working electrode under conditions of cyclic voltammetry.

Novel thiophene-containing push-pull chromophores that include carbazole and triphenylamine moieties: study of optical and electrochemical properties

Novel carbazole- and triphenylamine-containing alkylidene malononitriles that include thiophene and bithienyl fragments as π-spacers were synthesized. Quantum-chemical calculations of the frontier molecular orbital energies were performed using the B3LYP/6-31G(d) method with regard to solvent. Electronic absorption spectra and fluorescence spectra were recorded for all the obtained compounds; their electrochemical properties were also studied. The experimental energy values of HOMO and LUMO levels were derived from resulting data. Thin films were obtained by the spin coating technique, and their surface morphology was studied using a NTEGRA Prima scanning tunneling microscope.

New thiophene- and phenothiazine-containing chalcones: Synthesis, and electrochemical properties

Among the conjugated systems used in design of electronic devices based on organic materials the derivatives of carbazole and phenothiazine occupy are of key importance due to their high thermal stability, hole conductivity and light emission in various spectral regions when used in OLEDs and electrochromic devices, and to hole conductivity [1–4]. Phenothiazine contains electron-rich atoms N and S atoms, possesses a low oxidation potential, and is capable to form stable cation-radicals. The unique electronic and optical characteristics of phenothiazine proceed from its nonplanar geometry providing thereby the possibility to obtain π-packed aggregates and intermolecular excimers [5]. It has been established in our previous research that chalcones prepared on the base of carbazole, phenothiazine, and their substituted derivatives appeared to be good for creation of electrochromic polymer films [6–8]. It is also known that chalcones containing various aromatic fragments in their structure possess nonlinear optical properties indispensable for creation of optoelectronic devices, like electro-optic modulators, optical switches, lightemitting sources, etc. [9, 10]. Therefore it is expedient to synthesize new chalcone series including in their structure various carboand heterocyclic fragments and to examine their physicochemical properties, first, from the viewpoint of using them for preparation of polymer compounds, and second from the standpoint of tuning their electronic and optical characteristics by modifying the chemical structure.

Ferrocenes conjugated with thiophene, carbazole, and pyrimidine fragments: Synthesis and properties

Ferrocenyl-containing chalcones containing π-excessive heterocyclic fragments capable of electrochemical polymerization (carbazole, thiophene, 2,4-ethylenedioxythiophene) were prepared by the Claisen-Schmidt reaction. 2,4,6-Trisubstituted pyrimidines derived from them were synthesized.

Bis(1,3-dithiole-2-chalcogenones) and tetrathiafulvalenes in the synthesis of bridged tetrathiafulvalene-containing structures

Bis(1,3-dithiole-2-chalcogenones) in which the 1,3-dithiole fragments are linked through various bridging groups were synthesized by different methods. Some of these compounds were converted into substituted tetrathiafulvalenes with bridged 1,3-dithiole rings. The same structures were synthesized from preliminarily prepared symmetric tetrathiafulvalenes containing 2-cyanoethylsulfanyl groups in both 1,3-dithiole rings. Similar spacers were used to bridge two tetrathiafulvalene fragments. Syntheses of the involved initial compounds were described.

Preparation and properties of poly[9-hexadecyl-3-phenyl-6-(4-vinylphenyl)-9H-carbazole]

Preparation of new carbazole-containing polymer, poly[9-hexadecyl-3-phenyl-6-(4-vinylphenyl)-9H-carbazole], is reported. The optical properties of the product have been studied in comparison with those of the starting compounds. Electrochemical properties of the polymer solution and its thin film have been investigated. The polymer film images were obtained by atomic force and scanning tunneling microscopy. Thermogravimetric analysis has shown high thermal stability of the obtained polymer.

New conjugated monomers and oligomers derived from chalcones and containing thiophene, pyrrole, and pyrimidine fragments

Abstract4New hybrid systems based on a series of chalcones and containing pyrimidine, thiophene, and pyrrole fragments were synthesized, and their electrochemical properties were studied.

New nitrogen heterocycles containing a ferrocene fragment: Optical and physicochemical properties

New thermally stable 2,4,6-trisubstituted pyrimidines containing aromatic (ferrocene and para-substituted benzene) fragments at the C4 and C6 positions and an amino group or pyrrole ring at the C2 positions of the pyrimidine ring have been synthesized, and their optical and electrochemical properties have been studied. The redox potentials of the ferrocene fragments therein have been determined by cyclic voltammetry.

Synthesis and study of 2-alkoxy(2-alkylsulfanyl)-4,6-distyrylpyrimidines containing a terminal carbazole group

We report the synthesis of new 4,6-distyrylpyrimidines containing an unsubstituted carbazole ring linked with the pyrimidine moiety by a flexible aliphatic seven-membered –O(CH2)6– or –S(CH2)6– bridge. The electrochemical and spectral properties of the synthesized compounds were studied; optical band gaps were calculated from the relevant UV absorption onsets and were found to be equal to 2.55 and 2.54 eV, respectively. A thin film based on the derivative with sulfur-containing bridge (–S(CH2)6–) was deposited on a conductive material and demonstrated to have a smooth surface and hole conductivity.

New tetrathiafulvalenes containing a 2,5-bis(thiophen-2-yl)pyrrole fragment: Synthesis, optical properties, and electrochemical behavior

The reaction of 1-(3-bromopropyl)-2,5-bis(thiophen-2-yl)-1H-pyrrole with cesium 5-methylsulfanyl-2-thioxo-1,3-dithiole-4-thiolate generated in situ gave previously unknown 4-{3-[2,5-bis(thiophen-2-yl)-1H-pyrrol-1-yl]propylsulfanyl}-5-methylsulfanyl-1,3-dithiole-2-thione, and cross-coupling of the latter with 4,5-disubstituted 1,3-dithiole-2-thiones in the presence of triethyl phosphite afforded new substituted tetrathiafulvalenes containing a 2,5-bis(thiophen-2-yl)pyrrole fragment. Optical properties and electrochemical behavior of the synthesized compounds were studied, and their ability to undergo electropolymerization was confirmed.