Publications by authors named "Ekaterina A Knyazeva"

Two novel D-A-π-A1 metal-free organic dyes of the series containing benzo[][1,2,3]thiadiazole (isoBT) internal acceptor, indoline donors fused with cyclopentane or cyclohexane rings (D), a thiophene as a π-spacer, and a cyanoacrylate as an anchor part were synthesized. Monoarylation of 4,7-dibromobenzo[][1,2,3]thiadiazole by Suzuki-Miyamura cross-coupling reaction showed that in the case of indoline and carbazole donors, the reaction was non-selective, i.e.

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This paper presents an improved synthesis of 4,7-dibromobenzo[][1,2,3]thiadiazole from commercially available reagents. According to quantum-mechanical calculations, benzo[][1,2,3]thiadiazole (isoBTD) has higher values of E and energy band gap (E), which indicates high electron conductivity, occurring due to the high stability of the molecule in the excited state. We studied the cross-coupling reactions of this dibromide and found that the highest yields of π-spacer-acceptor-π-spacer type compounds were obtained by means of the Stille reaction.

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The possibility of using a single light-emitting layer consisting of newly synthesized fluorescent small organic molecules of D-A-π-A type incorporated into a conductive matrix together with an electron conductive Alq layer in order to form radiation in candle light-style OLEDs was shown for the first time. A record low color temperature of 1722 K OLED radiation was achieved, which is by 80 K lower than that of the best devices reported previously.

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The objective of this study is to investigate the association between methylation levels of and promoters, clinical parameters, and implantation outcomes after fertilization-embryo transfer (IVT-ET) cycles in women with repeated implantation failures and tubal infertility. Endometrium samples were collected from 34 women during implantation window before IVF-ET cycle to assess methylation status of and promoters using bisulfite sequencing. All participants had a tubal factor of infertility and at least two implantation failures in the anamnesis.

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Four new D-A-π-A metal-free organic sensitizers for dye-sensitized solar cells (DSSCs), with [1,2,5]thiadiazolo[3 ,4-]pyridazine as internal acceptor, thiophene unit as π-spacer and cyanoacrylate as anchoring electron acceptor, have been synthesized. The donor moiety was introduced into [1,2,5]thiadiazolo[3,4-]pyridazine by nucleophilic aromatic substitution and Suzuki cross-coupling reactions, allowing design of D-A-π-A sensitizers with the donor attached to the internal heterocyclic acceptor not only by the carbon atom, as it is in a majority of DSSCs, but by the nitrogen atom also. Although low values of power conversion efficiency (PCE) were found, a few important consequences were identified: (i) poor PCE data can be attributed to high electron deficiency of the internal [1,2,5]thiadiazolo[3,4-]pyridazine acceptor due to lower light harvesting by the dye; (ii) the manner in which the donor was attached to the internal acceptor (by carbon or nitrogen) did not play an essential role in the photovoltaic properties of the dyes; (iii) dyes based on the novel donor 2,3,4,4a,9,9a-hexahydro-1-1,4-methanocarbazolyl and 9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H- carbazole moieties showed similar photovoltaic properties to dyes based on the well-known 4-(p-tolyl)-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indolyl building block, which opens the door for further optimization potential of new dye families.

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A safe and efficient synthesis of 4,7-dibromo[1,2,5]thiadiazolo[3,4-]pyridazine from the commercial diaminomaleonitrile is reported. Conditions for selective aromatic nucleophilic substitution of one or two bromine atoms by oxygen and nitrogen nucleophiles are found, whereas thiols formed the bis-derivatives only. Buchwald-Hartwig or Ullmann techniques are successful for incorporation of a weak nitrogen base, such as carbazole, into the [1,2,5]thiadiazolo[3,4-]pyridazine core.

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A short synthetic approach to fused 1,2,5-thiadiazoles from the corresponding 1,2,5-oxadiazoles and 1,2,5-selenadiazoles has been developed. Mono- and bis(1,2,5-thiadiazoles) were selectively obtained in high yields. The pathways for these novel reactions were discussed.

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