Deposition of amorphous hydrogenated semiconductors by magnetron assisted silane decomposition

Magnetron assisted silane decomposition (MASD) is proposed as a method for deposition of a-Si:H and its alloys. In this method a silane containing gas mixture is passed through the magnetron plasma near a target and decomposed there. The deposition rate in the case of the c-Si target is increased 3 times compared to magnetron sputtering and film properties are changed. a-SiSn:H is obtained with a Sn target.     

Reactions of Acylpyruvic Acids and 2,3-Dihydrofuran-2,3-diones with 2,3-Diaminopyridine

Acylpyruvic acids readily react with 2,3-diaminopyridine to form (Z)-3-acylmethylene-1H-3,4-di- hydropyrido[2,3-b]pyrazin-2-ones. 5-Aryl-2,3-dihydrofuran-2,3-diones which can be regarded as lactones derived from -enolized aroylpyruvic acids react with 2,3-diaminopyridine under mild conditions, yielding regioisomeric (Z)-2-aroylmethylene-4H-1,2-dihydropyrido[2,3-b]pyrazin-3-ones. The structure of the products and reaction chemoselectivity are discussed.     

Synthesis of Novel Lipophilic Polyamines via Ugi Reaction and Evaluation of Their Anticancer Activity

Natural polyamines (PAs) are involved in the processes of proliferation and differentiation of cancer cells. Lipophilic synthetic polyamines (LPAs) induce the cell death of various cancer cell lines. In the current paper, we have demonstrated a new method for synthesis of LPAs via the multicomponent Ugi reaction and subsequent reduction of amide groups by PhSiH₃. The anticancer activity of the obtained compounds was evaluated in the A-549, MCF7, and HCT116 cancer cell lines. For the first time, it was shown that the anticancer activity of LPAs with piperazine fragments is comparable with that of aliphatic LPAs. The presence of a diglyceride fragment in the structure of LPAs appears to be a key factor for the manifestation of high anticancer activity. The findings of the study strongly support further research in the field of LPAs and their derivatives.     

Dzhemilev reaction in the synthesis of five-membered sulfur and selenium heterocycles*

A one-pot methods were developed for the synthesis of five-membered sulfur and selenium heterocycles based on the consecutive cyclometallation of olefins, allenes, and acetylenes using alkyl and haloalkyl derivatives of Al and Mg in the presence of catalytic amounts of titanium and zirconium complexes to give the corresponding alumina- and magnesacarbocycles in situ, which, without further purification, were introduced into reaction with sulfur or selenium, leading to various tetrahydrothiophenes, thiophenes, tetrahydroselenophenes, and selenophenes. * Dedicated to Academician B. A. Trofimov of the Russian Academy of Sciences on the occasion of his seventieth jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 393–403, March, 2009.     

Luminescence of amorphous silicon nanoclusters

Films of amorphous silicon suboxide α-SiO _x containing amorphous silicon nanoclusters have been grown by direct current magnetron sputtering. It has been found that two radiation bands are observed in the photoluminescence spectra of relatively large amorphous nanoclusters (a size of ∼2 nm) unlike one photoluminescence band of silicon nanocrystals of the same size. The form of the spectra upon the change in the nanocluster sizes agrees with that predicted in theoretical works, in which the energy spectrum of amorphous nanoclusters has been calculated taking into account quantum confinement of delocalized, weakly localized, and strongly localized states.     

Field-effect transistor structures on the basis of poly(3-hexylthiophene), fullerene derivatives [60]PCBM, [70]PCBM,and nickel nanoparticles

Organic field-effect transistor (OFET) structures with the active layers on the basis of composite films of semiconductor polymer poly(3-hexylthiophene) (P3HT), fullerene derivatives [60]PCBM, [70]PCBM, and nickel (Ni) nanoparticles are obtained, and their optical, electrical, and photoelectrical properties are studied. It is shown that introducing Ni nanoparticles into P3HT: [60]PCBM and P3HT: [70]PCBM films leads to an increase in the absorption and to quenching of photoluminescence of the composite in the 400–600 nm spectral band due to the plasmon effect. In P3HT: [60]PCBM: Ni and P3HT: [70]PCBM: Ni OFET structures at the P3HT: [60]PCBM and P3HT: [70]PCBM concentrations of ~1: 1 and Ni concentrations of ~3–5 wt %, current–voltage (I–V) characteristics typical of ambipolar OFETs with the dominant hole conduction are observed. The charge-carrier (hole) mobilities calculated from the I–V characteristic at V_G =–10 V were found to be ~0.46 cm²/(V s) for P3HT: [60]PCBM: Ni and ~4.7 cm²/(V s) for P3HT: [70]PCBM: Ni, which means that the mobility increases if [60]PCBM in the composition is replaced with [70]PCBM. The effect of light on the I–V characteristics of P3HT: [60]PCBM: Ni and P3HT: [70]PCBM: Ni OFETs is studied.     

Thermal stability of proton-conducting silicophosphate materials formed by sol-gel method

Russian Journal of Electrochemistry - This work estimated ionic conductivity and studied thermal stability of proton-conducting xerogel materials and films formed from sol-gel system based on...