Synthesis of New Iminocoumarins Bearing Parabanic Moieties

The synthesis of novel substituted 3-p-nitro-phenyliminocoumarins and corresponding N-ureaiminocoumarins is described. The condensation of these materials with oxalyl chloride leads to the corresponding N-parabanic iminocoumarins, which have not previously been described, in moderate or good yields and high selectivity. The structures were characterized by Fourier transform infrared, ¹H and ¹³C NMR, and elemental analysis.

Synthesis and antibacterial evaluation of diaminomaleonitrile-based azo-Schiff bases and 8,9-dihydro-7H-purine-6-carboxamides

Research on Chemical Intermediates - Some new DAMN-based Schiff base 6a–6g were synthesized via a condensation reaction of the corresponding azo dyes with...     

All-optical logic AND-NOR gate with three inputs based on cross-gain modulation in a semiconductor optical amplifier

We report the realization of a novel all-optical logic AND-NOR gate based on cross-gain modulation (XGM). The used scheme requires only one SOA to perform the logic gate with three input signals. A 8.5 dB dynamic extinction ratio with a switching time of about 650 ps for the rise time and 100 ps for the fall time.     

LC–DAD/ESI–MS/MS characterization of phenolic constituents in Rosa canina L. and its protective effect in cells

In an aim to prove the efficiency of polyphenols of Rosa canina fruits in promoting human health. A methanolic extract of R. canina fruits was prepared by successive maceration with solvents of increasing polarity. The polyphenol composition was analyzed by HPLC–DAD–ESI–MS. The biological activity of this extract on SH-SY5Y cells and HepG2 cells was then studied. The antioxidant activity was tested by various in vitro tests such as DPPH-radical-scavenging activity, FRAP assay, hydroxyl radical scavenging assay and total antioxidant capacity. The subacute toxicity of R. canina was tested on female rats by repeated intraperitoneal administration of various doses. The phenolic profiles showed 25 antioxidants distributed into three classes of phenolic compounds: glycosylated and agglomerated flavonoids/isoflavonoids, tannins and phenanthrenes. Qualitative phytochemical analyses showed that this extract lacks alkaloids. The methanolic extract of R. canina fruits has a total antioxidant capacity of 82.69 ± 1.18 μg EAA/mg of methanol extract and the IC₅₀ of the methods used is in the following increasing order: FRAP assay (61.88 μg/ml), then hydroxyl radical scavenging assay (67.45 μg/ml) and then DPPH radical-scavenging activity (129.81 μg/ml). The extract of R. canina did not cause any phenotypic signs of toxicity or mortality during and after treatment. The LD₅₀ was >5,000 mg/kg, hence, R. canina was considered nontoxic. An in vivo study proved the protective effect of R. canina against cardiac and hepato-renal toxicities. These results drew the importance of a healthy diet, where diets rich in R. canina fruits can be used as a rich natural source of antioxidants and anticarcinogenic phenolic compounds.     

Effect of composition,thickness and temperature on non-linear I–V curves in vanadium phosphate glasses

Summary Glass layers of (V₂O₅)_1−x (P₂O₅) _x were prepared by melting appropriate mixtures of V₂O₅ and P₂O₅ powders. The measurements ofI–V characteristic curves show three regions of conduction, namely high-resistance state, turnover point with zero-differential resistance region (∂V/∂I=0) and differential negative-resistance region. The turnover point is strongly dependent on composition, sample thickness and temperature. It is found that the increase of the ratio of phosphorus/vanadium reduces conductance as well as it raises the field required to produce turnover behaviour. The data in the range up to the turnover point are discussed on the basis of an electrothermal process. Results of the negative-resistance state could be explained in terms of a hopping mechanism.     

利用原位红外光谱与微分电化学质谱联用技术研究在Pt以及PtRu电极上发生的甲醇氧化反应

利用电化学衰减全反射原位傅里叶变换红外光谱与微分电化学质谱联用技术,在流动电解池环境以及恒电位条件下研究了Pt电极和Pt电极通过表面电沉积Ru形成的PtRu电极(Pt_xRu_y)上发生的甲醇氧化反应(反应电解质溶液为0.1 mol/L HClO₄+0.5 mol/L MeOH). 在0.3～0.6 V(参比电极为可逆氢参比)实验用到的所有电极上,CO是唯一能从红外光谱观察到的与甲醇相关的表面吸附物;在Pt_0.56Ru_0.44电极上可以观察到CO吸附在Ru原子形成的岛上和CO线式吸附在Pt电极表面红外波段,而其他电极上只能观察到Pt表面上线式吸附的CO;甲醇氧化活性按Pt_0.73Ru_0.27>Pt_0.56Ru_0.44>Pt_0.83Ru_0.17>Pt的顺序递减;在0.5 V 时,甲醇在Pt_0.73Ru_0.27电极上的氧化反应的CO₂电流效率达到了50%.     

Gas‐phase pyrolytic reactions of esters of 2‐pyridine and 8‐quinoline sulfonic acid

The rates of gas‐phase thermal elimination reaction of esters of 2‐pyridine sulfonic acid and 8‐quinoline sulfonic acid have been measured over at least 50° for each compound. The relative rates of the first‐order unimolecular decomposition at 500 K for the primary:secondary esters suggest that C O bond breaking is kinetically more significant than C H bond breaking, leading to a transition state of carbocationic character. This is consistent with the electron‐donating effect provided by the methoxy substituent in 2‐p‐methoxyphenylethyl of 2‐pyridine and 8‐quinoline sulfonate esters stabilizing the carbocation center. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 771–775, 2000     

Synthesis and characterization of active ester-functionalized polypyrrole-silica nanoparticles: application to the covalent attachment of proteins

Novel ester-functionalized polypyrrole-silica nanocomposite particles were prepared by oxidative copolymerization of pyrrole and N-succinimidyl ester pyrrole (50/50% initial concentrations), using FeCl3 in the presence of ultrafine silica nanoparticles (20 nm diameter). The N-succinimidyl ester pyrrole monomer was prepared in aqueous solution using 1-(2-carboxyethylpyrrole) and N-hydroxysuccinimide in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. The resulting nanocomposites (N-succinimidyl ester polypyrrole-silica) are raspberry-shaped agglomerates of silica sol particles "glued" together by the insoluble poly(pyrrole-co-N-succinimidyl pyrrole). The N-succinimidyl ester polypyrrole-silica particles were characterized in terms of their size, density, copolymer content, and polydispersity. Scanning electron microscopy and disk centrifuge sedimentometry confirmed that the nanocomposite particles had narrow size distributions. X-ray photoelectron spectroscopy analysis indicated a silica-rich surface and a high surface concentration of N-succinimidyl ester groups. These nanoparticles exhibited good long-term dispersion stability. The chemical stability of the ester functions in aqueous media after several weeks of storage was monitored by FTIR spectroscopy. The functionalized nanocomposites were tested as bioadsorbents of human serum albumin (HSA). The very high amount of immobilized HSA determined by UV-visible spectroscopy is believed to be due to covalent binding. Incubation of the HSA-grafted nanocomposite with anti-HSA resulted in immediate flocculation, an indication that they are alternative candidates for visual diagnostic assays.     

Equilibrium Study of the Mixed Complexes of Copper(II) with Adenine and Amino Acids in Aqueous Solution

Solution equilibria of the systems Cu(II)-adenine (A)-amino acids (L) have been studied pH-metrically. The formation constants of the resulting mixed ligand complexes have been calculated at 25 °C and ionic strength 0.1 mol⋅dm⁻³ NaNO₃. Ternary complexes are formed by simultaneous reactions. The relative stability of each ternary complex was compared with that of the corresponding binary complexes in terms of Δlog ₁₀ K values. The concentration distribution of the complexes in solution was evaluated.     

Boron chelate complexes with 4-[N-(R-pyrid-2-yl)carbamoyl]-3-amino-2-cyanobuten-2-ic acid esters (codimers of N-(R-pyrid-2-yl)amides and the ethyl ester of cyanoacetic acid)

Mono- and binuclear boron chelates have been synthesized by the action of butylthiodibutylborane on the ethyl esters of 4-[N-(R-pyrid-2-yl)carbamoyl]-3-amino-2-cyanobuten-2-ic acids (codimers of N-(R-pyrid-2-yl) amides and the ethyl ester of cyanoacetic acid). Complexes of this type can exist in solution in the form of two tautomers: acetamide acid derivatives or the corresponding ketene N,O-acetals.N. D. Zelinski Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2162–2170, September, 1992.