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131.
Abstract

The 1-hydroxyethylidene-1,1-bisphosphonic acid (HEDP) (I) reacts with epichlorohydrine (II) and aminoepoxypropanes (III) in water. Optimum pH for the esterefication is 6–7. The reaction completes in 20–30 h on 60°C at this pH and leads to the mixture of the original HEDP with the mono- and diesters. The mixture of di-Na salts of HEDP and the monochloroester (IV) in ratio 1:1.7 was precipitated from the reaction solution on using of the epichlorohydrine (II). This mixture was used for synthesis of aminoesters (VI a,b) unavailable by direct reaction of HEDP with corresponding aminoepoxides.  相似文献   
132.
We prove new lower bounds on the rate of codes for noisy multiple access adder channel and discuss its application to the well-known coin weighing problem in the case when some measurements are incorrect.  相似文献   
133.
Novel 4-arylcoumarin derivatives were obtained. They are water-soluble analogs of the well-known anticancer drug combretastatin A-4. The key step of the synthesis involves the Suzuki-Miyaura cross-coupling. The water-soluble salts obtained exhibit considerable cytotoxic activity against the HBL-100 and HaCaT cell lines.  相似文献   
134.
A new 5,10,15,20-tetrasubstituted porphyrin containing four 6-nitro-1,3,3-trimethylspiro(indolino-2,2-2H-chromene) substituents and its complexes with Zn2+ and Cu2+ ions were prepared and characterized by physicochemical methods of analysis.  相似文献   
135.
Reversibly switching the light absorption of organic molecules by redox processes is of interest for applications in sensors, light harvesting, smart materials, and medical diagnostics. This work presents a symmetrical benzothiadiazole (BTD) derivative with a high fluorescence quantum yield in solution and in the crystalline state and shows by spectroelectrochemical analysis that reversible switching of UV absorption in the neutral state, to broadband Vis/NIR absorption in the 1st oxidized state, to sharp band Vis absorption in the 2nd oxidized state, is possible. For the one-electron oxidized species, formation of a delocalized radical is confirmed by electron paramagnetic resonance spectroelectrochemistry. Furthermore, our results reveal an increasing quinoidal distortion upon the 1st and 2nd oxidation, which can be used as the leitmotif for the development of BTD based redox switches.  相似文献   
136.
Chemistry of Heterocyclic Compounds - Several previously unknown derivatives of 3,4-bis(indol-1-yl)maleimide, as well as 3-(2,3-dihydroindol-1-yl)-4-(indol-1-yl)maleimide were synthesized as...  相似文献   
137.
Polycyclic aromatic azomethine ylides (PAMYs) are powerful building blocks in the bottom-up synthesis of internally nitrogen-containing polycyclic aromatic hydrocarbons (N-PAHs) through 1,3-cycloaddition reactions. In this work, the cycloaddition reaction of PAMYs to asymmetric ortho-quinones is presented, which, in contrast to the addition to symmetric para-quinones, facilitates subsequent condensation reactions and allows the synthesis of three helical N-PAHs with ullazine-quinoxaline ( UQ - 1 – 3 ) backbones. UQ - 1 and UQ - 2 possess two helical centers; however, single-crystal X-ray analysis together with the computational modeling of UQ - 3 elucidate the formation of only the thermodynamically most stable geometry with four helical centers in a (P,P,M,M) configuration. For the series UQ - 1 – 3 , the number of redox steps is directly correlated with the number of ullazine or quinoxaline units incorporated into the targeted molecular backbones. A detailed investigation of the spectroscopic and magnetic properties of the radical cation and anion as well as the dication and dianion species by in situ EPR/UV/Vis-NIR spectroelectrochemistry is provided. The excellent optical and redox properties combined with helical geometries render them possibly applicable as chiral emitter or ambipolar charge transport material in organic electronics.  相似文献   
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140.
JETP Letters - The influence of antiadiabatic phonons on the superconducting transition temperature is considered within Eliashberg-McMillan approach in the model of discrete set of (optical)...  相似文献   
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