Synthesis and anti-influenza activity of 2-cyanoethoxy and 2-(1<Emphasis Type="Italic">H</Emphasis>-tetrazol-5-yl)ethoxy derivatives of dammarane-type triterpenoids

A series of 3-(2-1Н-tetrazol-5-ylethoxy- and 2-1Н-tetrazol-5-ylethoxyimino) derivatives of dammarane triterpenoids was synthesized by azidation of 3-(2-cyanoethoxy- and 2-cyanoethoxyimino)-dammaranes. The anti-influenza activity of the prepared tetrazolyldammaranes and intermediate compounds against influenza virus А H1N1 was tested. A considerable antiviral activity was observed for 20(S)-3-(2-1Н-tetrazol-5-ylethoxyimino)-25,26,27-trinor-20,24-olidedammarane (SI 26).     

Structure of (BEDT-TTF)-Based Organic Metals with Photochromic Nitroprusside Anion (BEDT-TTF)4M[FeNO(CN)5]2, where M = Na+, K+, NH+4, Tl+, Rb+, and Cs+

The crystal and molecular structures of a family of three-component radical cation salts bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF), (BEDT-TTF)₄M[NP]₂, where M = Na⁺, K⁺, NH⁺ ₄, Tl⁺, Rb⁺, and Cs⁺and NP is the nitroprusside anion [FeNO(CN)₅]^2–, are studied by X-ray structure analysis. These salts are isostructural and behave as stable metals down to helium temperatures. Their structures are characterized by radical cation layers of the "-type alternating with layers of complex anions [M⁺(NP^2–)₂]^3–. The conducting radical cation system and photochromic nitroprusside anion in the crystals were shown to affect each other. On the one hand, this changes the geometric parameters of the nitroprusside anion as compared to those of the Na₂[NP] · 2H₂O crystals in the ground state and, on the other hand, makes the geometries of the two crystallographically independent BEDT-TTF molecules with a different number of shortened contacts with the anion different. Based on the data of crystallochemical analysis of the (BEDT-TTF)₄M[FeNO(CN)₅]₂structures, we suggest their possible routes of chemical modification with the purpose of changing their physical properties.     

A general synthetic strategy for the design of new BODIPY fluorophores based on pyrroles with polycondensed aromatic and metallocene substituents

BODIPYrrole: A general strategy for the design of novel BODIPY fluorophores based on pyrroles with polycondensed aromatic and metallocene substituents has been developed. The strategy involves the acylation of the condensed substituent and treatment of the acylated derivative (as oxime) with acetylene in MOH/DMSO (M = alkali metal) to give pyrroles that were then used for assembly of the BODIPY fluorophores (see scheme).     

Synthesis and Optical Properties of 2‐(Benzo[b]thiophene‐3‐yl)pyrroles and a New BODIPY Fluorophore (BODIPY=4,4‐Difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene)

The light fantastic : Two new 2‐(benzo[b]thiophene‐3‐yl)pyrroles have been synthesized, and are shown to exhibit optical properties that are promising for optoelectronic materials and devices such as highly efficient fluorescent sensors (see scheme). In addition a new BODIPY fluorophore, derived from 2‐(benzo[b]thiophene‐3‐yl)pyrrole, was also isolated and shows good spectroscopic properties in solution which are fully preserved in the solid state.

     

Structural phase transition in crystals of the molecular conductor α′-(BDH-TTP)<Subscript>6</Subscript>[Hg(SCN)<Subscript>3</Subscript>][Hg(SCN)<Subscript>4</Subscript>]

Single crystals of the organic conductor α′-(BDH-TTP)₆[Hg(SCN)₃][Hg(SCN)₄] are studied by low-temperature X-ray diffraction at 100–300 K. It is shown that, in the temperature range 250–200 K, the compound undergoes a phase transition, which is accompanied by the appearance of superstructure reflections and a rapid increase in their intensity due to the partial anion and cation ordering. The superstructure is observed down to a temperature of 100 K, at which the set of diffraction data is collected. The temperature dependence of the electrical resistance exhibits a minimum in the range of the structural transition temperature. Under a pressure of up to 10 kbar, the general behavior of the dependence remains unchanged and only the minimum is shifted toward the low-temperature range. The phase transition is completely reversible.     

On the problems of the application of atomic-force microscopes for studying the surface roughness of elements for imaging optics

The key problems of applying atomic-force microscopes when studying the surface roughness of elements for imaging optics are discussed. Special attention is paid to optics of ultrahigh spatial resolution with an operating wavelength of no shorter than 100 nm. It is proposed that a specialized microscope for optical applications equipped with a tetraaxial goniometer be developed.     

Applying reactive ionic-beam etching to correcting the shape of X-ray mirrors

A procedure for correcting the shape of cylindrical surfaces by means of reactive ionic-beam etching is presented. The results from an experiment on manufacturing a glass surface as an elliptical cylinder are shown.     

Concerning the first-order phase transition in the low-dimensional organic superconductor (BEDO—TTF)2ReO4 · H2O. Crystal and electronic band structures below the phase transition (T = 170 K)

The effect of the first-order phase transition occurring around 220 K on the crystal and electronic structure of the molecular superconductor (BEDO-TTF) has been studied. The crystal structure at 170 K has been determined and it is found that the main structural change resulting from the phase transition is connected with a rotation of the anions. This rotation leads to changes in the SS and SO intermolecular contacts within the BEDO-TTF donor layers. How these structural changes affect the electronic structure of the salt is studied by comparing the transfer integrals for the different donordonor intermolecular interactions calculated for the room temperature and 170 K crystal structures. It is shown that Fermi surfaces for the 170 K and room temperature structures are very similar, do not exhibit nesting properties, and can be described as resulting from the hybridization of superposing ellipses. Received: 4 September 1997 / Received in final form: 2 December 1997 / Accepted: 3 December 1997     

Effect of mechanical treatment on the aggregative stability of latex and on consumption of coagulants in rubber recovery

The effect that mechanical treatment of SKS-30 ARK latex by mixing in a gap between coaxial cylinders exerts on the latex resistance to an electrolyte and on the polymer yield in coagulation with two types of coagulants, sodium chloride and N,N-dimethylaminopropyl carboxy betaines derived from vegetable oil fatty acids, was studied. Such treatment decreases the rapid coagulation threshold and increases the coagulum yield. The effect is caused by partial breakdown of hydrate shells of particles as a result of mechanical action in a shear stress field.