Competition of Different Addition and Cycloaddition Processes During Reaction of Phosphorus(II) and (III) Halides with Alkynes

Abstract

Addition of P-halogenophosphaalkenes to I-alkoxyalkynes provides either 2-phosphabutadienes 2 or P(II1)-substituted allenes 3. The reaction o f P-halogenophosphaalkenes I with I-aminoalkynes leads to the phosphetines 4 wa 5 - the product of 1,2-addition reaction.     

Polymer ultrathin films with immobilized photosynthetic reaction center proteins

Properties of mixed monolayers of lipid-photosynthetic reaction center proteins (RC) were studied and the optimum conditions for stable films fabrication were determined. The following synthetic: N-acryloylphosphatidylethanolamine (ACPE), tetracosa-11, 13-diinoic acid (TDA), pentacosa-10, 12-diinoic acid (PDA), dioctadecyldienoylphosphatidylcholine (DODL) and natural lipids: L-α-phosphatidylethanolamine (PE), L-α-phosphatidylcholine (PC) were used. The rate of polymerization of the mixed ACPE-RC and TDA-RC monolayers is lower in comparison with corresponding values for pure lipid-like monomers on air/water interface. The optical and photoelectrical measurements provide evidence for an orientation of RCs on interface. Hydrophilic H-subunit in monomeric and polymeric ACPE-RCs, and monomeric DODL-RCs monolayers is preferentially oriented towards water as in the pure RC monolayers. Opposite orientation was found with TDA-RCs and PDA-RCs films. No preferential orientation for lipid-RCs from C. aurantiacus monolayers was found because of the RCs having low assymmetry of hydrophobic subunits (M and L).     

Anomalous thermopower in the metalliclike phase of a 2D hole system

We report very low temperature ( T) thermopower and resistivity ( rho) measurements on variable-density, two-dimensional hole systems confined to GaAs quantum wells. As the hole density is lowered from 1.49x10(11) cm(-2) to 0.14x10(11) cm(-2), the system crosses from an insulating ( drho / dT less, similar0) to a metallic regime ( drho / dT>0) and finally displays insulating behavior ( drho / dT<0). Diffusion thermopower shows a striking sign reversal in a narrow range of density in the metallic regime, suggesting a qualitative change in the conduction or the scattering mechanism.     

Synthesis of nitrogen- and oxygen-containing macrocycles by palladium-catalyzed amination of 3,24-bis(6-chloropyridin-2-yloxy)cholane

3,24-Bis(6-chloropyrdin-2-yloxy)cholane prepared from cholane-3,24-diol by the Mitsunobu reaction was successfully used to synthesize various polyaza macrocycles via palladium-catalyzed amination with linear polyamines. The contribution of side formation of cyclic oligomers was found to depend on the polyamine nature.     

Successive substitution of halogen atoms in 4, 6-dihaloquinolines in palladium-catalyzed reactions with amines and arylboronic acids

A procedure was developed for the synthesis of 4,6-diamino- and 4,6- or 6,4-arylaminoquinolines by palladium-catalyzed C-N- and/or C-C-cross-coupling of 6-bromo-4-chloroquinoline.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 210–214, January, 2005.     

A monopole mass filter with a hyperbolic V-shaped electrode

In this article we compare the classical monopole mass filter of von Zahn and the monopole mass filter with a hyperbolic V-shaped electrode. The experimental results and those of computer simulation for both mass spectrometers are presented. We show that the replacement of a conventional 90 degrees V-shaped electrode by an electrode with a hyperbolic profile substantially improves the peak shape of any given mass, and increases the mass resolution by a factor of 3-4 and the abundance sensitivity by a factor of 100. The potential of high analytical performance combined with electroforming techniques for electrode manufacture indicate future practical uses of such instruments. Copyright 1999 John Wiley & Sons, Ltd.     

Palladium-catalyzed amination in the synthesis and modification of acyclic oxadiamino cholane derivatives

Palladium-catalyzed reactions of 24-(haloaryloxy)cholanes and 3,24-bis(haloaryloxy)cholanes with excess oxadiamines gave the corresponding mono- and bis(oxadiamino)-substituted cholanes which were subjected to palladium-catalyzed arylation with 1,3-dibromobenzene, 2,6-dibromopyridine, 1,8-dichloroanthracene, 9-bromoanthracene, 1-chloroanthracene, and 1-chloroanthraquinone. The results of these reactions were found to strongly depend on the haloarene nature. The arylation with 1,3-dibromobenzene and 2,6-dibromopyridine led to the formation of new macrocyclic compounds containing one cholane, one arene, and two oxadiamine fragments.     

Diode-pumped continuous-wave eye-safe Nd:YAG laser at 1415 nm

We describe the output performance of the 1415 nm emission in Nd:YAG in a plane-concave cavity under traditional pumping into the 4F5/2 level (808 nm) and direct in-band pumping into the 4F3/2 level (885 nm). An end-pumped Nd:YAG laser yielded maximum cw output power of 6.3 W and 4.2 W at 885 nm and 808 nm laser diode (LD) pumping, respectively. To the best of our knowledge, this is the highest output power of a LD-pumped 1415 nm laser.