Synthesis of unsaturated esters of pyridine- and quinolinedicarboxylic acids

The divinyl, diallyl, and dipropargyl esters of pyridine-2,4-, pyridine-2,6-, and quinoline-2,4-dicarboxylic acids and the divinyl and dipropargyl esters of pyridine-2,5-dicarboxylic acid have been synthesized.     

The behavior of thermoresponsive star-shaped poly-2-isopropyl-2-oxazoline in saline media

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Unusual directions in the reactions of [1.1.1]propellane with sulfonyl chlorides and sulfuryl chloride

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2451–2452, October, 1990.     

Syntheses,molecular structures,and thermal decomposition of cyclopentadienyldicarbonylmanganese chalcogenide derivatives

Transmetallation of the dichalcogenide complexes [CpMn(CO)₂]₂(-X₂) (X = S or Se) with M(CO)₅(thf) (M = Cr or W) afforded new heterometallic complexes CpMn(CO)₂(-Se₂)Cr(CO)₅, CpMn(CO)₂(-Se₂)[Cr(CO)₅]₂, CpMn(CO)₂(-X₂)[W(CO)₅]₂ (X = S or Se), and CpMn(CO)₂(-Se₂)[Cr(CO)₅][W(CO)₅]. According to the X-ray diffraction data, their molecular structures contain the cyclic MnX₂ fragments coordinated by one or two M(CO)₅ groups via the X atoms. Study of thermal decomposition of the manganese complexes with different Mn : M : X ratios (M = Cr, W; X = S, Se, Te) by differential scanning calorimetry (DSC) and thermogravimetry demonstrated that this process took place at rather low temperatures (100—400 °C) and was accompanied by complete elimination of the CO groups followed by elimination of the Cp groups. At any metal to chalcogen ratio, the resulting inorganic chalcogenides contained no impurities of metal oxides and carbides.     

Effect on optical anisotropy of intramolecular lability in various molecular rotational configurations

It is shown that the effect of intramolecular lability in complex molecules on the degree of fluorescence polarization of rarified vapors is mainly mediated through perturbations of rotational motion in the region of separatrixes of A- and C-forms of rotation stereo dynamics. It is most pronounced for the orientation of optical transition dipole moment components along the axis of the molecule average moment of inertia (B) and manifests itself in all types of molecular tops. Such lability for dipole orientations along the A and C axes usually causes the degree of anisotropy to decrease by an order of magnitude and more. So it is advisable to use optical transitions with dipole moments oriented along the A or C axes for optical polarization analysis of molecules in the gaseous state, for example in analytical high-temperature polarized fluorescence.     

Reductive dehalogenation of halo derivatives of bis(1,1′-bicyclo[1.1.1]pentane)

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 716–717, March, 1990.     

High-frequency electrical properties of a vertical-cavity surface-emitting laser with a monolithically integrated electro-optical modulator

The high-frequency electrical properties of a vertical-cavity surface-emitting laser with a monolithically integrated electro-optical modulator are studied using small-signal modulation analysis of the electroreflectance. The experimental data obtained are approximated using the suggested equivalent electrical circuit, which accounts for the formation of a nonequilibrium space charge in the carrier-depletion region of the modulator. The bandwidth of the high-frequency electrical-signal transfer to the electro-optical region, determined for the suggested equivalent electrical circuit of the modulator, is shown to be 3GHz.     

Single-Lobe Single-Wavelength Lasing in Ultrabroad-Area Vertical-Cavity Surface-Emitting Lasers Based on the Integrated Filter Concept

We have studied broad-area vertical-cavity surface-emitting lasers grown in the antiwaveguiding approach (AVCSELs). The AVCSEL-type devices were fabricated in the ridge stripe geometry with openings in the top contact layer. Surface lasing was realized and evaluated for the devices with and without the integrated absorber section, acting as a selective filter for the emission modes propagating at finite tilt angle with respect to the normal to the surface (F-AVCSEL). It was found that the conventional AVCSEL device lases in high-order excited modes, tilted with respect to the normal to the surface, while lower order modes evolve at higher current densities causing a dramatic broadening of the emission spectrum. On the contrary, the F-AVCSEL emission is composed of a single spectral feature, which remains hardly affected up to the highest current densities >10 kA/cm². The far-field pattern is composed of a single zero-angle lobe with a beam divergence defined by the size of the opening in the top contact. No spectral features due to parasitic high-order modes were observed. The Gaussian-type single-wavelength surface-emitting lasing with an output power of 70 mW was realized in all-epitaxial wavelength-selective filter concept.