Simulation of Transferred Electron Devices with Linearly Graded Composition of 3-5 Threefold Semiconductor in Active Zone

Two-level, displaced-maxwellian approach model of transfer electron effect in variband semiconductors has been created. With the help of the model research of TED based on variband semiconductor compounds In _x(z) Ga _1–x(z) As, Al _x(z) As, InP _1–x(z) Ga _1–x(z) As _x(z) has been done. Composition of the semiconductors x(z) in the active zone of TED depends linearly on the coordinate. It has been proved that work of TED with variband active zone is defined by dependence of relaxation frequency of electrons concentration in -valley upon coordinate. If the frequency is decreasing function dipole domains transit in the diode, but if the frequency is not decreasing function, so accumulation layers transit in the diode. Critical generation frequencies, power and frequencies characteristics of TED's based on semiconductor compounds In _x(z) Ga _1–x(z) As, Al _x(z) As, InP _1–x(z) Ga _1–x(z) As _x(z) have been defined.     

Structure of complexes formed by dissolution of palladium diacetate in methanol and chloroform. In situ NMR study

The behavior of palladium diacetate cyclic trimer [Pd(OAc)(2)](3) (1) upon its dissolution in methanol and wet chloroform was studied by (1)H and (13)C NMR including 2D-HSQC and 2D-DOSY techniques. Upon dissolution, trimer 1 reacts with methanol and is completely transformed first into the methoxo complex Pd(3)(μ-OMe)(OAc)(5) (2), which already at -18 °C undergoes a slow exchange of second bridging acetate ligand between the same palladium atoms to form the symmetric dimethoxo complex Pd(3)(μ-OMe)(2)(OAc)(4), the maximum relative concentration of which reaches 20-30 mol % of initial loading trimer 1. Along with the dimethoxo complex, both soluble and insoluble polynuclear palladium clusters are gradually formed at -18 °C, and their total amount reaches up to 60% of the starting Pd(2+) loading. The increase of temperature to 27 °C results in the reduction of palladium(II) to Pd metal by methanol, which is oxidized and transformed into formaldehyde hemiacetal and methyl formate. Upon dissolution in wet chloroform, trimer 1 is reversibly hydrolyzed to the hydroxo complex Pd(3)(μ-OH)(OAc)(5) (10) in ratio 1/10 ≈ 3/1. The temperature decrease and addition of acetic acid shift the equilibrium in this system toward trimer 1, and addition of water shifts it in the opposite direction. Addition of methanol to the equilibrium mixture of 1 and 10 results in the fast exchange of bridging acetate in trimer 1 by the μ-OMe group. Substitution of the μ-OH ligand by μ-OMe in 10 occurs in parallel but more slowly. Complex 2 formed in both cases is more stable in chloroform than in methanol.     

Synthesis and structure of <Emphasis Type="Italic">N</Emphasis>-(2-silatranylethyl)imidazoles

Organosilicon imidazole derivatives containing a 2-silatranylethyl [N(CH₂CH₂O)₃Si(CH₂)₂] group on the nitrogen atom were synthesized, and their steric and electronic structures, including the nature of interaction between the imidazole and silatrane fragments, were studied by X-ray analysis and ¹H, ¹³C, and ²⁹Si NMR spectroscopy.     

Dithienylethene-Based Single Molecular Photothermal Linear Actuator

By employing a mechanically controllable break junction technique, we have realized an ideal single molecular linear actuator based on dithienylethene (DTE) based molecular architecture, which undergoes reversible photothermal isomerization when subjected to UV irradiation under ambient conditions. As a result, open form (compressed, UV OFF) and closed form (elongated, UV ON) of dithienylethene-based molecular junctions are achieved. Interestingly, the mechanical actuation is achieved without changing the conductance of the molecular junction around the Fermi level over several cycles, which is an essential property required for an ideal single molecular actuator. Our study demonstrates a unique example of achieving a perfect balance between tunneling width and barrier height change upon photothermal isomerization, resulting in no change in conductance but a change in the molecular length, which results in mechanical actuation at the single molecular level.     

Hydrosilylation of unsaturated fluorinated esters and ethers with hydrochlorosilanes

Hydrosilylation of allyl esters of fluoro acids and ethers of fluoro alcohols with hydrochlorosilanes in the presence of the Speier’s catalyst was studied. Yields of adducts with ethers reach 62–68%, and with esters, 27–45%. By etherification of the adduts with ethers the respective ethoxysilanes were obtained in 41–43% yield. The latter reaction even in very mild conditions is complicated by the formation of a large amount of siloxanes. Yield of siloxanes is 22–32%.