Computer simulation of the theoretical contrast of various types of structure defects with noise factors

We present computer simulation results for the images of various types of structural defects in 6H-SiC and Si single crystals with taking into account noise factors (background heterogeneity and contrast graininess). If we know the parameters used to simulate the image, we can increase the reliability of defect identification and location in the single crystal’s bulk and find the quantitative and qualitative characteristics of defects by comparing the experimental and theoretical noise contrast.     

Section images of dislocations normal to the surface of a 6H-SiC single crystal

Section topographs of edge and screw dislocations with an axis along [0001] in 6H-SiC are taken and interpreted, and the image formation is explained for this case. The contrast induced by various arrangements of dislocations within the Borrmann triangle is experimentally studied. The sign of the Burgers vector of an edge or screw dislocation normal to the crystal surface is shown to be unambiguously determined from the section-topograph image of this dislocation. The sign of the Burgers vector of a screw dislocation can also be determined from its image taken with Lang projection topography. The contribution of a long-range strain field to the section images of edge and screw dislocations normal to the crystal surface is revealed. The experimental contrasts recorded using section topography and Borrmann-effect-based topography are compared.     

Cyclometallated Platinum(II) Complexes for Obtaining Phenyl-Containing Silicone Rubbers via Catalytic Hydrosilylation Reaction

Russian Journal of General Chemistry - C,N-Chelate deprotonated diaminecarbene platinum(II) complexes were studied as polysiloxane system hydrosilylation catalysts. Phenyl-containing silicone...     

New triamidophosphonium acetals and their condensation with resorcinol and its derivatives

A number of new acetals bearing phosphonium moieties with P-N bonds were prepared. Their condensation with resorcinols in acidic water-alcohol solutions was studied, which led to new phosphonium salts having a diarylmethane fragment.     

Modular,Homochiral, Porous Coordination Polymers: Rational Design,Enantioselective Guest Exchange Sorption and Ab Initio Calculations of Host–Guest Interactions

Two new, homochiral, porous metal–organic coordination polymers [Zn₂(ndc){(R)‐man}(dmf)]?3DMF and [Zn₂(bpdc){(R)‐man}(dmf)]?2DMF (ndc=2,6‐naphthalenedicarboxylate; bpdc=4,4′‐biphenyldicarboxylate; man=mandelate; dmf=N,N′‐dimethylformamide) have been synthesized by heating Zn^II nitrate, H₂ndc or H₂bpdc and chiral (R)‐mandelic acid (H₂man) in DMF. The colorless crystals were obtained and their structures were established by single‐crystal X‐ray diffraction. These isoreticular structures share the same topological features as the previously reported zinc(II) terephthalate lactate [Zn₂(bdc){(S)‐lac}(dmf)]?DMF framework, but have larger pores and opposite absolute configuration of the chiral centers. The enhanced pores size results in differing stereoselective sorption properties: the new metal–organic frameworks effectively and stereoselectively (ee up to 62 %) accommodate bulkier guest molecules (alkyl aryl sulfoxides) than the parent [Zn₂(bdc){(S)‐lac}(dmf)]?DMF, while the latter demonstrates decent enantioselectivity toward precursor of chiral anticancer drug sulforaphane, CH₃SO(CH₂)₄OH. The new homochiral porous metal–organic coordination polymers are capable of catalyzing a highly selective oxidation of bulkier sulfides (2‐NaphSMe (2‐C₁₀H₇SMe) and PhSCH₂Ph) that could not be achieved by the smaller‐pore [Zn₂(bdc){(S)‐lac}(dmf)]?DMF. The sorption of different guest molecules (both R and S isomers) into the chiral pores of [Zn₂(bdc){(S)‐lac}(dmf)]?DMF was modeled by using ab initio calculations that provided a qualitative explanation for the observed sorption enantioselectivity. The high stereo‐preference is accounted for by the presence of coordinated inner‐pore DMF molecule that forms a weak C? H???O bond between the DMF methyl group and the (S)‐PhSOCH₃ sulfinyl group.     

Two isomeric fourteen-membered bis-dithioacetals derived from (<Emphasis Type="Italic">Z</Emphasis>)- and (<Emphasis Type="Italic">E</Emphasis>)-but-2-ene-1,4-dithiols

(Z)-But-2-ene-1,4-dithiol was found to undergo isomerization into the E isomer. Condensation of (Z)- and (E)-but-2-ene-1,4-dithiols with acetaldehyde gave isomeric fourteen-membered bis-dithioacetals whose structure was determined by X-ray analysis.     

Anion complexation by calix[3]thieno[1]pyrrole: the medium effect

The interaction of calix[3]thieno[1]pyrrole, 1, and halide and dihydrogen phosphate anions in a variety of solvents (acetonitrile, propylene carbonate, N,N-dimethylformamide, and dimethyl sulfoxide) has been investigated through 1H NMR, conductance measurements, and titration calorimetry. 1H NMR measurements reveal the sites of interaction of the ligand with the anions in CD3CN while the composition of the complex was determined through conductance measurements. A quantitative assessment of anion-ligand interactions is provided. Thus the thermodynamics of complexation of 1 with halide and dihydrogen phosphate anions in dipolar aprotic media at 298.15 K is reported. These data are interpreted in terms of the thermodynamics of transfer of reactants and product from a reference solvent (acetonitrile) to other solvents. The crucial role played by the solvent on the ability of the ligand to interact with anions and on the composition of the complex is demonstrated.