Thiacalix[4]arenes: Extraction of palladium and the electronic structure

The extractability of palladium nitro complexes with the charge state of sulfur and oxygen atoms in thiacalix[4]arenas in the cone and 1,3-alternate conformations are compared. The results of X-ray photoelectron and X-ray emission studies indicate the presence of considerable electron density on the bridging sulfur atoms, which is due to the contribution of the sulfur 3p AO to the upper occupied MOs of molecules. A series of changes in the electron density on sulfur atoms in the order calixarene thioethers > thiacalixarenes > dialkylsulfides ((C₁₀H₂₁)₂S) > (C₆H₅)₂S not completely coincide with changes in their extrability, which can be caused by different nature and stoichiometry of the formed palladium complexes.     

Determining the molecular mass transfer boundary in a plane vertical channel with mass impermeable walls

The molecular mass transfer boundary in an isothermal ternary gas system is numerically determined for a plane vertical diffusive channel with mass-impermeable walls. The critical Rayleigh number of diffusion-convection transition is determined for a slot channel. Theoretical studies performed within the framework of the linear stability theory are shown to be in agreement with the experimental data.     

Limiting deformability and strength of basalt–plastic shells under internal explosive loading

The dynamic strength and deformability of basalt–plastic specimens under single pulsed (explosive) loading are studied experimentally. The results obtained show that the basalt–plastic specimens possess high specific strength and their strength characteristics are close to those of similar tubular specimens from glassreinforced plastic based on a highmodulus glass fiber. It is found that a twofold increase in all geometrical dimensions of the specimens does not affect their specific carrying capacity.     

X-ray emission study of the electronic structure of binuclear niobium complexes with (S<Subscript>2</Subscript>)<Superscript>2</Superscript>–disulfide bridging ligands

The electronic structure of binuclear niobium complexes [Nb₂S₄(acac)₄] and K₄[Nb₂S₄(ox)4] is studied by X-ray emission fluorescent spectroscopy and quantum chemistry techniques. Data on the partial atomic composition of highest occupied molecular orbitals of the complexes are obtained. The energy positions of bonding and antibonding frontier molecular orbitals observed in the X-ray emission spectra of binuclear [Nb₂((S₂)^2–)₂]⁴⁺ clusters are determined by the analysis of overlap populations.     

Nitrogen-containing analogues of boron difluoride benzoylacetonate: synthesis,structure, luminescence,and quantum chemical modeling

Nitrogen-containing analogues of boron difluoride benzoylacetonate (1), i.e., boron difluoride ketoiminates (boron difluoride 3-amino-1-phenyl-2-buten-1-onate (2) and 3-methylamino-1-phenyl-2-buten-1-onate (3)), were taken as examples to study the influence of a substituent (H, Me) at the nitrogen atom on structure and spectral-luminescent properties. The replacement of the oxygen atom with the nitrogen atom in compound 1 led to a bathochromic shift of the monomeric luminescence maximum. Quantum chemical modeling of absorption spectra for compound 2 was carried out. In contrast to compounds 1 and 3, crystals of compound 2 are characterized by the formation of J-aggregates and excimers on their basis, which leads to a bathochromic shift of the luminescence spectrum and an increase in the luminescence intensity.     

Cyclopropanecarbaldehyde with two protected hydroxymethyl groups

3,5-Dioxabicyclo[5.1.0]octane-8-carbaldehyde was synthesized in three steps, including initial stereoselective exo-cyclopropanation of 1,3-dioxacyclohept-5-ene with ethyl diazoacetate. The subsequent phosphorylation according to Abramov and Kabachnik-Fields gave the corresponding α-hydroxy(acetoxy)- and α-aminocyclopropylmethylphosphonates with protected hydroxymethyl moieties at the three-membered ring.