Crystal structure of a new chain diborate TmH[B2O5] and its comparison with related compound GdH[B2O5] based on the pseudosymmetry and the group-subgroup relation

Crystals of a new rare-earth chain diborate TmH[B₂O₅], space group C2/c, are obtained under hydrothermal conditions. The structure is determined without preliminary knowledge of the chemical formula. It is close to that of the GdH[B₂O₅] diborate studied earlier, but has a different orientation of the monoclinicity axis. In both structures the arrangement of atoms follows the pattern of the orthorhombic pseudosupergroup Cmca, which is most distinctly violated by the displacements of the rare-earth atoms. Their common anionic chain radical consists of diborate groups, namely, BO₃ triangles and BO₄ tetrahedra, 2[1T + 1Δ]. It is shown that the existence of two varieties that are based on the hypothetical orthorhombic prototype is determined by the pseudosymmetry and the difference between the ionic radii of the elements located at the middle and the end of the rare-earth series. The twinning and poor quality of the crystals are related to the effect of the m pseudoplane of the supergroup and cleavage. The structures of natural megaborates that contain diborate chains in complex boron-oxygen radicals are discussed.     

Crystal structure of the new radical cation salt (<Emphasis Type="Italic">DOET</Emphasis>)<Subscript>4</Subscript>[Fe(CN)<Subscript>5</Subscript>NO]<Subscript>1.25</Subscript>(C<Subscript>6</Subscript>H<Subscript>5</Subscript>Cl)<Subscript>0.75</Subscript>

A new radical cation salt based on 4,5-(1,4-dioxanediyl-2,3-dithio)-4′,5′-ethylenedithiotetrathiafulvalene (DOET) with the photochromic anion [Fe(CN)₅NO]^2?, namely, (DOET)₄[Fe(CN)₅ NO]_1.25(C₆H₅Cl)_0.75, is synthesized. Single crystals of this salt are studied using X-ray diffraction [a = 10.398(2) Å, b = 11.168(2) Å, c = 18.499(4) Å, α = 103.14(3)°, β = 92.80(3)°, γ = 106.02(3)°, V = 1996.3(7) ų, space group \(P\bar 1\), and Z = 1]. In the structure, radical cation layers alternate with anion layers along the c axis. The centrosymmetric dimers are formed by DOET radical cations in the donor layer with packing of the β type. Like the vast majority of DOET-based salts, the new salt possesses semiconductor properties.     

The 8 : 1 : 1 ternary hybrid framework in the system [EDT-TTF +][1,4-bis(iodoethynyl)benzene][Re6Se8(CN)6]4-: dual noncovalent expression of the octahedral halogen-bond hexa-acceptor nanonode

Complementary shapes of the neutral symmetrical halogen-bond bis-donor core and octahedral inorganic cluster core prevent halogen-bonded polymers developing in more than one direction, favouring further templating by conducting radical cation slabs and yielding an 8 : 1 : 1 phase formulation instead of n : 2 : 1, with a 2D net, or m : 3 : 1, with a pseudo-cubic architecture, which may in principle also be targeted.     

Comparative analysis of hydrogen bonding with participation of the nitrogen, oxygen and sulfur atoms in the 2(2'-heteroaryl)pyrroles and their trifluoroacetyl derivatives based on the 1H, 13C, 15N spectroscopy and DFT calculations

The N-H...X (X = N,O,S) intramolecular hydrogen bond in the series of 2(2'-heteroaryl)pyrroles and their trifluoroacetyl derivatives is examined by the (1)H, (13)C, (15)N spectroscopy and density functional theory (DFT) calculations. The influence of the hydrogen bond on coupling and shielding constants is considered. It is shown that the N-H...N intramolecular hydrogen bond causes a larger increase in the absolute size of the (1)J(N,H) coupling constant and a larger deshielding of the bridge proton than the N-H...O hydrogen bond. The effect of the N-H...S interaction on the (1)J(N,H) coupling constant and the shielding of the bridge proton is small. The NMR parameter changes in the series of the 2(2'-heteroaryl)pyrroles due to N-H...X hydrogen bond and the series of the 1-vinyl-2-(2'-heteroaryl)-pyrroles due to C-H...X hydrogen bond have the same order. The proximity of the nitrogen, oxygen or sulfur lone pair to the F...H hydrogen bridge quenches the trans-hydrogen bond spin-spin couplings (1h)J(F,H-1) and (2h)J(F,N).     

The effect of bombardment with neutralized neon ions on the roughness of a fused silica and beryllium surface

The effect of Ne ion beam etching on the roughness of materials for optical substrates—fused silica and beryllium—is studied. It is shown that the treatment of a fused silica surface by neutralized Ne ions with an energy of 400–800 eV makes it possible to smooth roughnessed in the range of higher spatial frequencies of 3–63 μm^–1 at an incidence angle of 0°–30°. For beryllium, the possibility of smoothing the surface roughness at an ion energy of 400 eV is found.     

A database for inventory of proteoform profiles: “2DE-pattern”

The human proteome is composed of a diverse and heterogeneous range of gene products/proteoforms/protein species. Because of the growing amount of information about proteoforms generated by different methods, we need a convenient approach to make an inventory of the data. Here, we present a database of proteoforms that is based on information obtained by separation of proteoforms using 2DE followed by shotgun ESI–LC–MS/MS. The database's principles and structure are described. The database is called “2DE-pattern” as it contains multiple isoform-centric patterns of proteoforms separated according to 2DE principles. The database can be freely used at http://2de-pattern.pnpi.nrcki.ru .     

From 1,4-diketones to N-vinyl derivatives of 3,3′-bipyrroles and 4,8-dihydropyrrolo[2,3-f]indole in just two preparative steps

Dioximes of hexane-2,5-dione and cyclohexane-1,4-dione react with acetylene in an autoclave (KOH/DMSO, 100 °C, 1 h, initial pressure 14 atm) to give 2,2′-dimethyl-1,1′-divinyl-[3,3′]bipyrrole and 1,5-divinyl-4,8-dihydropyrrolo[2,3-f]indole in 12% and 6% yields, respectively, thus exemplifying a very simple, straightforward route to inaccessible or unknown pyrrolic assemblies.     

Synthesis of 2-Mono- and 2,2-Bis[2-(1<Emphasis Type="Italic">H</Emphasis>-tetrazol-5-yl)ethyl] Derivatives of Dipterocarpol

The azidation of 2,2-bis(2-cyanoethyl)-20-hydroxydammar-24-en-3-one afforded new tetrazole derivatives of natural dipterocarpol, 2-(2-cyanoethyl)-2-[2-(1H-tetrazol-5-yl)ethyl]-20-hydroxydammar-24-en- 3-ones, 2,2-bis[2-(1H-tetrazol-5-yl)ethyl]-20-hydroxydammar-24-en-3-one, and 2,2-bis[2-(1H-tetrazol-5-yl)- ethyl]-3-oxo-25,26,27-trinordammaran-(20S),24-olide. The structure of the final and intermediate products was determined by NMR spectroscopy and X-ray analysis.     

Radical Cation Salts of Tetrathiotetracene and Tetraselenotetracene with Photochromic Anion [Fe(NO)(CN)5]2–

Radical cation salts of tetrathiotetracene (TTT) and tetraselenotetracene (TSeT) with photochromic anion [Fe(NO)(CN)₅]^2– having the compositions (TTT)₃[Fe(NO)(CN)₅] (I) and (TSeT)₃[Fe(NO)(CN)₅] (II) were synthesized. Their crystal structures and conducting and optical properties were studied. The salt structures are featured by stacks of TTT or TSeT triads. Analysis of the bond lengths in TTT and TSeT revealed localization of a charge in the triads, where one molecule is neutral and the other two molecules are charged (1+). At room temperature, the conductivity of crystals I and II along the stack direction is 6 × 10^–2 and 5–7 Ohm^–1 cm^–1, respectively. Unlike I, the temperature dependence of conductivity of II has peculiarities at 285 and 160 K due to phase transitions. The transition at 160 K was discovered also in the reflection spectra.