Phosphorylated flavonoids as selective carboxylesterase inhibitors

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Complexes based on citrus pectin for delivery of tetracycline

The formation of complexes of sodium polygalacturonate with the antimicrobial drug tetracycline was confirmed by UV spectroscopy, powder X-ray diffraction, and dynamic light scattering. The stoichiometry of the complexes with the maximum tetracycline content (6.68 wt.%) was determined. The morphological characteristics of the synthesized complexes were studied by scanning electron microscopy in comparison with the initial compounds.

     

Micellar nanocontainers based on sterically hindered cationic phosphonium amphiphiles

Russian Chemical Bulletin - Self-aggregation processes in an H2O—DMF (10%) medium were studied for a homologous series of tri-tert-butyl(n-alkyl)phosphonium tetrafluoroborates (PIL-n, where n...     

Spin fluctuations in hydrogen-stabilized Laves phase UTi2H5

Uranium Laves phase UTi₂ does not exist in a pure form, but can be stabilised by the presence of hydrogen, which can be absorbed in concentration exceeding 5?H atoms/f.u. Low temperature specific heat, magnetic susceptibility, and resistivity indicate that UTi₂H₅ is a spin fluctuator close to the verge of magnetic ordering. Its susceptibility follows at high temperatures the Curie–Weiss law with U effective moment µ_eff[ ?= 3.1?µ_B/U and paramagnetic Curie temperature Θ_p = ?200 K. The temperature dependence of specific heat exhibits a pronounced and weakly field dependent upturn in C_p/T versus T below 10 K reflecting the effect of spin fluctuations. It can be described by an additional T^½ term. The Sommerfeld coefficient γ = 256?mJ/mol K² classifies the compound as a mid-weight heavy fermion. Spin fluctuations are affecting also electrical and thermal transport and thermoelectric power, which all resemble UAl₂. A lattice anomaly at ≈ 240?K, attributed to the melting of hydrogen sublattice, reflects in most of bulk properties.     

The Role of Metal Ions in the Study of Ancient Paper by Electron Paramagnetic Resonance

Samples from covers and endleaves of sixteenth to eighteenth century books in good conservation state from the Biblioteca Nazionale Marciana in Venice have been investigated by means of electron paramagnetic resonance (EPR) spectroscopy and optical microscopy to characterize the embedded paramagnetic species and to test differences and similarities of the materials in the two types of book components. We detected the Mn(II), Fe(III), and Cu(II) paramagnetic ions, and analyzed their EPR signals by comparing them with previous results in literature of EPR studies on paper. Interestingly, the Mn(II) EPR spectrum profile appears as a fingerprint for samples coming from the same book, either from cover or endleaf, and it looks different for samples extracted from different books. We discuss the role of EPR as a spectroscopic tool for characterizing the interaction of the ions with the paper components and as possible agents of degradation.     

Fused Bis(hemi-indigo): Broad-Range Wavelength-Independent Photoswitches

Wavelength-independent conversion of organic photoswitches in the photostationary state is a rare phenomenon that opens up a way for many practical applications. In this work, three fused bis(hemi-indigo) derivatives with different substitution patterns were synthesized and their photoswitching was investigated by optical spectroscopy, real-time NMR spectroscopy and TD-DFT calculations. We disclosed that the Z-E photoisomerization of the meta-bis(hemi-indigo) derivative was remarkably independent of the irradiation wavelength from UV up to yellow light. The wavelength-independent forward photoswitching together with the inhibited backward photoisomerization, high thermal stability of the photoinduced isomers as well as significant overlap between the photoswitch absorption and the solar spectrum allows to suggest bis(hemi-indigo) derivatives as promising candidates for molecular solar thermal energy storage (MOST) systems.     

May thermal imaging be useful in the assessment of dental anaesthesia? Preliminary study

Journal of Thermal Analysis and Calorimetry - The main goal of this study was to find out if thermal imaging may be useful in the evaluation of two types of anaesthetic injections—with and...     

A new polymorph of Cu3B2O6

A new polymorph of nonacopper(II) bis(orthoborate) bis(hexaoxodiborate), Cu₉(BO₃)₂(B₂O₆)₂, or Cu₃B₂O₆ with Z′ = 3, has a pseudo‐layered monoclinic structure containing BO₃ triangles and B₂O₆ units consisting of corner‐sharing BO₃ triangles and BO₄ tetrahedra. The compound was obtained during an investigation of the Li–Cu–B–O system. In contrast to the triclinic form of Cu₃B₂O₆, the layers are linked to one another by BO₄ tetrahedra.     

Synthesis, characterization, and theoretical study of stable isomers of C70(CF3)n (n = 2, 4, 6, 8, 10)

Reaction of C70 with ten equivalents of silver(I) trifluoroacetate at 320-340 degrees C followed by fractional sublimation at 420-540 degrees C and HPLC processing led to the isolation of a single abundant isomer of C70(CF3)n for n = 2, 4, 6, and 10, and two abundant isomers of C70(CF3)8. These six compounds were characterized by using matrix-assisted laser desorption ionization (MALDI) mass spectrometry, 2D-COSY and/or 1D 19F NMR spectroscopy, and quantum-chemical calculations at the density functional theory (DFT) level. Some were also characterized by Raman spectroscopy. The addition patterns for the isolated compounds were unambiguously found to be C1-7,24-C70(CF3)2, C1-7,24,44,47-C70(CF3)4, C2-1,4,11,19,31,41-C70(CF3)6, Cs-1,4,11,19,31,41,51,64-C70(CF3)8, C2-1,4,11,19,31,41,51,60-C70(CF3)8, and C1-1,4,10,19,25,41,49,60,66,69-C70(CF3)10 (IUPAC numbering). Except for the last compound, which is identical to the recently reported, crystallographically characterized C70(CF3)10 derivative prepared by a different synthetic route, these compounds have not previously been shown to have the indicated addition patterns. The largest relative yield under an optimized set of reaction conditions was for the Cs isomer of C70(CF3)8 (ca. 30 mol % of the sublimed mixture of products based on HPLC integration). The results demonstrate that thermally stable C70(CF3)n isomers tend to have their CF3 groups arranged on isolated para-C6(CF3)2 hexagons and/or on a ribbon of edge-sharing meta- and/or para-C6(CF3)2 hexagons. For Cs- and C2-C70(CF3)8 and for C2-C70(CF3)6, the ribbons straddle the C70 equatorial belt; for C1-C70(CF3)4, the para-meta-para ribbon includes three polar hexagons; for C1-7,24-C70(CF3)2, the para-C6(CF3)2 hexagon includes one of the carbon atoms on a C70 polar pentagon. The 10.3-16.2 Hz 7JF,F NMR coupling constants for the end-of-ribbon CF3 groups, which are always para to their nearest-neighbor CF3 group, are consistent with through-space Fermi-contact interactions between the fluorine atoms of proximate, rapidly rotating CF3 groups.