Synthesis,Structure, and Theoretical Study of Trifluoromethyl Derivatives of C84(23) Fullerene

Trifluoromethylation of a higher fullerene mixture with CF₃I was performed in ampoules at 550 °C. HPLC separation followed by crystal growth and X‐ray diffraction study resulted in the structure elucidation of nine CF₃ derivatives of D_2d‐C₈₄ (isomer 23). The molecular structures of C₈₄(23)(CF₃)₄, C₈₄(23)(CF₃)₈, C₈₄(23)(CF₃)₁₀, C₈₄(23)(CF₃)₁₂, two isomers of C₈₄(23)(CF₃)₁₄, two isomers of C₈₄(23)(CF₃)₁₆, and C₈₄(23)(CF₃)₁₈ were discussed in terms of their addition patterns and the relative formation energies. Extensive theoretical DFT calculations were performed to identify the most stable molecular structures. It was found that the addition of CF₃ groups to the C₈₄(23) fullerene is governed by two main rules: no additions in positions of triple hexagon junctions and predominantly para additions in C₆(CF₃)₂ hexagons on the fullerene cage. The only exception with an isolated CF₃ group in C₈₄(23)(CF₃)₁₂ is discussed in more detail.     

Synthesis of spiro[imidazole-4,3'-thiochroman]ones from [2-(benzylsulfanyl)benzylidene]imidazolones

Chemistry of Heterocyclic Compounds - A methodology was developed for the synthesis of phenylspiro[imidazole-4,3'-thiochroman]ones by treatment of [2-(benzylsulfanyl)-benzylidene]imidazolones...     

Triphenylantimony(V) Catecholates of the Type (3-RS-4,6-DBCat)SbPh3-Catechol Thioether Derivatives: Structure,Electrochemical Properties,and Antiradical Activity

A new series of triphenylantimony(V) 3-alkylthio/arylthio-substituted 4,6-di-tert-butylcatecholates of the type (3-RS-4,6-DBCat)SbPh₃, where R = n-butyl (1), n-hexyl (2), n-octyl (3), cyclopentyl (4), cyclohexyl (5), benzyl (6), phenyl (7), and naphthyl-2 (8), were synthesized from the corresponding catechol thioethers and Ph₃SbBr₂ in the presence of a base. The crystal structures of 1, 2, 3, and 5 were determined by single-crystal X-ray analysis. The coordination polyhedron of 1–3 is better described as a tetragonal pyramid with a different degree of distortion, while that for 5- was a distorted trigonal bipyramid (τ = 0.014, 0.177, 0.26, 0.56, respectively). Complexes demonstrated different crystal packing of molecules. The electrochemical oxidation of the complexes involved the catecholate group as well as the thioether linker. The introduction of a thioether fragment into the aromatic ring of catechol ligand led to a shift in the potential of the “catechol/o-semiquinone” redox transition to the anodic region, which indicated the electron-withdrawing nature of the RS group. The radical scavenging activity of the complexes was determined in the reaction with DPPH radical.     

Synthesis of 4-Aryl-6-oxo-5-cyano-1,6-dihydropyridine-2-carboxylic Acids and Their Methyl Esters by Reacting Methyl Acylpyruvates with Malononitrile and Cyanoacetamide

Russian Journal of General Chemistry - A series of new methyl 4-aryl-6-oxo-5-cyano-1,6-dihydropyridine-2-carboxylates and 4-aryl-6-oxo-5-cyano-1,6-dihydropyridine-2-carboxylic acids were...     

Novel Tdp1 Inhibitors Based on Adamantane Connected with Monoterpene Moieties via Heterocyclic Fragments

Tyrosyl-DNA phosphodiesterase 1 (Tdp1) is a promising target for anticancer therapy due to its ability to counter the effects topoisomerase 1 (Top1) poison, such as topotecan, thus, decreasing their efficacy. Compounds containing adamantane and monoterpenoid residues connected via 1,2,4-triazole or 1,3,4-thiadiazole linkers were synthesized and tested against Tdp1. All the derivatives exhibited inhibition at low micromolar or nanomolar concentrations with the most potent inhibitors having IC₅₀ values in the 0.35–0.57 µM range. The cytotoxicity was determined in the HeLa, HCT-116 and SW837 cancer cell lines; moderate CC₅₀ (µM) values were seen from the mid-teens to no effect at 100 µM. Furthermore, citral derivative 20c, α-pinene-derived compounds 20f, 20g and 25c, and the citronellic acid derivative 25b were found to have a sensitizing effect in conjunction with topotecan in the HeLa cervical cancer and colon adenocarcinoma HCT-116 cell lines. The ligands are predicted to bind in the catalytic pocket of Tdp1 and have favorable physicochemical properties for further development as a potential adjunct therapy with Top1 poisons.     

Epitaxial gallium oxide on a SiC/Si substrate

Well-textured gallium oxide β-Ga₂O₃ layers with a thickness of ~1 μm and a close to epitaxial layer structure were grown by the method of chloride vapor phase epitaxy on Si(111) wafers with a nano-SiC buffer layer. In order to improve the growth, a high-quality silicon carbide buffer layer ~100 nm thick was preliminarily synthesized by the substitution of atoms on the silicon surface. The β-Ga₂O₃ films were thoroughly investigated using reflection high-energy electron diffraction, ellipsometry, X-ray diffraction, scanning electron microscopy, and micro-Raman spectroscopy. The investigations revealed that the films are textured with a close to epitaxial structure and consist of a pure β-phase Ga₂O₃ with the (\(\overline 2 01\)) orientation. The dependence of the dielectric constant of epitaxial β-Ga₂O₃ on the photon energy ranging from 0.7 to 6.5 eV in the isotropic approximation was measured.     

The optical module of Baikal-GVD

In April 2015, the first cluster of Baikal-GVD was deployed in Lake Baikal and put into operation. It comprises eight strings. Each string consists of 24 optical modules. An optical module is a detection element of Baikal-GVD; it includes a Hamamatsu R7081-100 photomultiplier tube with a high quantum sensitivity. We describe the design of the optical module, the front-end electronics, and the laboratory characterization and calibration.     

Pyranoside‐into‐Furanoside Rearrangement: New Reaction in Carbohydrate Chemistry and Its Application in Oligosaccharide Synthesis

Great interest in natural furanoside‐containing compounds has challenged the development of preparative methods for their synthesis. Herein a novel reaction in carbohydrate chemistry, namely a pyranoside‐into‐furanoside (PIF) rearrangement permitting the transformation of selectively O‐substituted pyranosides into the corresponding furanosides is reported. The discovered process includes acid‐promoted sulfation accompanied by rearrangement of the pyranoside ring into a furanoside ring followed by solvolytic O‐desulfation. This process, which has no analogy in organic chemistry, was shown to be a very useful tool for the synthesis of furanoside‐containing complex oligosaccharides, which was demonstrated by synthesizing disaccharide derivatives α‐D ‐Galp‐(1→3)‐β‐D ‐ Galf ‐OPr, 3‐O‐s ‐lactyl‐β‐D ‐ Galf ‐(1→3)‐β‐D ‐Glcp‐OPr, and α‐L ‐ Fucf ‐(1→4)‐β‐D ‐GlcpA‐OPr related to polysaccharides from the bacteria Klebsiella pneumoniae and Enterococcus faecalis and the brown seaweed Chordaria flagelliformis.     

Structures and Stability of Complexes of E(C6F5)3 (E = B,Al, Ga,In) with Acetonitrile

Complexes formed by interaction of E(C₆F₅)₃ (E = B, Al, Ga, In) with excess of acetonitrile (AN) were structurally characterized. Quantum chemical computations indicate that for Al(C₆F₅)₃ and In(C₆F₅)₃ the formation of a complex of 1:2 composition is more advantageous than for B(C₆F₅)₃ and Ga(C₆F₅)₃, in line with experimental observations. Formation of the solvate [Al(C₆F₅)₃ · 2AN] · AN is in agreement with predicted thermodynamic instability of [Al(C₆F₅)₃ · 3AN]. Tensimetry study of B(C₆F₅)₃ · CH₃CN reveals its stability in the solid state up to 197 °C. With the temperature increase, the complex undergoes irreversible thermal decomposition with pentafluorobenzene formation.     

Synthesis and antioxidant activity of new hydroxy derivatives of chalcones

New hydroxy derivatives of chalcones obtained via a condensation of 3-acetyl-2H-chromen-2-one with 2,4-dihydroxy- and 4-hydroxy-benzaldehydes and via an aldol crotonic condensation of methyl N-(4-acetylphenyl)carbamate with 4-hydroxy-3,5-di(tert-butyl)benzaldehyde have been isolated and characterized. A wide range of promising biological activity of the synthesized compounds, including the radical scavenging and antioxidant ones, was predicted by the in silico method. The anti- and pro-oxidant activities in model systems of peroxidation of cis-9-octadecenoic (oleic) acid and lipids from the liver homogenate of tilapia were estimated in vitro. The presence of sterically hindered hydroxy groups and a chromene moiety provides the prolonged antioxidant activity of new hydroxy derivatives of chalcones.