Synthesis of esters and amides of 2-aryl-1-hydroxy-4-methyl-1H-imidazole-5-carboxylic acids and study of their antiviral activity against orthopoxviruses.

Smallpox was eradicated >40 years ago but it is not a reason to forget forever about orthopoxviruses pathogenic to humans. Though in 1980 the decision of WHO to cease vaccination against smallpox had seemed logical, it led to the decrease of cross immunity against other infections caused by orthopoxviruses. As a result, in 2022 the multi-country monkeypox outbreak becomes a topic of great concern.

DNA-based assemblies with bischromophoric styryl dye-chromene conjugates and cucurbit[7]uril.

Novel conjugates consist of 4-styrylpyridinium dye and 2,2-diphenyl-2H-chromene moiety were obtained, and their affinity to double stranded DNA and cucurbit[7]uril was investigated. With a combination of absorption, fluorescence and circular dichroism spectroscopies as well as MALDI-TOF mass spectrometry, we demonstrate that these compounds can interact with macromolecules to form of the supramolecular assemblies due to two suitable binding sites. The ternary complex is formed as a result of the intercalation of a positively charged styryl part between DNA base pairs, while cucurbit[7]uril is located on the alkyl chain between two moieties of conjugate.

Divergent Reactivity of Triaryldivinyl Ketones: Competing 4π and Putative 6π Electrocyclization Pathways.

This work describes an acid-promoted cyclization of triaryldivinyl ketones containing a thiophene moiety in the α-position. Two cyclization pathways are accessible: one a 4π-Nazarov cyclization and the other we propose to proceed through a 6π electrocyclic mechanism. The relative proportion of products from these divergent pathways is affected by reaction conditions and steric bulk in the substrate.

Can We Merge the Weak and Strong Tetrel Bonds? Electronic Features of Tetrahedral Molecules Interacted with Halide Anions.

Using the orbital-free quantum crystallography approach, we have disclosed the quantitative trends in electronic features for bonds of different strengths formed by tetrel (Tt) atoms in stable molecular complexes consisting of electrically neutral tetrahedral molecules and halide anions. We have revealed the role of the electrostatic and exchange-correlation components of the total one-electron static potential that are determined by the equilibrium atomic structure and by kinetic Pauli potential, which reflects the spin-dependent electron motion features of the weak and strong bonds. The gap between the extreme positions in the electrostatic and total static potentials along the line linking the Tt atom and halide anion is wide for weak bonds and narrow for strong ones.

Real-Space Interpretation of Interatomic Charge Transfer and Electron Exchange Effects by Combining Static and Kinetic Potentials and Associated Vector Fields.

Intricate behaviour of one-electron potentials from the Euler equation for electron density and corresponding gradient force fields in crystals was studied. Channels of locally enhanced kinetic potential and corresponding saddle Lagrange points were found between chemically bonded atoms. Superposition of electrostatic and kinetic potentials and electron density allowed partitioning any molecules and crystals into atomic - and potential-based -basins; -basins explicitly account for the electron exchange effect, which is missed for -ones.

What are the prospects for using complexes of copper(ii) and zinc(ii) to suppress the vital activity of ?

New complexes of zinc(ii) and copper(ii) with 2-furoic acid (Hfur), acetic acids and N-donor ligands with the compositions [Zn(fur)] (1), [Zn(fur)(NHpy)] (2, NHpy = 3-aminopyridine), [Zn(fur)(neoc)] (3, neoc = 2,9-dimethyl-1,10-phenantroline), [Zn(OAc)(neoc)] (4, OAc = acetat-anion), and [Cu(fur)(neoc)(HO)] (5) were synthesized. The structures of the compounds were established by single crystal X-ray diffraction analysis. Complexes 1 and 2 are binuclear; whereas 3-5 are mononuclear.

Electrochemical thiocyanation of barbituric acids.

The electrochemical thiocyanation of barbituric acids with NHSCN was disclosed in an undivided cell under constant current conditions. The electrosynthesis is the most efficient at a record high current density ( ≈50-70 mA cm). NHSCN has a dual role as the source of the SCN group and as the electrolyte.

Nanoscale Visualization of Photodegradation Dynamics of MAPbI Perovskite Films.

Herein, we report the nanoscale visualization of the photochemical degradation dynamics of MAPbI (MA = CHNH) using infrared scattering scanning near-field microscopy (IR s-SNOM) combined with a series of complementary analytical techniques such as UV-vis and FTIR-spectroscopy, XRD, and XPS. Light exposure of the MAPbI films resulted in a gradual loss of MA cations starting from the grain boundaries at the film surface and slowly progressing toward the center of the grains and deeper into the bulk perovskite phase. The binary lead iodide PbI was found to be the major perovskite photochemical degradation product under the experimental conditions used.

Structural Insight into Complexation Ability and Coordination of Uranyl Nitrate by 1,10-Phenanthroline-2,9-diamides.

Reprocessing of spent nuclear fuel (SNF) is an important task in a frame of ecology and rational use of natural resources. Uranium, as the main component of SNF (>95%), can be recovered for further use as fresh nuclear fuel. To minimize an amount of solid radioactive waste generated during SNF reprocessing, new extractants are under investigation.

Electrifying Phthalimide--Oxyl (PINO) Radical Chemistry: Anodically Induced Dioxygenation of Vinyl Arenes with -Hydroxyphthalimide.

An electrochemical process of free-radical difunctionalization of vinyl arenes with -hydroxyphthalimide resulting in vicinal dioxyphthalimides was discovered. The reaction proceeds with the use of pyridinium perchlorate and pyridine as a supporting electrolyte and a base, respectively. The present approach involves the anodic generation of stabilized phthalimide--oxyl (PINO) radical, which adds to the carbon-carbon double bond of vinyl arenes and recombines with the subsequently formed benzylic radical.

The K139 capsular polysaccharide produced by Acinetobacter baumannii MAR17-1041 belongs to a group of related structures including K14, K37 and K116.

Capsular polysaccharide (CPS) is a key target for bacteriophage and vaccine therapies currently being developed for treatment of infections caused by the extensively antibiotic resistant bacterial species, Acinetobacter baumannii. Identification of new CPS structures and the genetics that drive their synthesis underpins tailored treatment strategies. A novel CPS biosynthesis gene cluster, designated KL139, was identified in the whole genome sequence of a multiply antibiotic resistant clinical isolate, A.

Correlation of Acinetobacter baumannii K144 and K86 capsular polysaccharide structures with genes at the K locus reveals the involvement of a novel multifunctional rhamnosyltransferase for structural synthesis.

Whole genome sequence from Acinetobacter baumannii isolate Ab-46-1632 reveals a novel KL144 capsular polysaccharide (CPS) biosynthesis gene cluster, which carries genes for d-glucuronic acid (D-GlcA) and l-rhamnose (l-Rha) synthesis. The CPS was extracted from Ab-46-1632 and studied by H and C NMR spectroscopy, including a two-dimensional H,C HMBC experiment and Smith degradation. The CPS was found to have a hexasaccharide repeat unit composed of four l-Rhap residues and one residue each of d-GlcpA and N-acetyl-d-glucosamine (D-GlcpNAc) consistent with sugar synthesis genes present in KL144.

Stable and reactive diacetyliminoxyl radical in oxidative C-O coupling with β-dicarbonyl compounds and their complexes.

As a rule, reactive free radicals used in organic synthesis are too labile to be isolated, whereas persistent radicals are inert and find limited synthetic application. In the present study, the unusually stable diacetyliminoxyl radical was presented as a "golden mean" between transient and stable unreactive radicals. It was successfully employed as a reagent for oxidative C-O coupling with β-dicarbonyl compounds.

Two-Membrane Acid-Base Flow Battery with Hydrogen Electrodes for Neutralization-to-Electrical Energy Conversion.

Acid-base flow batteries (ABFB) are a promising and environmentally benign class of flow batteries that utilize neutralization energy. Among the other flow batteries, ABFBs stand out with low cost and high solubility of the electrolytes and the possibility to harvest neutralization energy of acidic and alkaline wastewaters. However, the main ABFB issues, such as low power caused by discharge current limitation and low energy density, are limiting the possibility of their implementation.

Non-magnetic shell coating of magnetic nanoparticles as key factor of toxicity for cancer cells in a low frequency alternating magnetic field.

This work is devoted to studying the effects of non-magnetic shell coating on nanoparticles in a low frequency alternating magnetic field (LF AMF) on tumor cells in vitro. Two types of iron oxide nanoparticles with the same magnetic core with and without silica shells were synthesized. Nanoparticles with silica shells significantly decreased the viability of PC3 cancer cells in a low frequency alternating magnetic field according to the cytotoxicity test, unlike uncoated nanoparticles.

Synthesis of unstrained Criegee intermediates: inverse α-effect and other protective stereoelectronic forces can stop Baeyer-Villiger rearrangement of γ-hydroperoxy-γ-peroxylactones.

We address this question by exploring the interplay between the primary and secondary stereoelectronic effects in the Baeyer-Villiger (BV) rearrangement by experimental and computational studies of γ-OR-substituted γ-peroxylactones, the previously elusive non-strained Criegee intermediates (CI). These new cyclic peroxides were synthesized by the peroxidation of γ-ketoesters followed by cyclization using a BF·EtO/HO system. Although the primary effect (alignment of the migrating C-R bond with the breaking O-O bond) is active in the 6-membered ring, weakening of the secondary effect (donation from the OR lone pair to the breaking C-R bond) provides sufficient kinetic stabilization to allow the formation and isolation of stable γ-hydroperoxy-γ-peroxylactones with a methyl-substituent in the C6-position.

(2-Fluoroallyl)pyridinium tetrafluoroborates: novel fluorinated electrophiles for Pd-catalyzed allylic substitution.

An efficient two-step approach to 2-fluoroallyl amines was developed that involves the synthesis of (2-fluoroallyl)pyridinium tetrafluoroborates from readily available gem-bromofluorocyclopropanes and the application of the former as novel and stable 2-fluoroallyl electrophiles for Pd-catalyzed allylic substitution.

Stereochemistries and Biological Properties of Oligomycin A Diels-Alder Adducts.

Oligomycin A is a potent antibiotic and antitumor agent. However, its applications are restricted by its high toxicity and low bioavailability. In this study, we obtained Oligomycin A Diels-Alder adducts with benzoquinone and -benzylmaleimide and determined their absolute configurations by combining H and ROESY NMR data with molecular mechanics conformational analysis and quantum chemical reaction modeling.

Electrochemical Dehydrogenative C(sp )-H Amination.

A transition-metal-free direct electrolytic C-H amination involving an electrochemically generated nitrenium ion intermediate has been developed. The electrosynthesis takes place in the absence of any organoiodine catalysts and is enabled by an in situ generated electrolyte. A novel, efficient intramolecular and intermolecular C-H amination has been demonstrated using a simple reaction setup.

Synthesis and characterization of heteroleptic rare earth double-decker complexes involving tetradiazepinoporphyrazine and phthalocyanine macrocycles.

Reaction of (2,3,9,10,16,17,23,24-octabutylphthalocyaninato)lanthanide(iii) acetylacetonates (BuPcLn(acac), 1a-c, Ln = Lu (a), Eu (b), La (c)) with a tetrakis(5,7-bis(4-tert-butylphenyl)-6H-1,4-diazepino)[2,3-b,g,l,q]porphyrazine ligand (tBuPhDzPzH2, 2) produced sandwich compounds (tBuPhDzPz)Ln(BuPc) (3a-c), which represent the first heteroleptic double-deckers incorporating both Pc and DzPz decks. A combination of high-resolution mass spectrometry, UV-Vis/NIR, MCD, and 1H NMR spectroscopy, and square-wave voltammetry provided unambiguous characterization of target complexes 3 indicating that their spectral and electrochemical properties are generally intermediate with respect to their homoleptic relatives. Based on the data of solution-state 1H-1H NMR (COSY, NOESY) correlation spectroscopy supported by DFT calculations, a dimerization tendency of compounds 3 proportional to the Ln(iii) ion size was found.

Dispirooxindoles Based on 2-Selenoxo-Imidazolidin-4-Ones: Synthesis, Cytotoxicity and ROS Generation Ability.

A regio- and diastereoselective synthesis of two types of dispiro derivatives of 2-selenoxoimidazolidin-4-ones, differing in the position of the nitrogen atom in the central pyrrolidine ring of the spiro-fused system-namely, 2-selenoxodispiro[imidazolidine-4,3'-pyrrolidine-2',3″-indoline]-2″,5-diones () and 2-senenoxodispiro[imidazolidine-4,3'-pyrrolidine-4',3″-indoline]-2″,5-diones ()-were developed based on a 1,3-dipolar cycloaddition of azomethine ylides generated from isatin and sarcosine or formaldehyde and sarcosine to 5-arylidene or 5-indolidene-2-selenoxo-tetrahydro-4H-imidazole-4-ones. Selenium-containing dispiro indolinones generally exhibit cytotoxic activity near to the activity of the corresponding oxygen and sulfur-containing derivatives. Compounds , , and demonstrated considerable in vitro cytotoxicity in the 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) test (concentration of compounds that caused 50% death of cells (CC) 7.

Orbital-Free Quantum Crystallographic View on Noncovalent Bonding: Insights into Hydrogen Bonds, π⋅⋅⋅π and Reverse Electron Lone Pair⋅⋅⋅π Interactions.

A detailed analysis of a complete set of the local potentials that appear in the Euler equation for electron density is carried out for noncovalent interactions in the crystal of a uracil derivative using experimental X-ray charge density. The interplay between the quantum theory of atoms in molecules and crystals and the local potentials and corresponding inner-crystal electronic forces of electrostatic and kinetic origin is explored. Partitioning of crystal space into atomic basins and atomic-like potential basins led us to the definite description of interatomic interaction and charge transfer.

A Composite Membrane Based on Sulfonated Polystyrene Implanted in a Stretched PTFE Film for Vanadium Flow Batteries.

The quality of ion-selective membranes determines the efficiency of Vanadium Flow Batteries (VFBs), and alternatives to expensive Nafion™ materials are actively being searched for. One of the membrane architecture approaches is to imitate the Nafion™ structure with two separate phases: a conductive sulfonated polymer and an inner matrix. We introduce a new composite material based on sulfonated styrene polymerized inside the pores of a stretched PTFE matrix.

Orbital-free quantum crystallography: view on forces in crystals.

Quantum theory of atoms in molecules and the orbital-free density functional theory (DFT) are combined in this work to study the spatial distribution of electrostatic and quantum electronic forces acting in stable crystals. The electron distribution is determined by electrostatic electron mutual repulsion corrected for exchange and correlation, their attraction to nuclei and by electron kinetic energy. The latter defines the spread of permissible variations in the electron momentum resulting from the de Broglie relationship and uncertainty principle, as far as the limitations of Pauli principle and the presence of atomic nuclei and other electrons allow.

Electrolyte Flow Field Variation: A Cell for Testing and Optimization of Membrane Electrode Assembly for Vanadium Redox Flow Batteries.

A great deal of research has been dedicated to improving the performance of vanadium redox flow battery (VRFB). In this work, we propose the design of a cell for testing membrane electrode assembly of VRFB, which enables the optimization of the flow field, conditions of charge-discharge tests, and the nature of components (electrodes, membrane) with minimal time and material expenses. The essence of the proposed cell is that the system of channels distributing the electrolyte is made by cutting shaped holes in the sheets of graphite foil (GF).