New Chemo-, Regio- and Stereoselective Reactions and Methods in Organic Synthesis.

The Special Issue "New Chemo-, Regio- and Stereoselective Reactions and Methods in Organic Synthesis" collects eight articles that have developed advanced approaches to the chemo-, regio- and stereoselective synthesis of novel important compounds, scaffolds, synthons, and practically valuable products [...

Recent Advances in Design, Synthesis, and Biological Activity Studies of 1,3-Selenazoles.

The review examines recent advances in the design and synthesis of 1,3-selenazole derivatives since 2000. Various synthetic approaches to 1,3-selenazoles and reaction conditions are discussed. The beneficial properties of 1,3-selenazoles, especially their biological activity, are emphasized.

Experimental and Computational NMR Studies of Large Alkaloids Exemplified With Vindoline Trimer: Advantages and Limitations.

The complete H and C NMR assignments of a trimeric vindoline together with its individual components, dimeric vindolicine and monomeric vindoline, are performed based on a thorough analysis of the ROESY, COSY, HSQC, and HMBC spectra in combination with the state-of-the-art quantum-chemical calculations. A spatial structure of vindoline trimer is determined by means of computational conformational analysis in combination with the probability distribution map of its basic conformers. On the example of monoterpene indole alkaloid, the trimer vindoline, the present study reveals the power of modern computational NMR to perform identification and stereochemical studies of large natural compounds with some limitations, which may arise in the quantum chemical computing workflow.

The Use of AgNP-Containing Nanocomposites Based on Galactomannan and κ-Carrageenan for the Creation of Hydrogels with Antiradical Activity.

Series of composites containing 2.5-17.0% Ag and consisting of spherical silver nanoparticles with sizes ranging from 5.

Synthesis, Characterization, and Application Prospects of Novel Soluble Polysilsesquioxane Bearing Glutarimide Side-Chain Groups.

The requirement for the development of advanced technologies is the need to create new functional thermostable soluble polysilsesquioxanes. Combining the potential of organosilicon chemistry and the chemistry of heterocyclic compounds is a promising direction for the formation of novel organosilicon polymer systems with new properties and new possibilities for their practical application. Using the classical method of hydrolysis and polycondensation of previously unknown trifunctional (trimethoxysilylpropyl)glutarimide in the presence or absence of an acid or base catalyst, a universal approach to the formation of new thermostable soluble polysilsesquioxanes with glutarimide side-chain groups is proposed, which forms the basis for the synthesis of polysilsesquioxane polymers with different functionality.

A novel water-soluble polymer nanocomposite containing ultra-small FeO nanoparticles with strong antibacterial and antibiofilm activity.

A novel water-soluble polymer nanocomposite containing ultra-small iron oxide nanoparticles, intercalated into a biocompatible matrix of 1-vinyl-1,2,4-triazole and -vinylpyrrolidone copolymer has been synthesized for the first time. The use of an original polymer matrix ensured effective stabilization of the crystalline phase of iron oxides at an early stage of its formation in an ultra-small (2-8 nm, average diameter is 4.8 nm) nanosized state due to its effective interaction with the functional groups of copolymer macromolecules.

Supramolecular Structure of Sulfonamide-Substituted Silatranes: Quantum Chemical DFT Calculations.

The supramolecular structure of the crystal products--[2-chloro-2-(silatranyl)ethyl]-4-nitro-benzenesulfonamide and -chloro--[2-chloro-1-(silatran-1-yl-methyl)ethyl]benzene-sulfonamide was established by X-ray diffraction analysis data, FTIR spectroscopy and DFT quantum chemical calculations. Their crystal lattice is formed by cyclic dimers with intermolecular hydrogen NH∙∙∙O-Si bonds and CH∙∙∙O=S short contacts. The distribution of electron density in the monomers was determined using quantum chemical calculations of their molecular electrostatic potential (MESP) in an isolated state (in gas) and in a polar medium.

Macrocyclic Bridgehead Fluorophores, Pyrrolyl-diazabicyclo[8.3.1]tetradecadienones, with Giant Stokes Shifts.

A previously unknown class of fluorophores was discovered, which represents 14-membered bridgehead heterocycles, pyrrolyl-diazabicyclo[8.3.1]tetradecadienones, herein referred to as PY-14-ONEs.

Liquid-Phase NMR of Humic and Fulvic Acids.

Present review focuses on the most recent advances in the NMR of the coal-derived humic and fulvic acids, covering exclusively the results of the liquid-phase NMR and leaving apart an overwhelming amount of publications dealing with the solid-state NMR investigations in this field (the latter are comprehensively reviewed elsewhere). Owing to the complexity of humic and fulvic acids together with other coal-derived products, their H and C NMR spectra consist of a number of overlapping signals belonging to different hydrocarbon types. Comprehensive studies of humic and fulvic acids by means of NMR revealed characteristic functional groups of their composition together with spectral regions in which they resonate.

Rubizhne Institute - A Birthplace of Photochromic Molecules.

We introduce the community to the remarkable fact that two significant discoveries in the field of organic photoswitches are associated to the Rubizhne (Rubezhnoe) branch of the Research Institute of Organic Intermediates and Dyes during the last century. The institute in Rubizhne was a place where researchers of various nationalities carried out studies of organic dyes for printing and textiles. These efforts resulted in the discoveries of photoswitchable hemithioindigos by M.

Quelling the Geometry Factor Effect in Quantum Chemical Calculations of C NMR Chemical Shifts with the Aid of the pecG- ( = 1, 2) Basis Sets.

A root factor for the accuracy of all quantum chemical calculations of nuclear magnetic resonance (NMR) chemical shifts is the quality of the molecular equilibrium geometry used. In turn, this quality depends largely on the basis set employed at the geometry optimization stage. This parameter represents the main subject of the present study, which is a continuation of our recent work, where new pecG- ( = 1, 2) basis sets for the geometry optimization were introduced.

Discrete Hexa- and Binuclear Heterometallic Iodobismuthate(III) Complexes with Cu(I) and Ag(I).

The rare examples of discrete anionic halobismuthates(III) with group 11 elements were obtained. Those are (3-MePyH)[BiCuI] () and (3,5-MePyC)[BiAgI] () (3-MePyH = 3-methylpyridinium cation, 3,5-MePyC=1,6-bis(3,5-dimethylpyridinium)hexane dication). Both complexes were isolated as pure phases; the optical band gaps for and are 1.

Iodine-Rich Supramolecular Complexes of Chlorobismuthates(III): Unusual Lone Pair Activity and Features of Halogen Bonding in Crystals.

The first chrorobismuthate(III) supramolecular hybrids with halogen-bond-linked I, (Py(CH)Py){[BiCl](I)} () and (Py(CH)Py){[BiCl](I)} (), were synthesized via the reaction between BiO, I, and salts of the corresponding cations in HCl. The compounds featured one- and two-dimensional (2D) supramolecular motifs built by I···Cl contacts; in the case of , Bi(III) is pentacoordinated due to the lone pair activity, which also interacted with I pi-orbitals, as confirmed by density functional theory (DFT) calculations. Both complexes exhibited moderate thermal stabilities and relatively narrow optical band gaps.

Photoreactions of Semi-Stiff-Diarylethenes Based on the Cyclohexenol Motif.

Nonsymmetric diarylethenes with an additional "stiff" cyclohexenol ring undergo various types of tandem transformations launched by light-induced 6π-photocyclization. Among these, there are two novel reactions (formal [1,3]-H migration and complete aromatization to an anthracene derivative) as well as photorearrangement and formal methane elimination. This diverse reactivity demonstrates the great potential of --diarylethenes in synthetic photochemistry.

Selenium Transfer from Secondary Phosphine Selenides to Aminoacetylenic Ketones: Access to 1,2-Dihydro-3-pyrrole-3-selones with a Stable C═Se Bond.

Secondary phosphine selenides were found to react with γ-aminoacetylenic ketones (80-85 °C, MeCN, 17-40 h) to afford 1,2-dihydro-3-pyrrole-3-selones in 48-80% yields, products of unprecedented selenium transfer from the P═Se bond to replace the carbonyl oxygen and to form dihydro-3-pyrrole-3-selones having a C═Se bond stable under ambient conditions.

Evidence for the O-H⋅⋅⋅O=C Resonance-Assisted Hydrogen Bond in Tropolones and Quantification of its σ- and π-Components Using Molecular Tailoring Approach.

For a series of tropolones, the nature of the intramolecular O-H⋅⋅⋅O=C hydrogen bond closing the five-membered quasi-cycle was studied. Enhancement of conjugation in the hydrogen-bonded rotamer was revealed. Quantification of hydrogen bond energy in tropolones via the molecular tailoring approach yields values in the range from 15 to 20 kcal/mol suggesting that the intramolecular interaction in tropolones has nature of the resonance-assisted hydrogen bond.

Recent Advances on Fluorine Chemistry.

The purpose of this Special Issue is to showcase the latest findings in fluorine chemistry [...

Synthesis, structure, spectral and luminescence studies of novel guanidinium aryl(oxy)(sulfanyl)(sulfonyl)acetates.

A series of promising luminescent materials, nonlinear optical crystals, and physiologically active compounds - aryl(oxy)(sulfanyl)(sulfonyl)acetates of guanidine (A) of unknown type was synthesized. Various functional groups present in (A) were identified using FTIR spectroscopy. H and C NMR spectral studies further confirm the molecular structure (A).

Recent advances in liquid-phase NMR of the coal-derived products.

Present review focuses on the most recent advances in a liquid-phase nuclear magnetic resonance (NMR) of the coal-derived products-coal tar pitches, asphaltenes, and humic and fulvic acids, covering exclusively the results in the liquid-phase NMR studies leaving apart an overwhelming amount of publications dealing with the solid-state NMR investigations in this field (which are comprehensively reviewed elsewhere). Owing to the complexity of the coal-derived products, their H and C NMR spectra consist of a number of overlapping signals belonging to different hydrocarbon types. Comprehensive studies of coal tar pitches, asphaltenes, and humic and fulvic acids by means of NMR over the past several decades revealed characteristic functional groups of those fractions together with spectral regions in which they resonate.

Getaway from the Geometry Factor Error in the Molecular Property Calculations: Efficient pecG- ( = 1, 2) Basis Sets for the Geometry Optimization of Molecules Containing Light p Elements.

The basis of all molecular property quantum chemical calculations is the correct equilibrium geometry. In this paper, new efficient pecG- ( = 1, 2) basis sets for the geometry optimization of molecules containing hydrogen and p elements of 2-3 periods are proposed. These basis sets were optimized via the property-energy consistent (PEC) algorithm directed to the minimization of the molecular energy gradient relative to the bond lengths.

S NMR: Recent Advances and Applications.

The purpose of this review is to present advances and applications of S NMR, which is an underutilized NMR spectroscopy. Experimental NMR aspects in solution, chemical shift tendencies, and quadrupolar relaxation parameters will be briefly summarized. Emphasis will be given to advances and applications in the emerging fields of solid-state and DFT computations of S NMR parameters.

Computational NMR Study of Benzothienoquinoline Heterohelicenes.

Early NMR studies of several heterohelicenes containing an annular nitrogen atom and a thiophene ring in their structure suggested the possibility of the lengthening of the carbon-carbon bonds in the interior of the helical turn of the molecule based on the progressive upfield shift of C resonances toward the center of the helical turn. We now report a comprehensive analysis of the optimized geometry and a comparison of the calculated vs. observed H and C NMR chemical shifts of nineteen representative benzothienoquinoline heterohelicenes.

The Rivalry between Intramolecular Tetrel Bonds and Intermolecular Hydrogen Bonds in (O-Si) Chelates of N-Silylmethylamides and -ureas. A Theoretical Study.

The comparison of the results of theoretical calculations of (O-Si) chelates of N-silylmethylated amides and ureas with the axial chlorine or fluorine atom at silicon to the data of X-ray analysis of related compounds revealed the formation of covalent O-Si tetrel bonds (TB) or noncovalent O⋅⋅⋅Si tetrel bonds (NTB). The nature of the formed tetrel bond depends on the substituents at silicon and the polarity of the medium. The competition between the intramolecular TB and intermolecular hydrogen bonds (HB) with proton donors depends on the center of basicity involved in the formation of HB, which could be either oxygen or halogen.

The Use of Polysaccharide Matrices as a Basis for the Formation of Tellurium Nanoparticles with Different Morphologies.

The widening of possible areas of practical uses for zero-valent tellurium nanoparticles (TeNPs) from biomedicine to optoelectronic and thermoelectric applications determines the actuality of the development of simple and affordable methods for their preparation. Among the existing variety of approaches to the synthesis of TeNPs, special attention should be paid to chemical methods, and especially to "green" approaches, which are based on the use of precursors of tellurium in their powder bulk form and natural galactose-containing polysaccharides-arabinogalactan (Ar-Gal), galactomannan-(GM-dP) and κ-carrageenan (κ-CG) acting as ligands stabilizing the surface of the TeNPs. The use of basic-reduction system "NH HO-NaOH" for preliminary activation of bulk-Te and Ar-Gal, GM-dP and κ-CG allowed us to obtain in aqueous medium a number of stable nanocomposites consisting of TeNPs stabilized by the polysaccharides' macromolecules.

Catalyst- and solvent-free regiospecific SAr phosphinylation of pyridines with -phosphinates mediated by benzoylphenylacetylene.

Pyridines undergo a facile SAr phosphinylation with -phosphinates under catalyst- and solvent-free conditions (50-55 °C) in the presence of benzoylphenylacetylene to afford 4-phosphinylpyridines in up to 68% yield. In this reaction, benzoylphenylacetylene activates the pyridine ring by the formation of a 1,3(4)-dipolar complex, deprotonates -phosphinates to generate P-centered anions and finally acts as an oxidizer, being eliminated from an intermediate ion pair. Terminal electron-deficient acetylenes (methyl propiolate and benzoylacetylene) are inefficient as mediators in the above SAr process.