Structure of a bimolecular crystal of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane and methoxy-<Emphasis Type="Italic">NNO</Emphasis>-azoxymethane

The crystal structure of the bimolecular crystal of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and methoxy-NNO-azoxymethane (МАМ) (1:2) is studied. The CL-20 molecules adopt a ζ-conformation. The crystal structure is formed by layers of CL-20 and МАМ molecules, between which there are shortened NO^δ–?N^δ+O contacts of the neighboring CL-20 and МАМ molecules.     

Theoretical investigation of the molecular structure and spectroscopic properties of oxicams

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most frequently prescribed drugs and have multiple therapeutic uses. These drugs are predominantly used for the treatment of musculoskeletal diseases because of their analgesic, antipyretic, and antiplatelet activities. Oxicams constitute an interesting class of organic compounds and have been investigated in the search for new analgesic and anti-inflammatory drugs. In the present work, a theoretical investigation of the molecular structure and spectroscopic properties of a series of five oxicams in different solvents was performed using density functional theory (DFT) methods. The geometric optimizations of the oxicams were carried out using the M06 density functional and the CBSB7 basis set. The infrared data were all obtained at the same theoretical level. The UV-Vis absorption and NMR data of some oxicams were calculated using the DFT and CBSB3 basis sets. The analysis of structural parameters, particularly the bond length and spectroscopic data, indicated that interactions occurred between the hydrogen bond types for 4-meloxicam, isoxicam, and normeloxicam. Stereoelectronic interactions caused by the substitution of alkyl groups caused the bond lengths to elongate. Similarly, the substitution of heteroatoms, such as nitrogen, sulfur, or oxygen, increased the bond lengths and angular stresses.     

X-ray photoelectron and X-ray emission study of the electronic structure of hexanuclear Mn(II,III) pivalate complexes

The electronic structure of hexanuclear Mn(II,III) pivalate complexes with tetrahydrofuran and isonicotinamide are studied by X-ray photoelectron spectroscopy and X-ray emission spectroscopy. It is shown that when isonicotinamide substitutes for tetrahydrofuran the spin state of manganese ions is retained; the electron density increases on the manganese and oxygen atoms of the [Mn₆(O)₂Piv₁₀] core.     

<Emphasis Type="Italic">k</Emphasis>-Sum decomposition of strongly unimodular matrices

Networks are frequently studied algebraically through matrices. In this work, we show that networks may be studied in a more abstract level using results from the theory of matroids by establishing connections to networks by decomposition results of matroids. First, we present the implications of the decomposition of regular matroids to networks and related classes of matrices, and secondly we show that strongly unimodular matrices are closed under k-sums for \(k=1,2\) implying a decomposition into highly connected network-representing blocks, which are also shown to have a special structure.     

A polymer regulator of enzyme activity

The reaction of the amino group of α-chymotrypsin with poly(N,N-diethylacrylamides) bearing terminal carboxyl groups which have the degree of polymerization ranging from 30 to 180 and which possess an LCST of 34–29°C affords polymer derivatives of the enzyme. It is found that, upon an increase in the temperature of the aqueous solution of the resulting derivatives to 40°C, the derivative with a degree of polymerization of 180 precipitates at 34°C, while the derivatives with a degree of polymerization of 30–80 remain in solution. The activity of α-chymotrypsin as a part of the derivatives with a degree of polymerization of 30 does not change with increasing temperature, whereas the activity of the enzyme as a part of the derivatives with degrees of polymerization of 60 and 80 decays almost to zero near the LCST of the initial polymers. Such a change in the enzyme activity is reversible (the activity fully recovers with a decrease in temperature).     

Synthesis of pillar[5]arenes with a PH-containing fragment

The reactions of phosphorus(III) chloride and 2-chloro-1,3,2-dioxaphospholane with monohydroxypillar[5]arene afforded for the first time the corresponding PH-phosphonates. It was found that the newly formed P–O(Ar) bond is characterized by considerably reduced reactivity, which was rationalized by essential shielding of the phosphorus atom by the pillar[5]arene macrocycle. The pillar[5]arene scaffold stabilizes the highly reactive P^III–Cl fragment, so that the formation of macrocyclic dichlorophosphite can be detected under normal conditions.     

Bisisocyanide complexes of Zn(II) halides: Synthesis,structure, and application in the catalysis of isocyanides reaction with secondary amines

Isocyanide zinc complexes [ZnX₂(CNR)₂] (X = Cl, Br, I; R = Xyl, Cy, Bu^t) have been prepared via the interaction of the corresponding zinc halides ZnX₂ and isocyanide CNR in toluene at 100°C (yield 64–77%) and characterized by the data of elemental analysis, mass spectrometry, IR and NMR spectroscopy, and X-ray diffraction analysis. The zinc complexes [ZnBr₂(CNR)₂] (R = Xyl, Сy) have been used as catalysts for the synthesis of formamidines R¹N=CHNR₂ ² [R¹ = Xyl, Сy; R₂ ² = Et₂, (CH₂)₄, (CH₂CH₂)₂NMe, Me + CH₂Ph] from isocyanides CNR¹ and secondary amines HNR₂ ² in bulk (yield 92–98%).     

Cyclopropyl-containing sulfonyl amino acids: Exploring the enantioseparation through chiral ligand-exchange chromatography

Russian Journal of General Chemistry - In the scope of a broader study focused on glutamate receptors regulators, we have been engaged in synthesis, analysis and pharmacological characterization of...     

Preparation and optical properties of composite materials based on polybenzimidazole and silver nanoparticles

Rigid-chain heat resistant polymers (with poly-2,2'-p-oxydiphenylene-5,5′-bisbenzimidazole as example) were impregnated for the first time with a silver-containing precursor in formic acid and in supercritical carbon dioxide. A procedure allowing the precursor reduction to silver nanoparticles both throughout the volume by thermal annealing of the films in the temperature interval 100–150°С and in the targeted mode using lasers operating at 405 and 532 nm was developed. It opens prospects for developing a process for production of heatresistant optical gratings and light guides. The reduces nanoparticles and their agglomerates have the size in the interval 50–200 nm and give a plasmon band in the range 450–460 nm.     

Effect of the alkylidene spacer and the p-tert-butylthiacalix[4]arene macrocyclic platform on the reactivity of the hydroxyl groups in the acylation reaction

Russian Journal of General Chemistry - A series of cone and 1,3-alternate p-tert-butylthiacalix[4]arenes tetrasubstituted at the lower rim simultaneously by the amide, ester, and carboxyl functions...