Selective Reduction of ortho-Acylated β-Enaminones of Homoveratryamine and Their Cyclization to 1,2,3,4-Tetrahydroisoquinolines with β-Enaminone Moiety

Enaminones are very stable compounds and can be prepared from cheap and easily available starting materials. Therefore they are excellent starting materials in organic synthesis. The selective reduction of ortho-acylated β-enaminones under mild conditions, keeping the enaminone moiety intact, is reported. The appropriated conditions for cyclization of newly obtained hydroxienamides were found. Novel 1-substituted 1,2,3,4-tetrahydroisoquinolines with potential anticonvulsic activity were synthesized.     

Synthesis,Structure, Magnetic and Photoluminescent Properties of Dysprosium(III) Schiff Base Single‐Molecule Magnets: Investigation of the Relaxation of the Magnetization

We report here the synthesis, structure, magnetic and photoluminescent properties of three new bifunctional Schiff‐base complexes [Dy(L₁)₂(py)₂][B(Ph)₄]?py ( 1 ), [Dy(L₁)₂Cl(DME)] ? 0.5DME ( 2 ) and [Dy(L₂)₂Cl] ? 2.5(C₇H₈) ( 3 ) (HL₁=Phenol, 2,4‐bis(1,1‐dimethylethyl)‐6‐[[(2‐methoxy‐5‐methylphenyl)imino]methyl]; HL₂=Phenol, 2,4‐bis(1,1‐dimethylethyl)‐6‐[[(2‐methoxyphenyl)imino]methyl]). The coordination environment of the Dy³⁺ ion and the direction of the anisotropic axis may be controlled by the combination of the substituent groups of the Schiff bases, the nature of the counter‐ions (Cl^? vs. BPh₄^?) and the coordinative solvent molecules. A zero‐field slow relaxation of the magnetization is evidenced for all complexes but strong differences in the relaxation dynamics are observed depending on the Dy³⁺ site geometry. In this sense, complex 1 exhibits an anisotropy barrier of 472 cm^?1_, which may be favourably compared to other related examples due to the shortening of the Dy?O bond in the axial direction. Besides, the three complexes exhibit a ligand‐based luminescence making them as bifunctional magneto‐luminescent systems.     

Electrochemical and electrocatalytic stability of Prussian blue/Berlin green redox transformation in Prussian blue-polypyrrole composite films

Redox transformation of Prussian blue to Berlin green (PB/BG) in Prussian blue-polypyrrole (PB-PPy) composites synthesized via original one-step method has been studied. It was shown that the nature of anion and composition of background electrolyte play an important role for both the stability and the shape of electrochemical response of composite film during redox transfer of Prussian blue to Berlin green. Nitric acid, phosphoric acid, malic acid and citric acid 0.05 N (eq/L) solutions and the same acids partially neutralized with 0.01 N KOH were used as electrolyte to study the role of potassium ions presence in solution. The most stable electrochemical response of PB/BG redox transfer was obtained for the nitrate anions containing solutions in the presence of potassium ions. Nevertheless, the stability of the electrochemical transformation PB/BG in composite films in other media is enough to detect the sulphite ions content in wine samples via electrocatalytic reaction at the potentials of PB/BG redox transformation.

     

Small Gold(I) and Gold(I)–Silver(I) Clusters by C−Si Auration

Auration of o-trimethylsilyl arylphosphines leads to the formation of gold and gold–silver clusters with ortho-metalated phosphines displaying 3c–2e Au−C−M bonds (M=Au/Ag). Hexagold clusters [Au₆L₄](X)₂ are obtained by reaction of (L−TMS)AuCl with AgX, whereas reaction with AgX and Ag₂O leads to gold–silver clusters [Au₄Ag₂L₄](X)₂. Oxo-trigold(I) species [Au₃O]⁺ were identified as the intermediates in the formation of the silver-doped clusters. Other [Au₅], [Au₄Ag], and [Au₁₂Ag₄] clusters were also obtained. Clusters containing PAu−Au−AuP structural motif display good catalytic activity in the activation of alkynes under homogeneous conditions.     

Preparation of fine powders by clathrate-forming freeze-drying: a case study of ammonium nitrate

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Synthesis of Branched‐Chain Sugars with a DHAP‐Dependent Aldolase: Ketones are Electrophile Substrates of Rhamnulose‐1‐phosphate Aldolases

Dihydroxyacetone phosphate (DHAP)‐dependent rhamnulose aldolases display an unprecedented versatility for ketones as electrophile substrates. We selected and characterized a rhamnulose aldolase from Bacteroides thetaiotaomicron (RhuABthet) to provide a proof of concept. DHAP was added as a nucleophile to several α‐hydroxylated ketones used as electrophiles. This aldol addition was stereoselective and produced branched‐chain monosaccharide adducts with a tertiary alcohol moiety. Several aldols were readily obtained in good to excellent yields (from 76 to 95 %). These results contradict the general view that aldehydes are the only electrophile substrates for DHAP‐dependent aldolases and provide a new C?C bond‐forming enzyme for stereoselective synthesis of tertiary alcohols.     

3-Cyclopropyl-1,2-dimethyldiaziridine: synthesis and study of molecular structure by gas electron diffraction method

The molecular structure and conformational behavior of 3-cyclopropyl-1,2-dimethyldiaziridine have been for the first time experimentally studied by gas-phase electron diffraction and quantum chemical calculations. The two most stable conformers at 298 K possess anti and gauche mutual ring orientation (with prevalence of the anti conformer) whereas only one anti conformer is observed in solution. The determined structural parameters of gaseous 3-cyclopropyl-1,2-dimethyldiaziridine have been compared with those for 3,3-bidiaziridine structural analogues in the crystal phase. The simple and convenient procedure for the synthesis of 3-cyclopropyl-1,2-dimethyldiaziridine comprising cyclopropane and diaziridine rings in one molecule was developed. The standard enthalpy of formation of 3-cyclopropyl-1,2-dimethyldiaziridine in the gas phase was calculated using Gaussian-4 theory, yielding value of 281.9?±?5.0 kJ/mol.     

Synthesis,molecular structure,conformation and biological activity of Ad-substituted N-aryl-tetraoxaspiroalkanes

An efficient method has been developed for the synthesis of 7′-arylspiro{adamantane-[2,3′]-(1′,2′,4′,5′,7′-tetraoxazocanes)} by the ring transformation reaction of spiro{adamantane-[2,3’]-(1′,2′,4′,5′,7′-pentaoxacane)} with arylamines in the presence of Sm(NO₃)₃·6H₂O as the catalyst. NMR signals of the synthesized compounds were assigned considering the conformation dynamics of the tetraoxazocane ring with two rigid peroxide bonds. The structures of some of the compounds were studied by X-ray diffraction. The thermal stability of single crystal was determined by DSC method. Compounds 7′-(2-methylphenyl)spiro{adamantane-[2,3′]-(1′,2′,4′,5′,7′-tetraoxazocane)} and 7′-(4-fluorophenyl)spiro{adamantane-[2,3′]-(1′,2′,4′,5′,7′-tetraoxazocane)} exhibited cytotoxicity towards cancer cells.     

Using Infinite-server Resource Queue with Splitting of Requests for Modeling Two-channel Data Transmission

New Radio Access Technology 3GPP New Radio has become the fundamental wireless technology in the fifth-generation networks, which allows us to achieve high data rates due to the ability to work in the millimeter-wave band. But the key feature and the main problem of 5G New Radio networks is that people themselves, cars, buildings, etc. are signal blockers, while the base stations of the fourth generation networks have widescreen broadcasting and such small obstacles do not cause loss of connection. Service providers and mobile operators are already testing the proposed technology. In this connection, the scientific community has the task of analyzing the performance of these systems and increasing it in the future. Currently, there are known studies of “basic” mathematical models of such networks. By this term, we mean models built in the simplest possible assumptions. However, due to the justified necessity of introducing new technology into the daily lives of subscribers, service providers pose the scientific community with the task of analyzing the effectiveness of the most appropriate mathematical models. For example, a technology of splitting transmitted data into two streams using as 5G and both 4G transmission technologies is considered now by 3GPP Project Coordination Group. The paper is devoted to such a problem. We consider a mathematical model of the message transmitting with the implementation of the splitting function in the communication networks of New Radio technology in the form of a resource queueing system with a renewal arrival process and non-exponential service. For this problem, an approximation of a stationary two-dimensional probability distribution of the number of occupied resources in parallel service units is obtained. It is shown that this approximation coincides with the Gaussian distribution, and its area of applicability is shown.

     

Integrated microwave (centimeter-range) modulator on polycrystalline diamond layers

Measuring data for the parameters of a microstrip switching superhigh-frequency integrated circuit on a 100-μm-thick polycrystalline diamond film are reported. Measurements are taken in the frequency range 3–7 GHz. It is shown that the decay in developmental modulators is no greater than 1.5 dB in the on state and no less than 29 dB in the off state. Physicochemical analysis of the multilayer contact metallization technology as applied to synthetic diamond and a silicon p-i-n diode is carried out. The metallization is shown to be stable up to 400°C.